2024
Journal of— E n g l is h e d i t io n —2420

The Japan Association of Radiological Technologists

Journal of24

20— E n g l is h e d it io n —The Japan Association ofRadiological Technologists

CONTENTS
2

Overview of the Japan Association of Radiological Technologists/general principles

3

Regarding Publication of the English Edition

4

History of The Japan Association of Radiological Technologists ( JART)

6

original articles

Foreword
UEDA Katsuhiko, President, The Japan Association of Radiological Technologists

History
Arts and Sciences

Experiential learning of managerial responsibilities in radiological technologists: Implications forcareer development through a qualitative analysis of narratives
KOBAYASHI Hideyuki, SAKATA Yusuke, NAKAMURA Maki, KATO Ken, YONEMOTO Kuramoto

17

original articles

Human Resource Development for Radiological Technologists who can Respond to Nuclear AccidentExperience and Lessons Learned from the Fukushima Daiichi Nuclear Power Station Accident
OHBA Takashi, MABUNE Koichi, KANNO Shuichi, SATOH Kenichi, HASEGAWA Arifumi

29

original articles

A Prospective Study of Muscle Stiffness Using Ultrasound Shear Wave Elastography in the Biceps
Brachii of Patients with Parkinson’s Disease
KOBAYASHI Satoshi, KASAI Kenji, YABE Hitoshi, IMAO Masashi, HASHIMOTO Yuji, ICHIKAWA Tadashi

37

original articles

Fundamental study for application of 3D phasesensitive inversion recovery sequence to multiple sclerosis
ENOKI Takuya, JOMOTO Wataru, KIDA Katsuhiro, GOTO Sachiko, KOTOURA Noriko

45

original articles

Creation of work skill items in the field of radiotherapy
TSUDA Shintaro, SATO Kiyokazu, HIGUCHI Hiromitsu, ONO Yasushi, NISHIMURA Tomonori, AOYAMA Hideki, KATAYAMA Hiroki,
HONDA Hirofumi, KUMAMOTO Kengo, OKU Yoshifumi, GIBO Seiyo, NAKASHIMA Takeo, KIGUCHI Masao

55

original articles

Generation of standard time acquisition images from short time acquisition images of cerebral bloodflow SPECT using deep learning
YAMAMOTO Yasushi, SHIRAI Masato, TAKAMURA Masahiro, MATSUURA Kousuke, HINO Yuuki, FUKUDA Mitsuki, YADA Nobuhiro,
MIYAHARA Yoshinori, KURODA Hiroyuki, KAJI Yasushi

62

original articles

MiSDO:The Open-source Radiation Dose Management System
SUGIMOTO Kohei, MATSUMOTO Masaki, OITA Masataka, FUJIWARA Yuta, NAGASAKI Ryota, SHODA Takashi, KURODA Masahiro

69

original articles

Effects of radioprotective equipment on radiation exposure to the operator’s eye lens duringcomputed tomography fluoroscopy-guided procedure
HASEGAWA Takaaki, SHIMIZU Hidetoshi, CHATANI Shohei, MURATA Shinichi, HATTORI Hisashi, INABA Yoshitaka

75

original articles

Exploring the Significance of Subject Color Absorption and Indoor Lighting Interference in ThreeDimensional Surface Scanner ApplicationsSUZUKI Hidekazu, SAITO Masahide, UEDA Koji, KOIDE Tomoki, SANO Naoki, AIKAWA Yoshihito, ONISHI Hiroshi

82

note

Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients withprostate cancer
SAITO Hitoshi, MIURA Shuta, SASAKI Hiroshi, SUZUKI Keiko

93material

Effect of luminance non-uniformity caused by aged deterioration of a medical liquid-crystal display
for low-contrast detectability
TAKARABE Shinya, TAKAHASHI Keita, AKAMINE Hiroshi, AWAMOTO Shinichi, OGAWA Kazuhisa, KATO Toyoyuki

99material

Effective scan parameter setting of Quiet Suite combined readout segmented multi-shot EPI DWI(qRESOLVE) for decrease of image distortion and acoustic noise with a 3T MRI scanner
KOBAYASHI Yoshikazu, KANDA Toshimitsu, SAITO Yoko

109

Regulations and Requirements for Submissions to the Journal of the Japan Association of RadiologicalTechnologists
Note: The contents of this magazine are those that have been published in JART magazine.

Overview of the Japan Association ofRadiological Technologists
The Japan Association of Radiological Technologists, a public interest incorporated
association under the jurisdiction of the Ministry of Health, Labour and Welfare, wasestablished in 1947 with the purpose of contributing to the health of citizens throughraising the professional ethics of members, improving and furthering the study of medical
radiology and medical radiological technology, and enhancing public health.
In light of the startling progress being made in the fields of image diagnostics andradiation therapy where radiological technologists work, it is necessary to stay constantly
aware of the latest know-how and technology. JART collaborates with other certification
agencies to enhance the capacity of all radiological technologists in general throughproviding lifelong learning seminars, short courses, academic conferences and numerous
other learning opportunities. We believe that such activities constitute our obligation as
medical professionals to the general public.
As the only medical profession that has “radiological” in its name, we strive to limit
medical exposure, to raise the standing of our profession, and to realize a professionof specialist technologists that can be advertised. And we are committed to promoting
services with you all for the provision of safe and secure medical care.

general principles
We will render our services to those in need of health care.
We will act as individual members of a health care team.
We will perform our duties in our field of specialty.
We will continue to study for the benefit of mankind.
We will respect and practice the policy of informed consent.

2 ◆ Journal of JART English edition 2024

F o r e w o r dRegarding Publication of the
English Edition
UEDA Katsuhiko (President)

The journal of the JART English version issues every year. It has a favorable reception for wemembers of the world and general people. As well as this issue, 12 articles to be useful for radiological technologists are issued.
We will feature clinical, educational, and research-based achievements by radiological technologists in the monthly issues of the JART journal, and continually work to improve the magazine. I
truly hope that this English edition will benefit radiological technicians worldwide.
To give our radiological technologists from across the globe an insight into our business, I will
briefly explain the history of the JART. In March 1896, we succeeded in taking the first X-ray image
in Japan. In 1897, Shimadzu Corporation released an X-ray generator for educational use. In 1925,
there were approximately 1,500 X-ray technicians. In 1927, the first Shimadzu X-ray Technician
Training Institute was established, and evidence-based education was put in place. The JART wasfounded in 1947 to make “radiological technologist” a national qualification. Since its establishment,
we have worked towards broad acceptance of this national qualification, in collaboration with thegovernment, the Diet, the Japanese Medical Association, and occupational military authorities.
As a result in June 1951, we were finally able to see the promulgation of the Radiology X-ray
Technicians Act, Act No.226 of 1951. Since then, we have responded to the changing needs of thesociety, revising the original act to get the Radiology X-ray Technicians Act of 1968 passed, andpartially revising that to get the Radiology Technicians Act and Radiology X-ray Technicians Act of1983 passed, and finally getting the Radiology Technicians Act, which is in place currently, passed.
Back then, the scope of work was limited to general X-ray testing, television X-ray testing, angiography, X-ray computed tomography scanning, RI scanning, and radiation therapy. In 1993, the Radiology Technicians Act was further revised, and MRI scanning, ultrasonic testing, and non-mydriatic fundus camera examination were added to the list. In 2010, image interpretation assistance,
radiation examination explanation, and consultation work were added. In April 2015, intravenous
contrast agent injection using automated contrast injectors, needle removal and hemostasis, lower
digestive tract examination (anal catheter insertion and administration of contrast medium), anal
catheter insertion, and oxygen inhalation during radiation therapy were added as operations that
could be performed by radiological technologists.
In October 2021, the needle insertion for examinations of contrasting of the examination for CT,
MRI, Ultrasound and Radioisotope are added as the new operation that can be performed by radiological technologists.
The JART will continue to respond to the needs of the medical industry, and we hope to broaden
the operational scope of radiological technologists based on our foundation in scientific evidence.

Foreword ◆ 3

History

The Japan Association ofof Radiological Technologists ( JART)

1947
1951

Establishment of JART (July 13)
Promulgation of the Act on Medical Radiographers (June 11)

1983

1985

Authorization for Establishment of the Japan
Association of Radiographers (June 13)

1954

1956

1962

1968

First national examination for Medical Radiographers (May 30)
Event to commemorate the 10th anniversaryof founding, attended by Her Imperial Highness Princess Chichibunomiya
Event to commemorate the 15th anniversaryof founding and 10th anniversary of enactment of the Act on Medical Radiographers,
attended by Her Imperial Highness Princess
Chichibunomiya
Promulgation of the Act to Partially Revise
the Act on Medical Radiographers (establishment of two professions) (May 23)
First national examination for radiological
technologists

1969

1975

1979

1987

1989

1991

1993

1994

1995

1996

Event to commemorate the 80th anniversaryof the discovery of X-rays, attended by Her
Imperial Highness Princess Chichibunomiya

1998

Completion of the Education Center for
JART

1999

4 ◆ Journal of JART English edition 2024

Event to commemorate the 90th anniversaryof the discovery of X-rays, attended by Her
Imperial Highness Princess Chichibunomiya
Staging of the 1st Japan Conference of Radiological Technologists

Renaming as the JART
Staging of the 4th International Society of Radiographers & Radiological Technologist (ISRRT) World Congress at Tokyo Palace Hotel,
attended by Her Imperial Highness Princess
Chichibunomiya

Partial revision of the Act on Medical Radiographers and the Act on Radiological Technologists (unification of the professions)

General assembly resolution for establishment of the New Education Center and afour-year university
Completion of the New Education Center(Suzuka City)
Opening of Suzuka University of Medical
Science
The Act to Partially Revise the Act on Radiological Technologists, and Ministerial Ordinance to Partially Revise the Enforcement
Orders (April 28)
Appointment of the President of JART as the
11th President of ISRRT
Event to commemorate the 100th anniversaryof the discovery of X-ray, attended by Her
Imperial Highness Prince Akishinomiya
Start of the Medical Imaging and Radiologic
Systems Manager certification system
Staging of the 11th ISRRT World Congress at
Makuhari
Start of the Radiation Safety Manager certification system

2000

2001

2003
2004

2005

2006

Launch of the Radiological Technologists
Liability Insurance System with participationby all members“ Presentation of the Medical Exposure
Guidelines (Reduction Targets)” for patients

2013
Start of the Radiological Technologists Liability Insurance System
Enactment of X-Ray Week

2014

Relocation of offices to the World Trade
Center Building in Tokyo

Launch of the radiation exposure advisor
certification system

2015

Revision of the Medical Exposure Guidelines

2008

2009

2017
Establishment of the committee on Autopsy
imaging (Ai)2018
Revision to the national examination for radiological technologists
Launch of the Team Medicine Promotion
Conference, with the President of JART as its
representative
Appointment of the President of JART as
chairperson of the Central Social Insurance
Medical Council specialist committee

2010

2011

Health Policy Bureau Directorʼs notification
concerning promotion of team medicine
Support activities following the Great East
Japan Earthquake
Staging of an extraordinary general meeting
concerning transition to a public interest incorporated association

2012

2019

2020

2021

Renaming as public interest incorporated association JART

Event to commemorate the 120th anniversaryof the discovery of X-rays
Event to mark the 70th anniversary of founding (June 2)
Notice from the Regional Medical Care Planning Division Director, Health Policy Bureau,
Ministry of Health, Labour and Welfare, andDirector of the Economic Affairs Division
regarding Operational Considerations for
Securing a System for Safety Management
pertaining to Medical Equipment
Notice from the Health Policy Bureau ona Safety Management System for Medicinal
Use of Radiation
Partial revision of the Ordinance on Prevention of Ionizing Radiation Hazards
Relocation of offices to the Mita Kokusai Building in Tokyo
Revision of the Radiological Technologists
Act expanded the scope of practice.

Registration of transition to a public interest
incorporated association (April 1)
Event to mark the 65th anniversary of founding and transition to a public interest incorporated association (June 2)

Consignment of work to measure personal
exposure of residents
Revision of the Act on Radiological Technologists, Government Ordinance to Partially
Revise the Enforcement Orders, and Revisionof the Enforcement Regulations (June 25)

Start of the Medical Imaging Information Administrator certification system
Staging of a joint academic conference between Japan, South Korea, and Taiwan

Signing of the Comprehensive Mutual Cooperation Agreement on Prevention of Radiation Exposure (September 21)

Holding the 23th AACRT with 37th JCRT in
Tokyo

2022

Event to mark the 75th anniversary of founding (July 16)

History of JART ◆ 5

Arts and Sciences
original articles

Received May 24, 2021; accepted May 30, 2022

Experiential learning of managerial responsibilities in radiological technologists: Implications forcareer development through a qualitative analysis
of narratives
KOBAYASHI Hideyuki1）, SAKATA Yusuke2）, NAKAMURA Maki3）, KATO Ken4）,
YONEMOTO Kuramoto5）
1）M.S./Department of Radiation, Radiological Technologist, Seirei Hamamatsu General Hospital2）Fellow, M.S./Fujita Health University Graduate School3）Clinical Laboratory Technician, M.S./Clinical Laboratory, Chunichi Hospital
4）Ph.D./Faculty of Health and Medical Sciences, Aichi Shukutoku University5）Ph.D./Department of Medical Management and Information Science, Fujita Health University Graduate School

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 843: 16-23, 2023.
Key words: Radiological technologist, Management, Career development, Modiﬁed grounded theory approach,

Relationship with people【Abstract】

This study aimed to clarify the career development process of radiological technologist managers in the radiology
department. Nine managers of the radiology department were interviewed, and data were analyzed using the modiﬁed
grounded theory approach. Consequently, career development comprised 9 categories, 13 subcategories, and 83
concepts. Managers gained the information and experience necessary for them through interaction with doctors,
bosses, and senior engineers at their facilities, and engineers at other facilities through activities, such as radiological
technologistsʼ associations. Career and management learning opportunities are relatively few. To improve the careersof radiological technologists in managerial positions, systematically developing learning opportunities that transcendorganizational boundaries is essential.

1. Introduction
The advancement of radiographic imaging
equipment promotes the specialization of
medical radiology technicians; however, simultaneously, the role of managers who systematically integrate differentiated tasks and information and promote team medical care is becoming increasingly signiﬁcant. However, todate, the career development of managerial
positions in clinical radiological technologists
has relied on the so-called apprenticeship relationship between superiors and subordinates
as well as seniors and juniors, and training has
not necessarily been conducted in a scientiﬁcand systematic manner. Conversely, in otherindustries, instead of forcing students to unilaterally learn a uniform managerial style, “ iperi-

6 ◆ Journal of JART English edition 2024

ential learning career development ” was promoted, wherein students autonomously learn
their path to growth from diverse experiences
through work and repeat reﬂections.1) However, whether the career development of clinicalradiological technologist managers is progressing remains inconclusive.
Conversely, much research on career development in the medical profession has accumulated in the area of nurses. For example, innursing, career development education andtraining based on the clinical ladder model iscommonly performed.2) Moreover, as part oflifelong learning, several studies on human resource development through the fusion of academia and pragmatism have been conducted,
including a study on support systems collaborating with university teachers and hospitaloriginal articles
Experiential learning of managerial responsibilities in radiological technologists: Implications for career development through a qualitative analysis of narratives

nurses. 3) Although only a few studies on careerdevelopment in radiology departments areavailable, there is one called “ Basic Attitudes ofManagerial Skills ” by Higashimura et al.4) However, this study is concerned with the technicalresponsibilities that medical radiology technicians have acquired from their experience inradiography work, the career development
process, which includes the content of these
responsibilities, has not yet been clariﬁed as towhat kind of experiences excellent medical radiology department managers have learned,
acquired, and grown the ability to fulﬁll their
responsibilities, there is a lack of information
when considering methodologies for managerial training.
Therefore, this study aimed to obtain usefulknowledge for the career development methodology of excellent radiology department
managers who can demonstrate leadership inteam medical care and clarify through qualitative research based on interview data the process by which managers in clinical radiology
departments learn and acquire the ability to
fulﬁll their responsibilities and develop independently. Furthermore, this study aimed topresent a model of the characteristic career development process of radiological technologist
managers.

2. Method
1) Definition of terms

The word n of termhas various deﬁnitions;however, in this study, based on previous research, Douglas Hall deﬁned it as “a series ofwork-related experiences and activities over a
lifetime, as well as the attitudes and actions an
individual takes.”2) Survey target

The target participant is a member of the “Japan Association of Radiological Technologists”
and “Japanese Society of Radiological technology,” which are public interest incorporated

associations; has worked at a hospital with>200 beds; and has experienced working as aradiological technologist at the facility. The
participants included nine radiological technologists appointed by the facility director as
managers of medical radiology services, or
persons with equivalent responsibilities, who
agreed to participate in the study.
3) Data collection

The survey was conducted over a 2-month
period from June to July 2018. The interviews
were conducted in a way that asked participants to speak freely according to the following four semistructured questions: “what are
the experiences and events that have helpedme grow as a manager, ” “ what aspects of thatexperience/event led to your growth, ha “ what
abilities (e.g., knowledge and skills) did you
gain from it, dand “ddid opportunities that you
believe would be best to experience to become a manager in the medical radiology
department,” owhich are listed in the request
form in advance. The interviewee speciﬁed thetime and place of the interview, which was
conducted in a quiet place where only the researcher and the interviewee were allowed toenter and where the content of the conversation could not be overheard by others. The interview time was approximately 60 min, andconsent for recording and subsequent processing was obtained before the interview began.
The interview was conducted, and audio data
were recorded using an IC recorder.
4) Data analysis

For the analysis, all audio data obtained wastranscribed and the text data was analyzed
based on Kinoshitaʼs modiﬁed grounded theory approach (hereinafter referred to as M-GTA).
M-GTA is a qualitative research method developed by Kinoshita to make it easier to put into
practice the grounded theory approach devised in the 1960s by sociologists Glaser andStrauss. The grounded theory is related to diArts and Sciences ◆ 7

Sentence data coding
Transcription
from recorded data

Create analysis worksheet
for M-GTA

Configuration model
creation

Concept generation

Theoreticalsaturation
Sub-category generation
Category generation

Fig. 1 Flow until configuration model creation

rect interaction between humans, that is, social
interaction, and is effective in explaining andpredicting human behavior, and researchers
have clearly conﬁrmed its signiﬁcance. 5)
The procedure is shown in Figure 1. The
speciﬁc procedure was to transcribe the recorded voice data and repeatedly read theintervieweeʼn narrative, thereby encoding thetext data as a meaningful group. The worksheet comprised concept names, deﬁnitions,variations, and theoretical notes. To provide an
example of an analysis worksheet, ﬁrst, carefully observe the coded data, consider similarities and polarities, and create data variations,such as “ Subsequently, I showed him the direction of leading him in that direction worksheet
interaction, and is effective in expl wouldnʼt be
a bad idea to be the chief engineer (1-19)”
showed him the direc. When creating variation, ensure including an interpretation of themeaning of the data and a theoretical memo,such as “The chief engineer tried it and believed it was not bad (1-19)” based on this, wedeﬁned it as “It is better to have a higher position to express your thoughts.” Subsequently,
this process is repeated until all the coded data
have been classiﬁed into an analysis worksheet, and a concept such as bThe exercise ofcommunication power due to a high position”
eis generated. The concept generation ends after conﬁrming theoretical saturation where no
new concepts can be extracted. Furthermore,from multiple concepts generated from theanalysis worksheet, subcategories are createdusing related concepts as superordinate concepts. Furthermore, a category is generated asa superordinate concept of that subcategory. 5)

3. Results
1) Target person attributes

The participant characteristics are presented
in Table 1. All nine participants from eight facilities were male. The average age of the participants was 56.0 years, with the youngest andoldest being 51 and 63 years, respectively. The
average number of years of experience of clinical radiology technicians was 34.6 years of ranging from a minimum of 29 years to a maximumof 42 years. The number of years of managerial
experience ranged from a minimum of <1
nyear to a maximum of 10 years, with an average of 5.0 years, including two with <1 nyear.

Table 1 Outline of the target person
Target PersonageTechnicianHistory

Management CareerA

60s

Over 40 years

5 years or moreB

50s

30 〜 39 years

Less than 5 years

C

50s

30 〜 39 years

Less than 5 years

D

50s

30 〜 39 years

5 years or moreE

50s

30 〜 39 years

5 years or moreF

50s

30 〜 39 years

5 years or more

Facility Trancefer Histor

Yes

G

50s

30 〜 39 years

5 years or more

Yes

H

50s

30 〜 39 years

Less than 5 years

Yes

I

50s

29 Years or less

5 years or more

Yes

Average

56.0

34.6 years

5.0 years

8 ◆ Journal of JART English edition 2024

original articles
Experiential learning of managerial responsibilities in radiological technologists: Implications for career development through a qualitative analysis of narratives

In addition, four participants had a work experience outside their facility. The duration of theinterview survey ranged from a minimum of 55
min to a maximum of 85 min per participant.
2) Analysis results

The analysis results of the career development process of radiological technologist managers are shown in Tables 2 and 3. The components of career development for managers
in clinical radiology departments, extracted bycreating an analysis worksheet, were 83 concepts, 13 subcategories, and 9 categories. Furthermore, below, categories are indicated in, subcategories in, concepts in, andthe narratives of the interviewees in ｢ ｣.
(1) Relationship with people

Relationship with people comprised 16 concepts. Managers in radiology departments realized the need for teamwork from the relationships with other professions inside and outside
the hospital, rather than receiving advice fromnearby superiors or training where they could
obtain information themselves; it was believedthat managers acquired the communication
skills necessary for a managerial position. In
particular, in the process of Relationship with

Table 2 Analysis results of the career development process of radiological technologist managers ①
Category

Sub-category
・Relationshipwith doctors

・In-hospital

involvement① Relationshipwith people

・Out-of-hospital

involvement

・Teamwork

・Skills forhuman resource
development② Concept ofhumanresource
development

・Utilization ofhuman resources
・A place to learn

・Joy of action③ Satisfaction

from the factthat played arole・Superiority
complex fromjoy

Theory・Awareness of behavior based on opinions from doctors
・Knowledge and inspiration from working with a doctor
・Conﬁdence with doctors deepens by producing results・Thanks to the environment blessed with the surrounding staff
・Conﬂict with lack of understanding of managers from others
・Difﬁculty in selecting staff・Difﬁculty in treating staff equally・Efforts to build relationships with other departments
・Difﬁculty in taking on a position in the Engineersʼ Association
・Activeness to get out of the workplace
・Awareness through interaction with out-of-hospital technicians
・The importance of working with colleagues
・The importance of trusting staff
・Need for bargaining skills
・The importance of team・The importance of communication
・Have a theory of human resource development
・Feedback and disclosure of my experience
・Acquire knowledge of labor regulations
・Knowledge and leadership in medical safety
・Management resources that can be used by oneself in human resource development
・Attitude to think about training from a broad perspective
・Take advantage of interviews
・Bachelor's degree acquisition and its utilization
・Improvements to inadequate goal management
・Management learning that supplements management experience
・Workplace culture with little need for leader development
・Utilization of learning in training
・Awareness of becoming a manager
・Human resource development system not yet constructed
・Lack of opportunities to acquire management skills
・Possession for the signiﬁcance of learning
・The theory about educational methods
・Student experience
・Guidance from the boss・Experience of all modality
・The joy of returning good results to patients
・The joy of management
・The joy of working as a manager
・The joy of feeling results as an administrator
・Superiority complex to be entrusted with work
・Superiority complex of being recognized by a doctor
・Superiority complex of being recognized by your boss・Superiority complex recognized by staff at other facilities
・Satisfaction relied on in the workplace
・Self-satisfaction that fulﬁlled my role

Arts and Sciences ◆ 9

doctors, the professional identity of radiological technologists was conﬁrmed, 6) and the following experience was described in which thatsense of self-efﬁcacy led to motivation forgrowth.
｢It is not our strength in being able to return
images. I think it could be an image, or it could
be a number (with increased motivation). (Fordoctors) When you give something that exceeds
expectations, it makes them (doctors) happy｣.
(1–12)
Moreover, they stated that starting out-ofhospital involvement at an early stage in oneʼs
career, before becoming a manager, and forming several connections through engineering
associations and other institutions from ayoung age are signiﬁcant.
Regarding Teamwork , he mentioned regarding the signiﬁcance of being aware of thelimits of individual ability as well as the needfor organizational strength, and of delegatingtasks by forming relationships of trust with thesurrounding staff.
｢(Collaborative work by teams) is voluntaryor based on the needs of the hospital. I must doit. Well, I am thinking of purchasing a new radiation device (in the future); therefore, I haveto do this. But I don’ t have to handle everything
myself, Ummu. Didn’ t I say that my subordinates are in charge of everything? Leave
everything to those people. Everything, or tosome extent, document creation. I try to leavethings like that to them. Well, I think I’ve got alittle better at using people that way｣. (8–40)(2) Concept of human resource development

The concept of human resource development comprised 20 concepts. Here, along with

Table 3 Analysis results of the career development process of radiological technologist managers ②
Category④ The ideal

way of thepersonnel
systemSub-category
・What theevaluation systemshould be・Anxiety about

the system

・What your
⑤ Necessary

actions fromthe standpoint

organization
needs

・What you need

⑥ Actions you
want to take asanadministrator⑦ Way ofthinking about
management⑧ Information

handling⑨ The underlying
idea as a medical
professional⑩ other

Theory・Questions about promotion by seniority
・Worries about underdeveloped personnel evaluation system
・Current situation where management results are ambiguous・Trouble that the expected role of the administrator is not clear
・The gap between the ideal and reality of personnel changes
・Current status of lack of strategic personnel system
・A sense of crisis toward oneself due to distrust of the hospital organization
・Anxiety about the introduction of a new management system
・Organizational culture that considers human resource development important・Permeation and thorough management philosophy
・Visualization of management for subordinates
・Transparency of grounds in stafﬁng
・Work style reform of female engineers
・Show the results of management as a manager
・Self-control of emotional ups and downs
・Tolerant posture・Acquiring business initiatives
・Formulation and clariﬁcation of vision
・Coordinator of organizational management
・Awareness and responsible behavior as an administrator
・A perspective that sees a change of management as an opportunity
・Appropriate interpretation of past bossʼs behavior
・Objective understanding of hospital management
・Worries about lack of understanding of the site of management
・Difﬁculty in balancing medical care and management
・Thorough information management and proper handling・Information gathering activities required as an administrator
・Demonstrate the role of information dissemination on behalf of the department
・Ability to appeal the department
・Maintaining a strong sense of mission as an engineer
・Conﬁdence through accumulated experience・Achievements of skilled skills
・Words and deeds that keep your beliefs
・Demonstrate the spirit of challenge
・Make use of experience different from other staff
・Patient-ﬁrst thinking
・Anxiety due to lack of knowledge and experience in management

10 ◆ Journal of JART English edition 2024

original articles
Experiential learning of managerial responsibilities in radiological technologists: Implications for career development through a qualitative analysis of narratives

their experience, most respondents believedthat having an attitude of going through the
management cycle of P (planning), D (execution), C (conﬁrmation), and A (review) when
dealing with issues at their facility was important. Speciﬁcally, in Skills for human resource
development technical skills including Acquire knowledge of labor regulations andKnowledge and leadership in medical safety
are introduced. Furthermore, nontechnicalskills including Feedback and disclosure of
my experience , Take advantage of interviews , and Improvements to inadequate goal
management were cited. Moreover, they considered Utilization of learning in training aneffective learning opportunity. In addition, a
respondent discussed Awareness of becominga manager as a way of preparing himself. The
respondent reported that being aware of therole expected of the organization helps maintain motivation. Furthermore, in A place tolearn , he stated the following about Human
resource development system being not yet
constructed .
｢I do not know myself. It is natural for medical radiology technicians to improve their skillsby themselves, and they do not have to be told
what to do by others. Study by yourself, (Whether you do it or not) is up to you. I’ve spent mytime thinking that people who want to study,
study on their own, and present at an academic conference should do so｣. (2–48)
The respondent discussed the organizational
culture of radiology technicians. Conversely,
based on my experience, I believe that the future should be ｢(Omitted) I was able to takecare of my subordinates, because there was an
education system in place, If such things can beevaluated, (In other words) Maybe if we had asystem where we could say, oh, this guy will getbetter if he does it this way, so let us do that for
him, You will be able to change into the person
you want to be more quickly｣. (8–23) and theneed for systematic career development.

(3) Satisfaction from the fact that played a role

Satisfaction from the fact that played a rolecomprised 10 concepts. As an experience thatprovides you the joy of fulﬁlling your role, aparticipant discussed his sense of role accomplishment with respect to Joy of action in
two situations as follows: the joy of achieving
results for patients and the joy of achieving results as a manager. Moreover, the participant
stated that this Superiority complex from joy
has satisﬁed the need for approval from others.
(4) The ideal way of the personnel system

The ideal way of the personnel systemcomprised eight concepts. Two subcategories
were raised that spoke openly regarding Whatthe evaluation system should be . A respondent discussed his sense of crisis over an outdated personnel system based on seniority thatpoorly reﬂects abilities and results; conversely,
Anxiety about the system , although I feelthat the system must be changed, I ﬁnd it difﬁcult to take active steps to address it.
(5) Necessary actions from the standpoint

Necessary actions from the standpoint
comprised eight concepts. Here, items considered to be essential regarding the functions
within the organization that administrators are
responsible for are listed as What your organization needs . Moreover, it was classiﬁed into
the following two subcategories: What you
need , wherein managers discuss their personal theories on the basis of their experiences
about the actions they should take to performtheir functions within the organization.
(6) Actions you want to take as an administrator

Actions you want to take as an administrator comprised six concepts. Here, the respondents discussed the knowledge and skills thatthey are currently using to perform their duties
as managers, and what they are especiallyaware of and what they pay close attention todaily.
Arts and Sciences ◆ 11

(7) Way of thinking about management(10) Others

Way of thinking about management comprised three concepts. Several managers discussed how hospitals should be run while
managing the front lines. One manager statedthat rI realized that I could gain a different understanding if I looked at management issues
not only from the perspective of those in theﬁeld but also from the perspective of higherlevel hospital managers.” The following statement explains the signiﬁcance of an objective
understanding of hospital management togrow as a manager.
｢Also, the hospital’s management goals andnumbers, after all, things like that can be seen
at a glance (you can see the whole thing), well,anyone (even if you’re not a manager) can see
it if they want to. Well, that’e what we need to
do directly by getting together with only managers (looking at it in detail from a management perspective). Well, there was a meeting
today as well. Well, because you hear things
directly from management (you get the perspective of management). It was very exciting,and I learned a lot. Well, I think this is where I
could grow.｣ (8–35)

The concept of Anxiety due to lack ofknowledge and experience in management
refers to the reality that managers of clinicalradiological technologists have not had the opportunity to learn management, and even if
they want to learn, they are highly busy with
their daily work that they do not have the time.
In reality, several managers do not learn about
legitimate management when performing management. One manager mentioned that “As amanager who lacks knowledge and experience, I feel guilty, and I feel that I am not really suitable as a manager.” Furthermore, themanager discussed his feelings of anxiety owing to his lack of management knowledge
and experience , as he wonders if he can evaluate his subordinates and take responsibility
for them.
3) Configuration model for managerial careerdevelopment

On the basis of the abovementioned results,
we modeled the career development storyline
for managers in the medical radiology department, as shown in Figure 2. Rather than formal(8) Information handling

Information handling comprised four concepts. Here, as managers, they were required
to not only play the role of communicating information collection and handling subordinates and other departments but also the ability to quickly, appropriately, and simultaneously disseminate information.
(9) The underlying idea as a medical professional

The underlying idea as a medical professional comprised seven concepts. Here, theparticipants discussed professionalism thatperseveres through a uniﬁed sense of ethics,
which should be maintained as a medical professional regardless of oneʼr position within theorganization and whether one is a manager ornot.

12 ◆ Journal of JART English edition 2024

【Satisfaction from the fact that played a role】『Joy of action』『Superiority complex from joy』

【Necessary actions from thestandpoint】『What your organization needs』『What you need』【Actions you want to take as anadministrator】〔Anxiety due to lack of knowledge and experience in management 〕【Concept of humanresource
development】『Utilization of humanresources development 』『A place to learn』『Skills for human resource
development』【Relationshipwith people】『Relationship with doctors』『In-hospital involvement』『Out-of-hospital
involvement 』『Teamwork』【Way of thinking
about management】【Information
handling】【The ideal way ofthe personnel
system】『What the evaluation
system should be』『Anxiety about thesystem』【The underlying idea as a medical professional】

Fig. 2 Career development configuration model
for radiological technologist managers

original articles
Experiential learning of managerial responsibilities in radiological technologists: Implications for career development through a qualitative analysis of narratives

learning opportunities provided by the organization, the career development of a medical
radiological technologist manager involves
self-growth through repeated self-reﬂection
and self-directed practice of learning from interpersonal relationships with individuals inside and outside the workplace, including informal ones. In addition to the technical skills
required for managerial positions, students
have the opportunity to acquire the humanskills required for leaders and conceptual skills
for decision-making. Their personal interaction
with other individuals was driven by their underlying idea as medical professionals, that is,their desire to contribute to the medical ﬁeld,
which formed the basis for their career development throughout their lives. Moreover, thesigniﬁcance of Way of thinking about management , Information handling , and The
ideal way of the personnel system was shownas skills that are particularly necessary for managerial positions to acquire from Relationshipwith people . Furthermore, in departmental
operations, participation and management ofcorporate or facility management is necessary
for managerial works; therefore, information
handling for smooth functional collaboration
between organizations is required. The personnel systems that support them differ depending on the corporation or facility. Therefore, collecting information about other facilities and the neighborhood and recognizing
personnel systems that increase motivation are
essential to maintain competitiveness in acquiring human resources. Particularly in a business environment where work style reforms
are beginning to take hold, individuals may
feel Anxiety about the system at their facility;
however, such anxieties can be controlled byRelationship with people . Conversely, theConcept of human resource development isa signiﬁcant factor within the department, andthe development of staff within the department
will lead to the achievement of the next goals
and the growth of the organization. However,internally, managers felt anxious owing to alack of management knowledge and experience . In this regard, Relationship with people provided emotional support, and they
perceived this in a positive manner as Necessary actions from the standpoint and Actions
you want to take as an administrator . In thismanner, radiological technologists in managerial positions develop their careers by using
Satisfaction from the fact that played a role as
motivation for their next actions. Soon after
joining the company, we conducted a cycle ofobservation, experimentation, and reﬂection
on managers inside and outside the organization.

４．Consideration
Rather than through formal training, managers in medical radiology departments tended todevelop their careers as individuals throughRelationship with people inside and outside
the organization. In particular, the process ofinteracting with radiologists at oneʼI institution,with whom one has a close professional relationship, strongly inﬂuences the acquisition ofhuman skills, such as interpersonal communication, in addition to technical skills, such as
specialized knowledge. The inﬂuence of thisrelationship with radiologists on the career development of radiology technicians is believed
to be a characteristic of their work, unlike thenursing profession, which interacts with physicians from various medical departments. Thissuggests that facilities without radiologists canonly interact with part-time physicians fromother facilities, and the degree of career development can be inﬂuenced by that radiologist
despite the presence of a full-time physician.
Therefore, to overcome the educational environment that tends to lead to closed on-the-job
training, having speciﬁc doctors, hospital staff,
seniors, and superiors at work along with actively engaging with out-of-hospital activities
such as with radiological technologistsʼ associArts and Sciences ◆ 13

ations and connecting with managers and organizational cultures of other facilities are necessary; subsequently, they become aware ofdiverse perspectives and values. Creating situations for self-reﬂection is particularly signiﬁcant for career development for managers. In
other words, an effective way to systematicallydevelop the career of clinical radiology technicians is to support opportunities to interact
with others outside the workplace where they
can discover individuals who can serve as rolemodels for the leadership they aspire to andmake them aware of Activeness to get out of
the workplace .7) Furthermore, Relationshipwith people consists of the concepts of Needfor bargaining skills , The importance ofteam , and The importance of communication . This is because it is an ability that can beacquired through accumulated experiencerather than through classroom training or
knowledge from books. Combining this with
“experience in other games” such as beingtransferred to other facilities or off-the-job
training is necessary.
To systematically conduct career development for the next generation on the basis ofRelationship with people within the hospitalover a medium-to-long term, a change in themindset of the management who supports thisis required regarding the Concept of humanresource development ; however, in responseto the current immaturity such as Human resource development system not yet constructed and Lack of opportunities to acquire management skills , Necessary actions from thestandpoint Actions you want to take as anadministrator it seems that there is a growing
need within current managers to take action
themselves, rather than passing the responsibility on to management. 8) In addition, the reﬂective experiential learning cycle 9) based onhuman interactions for radiological technologists, Relationship with people was observed
to be a signiﬁcant educational method to acquire the ability to create improvement plans

14 ◆ Journal of JART English edition 2024

for career development in managerial positionsin the medical radiology department, as in other industries. Additionally, repeating active
new Relationship with people creates continuity in motivation for career development
and stimulates the identity of medical radiological technologists as a sense of Satisfaction
from the fact that played a role and that it isinteresting to be a manager. 10) Simultaneously,
the identity that stimulates this motivation includes a strong sense of mission, which is the
The underlying idea as a medical professional . Of note, this is an indispensable foundation for the career development of medical radiology technicians, who are involved in medical care among other professions. In otherwords, if you actually become a manager withmanagement responsibilities, you may face
conﬂicts in balancing medical services withmedical fees and costs. In making decisions insuch cases, radiological technologists must cultivate career anchors, 11) which are beliefs thatthey have as individuals, on the basis of theirreﬂective experience of connecting with patientsʼ diverse values. Moreover, a sense of insecurity arises from the fact that these abilities
as managers are opinions based on limited experience. To eliminate this anxiety, organizations require systematic education based on
management theory.
Although this study shows that informal Relationships with people inside and outside thehospital are important, the issue of how managers can promote Relationships with people
has once again come to light, considering thatthe radiology department is characterized by aclosed organizational culture with small staff
and self-contained work. In contrast, careerdevelopment through one-on-one communication has been recently introduced in somecompanies. 12) The theoretical notes under
Need for bargaining skills include ｢I recognize that the ability to see and observe subordinates is important｣, ｢First, listen to the otherpartyʼs wishes｣, and ｢top-down action is not anoriginal articles
Experiential learning of managerial responsibilities in radiological technologists: Implications for career development through a qualitative analysis of narratives

option｣. One-on-one communication is amethod of face-to-face interviews between superiors and subordinates, 13) and the role of thesuperior is to provide support for solving problems experienced by subordinates and help
subordinates achieve their goals. 14) We believethat this will be useful for career developmentin the radiology department, where job characteristics such as that in the nursing department
make it difﬁcult to gain experience in deep interaction with other people within the organization, such as other occupations, patients,and families. Build relationships of trust witheveryone we interact with, both inside andoutside the organization. Furthermore, managers must possess skills that allow them to create Relationships with people so that theycan engage in a cycle of experiential learning.
In nursing, a management ladder for managers
has been added to the lifelong education system based on the clinical ladder method, andits effectiveness has been conﬁrmed. 3) However, by adding the acquisition of one-on-one
communication skills for managerial training to
the Japan Society of Radiological Technologistsʼ Clinical Ladder, 15) promoting experiencein Relationships with people and enabling
more effective career development are possible.

５．Conclusion
From interacting with radiology specialists,
superiors, and senior technicians at your facility, and technicians at other facilities throughtechnical association activities in the career development of clinical radiological technologists
in managerial positions, it was suggested thatcareer development should be based on thecore concept of Relationships with people toobtain the information and experience necessary for managerial positions. However, in several cases, this Relationships with people isnot performed through formal career development in an organization, particularly in radiology departments, where organizations tend tobe small, and they tend to rely on motivation
based on individual career anchors and identity. Therefore, promoting career developmentfrom a new perspective on the basis of job
characteristics such as incorporating the acquisition of one-on-one communication skills into
the organizational career development of managers in medical radiology departments is desirable.

Research limitations and future challenges
The participants of this study were managers
who worked in a hospital with more than 200
beds and were employees who achieved signiﬁcant results in a limited environment. Therefore, the information obtained from only nine
managers may be biased or insufﬁcient. In the
future, conducting quantitative research with awider range of participant to verify whether career development can be achieved using the
conﬁguration model constructed in this study
will be necessary. Furthermore, to examine
novel continuous career development for managers, the development of not only the managers but also their teams and organizations aswell as the growth and satisfaction of their subordinates must be considered. The subordinatesʼ growth and satisfaction level must also
be considered.

Arts and Sciences ◆ 15

References
1） Atsushi Nakahara (editor): Introduction to corporate
human resource development Learn the basic
theories of psychology and pedagogy for developing
people. Diamond Inc., 2006.
2） Reiko Hara: How to create and utilize a nursing careerdevelopment ladder linked to goal management.
Japanese Nursing Association Press, 2015.
3） Kyoko Kojima, Kaneko Noji (eds.): Continuing nursing
education to develop nurses as professionals: Clinicalladder and management ladder in practice. Ishiyaku
Publishing, 2005.
4） Kyoji Higashimura (ed.): Professional guide forradiological technologists. Bunkodo, 2008.
5） Yasuhito Kinoshita: Live lecture M-GTA practicalqualitative research methods: All about the revised
grounded theory approach. Kobundo, 2011.
6） Sachiko Ochiai, et al.: Lifelong development processof professional identity of radiological technologists.
Bulletin of Ibaraki Prefectural Medical University,
ASVPI Volume 11; 23-32, 2006.
7） Takako Murai, Hiroko Harada: Structure of careerdevelopment of nursing managers with certified
nursing manager qualifications. 7, 17-25; 151-159,
2017.
8） P Hershey et al.: Seiji Yamamoto, Azusa Yamamototranslation: From introduction to application:

16 ◆ Journal of JART English edition 2024

Development of behavioral science. Productivity
Publishing, 2000.
9） Mutsumi Matsuo: Learning from experience: Theprocess of professional growth. Dobunkan Publishing,
2006.
10）Mutsumi Matsuo: An introduction to “ experiential
learning” that helps people thrive in the workplace
Diamond Inc., 2011.
11）Career anchor by Edgar H. Schein, translated by
Toshihiro Kanai Discover your true worth. Hakuto
Shobo, 2003.
12）HR Vision: Japanese human resources department
editorial department: Japanese human resources
department human resources white paper 2018. HR
Vision, 2018.
13）Atsushi Nakahara: Introduction to feedback:Techniques to rebuild your subordinates and theworkplace by communicating what hurts.
14）Kosuke Honma, Jun Nakahara: The company is fullof dilemmas: Training for on-site managers to makedecisions. Kobunsha Shinsho, 2016.
15）Academic Education Committee of the JapaneseSociety of Radiological Technologists: Overview oflifelong education system. The Japan Associationof Radiological Technologists, 68, 77-91; 413-427,
2021.

Arts and Sciences
original articles

Received February 25, 2022 ; accepted June 24, 2022

Human Resource Development for RadiologicalTechnologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi Nuclear Power Station Accident
OHBA Takashi, Ph.D.1），2）, MABUNE Koichi, M.Sc.3）, KANNO Shuichi, M.Sc.4）,
SATOH Kenichi, Ph.D.5）, HASEGAWA Arifumi, M.D., Ph.D.6）
1）Department of Radiological Sciences, Fukushima Medical University, School of Health Sciences2）Department of Radiation Health Management, Fukushima Medical University, School of Medicine
3）Department of Radiation Technology, Iwase Hospital4）Miyakoji Clinic 5）Faculty of Data Science, Shiga University6）Department of Radiation Disaster Medicine, Fukushima Medical University, School of Medicine

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 844: 19-28, 2023.
Key words: Education, Fukushima Daiichi nuclear power station accident, Qualitative analysis, Radiation protection,

Radiological Technologists【Abstract】

This paper aims to analyse the disaster response experiences of radiological technologists during the Fukushima
Daiichi nuclear power station (FDNPS) accident by participantsʼ backgrounds, and to suggest outcomes for humanresource development. We conducted focus group interviews with 23 radiological technologists in Fukushima
Prefecture (divided into 5 groups), who differed in terms of work location, position, and gender. Comparison of thecoded phrase rates and correspondence analysis of notable words took place. Our results showed characteristics ofphrases and words depending on participantsʼ workplace distance from the FDNPS, and in the same area, genderdifferences were noted. We consider that the content of human resource development for radiological technologists inthe event of a nuclear accident should include ﬂexible education based on the distance from a nuclear power plant,
and radiation protection measurements needed in daily life, including of family members, in addition to the existing
content.

1. Introduction
Effective radiation protection methods forthe affected population in the event of a nuclear disaster include evacuation, temporary relocation and indoor evacuation (sheltering) 1).
Human resource development to ensure radiation protection for affected populations is being carried out in Japan and globally. For example, the Radiation Emergency AssistanceCentre/Training Site (REAC/TS) in the UnitedStates is an international human resource development facility for nuclear disaster response 2) and in Japan, the Nuclear Regulation
Authority (NRA) is taking the lead in humanresource development activities related to anuclear disaster 3, 4).

In addition, international organisations suchas the International Commission on Radiological Protection (ICRP) expect medical personnel
to be involved in the radiation protection of
the affected population in the event of a nuclear disaster 5). Radiological technologists holdnational medical licenses in Japan and are required to play an important role in body surface contamination measurement and ambient
dose measurement at their facilities in a nuclear disaster 3, 6). However, the content of humanresource development for radiological technologists who are expected to work in such situations is uniform and does not necessarily consider the background of each radiological technologist (e.g. their work area, job position, andgender).
Arts and Sciences ◆ 17

Radiological technologists played diverseroles in the Fukushima Daiichi nuclear power
station (FDNPS) accident that occurred in
March 2011 related to the Great East Japan
Earthquake (GEJE), including measurement ofbody surface contamination and decontamination for radiation protection of the affected
population 7, 8). The lessons learned from the
FDNPS accident by radiological technologists
have been reported in many activity records,
but this information has been fragmentary.
Many radiological technologists experienced
the FDNPS accident while working at medical
facilities in Fukushima Prefecture, and systematically organising the activities of these radiological technologists at that time may provide
an important perspective for improving thecontent of human resource development.
Based on this background, we set out to systematically organise the experiences of radiological technologists at the time of the FDNPS
accident based on their individual backgrounds, such as their work area, job position,and gender at the time of the accident. The
results of this study may be applied to the human resource development of radiological
technologists who are responsible for responding to a nuclear disaster, and will have implications for their effective human resource development in the future.

Naka-dori area (Area 2), and the Aizu area
(Area 3) (Fig. 1). The Hama-dori area (Area 1)
is located on the Paciﬁc coast, where the FDNPS was located. In this study, radiological
technologists working at medical facilities
within 20 to 30 km of the FDNPS were considered as the Area 1 group. Those working at
medical facilities within 30 to 80 km were theArea 2 group, and those in medical facilities
outside the 80 km radius were in the Area 3
group (Fig. 1).
A total of 23 participants were classiﬁed into
ﬁve groups in the three areas of Fukushima Prefecture based on their work area, job position,age, and gender. Table 1 shows the details of
the participants and these groups. The Area 1
group consisted of four males in their 40s and
50s as department managers and section chiefs.
The Area 2 group comprised ﬁve males in their
50s as department managers (hereafter, Area 2
department manager), ﬁve females in their 30s
and 40s as section chiefs (Area 2 female section
chief), and ﬁve males in their 30s and 40s as
section chiefs (Area 2 male section chief). The

Fig. 1

Area 3
Aizu area

Area 2Naka-dori area

Area 1
Hama-dori area

FDNPS

2. Materials and methods

20 km
30 km

2-1. Study design and participantsThis study was a recall cross-sectional study
using a qualitative research approach with
text-mining, targeting radiological technologists who were working in Fukushima Prefecture at the time of the FDNPS accident. The
participants resided in three regions of Fukushima Prefecture (Aizu, Naka-dori and Hamadori areas) and were engaged in medical workat their facilities on 11 March 2011. Fukushima
Prefecture is geographically divided into threemain regions: the Hama-dori area (Area 1), the18 ◆ Journal of JART English edition 2024

140 km

80 km

Fig. 1 Three local areas (Area 1: Hama-dori area,
Area 2: Naka-dori area, and Area 3: Aizu
area) in Fukushima Prefecture are clarified
by the dotted lines. Distance lines fromthe Fukushima Daiichi nuclear power station (FDNPS) are the zone from 20 km to
140 km. The light-yellow marker on thismap depicts the zone of 20-30 km radiusfrom the FDNPS. The detailed municipalities of Naka-dori area (Area 2) are shownas the diagonal line.

original articles
Human Resource Development for Radiological Technologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi
Nuclear Power Station Accident

Area 3 group consisted of four men in their 20s
to 50s in a variety of positions, including department managers, section chiefs, and section
staff.

the FGIs and responsible for audio- and videorecording the sessions.
2-3. Data analysis
2-3-1. Coding the utterance content

2-2. Focus group interviews

Focus group interviews (FGIs) were conducted with the participants in Table 1. The
FGIs took place from October to November
2017 with groups of four to six interviewees.
We aimed for the interview process to be synergistic, with a snowball effect, stimulating, reassuring, and spontaneous. FGIs are useful for
uncovering latent factors within participants
and for collecting narrative information compared with one-to-one interviews 9). The duration of each FGI was 90 minutes per group in
this study.
The FGIs focused on two main items: (1) the
GEJE and their roles at work and in private,and (2) the GEJE and their health. Participantsʼ
opinions were sought separately for two time
periods: the early GEJE phase (immediately after the FDNPS accident) and six years after the
GEJE (at the time of the interview) 10). We asked
about two other aspects: (3) activities remembered during the GEJE, and (4) experiences ofbeing relied upon, which focused on theiropinions regardless of the time period such as
the early or recovery phases. FGI facilitators
asked open-ended questions and avoided
leading participants to respond in a particularway. Participants were encouraged to discuss
the topics freely as they saw ﬁt in any chronological order. An assistant was present during

Fig. 2 shows an overview of the analyticalprocedures in this study. First, the recorded
FGI utterances of each group were transcribedand converted into textual information. Next,
the textual transcription was corrected for any
Japanese notational errors (e.g. survey: “サーベイ” or “サーベー”, and radiological technologists: “診療放射線技師”, “放射線技師”, or “技師”)
and proper nouns were processed so that participants could not be identiﬁed. Finally, eachsentence was coded. Two authors of this article (T.O. and K.M.) individually examined thecontent of each sentence of each utterance andassigned each sentence to a subtopic based on
its intended meaning. Each subtopic was thenclassiﬁed into a larger concept – the main topic – so that every utterance was coded withtwo main topics {A, B} and six subtopics {a, b,
c, d, e, f}, with the aim of grasping the content
of the utterance (Fig. 2). Next, the results of thetwo coders were collated and, in case of discrepancies, the codes for the subtopics wereassigned after consultation between two authors (T.O. and K.M.), referring to the sentences before and after.
NVivo Release 1.1 (QSR International Inc.,
MA, US) Computer Assisted/Aided QualitativeData-Analysis Software (CAQDAS) was used
for the analysis 11). To assess the coding concordance between the two authors, a test of con-Table 1 General characteristics of the participantsWorking area in Fukushima
Prefecture

Position at the time of the FDNPS
accident

GenderAge group(number of participants)

Area 1

Department manager and section chiefMale

40s (2), 50s (2)Area 2

Department manager

Male

50s (5)

Section chiefMale

30s (3), 40s (2)Section chief

Female30s (3), 40s (2)Department manager, section chief, andsection staffMale

20s (1), 40s (1), 50s (2)Area 3

FDNPS, Fukushima Daiichi nuclear power station

Arts and Sciences ◆ 19

Fig. 2

Textualised Focus Group Interview (FGI) information
Processing of the FGI text for our analysis(Unification of each word with the same meaning andanonymisation of text information)
Coding the FGI text
Text lines
Sentence 1
Sentence 2
Sentence 3
Sentence 4
Sentence 5
Sentence 6:
Sentence 2,262

Comparison of the percentage forcoding data by participant groups(Tables 3 and 4)

Subtopic: a
Subtopic: b
Subtopic: c

Discussion of codingof subtopics and main
topics by two authors
in this study

Main topic: A
Main topic: B

Subtopic: dSubtopic: e
Subtopic: fComparison of the characteristicfrequency of words in participantgroups (Fig. 3)

Fig. 2 Flow of our research methods

cordance was conducted using SPSS version 28(IBM Corp., IL, US). The signiﬁcance level forthis study was set at 5%.
2-3-2. Analysis of the relationship between utterance content and interview groups basedon coding data

The number of relevant sentences and the
proportion of occurrences of codes related tothe main topic to the total utterances werecompared from the following two perspectives
for each FGI group: (1) The percentage of occurrence of codes related to the main topic in
total utterances among the work areas (Areas
1–3), and (2) the percentage of occurrence ofcodes related to the main topic in total utterances among the three groups with different
job positions and genders, restricting the target
to Area 2.
To examine the association between thethree main topics (including where the main
topic was “Unknown” (Not classiﬁable)) andthe three regions of work or the three groups,
a 3 by 3 cross-tabulation table was developed
and a Pearsonʼs χ2 test was applied to obtainp-values. The proportion of occurrences ineach cell after the χ2 test was compared withthe expected value under independence, and aresidual analysis was performed using the ztest. The signiﬁcance level of this study was
5%, and the adjusted residuals from the z-test

20 ◆ Journal of JART English edition 2024

used in the residual analysis showed a tendency to be signiﬁcantly higher or lower if the absolute value was greater than ±1.96. Statisticalanalysis was performed using SPSS version 28.
2-3-3. Analysis of the relationship between utterance content and groups based on frequent words and phrases

Frequently occurring words and phrases
were extracted for each coded main topic. The
words analysed were limited to nouns in general (words with two or more characters, including Kanji), nouns in the accusative case,adjectives, organisation names, place names,
unknown words, tags, verbs, adjectives, adverbs, and noun C (words with one Kanji character), to avoid confusion associated with ambiguous use. The tags (extraction of designatedwords) were: radiological technologist, decontamination, Hama-dori, Minamisoma, temporary house, whole body counter, monitoring
post, glass badge, and survey meter. Based on
the above criteria, the top 100 words with aminimum number of 13 or more occurrenceswere extracted for each main topic. A crosstabulation table was then created between thefrequently occurring words and interview
groups, and visualised using correspondence
analysis.
Correspondence analysis was conducted using the free software KH Coder version 3.
Beta.01.a (https://khcoder.net/) 12). Monkin®
Reporting for KH Coder 1.0.0 (SCREEN Advanced System Solutions Inc., Kyoto, Japan)
was used as a plug-in system for KH Coder tofacilitate visual evaluation of the correspondence analysis results.
2-4. Ethical considerations

This study was conducted with the approvalof the General Ethics Committee of Fukushima
Medical University (Approval No. 2573). We
explained the voluntary nature of research cooperation, the freedom to withdraw during thecourse of the research, the beneﬁts and disad-original articles
Human Resource Development for Radiological Technologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi
Nuclear Power Station Accident

vantages associated with research cooperation,
ensuring privacy, that identifying information
would not be revealed when the results were
published, and that no harm would be caused
to participants. Informed consent was then obtained from the participants.

3. Results
3-1. Understanding utterance content throughcoding

The results of the utterance coding carriedout through the analysis procedure shown in
Fig. 2 are presented in Table 2. The total number of recorded utterances was 2,262 acrossthe ﬁve FGI groups. The coding results for thetwo authors of this article showed that the degree of agreement (kappa coefﬁcient) was 0.82
( p < 0.01).
Ninety-six percent of the total utteranceswere coded as the following topics. The maintopic A: “anxiety about health effects of radia-

tion exposure and changes in their daily life”
consisted of 3 items in the subtopic code (thepercentage ratio of related sentences in thesubtopic against total utterances of the FGI in
this study), such as a. “Health effects within
their family (25.8%)”, b. “Interest in the radiation exposure situation (7.2%)”, and c. “Reconstruction and harmful rumours (9.5%)”. Notable words and phrases in the subtopic utterances were as follows: a. Relationships withfamily members, Implementation of evacuation, Anxiety about health effects of radiation
exposure, and Risk assessment of radiation exposure; b. Decontamination work, Personal radiation exposure dose, Radioactive contamination of food and water, and Measurement of
thyroid dose; c. Fading issues, Changing landscapes by reconstruction, Daily life during theevacuation, and Harmful rumours. The maintopic B: “Changes in their work and the issues
faced” also consisted of 3 items in the subtopic
code (the percentage ratio in total utterances),

Table 2 The coding list of main and subtopics with frequency in the focus group interviews (FGIs) based on
qualitative analysis
Code

Number of sentences
relating to subtopics inthe overall FGI data (%)

Main-topic

Subtopic

Notable words and phrases during the FGIs

A: Anxiety about
health effects ofradiation exposureand changes in their
daily lifea. Health effects
within their family

Relationships with family members,
Implementation of evacuation, Anxiety about
health effects of radiation exposure, Risk
assessment of radiation exposure583(25.8)

b. Interest in
the radiation
exposure situation

Decontamination work, Personal radiation
exposure dose, Radioactive contamination offood and water, Measurement of thyroid dose

164
(7.2)

c. Reconstruction
and harmful
rumours

Fading issues, Changing landscapes byreconstruction, Daily life during the evacuation,
Harmful rumours

215
(9.5)

d. GEJE-related
worksWork immediately after the GEJE, Evacuationof hospitals, Counselling for medical exposure,
Improvement of daily workﬂows after the GEJE

494
(21.8)

e. The measurementof radiation
exposure dose

Ambient dose rate, Body surface
contamination, Internal radiation exposure
dose measurement495(21.9)

f. Communicationand lessons
learned from theaccident

Activities to alleviate anxiety about radiation
exposure, Dissemination of information usingSNSs, Face-to-face talks about radiation
knowledge, Lack of knowledge about radiation
protection, Evaluation of previous training for anuclear disaster, Sharing experiences with thenext generation

221
(9.8)

B: Changes in theirwork and the issues
faced

FGI: Focus group interview, GEJE: Great East Japan Earthquake, SNS: Social Networking Services

Arts and Sciences ◆ 21

such as d. “GEJE-related works (21.8%)”, e.
“The measurement of radiation exposure dose
(21.9%)”, and f. “Communication and lessons
learned from the accident (9.8%)”. Notablewords and phrases in the utterances of thesubtopics included: d. Work immediately after
the GEJE, Evacuation of hospitals, Counsellingfor medical exposure, and Improvement ofdaily workﬂows after the GEJE; e. Ambient
dose rate, Body surface contamination, and Internal radiation exposure dose measurement; f.
Activities to alleviate anxiety about radiation
exposure, Dissemination of information usingsocial networking services (SNSs), Face-to-facetalks about radiation knowledge, Lack ofknowledge about radiation protection, Evaluation of previous training for a nuclear disaster,and Sharing experiences with the next generation. In total, 90 sentences (4.0% of the total
utterances) involved silent responses and noncodable utterances that were excluded fromthe coding.

Area 3 groups ( p < 0.05).
The analysis then focused on the Area 2
group, where the backgrounds of participants
were diverse. Table 4 shows the comparison of
the proportion of each main topic to the total
utterances between the three groups with different job positions and gender. For both main
topics A and B, the χ2 test showed that the
proportion of the total FGI utterances showeda signiﬁcantly different trend ( p < 0.01) between the groups. For the main-topic A: “anxiety about health effects of radiation exposureand changes in their daily life”, the z-test
showed that the Area 2 female section chiefsʼ
group had the highest percentage trend in the
total FGI utterances of the three groups ( p <0.05). Regarding the main-topic B: “Changes intheir work and the issues faced”, the z-test
showed that the proportion of occurrences for
the Area 2 male section chiefsʼ group to thetotal utterances had the highest proportion
trend among the three groups ( p < 0.05).

3-2. Comparison of utterance content with a

3-3. Comparison of utterance content focusing

focus on coding
The proportion of utterance occurrences ofeach main topic to the total utterances is shownby location for Areas 1-3 (Table 3) for the maintopic A: “anxiety about health effects of radiation exposure and changes in their daily life”,
main-topic B: “Changes in their work and theissues faced”, and non-codable utterances “unknown”. The proportions of utterance occurrence by location for each main topic showedsigniﬁcantly different trends in the χ2 test ( p <0.01). In particular, the z-test showed that Area
1 groupʼs proportion of all utterances for the
main-topic A: “anxiety about health effects ofradiation exposure and changes in their dailylife” was lower than that of the Area 2 and Area
3 groups ( p < 0.05). In contrast, for the maintopic B: “Changes in their work and the issues
faced”, a z-test showed that the proportion ofArea 1 group to total FGI utterances tended tobe higher than the proportion of Area 2 andon high frequency words
To analyse the relationship between frequently occurring FGI words and the workarea, job position, and gender of the participants, the relationship between frequently occurring words and the groups was analysed foreach main topic by correspondence analysis(Fig. 3). In the correspondence analysis, thecloser the words and FGI groups were locatedto each other in the diagram, the more characteristic and stronger the association was.
For the main-topic A: “anxiety about healtheffects of radiation exposure and changes intheir daily life”, a tendency was observed in
Area 1 and Area 3 groups to overlap characteristic frequent words related to evacuation, suchas “Minamisoma”, “tsunami”, and “water” (quadrant 2 in Fig. 3-1). In contrast, words related tothe acceptance of evacuees, such as “Hamadori” and “evacuate”, were found as characteristic frequent words only in the Area 3 group.

22 ◆ Journal of JART English edition 2024

original articles
Human Resource Development for Radiological Technologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi
Nuclear Power Station Accident

Table 3 The proportion rate of interview sentences related to the main-topics using coding analysis in thethree Fukushima Prefecture areas
Category
Main-topic A
Main-topic B
Unknown
Total＊

Area 1

Area 2

Area 3

Total

Frequency (%)

Group

185 (33.4)

540 (47.2)

237 (42.1)

962 (42.5)

Adjusted residual (z-test)‑ 5.01＊

4.51＊

Frequency (%)‑ 0.24340 (61.4)

578 (50.4)

292 (51.9)

Adjusted residual (z-test)

4.28＊‑ 2.91＊‑ 0.89Frequency (%)

29 (5.2)

27 (2.4)

34 (6.0)

Adjusted residual (z-test)

1.74‑ 3.99＊2.89＊

554 (100)

1,145 (100)563 (100)

Frequency (%)

1,210 (53.5)
90 (4.0)
2,262 (100)p < 0.05

Table 4 The proportion rate of interview sentences related to the main-topics using coding analysis in relation
to the work position and gender of three groups in Area 2
Category
Main-topic A
Main-topic B
Unknown
Total＊

Male section chief

Female section chief

Manager

Total

Frequency (%)

Group

126 (27.0)

273 (74.6)

141 (45.2)

540 (47.1)

Adjusted residual (z-test)‑ 11.4＊

12.7＊

Frequency (%)

328 (70.2)

86 (23.5)‑ 12.5＊Adjusted residual (z-test)

11.1＊

Frequency (%)

13 (2.8)

7 (1.9)Adjusted residual (z-test)

0.79‑ 0.68467 (100)

366 (100)

Frequency (%)‑ 0.82164 (52.6)

578 (50.5)

0.86
7 (2.2)27 (2.4)‑ 0.16312 (100)

1,145 (100)p < 0.05

Words related to the conﬂict between evacuation and work in relation to “retire” were foundto be characteristic of the Area 1 group only
(quadrant 2 of Fig. 3-1). The characteristic frequent words of the Area 2 department managersʼ and the Area 2 male section chiefsʼ groups
had considerable overlap, and “safety”, “stress”,“life”, and “thyroid” were found to indicate sudden changes in participantsʼ daily life and work
(quadrant 3 in Fig. 3-1). However, the characteristic frequent words of the Area 2 female
section chiefsʼ group were independent of theother groups, with words reﬂecting concerns
about radiation exposure related to children
and families, such as “children”, “elementary
school”, “evacuation”, and “home” (quadrants 1
and 4 in Fig. 3-1). In the correspondence analysis of the main-topic B: “Changes in theirwork and the issues faced”, the characteristicfrequent words of the Area 2 department managersʼ and male section chiefsʼ groups werevery similar, and words related to body surface

contamination examinations and working facilities, such as “hospital”, “self-defence force”,
and “cpm (count per minute)”, were found(quadrants 1 and 2 in Fig. 3-2). A tendency
was observed between the Area 1 group andthe Area 2 female section chief group to overlap characteristic frequent words for consultation on medical exposure, such as “come”, “explanation”, “hear”, “photo”, and “anxiety”(quadrant 4 in Fig. 3-2). The words that werecharacteristic of the Area 1 group only were“tsunami”, “nothing”, and “task”, which indicate
the critical situation of the disaster, and words
related to internal exposure measurement suchas “whole body counter”, “measurement”, and“hear” (upper part of quadrant 4 in Fig. 3-2).
Furthermore, frequent words characteristic of
the Area 2 female section chief group included“radiation,” which was close to the word “children”, indicating concerns about exposure tofamily members (upper part of quadrant 3 inFig. 3-2). In contrast, the frequent words charArts and Sciences ◆ 23

①②

English version

Japanese version

Fig. 3 The correspondence analysis using KH coder in 5 groups① Anxiety about health effects of radiation exposure and changes in their daily life at the main-topic A② Changes in their work and the issues faced at the main-topic B

acteristic of the Area 3 group were independent of the other groups and included “evacuate”, “examinations”, and “value”, – all words
related to body surface contamination testing(quadrant 3 of Fig. 3-2).

4. Discussion
We examined radiological technologistsʼ experiences of the FDNPS accident from immediately after the accident to the present-day using text mining methodology based on utterance content from ﬁve groups of interviewees
with different backgrounds. The proportion ofstatements and utterance content were charac-

24 ◆ Journal of JART English edition 2024

teristic of each participantʼs background, reﬂecting their experiences and lessons learned
from the nuclear disaster – important information for future generations. The results of thestudy contribute to human resource development contents in Japan to raise awareness ofradiological technologistsʼ roles in a future nuclear disaster.
4-1. Regional differences based on the ratio ofutterance occurrence by topic

The study found regional characteristics inthe work of radiological technologists in response to the FDNPS accident. In the Area 1
group, effects of the accident were reported,original articles
Human Resource Development for Radiological Technologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi
Nuclear Power Station Accident

such as hospital evacuation, other GEJE-related
tasks and internal exposure measurement examination. The proportion of utterances in the
main-topic B: “Changes in their work and theissues faced” in the Area 1 group was 61.4%,
which was higher than the proportion in theother groups (Table 3). In the Area 1 group,
words related to “critical situation of disaster”
and “implementation of internal exposure measurement” appeared as the main-topic B:“Changes in their work and the issues faced”(Fig. 3-2). The Area 1 group was strongly related to the subtopics d. “GEJE-related works”
and e. “The measurement of radiation exposure dose” in the main-topic B (Table 2). The
Area 1 group was forced to evacuate the hospitals during the GEJE. These medical workers
faced extreme stress because they were in a
“critical situation of disaster” 13). The statementssuggest that the indoor evacuation of medical
facilities was also related to the “critical situation of disaster”. Indoor evacuation is an effective measure for radiation protection in theevent of a nuclear disaster 1), but it was evident
that radiological technologists struggled to facilitate effective indoor evacuation after the
nuclear disaster. The frequent occurrence ofthe term “implementation of internal exposure
measurement” suggests that this was becauseinternal exposure examinations using wholebody counters had been conducted in the 20–
30 km radius from the FDNPS, including Area
1 (Fig. 1), from the early stages of the accident 14). Thus, the participants in the Area 1
group were required to respond to demands
that they had never experienced before, andthey were strongly affected by the FDNPS accident. Based on the lessons learned from theaccident, the education programme for radiological technologists in municipalities within a
30 km radius of a nuclear power station – thatis within the UPZ (Urgent Protective action
planning Zone) – should be designed to provide them with the opportunity to perform unexpected and special tasks, such as internal

exposure examinations in crisis situations. The
need to provide educational content on knowledge and skills for sudden and special workrelated tasks was emphasised.
The Area 2 group was required to maintainthe in-hospital healthcare delivery capacity in
the GEJE, and manage radiation protection forresidents and their families outside the hospital. This group had a higher rate of utterance
occurrence for the main-topic A: “anxiety about
health effects of radiation exposure and changes in their daily life” than the Area 1 group, anda lower rate of utterance occurrence for the
main-topic B: “Changes in their work and theissues faced” than those in Area 1 (Table 3).
The results of the correspondence analysis(Figs. 3-1 and 2) showed that the characteristicfrequent utterances represented the participantsʼ daily life, rapid changes in their work
(Area 2 department managersʼ and the Area 2
male section chiefsʼ groups) and daily concerns
related to children and family (Area 2 female
section chiefsʼ group). These utterances wererelated to the Table 2 subtopics a. “Health effects within their family”, d. “GEJE-related
works”, and e. “The measurement of radiation
exposure dose”. The reason for the emergenceof “GEJE-related works” was that the localities
in Area 2 were not ordered to evacuate eventhough many medical facilities were affectedby the GEJE, and therefore, efforts were madeto maintain the normal level of medical careprovision despite the excessive burden ofmaintaining both disaster and routine medicalcare in that context. Subtopic e. “The measurement of radiation exposure dose” reﬂected thefact that at the time of the FDNPS accident,
body surface contamination examination sites
were set up in various municipalities in Area
2 15), and Area 2 radiological technologists were
mobilised as body surface contamination surveyors and decontamination staff 8). In contrast,a. “Health effects within their family”, conﬁrmed that medical personnel were involved
with their families and communities away from
Arts and Sciences ◆ 25

the workplace and “needed knowledge of radiation protection to cope with concerns about
radiation exposure in their daily lives” evenoutside of their work. Therefore, it was suggested that in areas outside the 30 km radius ofa nuclear power station (outside the UPZ), radiological technologists still need to haveknowledge and skills to deal with a nuclear
disaster and knowledge about radiation protection for use in their daily lives.
This study showed that the Area 3 group was
required to know about radiation protection in
the event of a nuclear disaster and to communicate effectively to convey this knowledge.
The Area 3 group had a higher rate of occurrence of the main-topic A: “anxiety about
health effects of radiation exposure and changes in their daily life” than the Area 1 participants, and a lower rate of occurrence of themain-topic B: “Changes in their work and theissues faced” than the Area 1 group (Table 3).
The results of the correspondence analysis(Figs. 3-1 and 2) suggest that words related to“acceptance of evacuees” appeared among thecharacteristic frequent utterances, originatingfrom the body surface contamination examinations in subtopic e. “The measurement of radiation exposure dose” (Table 2). In fact, in theacute phase of the GEJE, the damage to medical facilities and radioactive contamination in
Area 3 was less severe than in Areas 1 and 2,
and thus, the “acceptance of evacuees” wasneeded to establish a system to conduct bodysurface contamination examinations. In addition, the Area 3 group noted that “there weremany questions about how to cope with radiation exposure during the body surface contamination examinations”. Therefore, it was considered that the education curriculum in areas
relatively far from a nuclear power station (e.g.
outside the 80 km zone in the case of the FDNPS accident) should focus on education that
includes communication about radiation protection for evacuees with body surface contamination.

26 ◆ Journal of JART English edition 2024

In summary, the ﬁndings suggest that humanresource development for radiological technologists responding to a nuclear disaster needs
to be ﬂexible in providing knowledge andtechnical content with an awareness of the different roles based on the distance from a nuclear power station.
4-2. Occurrence of utterance topics based on
job position and gender

Utterance topic occurrence rates were distinctive according to job position and gender,
even if the work area was the same.
The Area 2 department managersʼ group andthe Area 2 male section chiefsʼ group had signiﬁcantly different frequencies of each main
topic in relation to the total utterances (Table4). However, a correspondence analysis showedthat the characteristic words of these twogroups were similar and overlapping (Figs. 3-1
and 2). These characteristic tendencies wererelated to the subtopics d. “GEJE-related works”
and e. “The measurement of radiation exposure dose” in Table 2. However, the membersof the Area 2 department managersʼ group in
this study were male only (Table 1). Therefore,
the strong association between the Area 2 department managers and Area 2 male section
chiefs (in Figs. 3-1 and 2) was that, regardlessof their job, the men were required to perform
duties such as body surface contamination
measurement, air radiation dose rate measurement 8), and radiation protection activities forresidents and hospital patients and staff at
medical facilities following the FDNPS accident.
In contrast, the proportion of occurrences ofthe main-topic A: “anxiety about health effectsof radiation exposure and changes in their daily life” in the Area 2 female section chiefsʼ
group was signiﬁcantly higher than in the other groups (Table 4). This was strongly related
to subtopic a. “Health effects within their family” in Table 2. The correspondence analysis(Figs. 3-1 and 2) showed that the characteristic

original articles
Human Resource Development for Radiological Technologists who can Respond to Nuclear Accident-Experience and Lessons Learned from the Fukushima Daiichi
Nuclear Power Station Accident

frequent utterances of the Area 2 female section chiefsʼ group were mainly concerns about
radiation exposure related to children and family in daily life. The Area 2 female section
chiefs in this study were in their 30s and 40s,
the age group most concerned about “Healtheffects within their family” compared with other generations. Previous studies have shownthat women working in radiation-related jobs
have a more conservative level of radiation exposure tolerance with regard to radiation risk
perception than men 16). The ﬁndings of ourstudy suggest that Area 2 female section chiefs
were very concerned about radiation protection of their families and children.
Regardless of their position, male radiologists were interested in radiation protection of
local residents and medical facility personnel
as part of their work. In contrast, women weremore interested in radiation protection for theirfamilies in their daily lives. Although training
related to nuclear disasters has been systematised in recent years 3), it does not necessarily
consider health workersʼ backgrounds, mainly
focusing on education and training to carry out
radiation protection for local residents andmedical facility personnel. The results of thisstudy suggest that human resource development of radiological technologists for futurenuclear disasters should consider establishededucational content and comprehensive
knowledge and skills from the viewpoint of affected residents, with an awareness of radiation protection in daily life.
4-3. Limitations and future research

The study has some limitations that shouldbe acknowledged. 1) We reported the experiences of radiological technologists who responded to the FDNPS accident. Therefore, thepossibility that the participantsʼ utterances wereinﬂuenced by regional characteristics speciﬁc
to Fukushima Prefecture cannot be denied.
However, the trend of activities during the FDNPS accident depending on the distance froma nuclear power station can be considered as areference for human resource development in
the event of a nuclear disaster; 2) The study
did not include FGIs with female radiological
technologists in Areas 1 and 3. Thus, uncertainties in the study of human resource development related to gender remain. However,Area 2 is located between Areas 1 and 3 interms of distance from the FDNPS and, as
shown in Table 3 and Fig. 3-2, it is possiblethat Area 1 and Area 3 were similar in terms of
the activities undertaken. Therefore, comprehensive education on radiation protection
measures that can be taken in daily life is necessary regardless of the distance from a nuclear
power station; 3) The considerations on distance from a nuclear power station in this study
were applicable to some nuclear accidents at
facilities for commercial power reactors because of the lessons learned from the FDNPS
accident. Flexible modiﬁcation of educationaccording to the size of the nuclear facility isnecessary because the radius of PAZ (Precautionary Action Zones) and UPZ for other nuclear-related facilities varies depending on thetype and size of the facility 4); and 4) The results of this study may not necessarily be generalisable because of the relatively small number of participants and the use of qualitative
research methods. In the future, we plan to
conduct a questionnaire survey that would allow greater generalisation of the ﬁndings andthe proposal of an appropriate educational
programme for human resource development
based on the background of radiological technologists.

5. Conclusion
To effectively manage a future nuclear disaster, human resource development needs to focus on comprehensive educational content
that takes differences in work regions into account, based on distance from a nuclear power
station. Radiation protection in everyday family
Arts and Sciences ◆ 27

life should also be included when preparing
for potential nuclear accidents and emergencies. In Japan, the NRA and other organisations
are taking the lead in standardising educational
content for the human resource developmentof responders to a nuclear disaster 3, 6). They
need to reﬂect the characteristics of the location level based on the experience of the FDNPS accident and ensure these characteristics
are passed on to the next generation. This
study contributes to the human resource development of radiological technologists who can
respond appropriately in the event of a nuclear
disaster.

6. Acknowledgements
We would like to thank all the participants inthis study. We would also like to express our
sincere gratitude to Ms. Mami Nemoto, Secretary of the Department of Radiation Disaster
Medicine, Faculty of Medicine, Fukushima
Medical University, for her efforts in the smooth
conduct of this study. This work was supported by the Research project on the Health Effects of Radiation (JFY 2015-2017) “Proposal offeasible group-tailored risk communication onradiation-related health anxiety” organised by
Ministry of the Environment, Japan. We thankMichelle Pascoe, PhD, from Edanz (https://jp.
edanz.com/ac) for editing a draft of this manuscript.

References
1） Ohba T, et al.: Evacuation after a nuclear accident:
Critical reviews of past nuclear accidents and proposal
for future planning. Environ Int, 148, 106379, 2021.
2） U.S. Department of Energy. Radiation emergency
assistance center/training site. https://orise.orau.
gov/reacts/index.html (22 February 2024, date lastaccessed)．

28 ◆ Journal of JART English edition 2024

3） Tominaga T.: Current status of education and training
on medical responses in the event of a nuclear disaster(Japanese). Isotope News, 770, 18-20, 2020.
4） Nuclear Regulation Authority.: Guide for Emergency
Preparedness and Response (Japanese). https://www.nra.go.jp/activity/bousai/measure/index.html (22February 2024, date last accessed)．
5） ICRP: Application of the commissionʼs recommendations
for the protection of people in emergency exposure
situations. Ann ICRP, 39(1), 1-67, 2009.
6） Tsujiguchi T, et al.: Survey on training of the nuclear
emergency medical assistance team and theireducational needs. Radiat Environ Med, 8(1), 16-20,
2019.
7） Tosa T.: Radiation survey initiatives (Special issues:27th
Japan Conference of Radiological Technologists)(Japanese)．JART, 58(12), 1143-1146, 2011.
8） Yusa T.: Efforts and future responses to the Great East
Japan Earthquake by the Fukushimaken Associationof Radiological Technologist (Special issues:28th
Japan Conference of Radiological Technologists)(Japanese)．JART, 59(12), 1541-1545, 2012.
9） Anme T.: Group interview methods in human servicesDevelopment of scientifically based qualitative
research methods (Japanese). 1-138, Ishiyaku
Pub,Inc., Tokyo, 2001.
10）Hasegawa A, et al.: Lexical analysis suggests
differences between subgroups in anxieties overradiation exposure in Fukushima. J Radiat Res, 59(2_suppl), ii83-ii90, 2018.
11）Furukawa R.: Introduction to Nvivo for Nursing
Research (Japanese). 1-232, Shinyousya, Tokyo, 2019.
12）Higuchi K.: Quantitative text analysis for social
research-Inheritance and development of content
analysis (Japanese). 1-264, Nakanishiya Shuppan,
Kyoto, 2020.
13）Sawano T, et al.: Emergency hospital evacuationfrom a hospital within 5 km radius of Fukushima
Daiichi nuclear power plant: A retrospective analysis
of disaster preparedness for hospitalized patients.
Disaster Med Public Health Prep, 16(5), 2190-2193,
2022.
14）Hayano RS, et al.: Whole-body counter survey results
4 months after the Fukushima Dai-ichi NPP accident
in Minamisoma City, Fukushima. J Radiol Prot, 34(4),787-799, 2014.
15）Kondo H, et al.: Screening of residents following theTokyo electric Fukushima Daiichi nuclear power plant
accident. Health Phys, 105(1), 11-20, 2013.
16）Miura M, et al.: Perception of radiation risk by
Japanese radiation specialists evaluated as a safe
dose before the Fukushima nuclear accident. HealthPhys, 110(6), 558-562, 2016.

Arts and Sciences
original articles

Received February 28, 2022 ; accepted December 8, 2022

A Prospective Study of Muscle Stiffness Using
Ultrasound Shear Wave Elastography in the Biceps
Brachii of Patients with Parkinson’s Disease
KOBAYASHI Satoshi, RT, PhD1）, KASAI Kenji, PT, MS2）, YABE Hitoshi, MS3）,IMAO Masashi, RT, MS 4）, HASHIMOTO Yuji, MD, PhD5）, ICHIKAWA Tadashi, MD, PhD5）
1）Department of Radiology, Saitama Prefectural Rehabilitation Center2）Department of Physical Therapy, Saitama Prefectural Rehabilitation Center3）Department of Radiology, Faculty of Health Sciences, Tsukuba International University4）School of Radiological Sciences, Faculty of Health Science, Gunma Paz University5）Department of Neurology, Saitama Prefectural Rehabilitation Center

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 848: 5-11, 2023.
Key words: Parkinsonʼs disease, biceps brachii muscle, ultrasound shear wave elastography, Movement DisorderSociety-Sponsored Revision of the Uniﬁed Parkinsonʼs Disease Rating Scale (MDS-UPDRS), rigidity【Abstract】

In patients with Parkinsonʼs disease (PD), the relationship between biceps brachii muscle stiffness measured using
ultrasound shear wave elastography (SWE) and upper extremity rigidity score (indicating severity) evaluated using
the Movement Disorder Society-Sponsored Revision of the Uniﬁed Parkinsonʼs Disease Rating Scale (MDS-UPDRS) is
unclear. This study measured biceps brachii muscle stiffness using SWE and scored upper extremity rigidity based on
the MDS-UPDRS in 43 patients with PD. Factors affecting muscle stiffness measured using SWE were identiﬁed using
multiple regression analysis. Threshold values of muscle stiffness detected on SWE were calculated for each upper
extremity rigidity score according to MDS-UPDRS. This study included 43 patients with PD (20 men and 23 women).
MDS-UPDRS upper extremity rigidity scores of 2 and 3 were identiﬁed as factors affecting muscle stiffness measured
using SWE. The results suggest that the threshold values of muscle stiffness measured using SWE in the dominant arm
can be used to determine MDS-UPDRS upper extremity rigidity scores of 1, 2, and 3.

1. Introduction
Parkinsonʼs disease (PD) is a progressive
neurodegenerative disorder characterized byresting tremors, bradykinesia, rigidity, and postural reﬂex impairment 1). Rigidity refers to anincreased state of muscle tonus, which is perceived as resistance when the joints are moved
passively. Muscle rigidity is different between
the left and right sides in many patients, withthe dominant side often remaining unchanged
throughout the medical history 2).
To assess the severity of Parkinsonʼs disease(PD) based on multiple assessment items encompassing both motor and non-motor symptoms, the Uniﬁed Parkinsonʼs Disease Rating
Scale (UPDRS), proposed by Fahn et al. 3), andsubsequently revised by the Movement Disor-

der Society (MDS) as the MDS-UPDRS 4), is
widely used in clinical and research settings
worldwide. The MDS-UPDRS is composed ofparts I – IV 4), as follows. Part I: nonmotor experiences of daily living, Part II: motor experiences of daily living, Part III: motor examination, and Part IV: motor complications. Part III
includes an assessment of the severity of upper
extremity rigidity (3.3) 4). The severity of upper
extremity rigidity is evaluated separately on theleft and right sides on a 5-point scale: 0 - normal, 1 - very mild, 2 - mild, 3 - moderate, and4 - severe (Table 1) 4).
Rigidity is assessed by the resistance (stiffness) to muscle stretch encountered when theexaminer passively moves the patient's joints 4).
Due to the difﬁculty in evaluating this resistance quantitatively and the need for expertise,
Arts and Sciences ◆ 29

Table 1 MDS-UPDRS rigidity scoring criteria for upper extremities4）
Instructions to examiner: Rigidity is judged on slow passive movement of major joints with the patient in arelaxed position and the examiner manipulating the limbs and neck. First, test without an activation maneuver.
Test and rate the neck and each limb separately. For arms, test the wrist and elbow joints simultaneously. Forlegs, test the hip and knee joints simultaneously. If no rigidity is detected, use an activation maneuver, such as
tapping ﬁngers, ﬁst opening/closing, or heel tapping, in a limb not being tested. Explain the patient to go as
limp as possible as you test for rigidity.
0: Normal: No rigidity.
1: Slight:
Rigidity only detected with activation maneuver.
2: Mild:
Rigidity detected without the activation maneuver, but full range of motion is easily achieved.
3: Moderate: Rigidity detected without the activation maneuver; full range of motion is achieved with effort.
4: Severe: Rigidity detected without the activation maneuver and full range of motion not achieved.

SCORE
RUE

LUE

Note: MDS-UPDRS, Movement Disorder Society-Sponsored Revision of the Uniﬁed Parkinsonʼs Disease Rating Scale;
RUE, right upper extremity; LUE, left upper extremity.

assessing the rigidity score (severity) is challenging4）. Therefore, there is a demand formethods that utilize objective and quantiﬁable
indicators to assess the rigidity score (severity).
Ultrasound shear wave elastography (SWE)
can be used to determine tissue stiffness(Youngʼs modulus) based on the propagation
speed of the shear waves generated in the
body 5), 6). The propagation speed of the shear
waves varies according to tissue stiffness 7).
SWE is employed to study the mechanicalproperties of skeletal muscles, including theassessment of passive stiffness 8-11) and stiffnesschanges during voluntary contractions 7), 12).
Chen et al. investigated muscle stiffness using
SWE of the biceps brachii muscle in 10 healthy
controls according to sex during 30° ﬂexionand extension of the elbow 13). They reported
that SWE is reproducible and valid for quantiﬁcation of biceps brachii stiffness. However,there have been few reports on the quantitative assessment of muscle stiffness in patientswith PD 14). Du et al. found a relatively strong
correlation between muscle stiffness measured
using SWE in the biceps brachii of patientswith PD and the comprehensive motor symptom score (r = 0.646, P < 0.001) from 14 assessment items in the UPDRS Part III 14). They reported that SWE of the biceps brachii was effective for the quantitative evaluation of muscle
stiffness in patients with PD. Additionally, theyobserved that the higher the muscle rigidity of
the upper limb, the higher the measured

30 ◆ Journal of JART English edition 2024

Youngʼs modulus (muscle stiffness), which directly correlated with a decline in upper limb
motor function. Therefore, they stated that“muscle stiffness assessed using SWE in the biceps brachii of patients with PD seems to beclosely related to the rigidity score (severity)” 14).
However, this report did not explicitly elucidate the relationship between muscle stiffness
measured using SWE in the biceps brachii ofpatients with PD and the rigidity score (severity) for the upper limbs, a single evaluation
item in the UPDRS for the same location.
The objective of this study was to clarify the
relationship between biceps brachii muscle
stiffness measured using SWE and the upper
extremity rigidity score (severity) evaluatedusing the MDS-UPDRS in patients with PD. Additionally, this study aimed to clarify thresholds
for muscle stiffness using SWE for each rigidityscore.

2. Methods
2-1 Participants and Evaluation

This was a single-center prospective investigation conducted at our institution. This study
included patients with PD who were admitted
to our hospital between January and July 2019.
PD was diagnosed in these patients by neurologists based on the widely used clinical diagnostic criteria for Parkinsonʼs disease established by the MDS 15). In contrast, the control
group consisted of healthy individuals without

original articles
A Prospective Study of Muscle Stiffness Using Ultrasound Shear Wave Elastography in the Biceps Brachii of Patients with Parkinson’s Diseasea history of neuromuscular disorders or receiving any medication therapy.
For patients with PD, muscle stiffness wasmeasured using SWE in the biceps brachii andupper extremity rigidity was assessed using the
MDS-UPDRS. For comparison, healthy controls
underwent muscle stiffness measurements using SWE in the biceps brachii.

laid on the B-mode image represent the regions of interest (ROI) (Fig. 1a). The color
scale within these coded boxes, featuring blue
(soft tissue) and red (hard tissue), reﬂects thevalues of muscle stiffness within the ROI (Fig.
1a). For the quantitative analysis, a circular
ROI with a diameter of 5 mm was placed within the box 14), 23). This allowed the calculation ofmuscle stiffness (Youngʼs modulus) within thecircle (Fig. 1a). The settings for muscle stiffness
measurements included a depth of ﬁeld of 4
cm, a single focal point, and tissue harmonic
imaging. Muscle stiffness measurements wereconducted three times separately in the left
and right biceps brachii of all participants (patients with PD and healthy controls) 13, 14). The
average value was then calculated, serving as
the representative value for muscle stiffness in
the left and right biceps brachii separately 13, 14).
These measurements were applied to all par-2-2 Measuring muscle stiffness (Youngʼs modulus) using SWE in biceps brachii

Muscle stiffness (Youngʼs modulus) was measured using SWE in patients with PD and
healthy controls separately for the biceps brachii muscles on the left and right sides. All participants were positioned in a supine position
with their arms placed at their sides to ensurecomplete relaxation of the hands and limbs 14).
Muscle stiffness was measured using an Aplio
i700 system (Canon Medical Systems, Tochigi,
Japan) equipped with a linear probe operating
at frequencies of 4.0 –18.2 MHz. The scan was
initiated with a B-mode image set of skeletal
muscles to observe the biceps brachii 16), 17).
Subsequently, the probe orientation was adjusted in the direction of the biceps brachii muscle
ﬁbers (longitudinal view) 5), 13), 14), 18). Furthermore, the probe was gently positioned on theskin overlying the biceps brachii without exerting tissue compression. The middle portion of
the muscle belly, where the thickest muscle
bundle was located, was identiﬁed 11), 14), 19-22).
Thus, our measurement approach closely followed methods with documented researchoutcomes 11), 14), 19-22). Subsequently, the measurement mode was switched to SWE to quantify the muscle stiffness. The SWE function offers three image display modes: propagation
speed, muscle stiffness, and propagation (arrival-time contours). In Fig. 1, the left side (1a)represents the muscle stiffness display and theright side (1b) illustrates the propagation display. The propagation display presents shear
waves propagating within the muscle as moving images (Fig. 1b). Color-coded boxes over-

(1a)

(1b)

Fig. 1 Measuring muscle stiffness using SWE inlongitudinal plane of biceps brachii
Muscle stiffness (Youngʼs modulus) was measured at the
middle portion of the biceps brachii muscle belly where
the muscle bundle was the thickest 14). SWE has three image display modes: propagation speed, muscle stiffness,and propagation (arrival time contour). The left image (1a)shows the muscle stiffness display mode, and the right image (1b) shows the propagation display mode. The propagation display mode shows the shear wave propagation
within the muscle tissue as a moving image (1b). The
colored box superimposed on the B-mode scan image
represents the region of interest (ROI) (1a). Muscle stiffness (Youngʼs modulus) values are represented by a color
scheme in the ROI box: blue indicates soft tissue and red
indicates hard tissue (1a). A 5-mm diameter circle wasplaced within the ROI for quantitative measurement 14), 23),and the muscle stiffness (Youngʼs modulus) was calculated within the circle (1a). Muscle stiffness measurements
were conducted three times separately in the left andright biceps brachii of all participants (patients with PD
and healthy controls) 13), 14).

Arts and Sciences ◆ 31

ticipants. Muscle stiffness measurements wereconducted by a single radiological technologist, a certiﬁed sonographer with over 14 yearsof experience in ultrasound examinations.
The reasons for conducting the measurements
in triplicate are as follows. Previous studies on
stiffness measurement of the biceps brachii
muscle using SWE have reported good intraand inter-rater reliability even with 2–3 measurements 13), 14), 20), 21). In our preliminary study,
however, we could not conﬁrm the inter-rater
reliability because there was only one examiner; however, the intra-rater reliability was
good. Therefore, we adopted three measurements in this study.
2-3 Upper extremity rigidity scores evaluatedusing the MDS-UPDRS

Rigidity score (severity) was assessed using
Part III, 3.3 of MDS-UPDRS to evaluate upper
extremity rigidity (Table 1) 4). This assessment
was performed separately for the left and rightupper limbs in all patients with PD. The limb
with higher rigidity was designated as thedominant arm, whereas the limb with lower
rigidity was considered the non-dominant arm.
Muscle rigidity was scored by a physical therapist with > 16 years of experience in physicaltherapy for patients with PD. Muscle stiffness
and rigidity scores were rated on the same day
at the same time.
2-4 Statistical analysis

To analyze the factors inﬂuencing muscle
stiffness measured using SWE, a multiple regression analysis was conducted with muscle
stiffness using SWE as the dependent variable.
The seven independent variables were age,sex, and MDS-UPDRS rigidity scores ranging
from 0 to 4, each for both upper extremities(dominant and non-dominant arms), and thedominant arm. Sex and dominant arm wererepresented as dummy variables in the analysis. The selection of seven independent variables in the multiple regression analysis was

32 ◆ Journal of JART English edition 2024

based on the results of previous studies andclinical judgment 14). Additionally, the thresholdfor muscle stiffness in the dominant arm wascalculated using Receiver Operating Characteristic (ROC) curve analysis. The intra-rater reliability of SWE muscle stiffness measurements
was assessed using the intraclass correlation
coefﬁcient (ICC). The signiﬁcance level was set
at 5%, with a P-value < 0.05 considered statistically signiﬁcant. All analyses were performed
using EZR software (Jichi Medical University
Saitama Medical Center, Saitama, Japan) 24).
2-5 Ethical Consideration

This study was approved by the Ethics Committee of our institution (Approval Number:
H29-015). Written informed consent was obtained from all the participants. This study was
conducted in accordance with the principles of
the Declaration of Helsinki.

3. Results
In 43 patients with PD, muscle stiffness measurements using SWE in the biceps brachii andassessments of upper extremity rigidity using
the MDS-UPDRS were conducted. Additionally,
12 healthy controls underwent muscle stiffness
measurements using SWE in the biceps brachii.
The 43 patients included 20 males (40 limbs)
and 23 females (46 limbs) (Table 2). The average age was 69.7 years ± 8.3 years. The 12
healthy controls included 5 males (10 limbs)
and 7 females (14 limbs), with an average ageof 67.9 ± 5.3 years.
Based on the criteria for upper extremity rigidity scores using the MDS-UPDRS assessment(Table 1) 4), the frequency of each rigidity scorein the 43 patients with PD (86 limbs) was asfollows: score 0, eight limbs (9.3%); score 1, 23
limbs (26.7%); score 2, 44 limbs (51.2%); score3, 11 limbs (12.8%); and score 4, 0 limbs (0%).
Fig. 2 illustrates the muscle stiffness (Youngʼs
modulus) as measured on SWE for each rigidity score in the MDS-UPDRS upper limb assess-original articles
A Prospective Study of Muscle Stiffness Using Ultrasound Shear Wave Elastography in the Biceps Brachii of Patients with Parkinson’s Disease

Item

Control(n =12)PD(n = 43)

P -value

Age, mean±SD67.9±5.3

69.7±8.3

p ≧0.05

Female sex, n (%)

7 (58.3%)

23 (53.5%) p ≧0.05

Biceps brachii muscle stiffness (Young’s modulus) measured
using SWE 〔kPa〕

Table 2 Clinical characteristics of patients with PD
and control groups

Note: PD, Parkinsonʼs disease.

ment in patients with PD. Speciﬁcally, it shows
the stiffness of the right biceps brachii with respect to the rigidity score of the right upper
limb in patients with PD. Similarly, the stiffnessof the left biceps brachii is depicted with respect to the rigidity score of the left upper limb
(Fig. 2). Additionally, the ﬁgure includes themuscle stiffness measured using SWE in the biceps brachii of healthy controls (control). For
patients with PD, the muscle stiffness on SWE
in the upper limbs for each rigidity score was
as follows: score 0, 49.66 [40.80–61.20] kPa;
score 1, 57.81 [40.29–84.93] kPa; score 2, 110.13[63.69–159.14] kPa; and score 3, 180.75 [112.93–
259.84] kPa. The muscle stiffness measured using SWE in the biceps of healthy controls was
53.99 [43.66–61.62] kPa.
Multiple regression analysis for both upper
limbs (dominant and non-dominant arms) revealed that the factors inﬂuencing muscle stiffness measured using SWE were MDS-UPDRS
upper extremity rigidity scores of 2 (P < 0.001)
and 3 (P < 0.001), age (P = 0.030), and domi-

250

200

150

100

50

Control

0

1

2

3

MDS-UPDRS upper extremity rigidity scores in patients with PD

Fig. 2 Muscle stiffness (Youngʼs modulus) measured
using SWE for each MDS-UPDRS upper extremity rigidity score in patients with PD.

nant arm (P = 0.012) (Table 3). Age was excluded as a factor for threshold consideration
because its regression coefﬁcient estimate was
1.44, indicating a small effect on muscle stiffness measured using SWE. The threshold formuscle stiffness in the dominant arm of patients with PD was calculated using ROC analysis. The threshold for MDS-UPDRS upper extremity rigidity scores 1 and 2 in the dominantarm was 93.55 kPa, with an area under the
curve (AUC) of 0.74, and a 95% conﬁdence interval (CI) of 0.56–0.93 (Fig. 3). For scores 2
and 3, the threshold was 170.53 kPa, with an
AUC of 0.78 and a 95% CI of 0.59–0.98 (Fig. 4).
The ICC for SWE was 0.94 (p < 0.05).

Table 3 Factors affecting muscle stiffness measured using SWE in both upper limbs (dominant and nondominant arms)
Regression Coefficient
Constant

t -valuep -value–45.515

Age

1.443

2.202

0.030

Female sex–1.233–0.131

0.90

MDS-UPDRS upper extremity rigidity score ：0

0.764

0.037

0.97

MDS-UPDRS upper extremity rigidity score ：1–0.197–0.013

0.99

MDS-UPDRS upper extremity rigidity score ：2

50.704

3.793

P <0.001

MDS-UPDRS upper extremity rigidity score ：3

98.327

4.839

P <0.001

Dominant arm

27.450

2.550

0.012

2

Note: Analysis of variance p <0.001, Coefﬁcient of determination (R ) = 0.440;
MDS-UPDRS, Movement Disorder Society-Sponsored Revision of the Uniﬁed Parkinsonʼs Disease Rating Scale; SWE, shear
wave elastography.

Arts and Sciences ◆ 33

1.0

0.8

0.8
93.549（0.826, 0.682）

0.6

Sensitivity

Sensitivity

1.0

0.4

0.6

170.526（0.773, 0.636）

0.4

Threshold value of muscle stiffness 93.55
0.2

Threshold value of muscle stiffness 170.53
0.2

AUC 0.74
95%CI 0.56–0.93
Specificity 82.6%
Sensitivity 68.2%

0.0
1.0

0.8

0.6
0.4
Specificity

AUC 0.78
95%CI 0.59–0.98
Specificity 77.3%
Sensitivity 63.6%

0.0
0.2

0.0

Fig. 3 ROC analysis of patients with PD with an MDSUPDRS rigidity score of 1 or 2 in the dominantarm

4. Discussion
The objective of this study was to clarify the
relationship between biceps brachii muscle
stiffness measured using SWE and the upper
extremity rigidity score (severity) evaluatedusing the MDS-UPDRS in patients with PD. Additionally, this study aimed to determine thethreshold for muscle stiffness using SWE foreach rigidity score.
The results of the multiple regression analysis
indicated that MDS-UPDRS upper extremity
rigidity scores of 2 and 3, age, and dominantarm (Table 3) were factors affecting muscle
stiffness measured using SWE. Furthermore,
the use of threshold values for muscle stiffness
using SWE in the dominant arm suggests thepotential to distinguish between rigidity scoresof 1, 2, and 3 in the upper extremities.
Du et al. investigated muscle stiffness using
SWE of the biceps brachii in patients with PD
and healthy controls 14). They reported thatmuscle stiffness in the biceps brachii of patients with PD with noticeable or mild upper
limb rigidity was signiﬁcantly higher than thatin healthy controls. However, this study did

34 ◆ Journal of JART English edition 2024

1.0

0.8

0.6
0.4
Specificity

0.2

0.0

Fig. 4 ROC analysis of patients with PD with an MDSUPDRS rigidity score of 2 or 3 in the dominantarm

not examine the relationship between muscle
stiffness measured using SWE in the biceps
brachii and upper extremity rigidity scores using UPDRS. Therefore, it remains unclear
whether rigidity scores affect muscle stiffness
as measured using SWE.
As a result of our multiple regression analysis, we identiﬁed that upper extremity rigidityscores of 2 and 3 were factors affecting muscle
stiffness measured using SWE. Although age
was also detected as a factor inﬂuencing muscle stiffness, the regression coefﬁcient estimate
was 1.44 (Table 3), suggesting that age had aminor impact on muscle stiffness. We focusedon other factors that strongly inﬂuence muscle
stiffness.
In the subsequent multiple regression analysis of both upper limbs (dominant and nondominant arms), the coefﬁcient of determination was 0.440 (Table 3). In contrast, the coefﬁcient of determination for the dominant arm
alone was 0.536, suggesting a better ﬁt thanthat observed for both upper limbs. Therefore,
we calculated the threshold for muscle stiffnessfor each upper extremity rigidity score in the
MDS-UPDRS using muscle stiffness on SWE inoriginal articles
A Prospective Study of Muscle Stiffness Using Ultrasound Shear Wave Elastography in the Biceps Brachii of Patients with Parkinson’s Disease

the dominant arm. Through ROC analysis of
the dominant arm only, we calculated thethreshold for muscle stiffness using the MDSUPDRS in the dominant arm as 93.55 kPa for
rigidity scores 1 and 2 (Fig. 3) and 170.53 kPa
for rigidity scores 2 and 3 (Fig. 4). Based onthese results, it is considered possible to distinguish between rigidity scores 1, 2, and 3 using
the threshold for muscle stiffness using SWE in
the dominant arm: < 93.55 kPa for rigidityscore 1, 93.55–170.53 kPa for rigidity score 2,
and > 170.53 kPa for rigidity score 3.
Table 1 shows the criteria for upper extremity rigidity scores in the MDS-UPDRS 4). A scoreof 0 indicates “Normal,” while a score of 4 indicates “Rigidity detected without the activation
maneuver, and full range of motion notachieved” (Table 1) 4). In other words, it is generally assumed that the examiner can assess
accurately when the score is 0 or 4. In contrast,
scores 1–3 are subjectively evaluated by theexaminer, suggesting potential variability inscoring compared with scores of 0 and 4 (Table
1) 3), 4). However, the results of this study suggest the possibility of objectively distinguishingeach rigidity score using the threshold for muscle stiffness obtained using SWE. To determine
an appropriate treatment approach and assess
the therapeutic effects of medications, it is essential to evaluate the rigidity score (severity)using the MDS-UPDRS with objective andquantiﬁable indicators. Furthermore, it is crucial to ensure standardized evaluation acrossall medical facilities. Based on the results ofthis study, SWE is considered an effective
method for quantifying muscle stiffness in thebiceps brachii of patients with PD.

5. Limitations
The authors acknowledge the limitations of
this study as a single-center investigation. In
previous studies on muscle stiffness measurement, no reports have compared muscle stiffness using SWE on ultrasound devices fromdifferent manufacturers. Therefore, a futurechallenge is to conduct collaborative, multicenter studies, including assessments of muscle stiffness using SWE, considering the differences between manufacturers.

6. Conclusion
Upper extremity rigidity scores of 2 and 3 on
the MDS-UPDRS were factors affecting muscle
stiffness measured using SWE. Furthermore,
the use of threshold values for muscle stiffness
using SWE in the dominant arm suggests thepotential to distinguish between rigidity scoresof 1, 2, and 3 in the upper extremities.

Acknowledgments
We express our heartfelt gratitude for theguidance and cooperation of the many people
who participated in this study. We would liketo thank Editage (www.editage.jp) for the English language editing.
Conflict of Interest

The authors declare no conﬂicts of interest
regarding this study.

References
1） Jankovic J: Parkinsonʼs disease: clinical features anddiagnosis. J Neurol Neurosurg Psychiatry, Apr, 79(4),368-376, 2008.
2） Djaldetti R, et al.: The mystery of motor asymmetry in
Parkinsonʼs disease. Lancet Neurol, Sep, 5(9), 796802, 2006.
3） Fahn S, et al.: Members of the UPDRS Development
Committee: Unified Parkinsonʼs Disease Rating Scale.
in Recent Developments in Parkinson ʼ s Disease,
Vol.2 (ed. by Fahn S, et al.):. Macmillan Health Care
Information, Florham Park, NJ, 153-163, 293-304,
1987.
4） Goetz CG, et al.: Movement Disorder Societysponsored revision of the Unified Parkinsonʼs Disease
Rating Scale (MDS-UPDRS): scale presentation andclinimetric testing results. Mov Disord, Nov, 23(15),2129-2170, 2008.
5） Creze M, et al.: Shear wave sonoelastography ofskeletal muscle: basic principles, biomechanicalconcepts, clinical applications, and future
perspectives. Skeletal Radiol, Apr, 47(4), 457-471,
2018.

Arts and Sciences ◆ 35

6） Brandenburg JE, et al.: Ultrasound elastography:
the new frontier in direct measurement of muscle
stiffness. Arch Phys Med Rehabil, Nov, 95(11), 22072219, 2014.
7） Shinohara M, et al.: Real-time visualization of muscle
stiffness distribution with ultrasound shear wave
imaging during muscle contraction. Muscle Nerve,
Sep, 42(3), 438-441, 2010.
8） Maïsetti O, et al.: Characterization of passive elastic
properties of the human medial gastrocnemius muscle
belly using supersonic shear imaging. J Biomech, Apr,
45(6), 978-984，2012.
9） Chino K, et al.: Measurement of gastrocnemius
muscle elasticity by shear wave elastography:
association with passive ankle joint stiffness and sex
differences. Eur J Appl Physiol, Apr, 116(4), 823-830,
2016.
10）Gennisson JL, et al.: Viscoelastic and anisotropic
mechanical properties of in vivo muscle tissue
assessed by supersonic shear imaging. Ultrasound
Med Biol, May, 36(5), 789-801, 2010.
11）Eby SF, et al.: Shear wave elastography of passive
skeletal muscle stiffness: influences of sex and age
throughout adulthood. Clin Biomech (Bristol, Avon),Jan, 30(1), 22-27, 2015.
12）Nordez A, et al.: Muscle shear elastic modulus
measured using supersonic shear imaging is highly
related to muscle activity level. J Appl Physiol, May,
108(5), 1389-1394, 2010.
13）Chen J, et al.: Ultrasound shear wave elastography
in the assessment of passive biceps brachii muscle
stiffness: influences of sex and elbow position. Clin
Imaging, Sep-Oct, 45, 26-29, 2017.
14）Du LJ, et al.: Ultrasound shear wave elastography
in assessment of muscle stiffness in patients with
Parkinson ʼ s disease: a primary observation. Clin

36 ◆ Journal of JART English edition 2024

Imaging, Nov-Dec, 40(6), 1075-1080, 2016.
15）Postuma RB, et al.: MDS clinical diagnostic criteria for
Parkinsonʼs disease. Mov Disord, Oct, 30(12), 1591601, 2015.
16）Gennisson JL, et al.: Transient elastography inanisotropic medium: application to the measurementof slow and fast shear wave speeds in muscles. J
Acoust Soc Am, Jul, 114(1), 536-541, 2003.
17）Gennisson JL, et al.: Human muscle hardness
assessment during incremental isometric contraction
using transient elastography. J Biomech, Jul, 38(7),1543-1550, 2005.
18）Eby SF, et al.: Validation of shear wave elastography
in skeletal muscle. J Biomech, Sep, 46(14), 23812387, 2013.
19）Murayama M, et al.: Changes in biceps brachii
muscle hardness assessed by a push-in meter andstrain elastography after eccentric versus concentric
contractions. Sci Rep, Jun 2;12(1), 9214, 2022．
20）Gao J, et al.: Quantitative ultrasound Imaging toassess the biceps brachii muscle in chronic poststroke spasticity: Preliminary observation. Ultrasound
Med Biol, Sep, 44(9), 1931-1940, 2018．
21）Phan A, et al.: Ultrasound shear wave elastography
in assessment of skeletal muscle stiffness in senior
volunteers. Clin Imaging, Nov-Dec, 58, 22-26, 2019．
22）Lacourpaille L, et al.: Non-invasive assessment ofmuscle stiffness in patients with Duchenne muscular
dystrophy. Muscle Nerve, Feb, 51(2), 284-286, 2015．
23）Akagi R, et al.: Acute effect of static stretching on
hardness of the gastrocnemius muscle. Med Sci
Sports Exerc, Jul, 45(7), 1348-1354, 2013.
24）Kanda Y: Investigation of the freely available easyto-use software ʻ EZR ʼ for medical statistics. Bone
Marrow Transplant, Mar, 48(3), 452-458, 2013.

Arts and Sciences
original articles

Received July 31, 2022 ; accepted January 3, 2023

Fundamental study for application of 3D phasesensitive inversion recovery sequence to multiple
sclerosis
ENOKI Takuya1），2）, JOMOTO Wataru2）, KIDA Katsuhiro1）, GOTO Sachiko1）,
KOTOURA Noriko2）
1）Graduate School of Health Sciences, Okayama University2）Department of Radiological Technology, Hyogo Medical University Hospital

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 848: 20-27, 2023.
Key words: Phase sensitive inversion recovery, Inversion time, Magnetic resonance imaging, Brain【Abstract】

This study clariﬁed the relationship between imaging parameters and contrast during application of the 3D phasesensitive inversion recovery (PSIR) method for detection of multiple sclerosis. In this phantom study, we investigatedthe effects of the turbo ﬁeld echo (TFE) factor, shot interval, and inversion time (TI) on contrast. A TFE factor of 30
and shot interval of 1000 ms were employed. In the in vivo study, visual evaluations were performed to assess thebrain tissue contrast when TI variations were noted. This in vivo study enrolled 10 healthy volunteers. 3D-PSIR images
were acquired with six different inversion times (300, 400, 500, 600, 700, and 800 ms). A longer inversion time for
3D-PSIR increased the contrast of the brain tissue. To apply 3D-PSIR to multiple sclerosis lesions, a TI of 700 ms issuitable when the TFE factor is 30 and the shot interval is 1000 ms.

1 Introduction
Double inversion recovery (DIR) has been
widely used to detect cortical lesions inpatients diagnosed with multiple sclerosis(MS) 1–4). However, DIR has been reported tohave a low signal-to-noise ratio (SNR) andsensitivity for cortical lesions 4). Phase-sensitive
inversion recovery (PSIR) is a T 1-weighted
sequence that uses the inversion recovery (IR)method, which has been reported to improvethe detection of cortical lesions in patients withMS, compared to that of DIR, because of its
excellent contrast between the white matter(WM), gray matter (GM), and cerebrospinal
ﬂuid (CSF) and higher SNR 5–11).
In a previous study, PSIR was obtained byreconstructing real images acquired using a
2D-IR turbo spin-echo (TSE) sequence 5–11).
In the present study, we investigated thecontrast of 3D-PSIR based on a gradient echo
sequence, in which two signals were acquired

and phase correction was performed. Since
3D-PSIR can prevent IR-induced signal polarity
reversal by phase correction, it is a well-known
imaging sequence that enables visualizationof the injured myocardium regardless of
the inversion time (TI) to nullify the signal
intensity of the normal myocardium in lategadolinium-enhanced cardiac imaging 12) .
However, because PSIR uses the IR method,
the contrast is expected to change dependingon the timing of signal acquisition 7, 13). In
a previous study, a TI of approximately
400 ms was used in 2D-PSIR 5–11); however,
because the repetition time (TR) and echo
time (TE) are different in each report, thecontrast is expected to differ with the same TI.
Furthermore, the optimal TI may differ whenusing 3D-PSIR, and the turbo ﬁeld echo (TFE)
factor and shot interval are also expected toaffect the contrast.
The purpose of this study was to clarify the
relationship between imaging parameters andArts and Sciences ◆ 37

contrast when applying the 3D-PSIR methodfor detection of MS.

2 Materials and Methods
2.1 Theory

Magnetic resonance imaging (MRI) scans
were acquired using a 3.0-T MRI system witha 32-channel phased-array head coil (Ingenia;
Philips Healthcare, Best, Netherlands). In
the PSIR of this study, after the nonselective
inversion pulse, signal acquisition was
performed with a fast gradient echo after eachof the two TIs. The ﬁrst TI (ﬁrst acquisition)acquired the magnitude-T 1 contrast image,and the second TI (second acquisition)acquired the reference image. Since the T1
contrast image has an inverted signal polarity
depending on the TI setting, the following
procedure was used to calculate the PSIR
image with preserved signal polarity: A B1
field correction map was created from thephase information obtained in the second
acquisition, and phase correction was
performed on the signals obtained in thefirst and second acquisitions. The phasecorrected signal was divided into real andimaginary parts using quadrature phasesensitive detection, and the real and imaginary
images were calculated using a complex
Fourier transform. Subsequently, a magnitude
image was calculated from the ﬁrst acquisition
and a phase image was calculated from thesecond acquisition. The magnitude image wasmultiplied by the phase image to reconstruct
the real image and obtain the PSIR image. The
timing of the two acquisitions can be adjusted
using shot intervals. Figure 1 presents an
overview of the sequence.
2.2 Phantom study

To evaluate the image quality, we diluted
manganese chloride tetrahydrate (MCT) andagar with saline to create phantoms for theWM model (MCT 16 w/v%, agar 0.2 w/v%),

38 ◆ Journal of JART English edition 2024

Fig. 1 Overview of PSIR sequenceFig. 1 After TI from the inversion pulse, the T1 contrast image

was acquired by a fast gradient echo. After a certain time,a fast gradient echo was used to acquire a reference
image. The PSIR was reconstructed from the two images,
and the timing of the two image acquisitions was adjusted
by the shot interval.

GM model (8 w/v%, agar 0.3 w/v%), and CSF
model (saline). The three phantoms werestored in a polypropylene case, which was
ﬁlled with agar diluted with saline (0.1 w/v%).
Figure 2 shows an overview of the phantom.
T1 and T2 values of these materials are listed
in Table 1. Image quality was evaluated by thecontrast-to-noise ratio (CNR) using a regionof interest (ROI) for each phantom (Fig. 3).
The signal intensity was measured on the
console and the CNR was calculated using thefollowing formula:
CNR=|SIa-SIb|/SDBG, (1)where SIa and SIb are the mean signal intensities
in phantoms a and b, respectively; SD BG isthe standard deviation of the backgroundsignal intensity. The background ROI was
elliptical and large to reduce variation
with measurement location. Preliminary
experiments confirmed that the phantom
created in this study provided a contrast similar
to that of the in vivo phantom. Although it isdesirable to create a phantom that simulates
an MS lesion, the relaxation time of the lesion
has not been clariﬁed; therefore, it was difﬁcult
to create a phantom. In previous studies,original articles
Fundamental study for application of 3D phase-sensitive inversion recovery sequence to multiple sclerosis

Table 1 T1 and T2 values of materials
Material

T1 relaxation time(ms)

T2 relaxation time(ms)

WM model

824.0

67.6

GM model1329.0

114.1

CSF model

2906.22047.0

bandwidth (BW), 540 Hz/pixel; and scan time,
29 s –1 min 38 s.
2.2.1 Investigation of TFE factor

The shot interval and TI were ﬁxed at 1000
ms and 600 ms, respectively, and the TFE
factor varied between 20, 30, and 40. We
measured the CNR between the WM modeland GM models (WMm-GMm), WM model and
CSF models (WMm-CSFm), and GM model and
CSF models (GMm-CSFm) and evaluated thechange in CNR with changes in the TFE factor.
2.2.2 Investigation of shot interval

Fig. 2 Overview of the phantom

The TFE factor and TI were ﬁxed at 30 and
600 ms, respectively, and the shot intervalvaried between 800, 1000, 1200, and 1400 ms.
We measured the CNR between WMm-GMm,
WMm-CSFm, and GMm-CSFm and evaluated thechange in CNR with the changes in the shot
interval.
2.2.3 Investigation of TI

Fig. 3 Example of region of interest setting

MS lesions were more hypointense than GM
lesions on 2D-PSIR 5–11) and were expected tohave a signal intensity between those of GM
and CSF.
3D-PSIR was performed using a 3D TFE
sequence. 3D-PSIR images with three different
TFE factors (20, 30, and 40), four different
shot intervals (800, 1000, 1200, and 1400 ms),and nine different TIs (160, 200, 300, 400, 500,
600, 700, 800, and 840 ms) were acquired
to investigate the CNR. Other parameters
were as follows: ﬁeld of view, 250 mm; sliceorientation, coronal; pixel size, 0.98 × 0.96mm; slice thickness, 4 mm; number of slices, 6;
number of excitations, 1; sensitivity encoding
factor, 1; profile order, linear; TR, 10 ms;
TE, 4.6 ms; ﬂip angle (FA), 20 °; PSIR FA, 5 °;The TFE factor and shot interval were
ﬁxed at 30 and 1000 ms, respectively, and TI
varied between 160, 200, 300, 400, 500, 600,
700, 800, and 840 ms. We measured the CNR
between WM m-GM m, WM m-CSF m, and GM mCSFm and evaluated the change in CNR withthe changes in TI. We evaluated the changes
in the mean signal intensities of each phantom
associated with TI change.
2.3 In vivo study

Ten healthy volunteers (five males andﬁve females; age range, 23–57 years; median[interquartile range] age, 39.5 [12.5] years) wereenrolled in this study. The Institutional Review
Board of Hyogo Medical University approved
this study, and informed consent was obtained
from all participants in accordance with the
Declaration of Helsinki (approval number
202104-521).
3D-PSIR was performed using a 3D TFE
sequence. 3D-PSIR images with six different
Arts and Sciences ◆ 39

TIs (300, 400, 500, 600, 700, and 800 ms)
were acquired to investigate the brain tissue
contrast. Other parameters were as follows:
field of view, 230 mm; slice orientation,transverse; pixel size, 0.85 × 0.85 mm; slice
thickness, 3 mm; number of slices, 35; numberof excitations, 1; sensitivity encoding factor,
2; profile order, linear; TFE factor, 30; shot
interval, 1000 ms; TR, 10 ms; TE, 4.6 ms;
FA, 20 °; PSIR FA, 5 °; BW, 540 Hz/pixel; andscan time, 2 min 17 s. The imaging slab wasparallel to the anterior commissure-posterior
commissure line, and the center of the imaging
slab was set at the level of the insular cortex.

normalized, and a one-way analysis ofvariance was performed on the means of
the normalized scores. The modified leastsignificant difference (MLSD) of the Fisher–
Hayter procedure was used to determine
signiﬁcant differences among the ranks 15).
Statistical analysis was performed using the
JMP Pro ver.15.2.0 software (SAS Institute,Cary, NC, USA). Statistical signiﬁcance was set
at p < 0.05.

3 Results
3.1 Phantom study
Figures 4 and 5a show MR images and
CNR results for the different TFE factors. The
CNR decreased as the TFE factor increased.
When the TFE factor was 40, strong blurring
occurred. The CNR increased as the shot
interval and TI increased (Fig. 5b and c). The
signal intensities of WM m, GM m, and CSF m
increased as TI increased. The signal intensitiesof each phantom increased as TI increased,

2.3.1 Visual evaluation

Five radiologists (10–26 years of reading
experience) performed the visual evaluation
using the normalized ranking method 14) .
WM-GM, WM-CSF, and GM-CSF contrasts at
the insular cortex level were evaluated. The
medical imaging display monitor was set to a
six-split display, and the six TI images wererandomly placed foreach evaluation item andfor each volunteer, andranked accordingly. Since
3D-PSIR has a different
background signal, theimage was magnified to
the furthest extent, so thatthe background signal wasFig. 4 MR images for different TFE factor
not observed.
Fig. 4(a) TFE factor=20. (b) TFE factor=30. (c) TFE factor=40.

2.3.2 Statistical analysis
b

60
50

WMm‐CSFmc60
50

Fig. 430

WMm‐GMm

20

GMm‐CSFm

030

WMm‐GMm

30

TFE factor

40

0

30

WMm‐GMm

20

GMm‐CSFm

1020

WMm‐CSFm

40

20

10

60
50

WMm‐CSFm

40

CNR

40

CNR

a

CNR

Kendallʼs coefficient ofconcordance (W) was
calculated from the ranked
r es u l t s o b t ained fr om
the visual evaluation. W
ranges from 0 to 1, where
0 indicates no agreement
among raters and 1 indicates complete agreement.
The ranked results were

800

1000

1200

Shot interval (ms)1400

GMm‐CSFm

10
0

100

200

300

400

500

600

700

800

900

TI (ms)Fig. 5 Relationship between CNR of the phantom and each parameter(a) CNR of
Fig.WM
5 m-CSFm, WMm-GMm, and GMm-CSFm for different TFE factors.
(b) CNR of WMm-CSFm, WMm-GMm, and GMm-CSFm for different shot intervals.
(c) CNR of WMm-CSFm, WMm-GMm, and GMm-CSFm for different TIs.

40 ◆ Journal of JART English edition 2024

original articles
Fundamental study for application of 3D phase-sensitive inversion recovery sequence to multiple sclerosis

and the difference in the signal intensities ofeach phantom became larger (Fig. 6).

2500

WMm

2000

Signal intensity

1500

3.2 In vivo study
Figure 7 shows MR images of a volunteer.

GMm

1000

CSFm

500
0
500

The tissue contrast varied for each TI. The
signal intensities of WM, GM, and CSF
increased as TI increased.
The rank order of the visual evaluation of
TI (ms)the WM-GM contrast was 600 > 700 > 500 >Fig.
Fig. 66 Relationship between signal intensity of the
800 > 400 > 300 (Table 2). The differences inphantom and each TI
the normal scores among these ranks were0.323, 0.212, 0.350, 0.359, and
0.628, respectively, and there
were no signiﬁcant differences
between 500 and 700 (W= 0.55, p < 0.001, MLSD =0.306). The rank order of thevisual evaluation for WM-CSF
contrast was 700 > 800 > 600> 500 > 400 > 300 (Table 3).
The differences in the normalscores among these ranks were
0.057, 0.264, 0.687, 0.456, and
0.630, respectively, and there
were no signiﬁcant differences
between 700 and 800 (W= 0.89, p < 0.001, MLSD =Fig. 7 Example of a PSIR image with the TI varying from 300 ms to0.168). The rank order of visual
800 msFig. 7
evaluation for GM-CSF contrast(a) TI = 300 ms. (b) TI = 400 ms. (c) TI = 500 ms. (d) TI = 600 ms. (e) TI = 700 ms.
was 700 > 800 > 600 > 500( f ) TI = 800 ms.
1000

‐1500
‐2000

‐2500
100

200

300

400

500

600

700

800

900

Table 2 Results of visual evaluation in WM-GM and significant differences in normal scores
between each rank using Fisher–Hayter procedure (MLSD = 0.306)
TI (ms)Rank TI (ms)
1

600

2

700

3

500

4

800

5

400

6

300

600

700

0

0.323
0

500
*

0.535

800
*

0.212 n.s.
0

0.885

400
*

1.245

300
*

1.873

*

0.562

*

0.921

*

1.550

*

0.350

*

0.709

*

1.338

*

0.359

*

0.987

*

0.628

*

0

0

0

Signiﬁcant difference: the difference between each rank is larger than that of the MLSD (α = 0.05)
and indicated with *. MLSD, modiﬁed least signiﬁcant difference; n.s., not signiﬁcant; TI, inversion time

Arts and Sciences ◆ 41

Table 3 Results of visual evaluation in WM-CSF and significant differences in normal scores
between each rank using Fisher–Hayter procedure (MLSD = 0.168)
TI (ms)Rank TI (ms)
1

700

2

800

3

600

4

500

5

400

6

300

700

800

0

0.057 n.s.
0

600

500

400

300

0.321

*

1.008

*

1.464

*

2.094

*

0.264

*

0.951

*

1.407

*

2.037

*

0.687

*

1.143

*

1.773

*

0.456

*

0

0

0

1.086

*

0.630

*

0

Signiﬁcant difference: the difference between each rank is larger than that of the MLSD (α = 0.05)
and indicated with *. MLSD, modiﬁed least signiﬁcant difference; n.s., not signiﬁcant; TI, inversion time

Table 4 Results of visual evaluation in GM-CSF and significant differences in normal scores
between each rank using Fisher–Hayter procedure (MLSD = 0.183)
TI (ms)Rank TI (ms)
1

700

2

800

3

600

4

500

5

400

6

300

700

800

600

0

0.148 n.s.

0.229

0

500

400

300

*

0.977

*

1.458

*

2.071

*

0.081 n.s.

0.829

*

1.310

*

1.923

*

0.748

*

0

0

1.228

*

1.842

*

0.480

*

1.094

*

0.614

*

0

0

Signiﬁcant difference: the difference between each rank is larger than that of the MLSD (α = 0.05)
and indicated with *. MLSD, modiﬁed least signiﬁcant difference; n.s., not signiﬁcant; TI, inversion time

> 400 > 300 (Table 4). The differences in thenormal scores among these ranks were 0.148,
0.081, 0.748, 0.480, and 0.614, respectively.
There were no signiﬁcant differences between
700 and 800 or 800 and 600 (W = 0.87, p <0.001, MLSD = 0.183).

4 Discussion
We conducted a fundamental study ofimaging parameters for the application of
3D-PSIR in the detection of MS. The contrast
between GM and CSF was important because
MS lesions were expected to have a signal
intensity between those of GM and CSF 5–11).
However, because MS lesions are located not
only at the WM but also at the GM, evaluationof WM-GM and WM-CSF contrasts wasnecessary. Our study clariﬁed the relationshipbetween WM, GM, and CSF contrasts andvarying TFE factors, shot intervals, and TIs in

42 ◆ Journal of JART English edition 2024

3D-PSIR.
The phantom study showed that the CNR
increased with a lower TFE factor, longer
shot interval, and longer TI. A high TFE factor
caused blurring and a decrease in CNR owing
to the large number of echoes to be recorded
and the inclusion of echoes with low signal
intensities. A longer shot interval and TI
accelerated the recovery of the longitudinalmagnetization; therefore, the CNR of eachphantom increased. The TFE factor and shot
interval significantly affected the scan time.
Since the phantom study showed that the CNRof GM m-CSF m was maintained up to a TFE
factor of 30 and that the shot interval did notcontribute signiﬁcantly to CNR improvement, a
TFE factor of 30 and shot interval of 1000 ms
were employed. In the in vivo study, visualevaluations were performed to assess thecontrast when TI variations were noted.
In the visual evaluation, considering theoriginal articles
Fundamental study for application of 3D phase-sensitive inversion recovery sequence to multiple sclerosis

results of the phantom study, the WM-CSF
and GM-CSF contrasts were expected to be
the highest among the images with a TI of
800 ms; however, this was not the case. As
TI increased, the signal intensity and contrastof each tissue increased. Nevertheless, we
assumed that it was impossible to visually
distinguish the contrast above a speciﬁc value.
W values in the visual evaluation of WM-GM(0.55) were lower than those of WM-CSF and
GM-CSF (0.89 and 0.87, respectively). Since
the CNR of WMm-GMm was almost constantat a TI of 500–700 ms in the phantom study,
we assumed that the inter-rater variance wasincreased in the visual evaluation of WM-GM.
Based on the changes in the signal intensitiesof GMm and CSFm in the phantom study, alonger TI is expected to improve the contrast
with the MS lesion. However, considering
the results of the phantom study and visualevaluations, we assumed that a TI of 700 ms
was appropriate.
A TI of approximately 400 ms was usedin previous studies that utilized TSE 5–11) and
was different from the optimal TI noted inthis study, which utilized the gradient echo.
Gradient echo-based 3D-PSIR imaging has
been reported to improve the detection of
spinal cord lesions in patients with MS witha TI of 350–400 ms 16, 17). These reports also
differ from our results, but this is owing to
the differences in the target area. In the spinal
cord, CSF is distributed around the WM, and
the WM-CSF contrast is high, even with arelatively short TI. Therefore, we assumed
that a TI of 350–400 ms is acceptable in the
spinal cord region. These studies also used a
TFE factor of 67–69, which was higher thanour imaging parameters of 30. A high TFE
factor reduces the scan time but also causes a
decrease in contrast and blurring; therefore, it

must be considered carefully.
This study had some limitations. First, the
TI setting is limited to a TFE factor of 30 andshot interval of 1000 ms. If other parameters
are changed, the TI setting must be modiﬁed
again. Secondly, a slice thickness of 3 mm
was used. In a 3D sequence, it is desirable
to use a slice thickness of approximately 1
mm. However, thicker slices were used toreduce the effect of noise because we focusedon evaluating contrast. Third, the imaging
parameters obtained in this study have notbeen evaluated in clinical use. Therefore, it isnecessary to apply the results of the present
study to the diagnosis of MS.

5 Conclusion
In 3D-PSIR, a smaller TFE factor, longer shot
interval, and longer TI improve tissue contrast.
To apply 3D-PSIR to MS lesions, a TI of 700 ms
is suitable when the TFE factor is 30 and theshot interval is 1000 ms.

Declarations
Conflicts of Interest:

The authors declare that they have noconﬂicts of interest.
Ethical approval:

All procedures performed in this study
involving human participants were inaccordance with the ethical standards of theInstitutional Review Board (IRB) and withthe 1964 Helsinki declaration and its later
amendments or comparable ethical standards.
Informed consent:

Informed consent was obtained from allindividual participants included in the study.

Arts and Sciences ◆ 43

References
1） Geurts JJ, et al.: Intracortical lesions in multiple
sclerosis: improved detection with 3D double
inversion-recovery MR imaging. Radiology, 236: 25460, 2005.
2） Calabrese M, et al.: Detection of cortical inflammatory
lesions by double inversion recovery magnetic
resonance imaging in patients with multiple sclerosis.
Arch Neurol, 64: 1416-22, 2007.
3） Calabrese M, et al.: A 3-year magnetic resonanceimaging study of cortical lesions in relapse-onset
multiple sclerosis. Ann Neurol, 67: 376-83, 2010.
4） Seewann A, et al.: Postmortem verification of MS
cortical lesion detection with 3D DIR. Neurology, 78:
302-8, 2012.
5） Sethi V, et al.: Improved detection of cortical MS
lesions with phase-sensitive inversion recovery MRI. J
Neurol Neurosurg Psychiatry, 83: 877-82, 2012.
6） Harel A, et al.: Phase-sensitive inversion-recovery
MRI improves longitudinal cortical lesion detection inprogressive MS. PLoS One, 11: e0152180, 2016.
7） Hou P, et al.: Phase-sensitive T1 inversion recovery
imaging: a time-efficient interleaved technique for
improved tissue contrast in neuroimaging. AJNR Am
J Neuroradiol, 26: 1432-8, 2005.
8） Nelson F, et al.: Improved identification of intracorticallesions in multiple sclerosis with phasesensitive
inversion recovery in combination with fast double
i n v e r s i o n re c o v e r y M R i m a g i n g . A J N R A m J
Neuroradiol, 28: 1645-9, 2007.
9） Nelson F, et al.: Intracortical lesions by 3T magnetic
resonance imaging and correlation with cognitive
impairment in multiple sclerosis. Mult Scler, 17: 11229, 2011.

44 ◆ Journal of JART English edition 2024

10）Sethi V, et al.: MS cortical lesions on DIR: not quite
what they seem? PLoS One, 8: e78879, 2013.
11）Favaretto A, et al.: The parallel analysis of phasesensitive inversion recovery (PSIR) and double
inversion recovery (DIR) images significantly improves
the detection of cortical lesions in multiple sclerosis(MS) since clinical onset. PLoS One, 10: e0127805,
2015.
12）Kellman P, et al.: Phase-sensitive inversion recovery
for detecting myocardial infarction using gadoliniumdelayed hyperenhancement. Magn Reson Med, 47:
372-83, 2002.
13）Ishimori T, et al.: Preoperative identification ofsubthalamic nucleus for deep brain stimulation using
three-dimensional phase sensitive inversion recovery
technique. Magn Reson Med Sci, 6: 225-9, 2007.
14）Harter HL: Expected values of normal order statistics.
Biometrika, 48: 151-65, 1961.
15）Williams LJ, et al.: Fisherʼs least significant difference(LSD) test. Encyclopedia of Research Design, 218:
840-53, 2010.
16）Mirafzal S, et al.: 3D PSIR MRI at 3 Tesla improvesdetection of spinal cord lesions in multiple sclerosis. J
Neurol, 267: 406-14, 2020.
17）Fechner A, et al.: A 3T phase-sensitive inversion
recovery MRI sequence improves detection of
cervical spinal cord lesions and shows active lesions
in patients with multiple sclerosis. AJNR Am J
Neuroradiol, 40: 370-5, 2019.

Arts and Sciences
original articles

Received September 23, 2021; accepted April 18, 2023

Creation of work skill items in the field of radiotherapy
TSUDA Shintaro1）, SATO Kiyokazu2）, HIGUCHI Hiromitsu3）, ONO Yasushi 4）,
NISHIMURA Tomonori 5）, AOYAMA Hideki 6）, KATAYAMA Hiroki 7）, HONDA Hirofumi 8）,
KUMAMOTO Kengo8）, OKU Yoshifumi 9）, GIBO Seiyo10）, NAKASHIMA Takeo1）,
KIGUCHI Masao11）

1）Division of Radiation Therapy, Department of Medical Support, Hiroshima University Hospital2）Division of Radiation, Department of Medical Technology, Tohoku University Hospital3）Department of Radiation, Gunma University Hospital4）Department of Radiation, Tottori University Hospital5）Department of Radiation, Shimane University Hospital6）Division of Radiological Technology, Okayama University Hospital
7）Department of Radiation, Kagawa University Hospital8）Division of Radiation Technology, Department of Clinical Support, Ehime University Hospital9）Division of Radiation, Department of Clinical Engineering, Kagoshima University Hospital10）Department of Radiation, Ryukyu University Hospital11）Department of Medical Support, Hiroshima University Hospital

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 853: 26-33, 2023.
Key words: Work skill items, Radiation Therapy, Radiotherapy Technologist, Objective skill evaluation,

Human resources development【Abstract】

This study aimed to create knowledge and skills in the ﬁeld of radiotherapy as work skill items through a multiinstitutional collaboration. We created work skill items that cover the work forms of each institution, and considering
the userʼs burden, we devised the order, number of items, and category classiﬁcation that allows efﬁcient input andevaluation. Work skill items consist of levels, items, tasks, and action goals and are divided into four levels, six items,
seven tasks, and 123 action goals. Since the percentage of treatment generalists at the “level” was over 50% of the total
items, it is considered to be of high importance for the development of newcomers and young staff. In addition, it isimportant to incorporate the contents of work skill items into the operation of each institution at the time of system
introduction and to maintain the items due to periodic changes in work operations. It is hoped that the results of thisstudy will serve as a reference for the development of human resources at facilities that perform radiation therapy andthat the development of educational programs will proceed.

Introduction
In recent years, the situation surrounding radiotherapy has changed signiﬁcantly becauseof high-precision radiotherapy techniques,
such as stereotactic radiotherapy (SRT) andintensity-modulated radiation therapy (IMRT),
as well as the increasing number of facilities
offering particle beam therapy. Moreover, radiological technologists are responsible for radiation therapy 1). Technical skills related to radiation therapy are acquired through on-thejob training (OJT) at employment facilities.
However, due to the absence of a uniﬁed index or system for skill acquisition, the quality

and technical level of technology depends on
the work environment.
In the ﬁeld of information technology (IT),IT skill standards 2) have been established by
the Ministry of Economy, Trade, and Industry
and the Information-Technology Promotion
Agency, and intellectual property human resource skill standards 3) by the Ministry of
Economy, Trade, and Industry and the Patent
Ofﬁce. The importance of using these uniﬁed
indicators based on skill standards for humanresource development has been reported 4). In
the medical ﬁeld, the Japanese Nursing Association has released the “Nurse Clinical Ladder(Japanese Nursing Association Version)” for naArts and Sciences ◆ 45

tional standard indicators 5). The goal of nursing education is to deﬁne job capabilities common to all nurses in stages or criteria to foster
personnel who can provide diverse and highquality nursing practices. The Clinical Ladder isa system for skill development and evaluation
applied in nursing theory 6, 7).
The Japan Association of Radiological Technologists has outlined a new lifelong education
system that incorporates the Clinical Ladderapproach introduced by the Academic Education Committee. In the ﬁeld of radiation therapy, levels 3 and 4 (specialists) have been established as the Clinical Ladder for radiation
therapy professionals 8, 9). Furthermore, in response to a request from the Ministry of Education, Culture, Sports, Science, and Technology(MEXT) to create standardized evaluation criteria for postgraduate education and its assessment for radiological technologists, the Association of Radiological Technologists at the
National University has been planning and supervising the Skill Moral Cloud System (hereinafter referred to as the Skill Moral System) since2016 and has been operating it under contract
with BeNest Corporation 10). The system, developed by the Association of Radiological Technologists at the National University, was created by the Skill Moral Evaluation Working
Group and serves as a personnel management
system for assessing job duties by multiple
evaluators. It evaluates professional and moral(non-technical) skills in various ﬁelds, including general radiography, computed tomography (CT), magnetic resonance imaging (MRI),
nuclear medicine, angiography, radiation therapy, and ﬂuoroscopy. Using a cloud-based system, self-assessment and evaluator assessment
results can be disseminated, enabling facilities
to ensure consistent evaluations based on thesame standards across organizational structures.
When considering the development of radiological technicians, it is important to utilize
uniﬁed indicators and systems for skill acquisi-

46 ◆ Journal of JART English edition 2024

tion to organize and categorize the knowledge
and skills necessary for job duties. The conversion of tacit to explicit knowledge is crucial.
Nonaka et al. described tacit knowledge asknowledge based on personal experience,
thoughts, or know-how that is difﬁcult to express in language or writing and as subjective
knowledge that individuals unconsciously understand and use 11, 12). Furthermore, formal
knowledge is visualized through symbols, suchas words or formulas, and can be expressed inlanguage, manuals, or other written forms as
objective knowledge. Deﬁning job skill items
that categorize skills in the workplace helps
clarify job responsibilities, making it easier for
new hires or transferees to understand theoverview of the knowledge and skills required
for their assigned tasks. It also promotes transparency of job responsibilities to other departments. For supervisors, this contributes to reassessing the knowledge and skills that they implicitly understand when developing their subordinates. By utilizing these factors, the required level of skill acquisition in salary increases, promotions, and other selection processes are reﬂected and foster expectations for
OJT. Considering these points, it is believedthat creating job skills is highly signiﬁcant inconstructing an educational system for radiological technologists involved in radiation therapy and can be effectively utilized for personnel development.
Matsuo et al 13). categorized the abilities ofradiological technologists into technical skills
and human skills, dividing their career stages
into early (1-10 years) and late (11 years andbeyond), based on an analysis of questionnaire
survey data. They emphasized the importanceof training responsibilities and interactions
with other professions. Within this context,
they advocated the necessity of creating checklists to identify the abilities that should be acquired at each career stage, developing training plans, and establishing an OJT system tofacilitate the smooth transfer of knowledge andoriginal articles
Creation of work skill items in the field of radiotherapy

skills when transitioning modalities.
Based on the research ﬁndings on the development of radiological technologists, it is important to conduct studies aimed at creating
speciﬁc work skill items. Furthermore, in national university hospitals where the skill moral
system is implemented, operational practices
vary among facilities owing to factors such asstaff numbers, equipment usage, and work rotations, and the initial conﬁguration of the skill
moral system does not necessarily encompass
the operational forms of each facility. In thisstudy, we aimed to collaborate with radiological technologists at national university hospitals in the ﬁeld of radiation therapy to objectively assess skills based on evaluation items of
the skill moral system and examine work skill
items. Our goal was to develop content that
could be implemented in facilities nationwide,
including comprehensive hospitals performing
radiation therapy, by focusing on creating
work skills in the ﬁeld of radiation therapy.

Materials and Methods
We examined work skill items in the ﬁeld ofradiation therapy at 15 facilities in national university hospitals. The linear accelerator numbers at the 15 facilities were as follows: one
facilities had ﬁve units, six facilities had threeunits, eight facilities had two units, and two
facilities had separate particle-beam devices. In
the initial setting of the skill moral system evaluation items for the 15 facilities, the operational forms for each facility were not fully covered. Therefore, we ensured comprehensive
coverage and considered the sequence, number of items, and categorization for efﬁcient
input and evaluation based on improvement
requests from users of the skill moral system at
the 15 facilities.
The evaluation criteria for the skill moral system are divided into “levels” based on the proﬁciency and years of experience of radiological
technologists, and into “items,” “tasks,” and“behavioral objectives” based on the nature of

their duties. In the initial setup for radiation
therapy, the “levels” are hierarchically structured into three stages: radiotherapy generalist,
radiotherapy clinical coach, and radiotherapy
department leader, which correspond to thecareer ladder. In this context, the considerationof which stage to set based on years of experience, qualiﬁcations, and positions is examined,
considering the purpose of utilizing work skill
items. Furthermore, the nature of the duties
was hierarchically structured into “items,”“tasks,” and “behavioral objectives,” where“items” were categorized into equipment management, treatment planning, safety management, simulation, and irradiation techniques.
“Tasks” were classiﬁed into knowledge, skills/
practice, and management, and “behavioral
objectives” speciﬁed the concrete content ofwork skill items for radiation therapy duties.
Here, “simulation” refers to the workﬂow for
conducting radiation therapy, including immobilization device fabrication, CT imaging, surface marking, and breath management. Additionally, due to variations in naming and operational methods among manufacturers forpatient information systems, a uniform representation using the general term “record andverify (R&V)” was adopted in the work skill
items. Regarding content related to total body
irradiation (TBI), facilities may also perform
other specialized irradiation techniques suchas half body irradiation (HBI) and total skinelectron irradiation (TSEI), so the term “TBI,
etc.” was uniformly used. In this context, considering the workﬂow of radiation therapy duties, staff rotation, and effort involved in user
input for items, opinions were aggregated to
explore and encompass the various operational modes of each facility as much as possible.

Results
1. “Levels”

The levels were set in four stages: ① radioArts and Sciences ◆ 47

therapy generalist (1st year), ② radiotherapy generalist (2nd year and beyond), ③ radiotherapy clinical coaches,and ④ radiotherapy department leaders.
For each, the years of practical experience, professional qualiﬁcations, andguidance based on managerial positions
were recorded. Professional qualiﬁcations explicitly included radiotherapy
technologists (RTT) (Table 1). radiotherapy generalists were divided into the ﬁrstyear, second-year, and beyond categories.

Table 1 We have established four “levels” and categorized
Radiotherapy generalists into ①first year and ②second year and beyond. Guidelines and reference
information have been added for each level.
LevelsSupplementary
Information

Guidelines① Radiotherapy generalists② Radiotherapy Generalist③ Radiotherapy Clinical

Coach④ Radiotherapy Department

Leader

1st year

Newcomer 2nd to 5th Until obtaining RTT
certiﬁcationyear
6th yearonwards

RTT Qualiﬁed, Chief

Deputy Chief Engineer,
Managerial
Department Head or
positionabove

Table 2 “Items” are categorized by work unit anddivided into several “Tasks”. “Items” arefurther divided into six categories, and“Tasks” into seven categories.

2. “Items” and “Tasks”

Based on staff rotation as a criterion, six“items” were set: irradiation, simulation, treatment planning, brachytherapy, quality management, and management. Seven “tasks” were
designated for “Tasks,” including patient care,
irradiation, equipment management, simulation, treatment planning, data transfer, andmanagement (Table 2).

Items

Tasks
Patient Care

Irradiation

Irradiation
Equipment Management
Patient Care

Simulation

Simulation
Equipment Management
Treatment Planning

Treatment Planning

Data Transfer
Simulation

3. Work Skill Items (Levels, Items, Tasks, andBehavioral Objectives)

The work skills items are presented in Tables
3-5. For ① radiotherapy generalist (1st year),

Treatment Planning
Brachytherapy

Irradiation
Equipment Management
Management

Quality Management

Equipment Management

Management

Management

Table 3 The work skill items for Radiotherapy Generalists (①). Fifteen behavioral objectives are set for first year
Radiotherapy Generalists.
Levels

Items

Tasks

Behavioral Objectives
Capable of providing appropriate explanations of procedures to patients or families

Patient Care

Able to establish good rapport with patients and their families
Able to effectively explain the side effects of radiation therapy to patients or their families
Able to safely perform irradiation tasks in the head region
Able to safely perform irradiation tasks in the head and neck region
Able to safely perform irradiation tasks in the chest region

Irradiation① Radiotherapy

Generalist

Able to safely perform irradiation tasks in the abdominal region
Able to safely perform irradiation tasks in the pelvic region

Irradiation

Able to safely perform irradiation tasks in the extremity region
Able to safely perform irradiation tasks in electron beam therapy
Able to collect patient information necessary for irradiation tasks using HIS, RIS, R&V, etc
Equipment
Management

Able to understand and implement the recording and storage methods for irradiation andpositioning veriﬁcation
Able to understand the medical fee schedule and perform or verify irradiation accounting
Able to understand the structure and operation of the accelerator, and operate it safely
Able to understand and perform the start-up and shutdown checks of the accelerator

48 ◆ Journal of JART English edition 2024

original articles
Creation of work skill items in the field of radiotherapy

all were under irradiation with 15 behavioral
objectives (Table 3). For ② radiotherapy generalist (2nd year and beyond), there were items
such as irradiation, simulation, treatment planning, brachytherapy, and quality management,
comprising 57 behavioral objectives (Table 4).
Similarly, ③ radiotherapy clinical coach includ-ed items such as irradiation, simulation, treatment planning, brachytherapy, and quality
management, with 35 behavioral objectives. ④
radiotherapy department leaderʼs items were
all under management, with 16 behavioral objectives (Table 5). Work skill items were classiﬁed into 123 behavioral objectives.

Table 4 The work skill items for Radiotherapy Generalists (②). Fifty-seven behavioral objectives are set forRadiotherapy Generalists in their second year and beyond.
Levels

Items

Tasks

Behavioral Objectives

Patient Care

Able to understand the purpose and methods of infection control, and implement themappropriately
Able to respond appropriately during disasters or emergencies
Able to understand the irradiation procedures of Intensity Modulated Radiation Therapy(IMRT/VMAT) and perform them safely
Able to understand the irradiation procedures of Stereotactic Radiotherapy (SRS/SRT/
SBRT) and perform them safely

Irradiation

Irradiation

Able to understand the irradiation procedures involving respiratory motion management
and perform them safely
Able to understand the irradiation procedures for special treatments such as whole-body
irradiation and perform them safely
Able to perform particle beam irradiation
Able to perform intraoperative irradiation
Able to respond appropriately to incidents

Equipment
Management

Able to handle interlock issues and perform recovery operations on the accelerator
Able to perform emergency shutdown and normal startup of the accelerator
Able to understand and perform standard measurements of water absorbed dose

Patient Care

Able to provide appropriate explanations of procedures to patients or their families
Able to perform simulation tasks in the head region
Able to perform simulation tasks in the head and neck region
Able to perform simulation tasks in the chest region② Radiotherapy

Able to perform simulation tasks in the abdominal region

Generalist

Able to perform simulation tasks in the pelvic region
Able to perform simulation tasks in the extremity region
Able to perform simulation tasks in electron beam therapy
Able to understand and perform the simulation procedures for IMRT/VMAT appropriately
Simulation

Able to understand and perform the simulation procedures for SRS/SRT/SBRT appropriately
Able to understand and perform the simulation procedures for irradiation involving
respiratory motion management appropriately

Simulation

Able to understand and perform the simulation procedures for special treatments such as
whole-body irradiation appropriately
Able to create electron beam ﬁeld shaping blocks
Able to perform CT simulation using contrast agents safely
Able to perform simulation tasks for particle beam irradiation
Able to perform simulation tasks for intraoperative irradiation
Able to appropriately collect patient information necessary for simulation tasks using HIS,
RIS, etc
Able to understand the medical fee schedule and perform or verify simulation accounting
Equipment
Management

Able to understand the structure and operation of simulation equipment, and operate it
safelyAble to perform emergency shutdown and normal startup of simulation equipment
Able to understand and perform the start-up and shutdown checks of simulationequipment

Arts and Sciences ◆ 49

Levels

Items

Tasks
Treatment
Planning

Behavioral Objectives
Able to understand the usage of treatment planning equipment and use it safely
Able to perform data transfer and registration tasks of treatment plans created in thehead region to the R&V system
Able to perform data transfer and registration tasks of treatment plans created in thehead and neck region to the R&V system
Able to perform data transfer and registration tasks of treatment plans created in thechest region to the R&V system
Able to perform data transfer and registration tasks of treatment plans created in theabdominal region to the R&V system

Treatment
Planning

Able to perform data transfer and registration tasks of treatment plans created in thepelvic region to the R&V system
Data Transfer

Able to perform data transfer and registration tasks of treatment plans created in theextremity region to the R&V system
Able to perform data transfer and registration tasks of treatment plans created with SRS/
SRT/SBRT to the R&V system
Able to perform data transfer and registration tasks of treatment plans created for special
treatments such as whole-body irradiation to the R&V system② Radiotherapy

Able to perform data transfer and registration tasks of treatment plans created withelectron beam therapy to the R&V system

Generalist

Able to perform treatment plan veriﬁcation using independent veriﬁcation devices
Able to perform data transfer and registration tasks of treatment plans created withparticle beam therapy to the R&V system
Able to appropriately perform data transfer and registration tasks of treatment plans
created with intraoperative irradiation to the R&V system
Simulation

Able to perform simulation tasks for RALS

Treatment
Planning

Able to create treatment plans for RALS

Irradiation

Able to safely perform irradiation tasks for RALS
Able to appropriately collect patient information necessary for RALS tasks using HIS, RIS,
etc

Brachytherapy

Able to understand the medical fee schedule and perform or verify accounting for RALS
Equipment
Management

Able to understand the structure and operation of RALS, and operate it safely
Able to understand the interlock system of RALS and respond appropriately
Able to understand and perform the start-up and shutdown checks of RALS
Able to understand and perform output measurements for RALS
Able to perform emergency shutdown and normal startup for RALS

Quality
Management

Equipment
Management

Able to perform measurements using dosimetry equipment for patient dose veriﬁcationplans of IMRT/VMAT

Table 5 The work skill items for Radiotherapy Clinical Coaches and Radiotherapy Department Leaders (③, ④).
Thirty-five behavioral objectives are set for Radiotherapy Clinical Coaches (③), and sixteen behavioral
objectives are set for Radiotherapy Department Leaders (④).
Levels

Items
Irradiation③ Radiotherapy Clinical

Coach
Simulation

Tasks
Equipment
Management
Equipment
Management

50 ◆ Journal of JART English edition 2024

Behavioral Objectives
Able to identify any inappropriate aspects in treatment plans or registration information
Able to perform calibration of monitor ionization chamber
Able to manage the schedule of the irradiation room
Able to understand and implement geometric accuracy and image quality management
in images from simulation equipment
Able to understand and perform output measurements of simulation equipment

original articles
Creation of work skill items in the field of radiotherapy

Levels

Items

Tasks

Behavioral Objectives
Able to create treatment plans for the head region
Able to create treatment plans for the head and neck region
Able to create treatment plans for the chest region
Able to create treatment plans for the abdominal region
Able to create treatment plans for the pelvic region
Able to create treatment plans for the extremity region

Treatment
Planning

Treatment
Planning

Able to create treatment plans for whole-body irradiation
Able to create treatment plans for electron beam therapy
Able to create treatment plans for IMRT/VMAT
Able to create treatment plans for SRS/SRT/SBRT
Able to understand the indications and irradiation methods for particle beam therapy andcreate treatment plans③ Radiotherapy ClinicalAble to understand the indications and irradiation methods for intraoperative irradiationand create treatment plans

Coach

Brachytherapy

Equipment
Management

Able to understand and implement the accuracy control items of RALS

Simulation

Able to perform simulation tasks for temporary insertion of sealed brachytherapy sources

Treatment
Planning

Able to create treatment plans for temporary insertion of sealed brachytherapy sources

Irradiation

Able to perform irradiation tasks for temporary insertion of sealed brachytherapy sources

Simulation

Able to perform simulation tasks for permanent insertion of sealed brachytherapy sources

Treatment
Planning

Able to create treatment plans for permanent insertion of sealed brachytherapy sources

Irradiation
Management

Able to perform irradiation tasks for permanent insertion of sealed brachytherapy sourcesAble to perform tasks related to unsealed brachytherapy treatment
Able to perform tasks related to source management
Able to create patient dose veriﬁcation plans for IMRT/VMAT
Able to understand and implement geometric accuracy management of the accelerator
Able to understand and implement dosimetric accuracy management of the accelerator
Able to understand and implement accuracy management of the positioning veriﬁcation
deviceAble to understand and implement accuracy management of dosimetry equipment③ Radiotherapy Clinical

Coach

Quality
Management

Equipment
Management

Able to understand and implement data registration, management, and commissioningof treatment planning systems
Able to understand and implement data registration and accuracy management of
independent veriﬁcation devices
Able to understand and implement various factor evaluations and cross calibrations of
dosimeters
Able to understand the measurement points and methods for leakage dose measurements, and plan and conduct them
Able to create speciﬁcations
Able to create documentation for equipment updates
Able to understand and explain maintenance contracts
Able to develop equipment procurement plans
Able to create ﬁnancial plans for equipment upgrades
Able to review treatment procedures in response to revisions in medical fee schedules
Able to collaborate with medical departments to improve treatment methods
Able to discuss examination content and operations with other professions④ Radiotherapy

Department
LeaderManagement

Management

Able to manage, record, and understand various aspects related to RI (Radioisotope)
laws
Able to develop risk management plans
Able to respond to and address incidents
Able to respond to and implement measures for infectious diseases
Able to conduct inspections and respond to medical surveillance
Able to manage overtime work
Able to handle patient complaints and issues
Able to respond to the Radiation Therapy Quality Management Committee, etc

Arts and Sciences ◆ 51

Discussion
1. “Levels” Setting

In the skill moral system operated by national
university hospitals, an appropriate level setting
is crucial for clarifying the tasks for which users
should aim. However, the roles and criteria ofradiotherapy generalists, radiotherapy clinicalcoaches, and radiotherapy department leaders
were perceived differently among the facilities.
Therefore, by specifying guidelines such aspractical experience and professional qualiﬁcations for each level, regardless of the actual
practices of the facility, the system allows assessors to understand the skills and professional
qualiﬁcations required for their current position. Since the proportion of radiotherapy generalists in the “level” exceeded 50% of the entire
items, it is believed that there is a high demand
for system usage among radiological technologists involved in radiotherapy through rotations
from diagnostic departments or as recruits in
the radiotherapy department. By setting radiotherapy generalists into ① radiotherapy generalist (1st year) and ② radiotherapy generalist(2nd year and beyond), the priority of skills tobe acquired in the ﬁrst year of employment andthe skills to be mastered in the second to ﬁfth
years are clariﬁed. This aims to organize thepathway to obtain RTT qualiﬁcation, which requires more than ﬁve years of practical experience, and to encourage further growth towards
the stage of radiotherapy clinical coach.

cility, the setting of “items” and “tasks” was adjusted to enable smooth input and evaluation,
thereby reducing the burden and complexity
for users. However, because the evaluation
methods for each itemʼs achievement level
largely depended on the discretion of the evaluator, each facility needed to establish evaluation criteria to reduce differences among evaluators. Additionally, when comparing results
between facilities, attention must be paid tothe evaluation criteria for each facility.
3. Utilization for Personnel Development

When utilizing work skills for personnel development, the use of personnel management
systems should be considered instead of Excelﬁles to avoid the risk of inadvertent ﬁle loss or
disposal. The introduction of such a system enables continuous data collection and analysis,
allowing users to visually grasp their strengths
and weaknesses using tools such as radar
charts (Fig. 1). During the re-evaluation, thecontent of the unachieved items was indicated(Fig. 2). Furthermore, it served as a communication tool for superiors and subordinates tocollectively consider clinical duties, thus serving not only as a tool for visualizing duties but
also as a tool for personnel development andthe smooth progress of clinical duties. An example of the operating mode is shown in theﬂowchart format (Fig. 3).
4. Usage, Modification, and Maintenance of
Items

2. Setting of “Items,” “Tasks,” “Behavioral Objectives,” and “Detailed Behavioral Objectives”

In the initial setting, tasks such as equipment
management, safety management, and irradiation techniques were related to the irradiation
tasks. In brachytherapy, tasks such as irradiation, simulation, and treatment planning wererelated, causing complexity in system usage
during input and evaluation across multiple
items. Based on the rotation of duties and operational forms in radiation therapy at each fa-

52 ◆ Journal of JART English edition 2024

Through a multi-facility study conducted in
15 facilities, concerns were raised about differences in operational practices and personnel
development philosophies owing to differences in operational practices and staff rotation
policies between diagnostic areas. Therefore, itis necessary to establish the usage of personnel
management systems and personnel development policies in each facility beforehand andadjust the contents of work skill items according to the facilityʼs operation when introducing

original articles
Creation of work skill items in the field of radiotherapy

the system. Even in small-scale facilities with
only one accelerator, it is assumed that deployment is possible by similarly modifying thework skill items at the time of system introduction, such as by removing unnecessary items.
Additionally, radiation therapy systems, including accelerators and peripheral equipment,
have changed composition and functionality
with technological advancements. Especiallyduring equipment updates, there may be signiﬁcant changes in operation owing to new
functions or new treatment methods, such as
particle therapy may be introduced. Because
the items formulated at the time of system introduction may require reconsideration owing

Fig. 1 An Example of Radar Chart Display: By indicating the achievement level of each item
as a percentage, both the evaluator and theevaluated individual can visually grasp theirstrengths and weaknesses.

Fig. 2 An example of screen display of item contents. At the time of re-assesment, the contents of theitems that have not been achieved are specified. It is possible to visually compare the progress of
their achievement level with their previous results.

Fig. 3 An example of operational mode: By adapting the items to the operation of oneʼs own institution andconfirming oneʼs level of attainment through regular assessment of skill items, communication between evaluators and those being evaluated is facilitated. The results can be applied to oneʼs career
path development and personnel evaluations.
Arts and Sciences ◆ 53

to changes in operation over several years or
decades, regular maintenance of items is crucial
to prevent the system from becoming obsolete.

Conclusion
Through multi-facility deliberation, we created work skill items tailored to the realities
and workﬂows of national university hospitals.
These work-skill items feature common andgeneral terms and names, allowing them to be
reﬂected in the operations of each facility without being inﬂuenced by factors such as facility
size or stafﬁng levels. This enables an efﬁcientand appropriate evaluation. Additionally, by
visualizing the evaluations corresponding toeach level, achievement status can be sharedwithin the radiation therapy department. Byutilizing the proposed work skill items, a personnel development system for radiological
technologists involved in radiation therapy is
expected to motivate radiological technologists
and improve the quality of healthcare. Furthermore, it is anticipated to lead to the advancement and bottom-up development of radiological technologists.

Acknowledgments
We would like to express our sincere gratitude to Mr. Yamato Wakabayashi from the Department of Radiology, Medical Technology Division, Hokkaido University Hospital; Mr. Takahiro Fujimoto from the Department of Radiology, Kyoto University Hospital; Mr. Koya Fujimoto from the Graduate School of Medicine,
Yamaguchi University; Mr. Tetsuya Kawashita
from the Department of Radiological Technology, Medical Technology Division, Tokushima
University Hospital; and Mr. Akira Tsuzuki fromthe Department of Radiology, Medical Technology Division, Faculty of Medicine, Kochi University (currently Kakogawa Central Citizensʼ
Hospital Radiology Department) for their collaboration in developing the work skills and as-

54 ◆ Journal of JART English edition 2024

sistance in writing this manuscript.
We also wish to extend our heartfelt appreciation to Professor Yoshitada Masuda, Chairman of the Association of Radiological Technologists at National University, and former
Chairman Katsuhiko Ueda for their guidance inwriting this manuscript.
Some sections of this paper were presented
at the 36th Japan Conference of RadiologicalTechnologists (January 2021, held online).
Conflicts of Interest

The authors declare that they have no conﬂict of interest.
References
1） Okumura Masahiko, et al.: Standard Textbook of
Radiation Therapy Techniques. Medical Science
International, 2019.
2） Information-technology Promotion Agency, Japan, IT
Skill Standards Center: IT Skill Standards V3 2011.
https://www.ipa.go.jp/jinzai/itss/download_V3_2011.
html (Accessed 2021.9.22)
3） Japan Patent Office: Intellectual Property Talent Skill
Standards (version 2.0).
https://www.jpo.go.jp/support/general/chizai_skill_ver_2_0.html (Accessed 2021.9.22)
4） Shigeyuki Ohara, et al.: Skill Standards and Human
Resource Development in Information Technology.
IPSJ Magazine, Vol.46, No.12, Dec 2005.
5） Japanese Nursing Association: Clinical Ladder for
Nurses (Japanese Nursing Association Version).
https://www.nurse.or.jp/nursing/education/jissen/
index.html (Accessed 2021.9.22)
6） Hubert Dreyfus & Stuart Dreyfus, translated by Naoko
Mukuta: What Computers Canʼt Do: The Limits ofArtificial Intelligence. ASCII Corporation, 1987.
7） Patricia Benner: From novice to expert: Excellenceand power in clinical nursing practice. AddisonWesley Publishing, 1984.
8） Overview of Lifelong Education System by the
Academic Education Committee of the Japan
Association of Radiological Technologists, The Japan
Association of Radiological Technologists, 67. 4: 8093, 2020.
9） Overview of Lifelong Education System by the
Academic Education Committee of the Japan
Association of Radiological Technologists, The Japan
Association of Radiological Technologists, 68. 4: 7791, 2021.
10）Introduction to PE-net on Cloud: Support for Training
Radiological Technologists. BeNest Co., Ltd.
https://benest.co.jp/archives/products/79 (Accessed
2021.9.22)
11）Ikujiro Nonaka, et al.: The Knowledge ­ Creating
Company.− published by Toyo Keizai Inc. 1995.
12）Ikujiro Nonaka: The Essence of Innovation Leadership in Knowledge Creation. − in Trends in
Academic Research, 12. 5: 60-69, 2007.
13）Makoto Matsuo, et al.: The Experiential Learning
Process of Radiological Technologists, The Japan
Association of Radiological Technologists, 61. 3: 1320, 2014.

Arts and Sciences
original articles

Received January 4, 2023; accepted May 16, 2023

Generation of standard time acquisition images
from short time acquisition images of cerebral
blood flow SPECT using deep learning
YAMAMOTO Yasushi1）, SHIRAI Masato2）, TAKAMURA Masahiro3）,
MATSUURA Kousuke4）, HINO Yuuki4）, FUKUDA Mitsuki4）, YADA Nobuhiro4）,
MIYAHARA Yoshinori4）, KURODA Hiroyuki1）, KAJI Yasushi1）1）Department of Radiology, Faculty of Medicine, Shimane University2）Interdisciplinary Faculty of Science and Engineering, Shimane University3）Department of Neurology, Shimane University Faculty of Medicine
4）Department of Radiology, Shimane University Hospital

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 853: 34-39, 2023.
Key words: deep learning，pix2pix，GAN，3D-SSP，Brain SPECT【Summary】

We attempted image generation of cerebral blood ﬂow SPECT from short time acquisition (10 minutes) to standard
time acquisition (40 minutes) using artiﬁcial intelligence based image generation technique. The model was pix2pix
and was constructed from training data of 19484 images both 10 min and 40 min. Using constructed model, 4878
images were generated and evaluated similarity to standard images.MSE, PSNR, SSIM, and DSC were used for physicalevaluation, and 3D-SSP was used for visual evaluation. Although image quality improved in the physical evaluation,
there were cases where the depiction of abnormal blood ﬂow areas differed from standard time in 3D-SSP. In order toimprove the accuracy, we consider it is necessary to reexamine this issue with training data using extended acquisition
time.

Introduction
In image diagnosis of dementia, nuclearmedical Single Photon Emission Computed Tomography (SPECT) of brain perfusion has important roles. But the images are produced bya little gamma-ray information, so the inspection time is 40 minutes on routine of our facilities, which is long and painful for brain disease
patients.
Therefore, there are some cases where wecanʼt collect whole inspection data, and we
produce images despite not collecting enoughdata, whose impact on image diagnosis is inevitable.
Furthermore, because of using isotope, theinspection cost is expensive, and from a viewpoint of cost, reexamination is difﬁcult. If there
is a way to improve the image quality which
can be used for diagnosis even the collected
data is insufﬁcient, its value is great.

In these years, improvement of image quality
is being achieved by the image generating taskwith deep learning, and the technology has
possibility to enable us to use aforesaid SPECT
images of brain perfusion from insufﬁcient
data.
There are various reports for reference. Regarding CT, there is a study to make image
quality close to that at high-dose from collected data at low-dose 1). In terms of MRI, a study
has reported that noise reduction and image
quality improvement effects get possible 2, 3).
In nuclear medical domain, there is a reference that when using PET, even if the dose ofadministrated isotope is lowered, image quality which is equivalent to normal dose can beensured 4).
Thus, we introduced deep learning, and examined if its method can improve the image
quality of data collected in a short period oftime and can generate images which is worthy
Arts and Sciences ◆ 55

of diagnostic use.

1. Methods
1-1．Equipment and Collection Conditions

For SPECT data of brain perfusion that we
prepared, 123I-isopropyl-p-iodoamphetamine(¹²³I-IMP), 167 MBq was used, Graph Plot Method 5, 6) was employed to collect data, and at thesame time as drug was injected, 5 min/360 -collecting was carried out for 8 cycles on continuous-mode, and then 40-minute (normal examination time) -collecting-data was obtained. For
image-reconstruction, Ordered Subset Expectation Maximization (OSEM) method was employed, and the setting were as follows. Iteration was 2, Subset was 24, Scattered light correction was Triple Energy Window (TEW), andAttenuation correction was CT-based Attenuation Correction (CTAC). Collecting equipment is
GE Healthcare Discovery 670 pro, and reconstructing workstation is Xeleris 3.0. Computer
which is used to generate images is server type
Philips Intellispace Discovery (CPU: Intel Xeon
Gold 5120, RAM: 192 GB, GPU: NVIDIA Tesla
V100 16 GB, Operating system: Ubuntu 16.04
LTS 64-bit). Image generating program is Python 3.6.10, and PyTorch 1.8.0 is employed as
Framework.
In addition, whole of this research, including
the use of clinical data, was conducted after it
was approved by the Shimane University Medical Research Ethics Committee (Research Management Number: 20211228-1).

min_S and 40 min_S in the same case wereprepared. What is used as Train-data is samples of 400 patients who could take 123I-IMP
Graph Plot Method to the end for 40 minutes.
That includes 191 females whose old mean is73.6 (SD 13.4) and 209 males whose old meanis 73.6 (SD 13.4). As a result of diagnosis byradiologist, there are 152 samples of dementia,
109 cerebrovascular diseases, 47 the other disorders, and 92 no abnormal ﬁndings. A seriesof data which is used to evaluate the accuracyof generated model (Test_data) is needed to beprepared apart from Train_data, so we prepared 101 samples which were continuously
surveyed from Jan 2020 to Jun 2020. That includes 43 females whose old mean is 72.6 (SD13.3) and 58 males whose old mean is 72.4 (SD11.6). there are 45 samples of dementia, 23
cerebrovascular diseases, 7 the other disorders,and 26 no abnormal ﬁndings. The number ofimages used in 10 min_S and 40 min_S for
Train_data are 19484, and that for Test_data
are 4878. From the parietal to the inferior cerebellar margin, 48 images per case were usedas the basis for the composition. Recomposed
16 bit-Dicom data (matrix: 128×128, pixel size:
2.94 mm) was converted into 8 bit PNG ﬁlethat can work with the image generative model. To include large area of brain parenchyma
which is essential to generate images, we enlarged them 1.7 times when they are translated
into PNG ﬁles to reduce the area outside ofsubject, and preserved them in 256×256 matrix so that blurring due to enlargement is taken into account.

1-1-1．Data used for image generation

To generate images, a series of training data
for learning is needed to be prepared. In thisresearch, the aim is generating normal-timecollecting-image by using short-time-collecting-image, so we treat SPECT image which is generated by 10-minute collecting data as short-timecollecting-image (10 min_S), and one which isdone by 40-minute data as normal-time-collecting-image (40 min_S), and then both 10

56 ◆ Journal of JART English edition 2024

1-2．Image generative model

To generate images, we used a model called
pix2pix which was reported by Isora 7). Pix2pix
is a derivation model of Generative Adversarial
Network (GAN). Generator in it generates images as close to the real thing as possible, andDiscriminator identiﬁes whether the images arereal or fake, ﬁnally it generates images thatDiscriminator recognizes as real. In GAN, theoriginal articles
Generation of standard time acquisition images from short time acquisition images of cerebral blood flow SPECT using deep learning

paper 7) for details on the pix2pix architectureand hyperparameters. The source code wasdownloaded from the publicly available PyTorch implementation (https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix).

initial input to the Generator is a random noise
vector from which image generation starts. In
pix2pix, on the other hand, real images areused as input, allowing image generation
based on real images. In this study, the same
rules were used to train pairs of 10 min_S and
40 min_S images (same case, same coordinates), so that artiﬁcial intelligence (AI) canﬁnd detailed correspondence between the two
images and the training data for the conditional adversarial generative network, which generates standard-time images from the shorttime images, is completed. The AI can generate a 40-minute image (fake_S) that is close to
the real one by inputting 10 min_S, which is
the Test_data prepared separately from thetraining data, to the generator based on therelationships among the training data. Fig. 1
shows the architecture of pix2pix in this study,
using U-net as the generator and PatchGAN 7)
as the discriminator. L1 Loss 7) is used as theloss function, which enables us to identify theentire image and the so-called low-frequency
component, and improves the agreement between the conditional image (10 min_S), thegenerated image (fake_S), and the correct image (40 min_S). The optimization algorithm isbased on Adam 8); please refer to the original

1-3．Physical evaluation of similar images

The physical evaluation of the generated images was performed using Mean squared error(MSE), Peak signal to noise ratio (PSNR), Structural similarity index (SSIM), and Dice similarity coefﬁcient (DSC). MSE (Equation-1) is thesum of the squared difference between thecorresponding pixel values of the generated
image ( ŷi ) and the reference image ( yi ) divided
by the total number of pixels, where the smaller the value, the closer the pixel values are
between the images. When the image to behandled is 8 bits, MSE takes a maximum valueof 255 × 255, which is difﬁcult to evaluate. In
PSNR (Equation-2), a larger dB value can beeasily judged as an approximate image by normalizing by R (255). MSE and PSNR evaluate
pixel values by obtaining an approximation of
the pixel values at the corresponding coordinates between images, but there may be cases
where this does not correspond to the visualevaluation in diagnostic imaging. On the other
hand, SSIM (Equation-3-1)
can evaluate changes in pixfake_S
40min_S
10min_S
fake_S
40min_S
10min_Sel value, contrast, and structure in terms of variance, andis an index that is close toGenerator
Generator
real
fake
real
fake
visual evaluation because it(U-net)(U-net)can be calculated for each
Discriminator
Discriminator
Discriminator
Discriminator(PatchGAN)(PatchGAN)
small region while shifting its
10min_S
10min_S
10min_S
position within the image
10min_S
Imput:256×256×3
Imput:256×256×3
U-net
U-net
Conv2DLayer
Conv2DLayer
Output: 256×256×3
256×256×3
Output:area, and ﬁnally evaluate
skip connection
connection
PatchGAN
BatchNorm
Imput:256×256×3
skip
PatchGAN
BatchNorm
Imput:256×256×3
Depthconcatenation
Depthconcatenation
Conv2DLayer
ReLU
Conv2DLayer
ReLU
Leaky ReLU
ReLU
Leaky
BatchNorm
Output: 32×32×1
32×32×1
structural differences across
BatchNorm
Output:DropoutLayer
DropoutLayer
Leaky ReLU
ReLU
Leaky
Conv2D::3Layers
3Layers
BatchNorm
Conv2D
BatchNorm
Kernel=4,Padding=1,
Padding=1,stride=2
stride=2
TransposedConv2D
the entire image. In equation
Kernel=4,
TransposedConv2D
Conv2D::2Layers
2Layers
Conv2DLayer
TransposedConv2DLayer
Conv2D
Conv2DLayer
TransposedConv2DLayer
Kernel=4,Padding=1,
Padding=1,stride=2
stride=2
Kernel=4,Padding=1,
Padding=1,stride=2
stride=2
Kernel=4,Padding=1,
Padding=1,stride=1
stride=1(3-1), μx and μy , σx and σy
Kernel=4,
Kernel=4,
Kernel=4,
denote the local mean pixel
Fig. 1 Pix2pix architecture is shown. Generator generates fake_S fromvalues and standard devia10 min_S.
tions of the image, respecDiscriminator is trained to judge 40 min_S as real and fake_S as fake. Generator uses
tively, and σxy denotes the
U-net and Discriminator uses PatchGAN.
→→
→→
→ →
→
→

＊
＊

＊
＊

＊
＊

＊
＊

1×1×512
1×1×512

＊
＊

＊
＊

＊
＊

Arts and Sciences ◆ 57

covariance. C1 and C2 are the values C1 =format, and the Z-score maps from 40 min_S,
0.01×2562 and C2 = 0.03×2562 used in the 8-bit
10 min_S, and fake_S were compared. When9)setting as reported by Fukui et al. Mean SSIM
converting from PNG to Dicom format, each
(MSSIM) is the average of the calculated SSIM
voxel value was multiplied by 128 times calculated from the ratio of the signal values of thefor each small area over the entire image and isoriginal Dicom image and the PNG ﬁle to apcalculated as Equation (3-2). DSC (Equation-4)
proximate the counts of the Dicom image, andevaluates the congruency of the shape of thethe header information was added. Z-score
binarized images. Nχ and Ny are the total number of pixels in the evaluation target region of
map needs objective evaluation, so Stereotactic
the binarized image, and N(χ∩y) is the number
extraction estimation (SEE) analysis 12) was added. SEE uses the Talairach daemon to convertof pixels where both images overlap on theeach pixel of the 3D-SSP Z-score map into thesame coordinate. In the above physical evaluation, the regions outside the brain parenchycoordinate information that matches the Talaima that are unnecessary for image generationrach brain coordinate map, enabling absolute
1
な平均ピクセル値と標準偏差を，𝜎𝜎�� は共分散を示す．C1 と C2 は福井らの報告
shouldbe excluded from the evaluation target
evaluation according to the classiﬁcation of2同様 9)に 8 ビットでの設定で用いられている C1＝0.01×2562，C2＝0.03×2562 を
and the Otsu binarization method 10) was used
Brodmann ﬁelds.
𝜎𝜎�� は共分散を示す．C1と C2 は福井らの報告
1
な平均ピクセル値と標準偏差を，𝜎𝜎C2 は福井らの報告
3採用した．Mean
SSIM（MSSIM）は算出された小領域毎のSSIMの画像全体の平�� は共分散を示す．C1 とto determine
the regions to be evaluated. This9)
られている24 C1＝0.01×2562，C2＝0.03×2562を同様に
8ビットでの設定で用いられている
C1＝0.01×2562，C2＝0.03×2562
を均で式 3-2 として求められる．DSC（式-4）は２値化画像の形の一致を評価してmethoddetermines the optimal threshold
val1
な平均ピクセル値と標準偏差を，𝜎𝜎は共分散を示す．C1とC2
は福井らの報告
��差を，𝜎𝜎とC2 は福井らの報告は算出された小領域毎のSSIMは２値化画像の評価対象領域の全ピクセル数，N（χ∩y）は両画像の画像全体の平3採用した．Mean
SSIM（MSSIM）は算出された小領域毎のSSIM の画像全体の平�� は共分散を示す．C1
5
いる．Nχ，Ny
2. Resultue(t)9)にfor 8each
image so that the sum of the C1＝0.01×2562，C2＝0.03×2562 を2
同様ビットでの設定で用いられているで用いられている
C1＝0.01×2562，C2＝0.03×2562
をC（式-4）は２値化画像の形の一致を評価して
4均で式
3-2 として求められる．DSC（式-4）は２値化画像の形の一致を評価して6が同一座標上に重なって存在するピクセル数を示す．以上の物理評価において，
The SSIM
resultsの画像全体の平of each index are shown in Fig.
weighted
intensity
variance(σ12, σ22 ) of each
準偏差を，𝜎𝜎は共分散を示す．C1と C2 は福井らの報告��3採用した．Mean
SSIM（MSSIM）は算出された小領域毎のIM）は算出された小領域毎のSSIM の画像全体の平価対象領域の全ピクセル数，N（χ∩y）は両画像
5いる．Nχ，Ny
は２値化画像の評価対象領域の全ピクセル数，N（χ∩y）は両画像
7
画像生成に不必要な脳実質外の領域は評価対象から外して指標値を算出すべき
regionafter
segmentation (Equation-5) is を
mini2: MSE mean and standard deviation for 10
設定で用いられている
C1＝0.01×2562，C2＝0.03×2562
4
均で式
3-2
として求められる．DSC（式-4）は２値化画像の形の一致を評価してる．DSC（式-4）は２値化画像の形の一致を評価してピクセル数を示す．以上の物理評価において，6が同一座標上に重なって存在するピクセル数を示す．以上の物理評価において，8と考え，大津の二値化法 10)により評価対象領域を決定した．この手法は分割後
mized.
Also, to は２値化画像の評価対象領域の全ピクセル数，N（χ∩y）は両画像
visually
evaluate
SSIM, a unique
min_S and fake_S were 540.79±458.02 and（MSSIM）は算出された小領域毎のSSIMの画像全体の平5
いる．Nχ，Nyの評価対象領域の全ピクセル数，N（χ∩y）は両画像
領域は評価対象から外して指標値を算出すべき
7
画像生成に不必要な脳実質外の領域は評価対象から外して指標値を算出すべき
9の各領域の強度分散（σ12，σ22）を重みづけした和（式 5）が最小になるように画SSIM
map, which visualizes10)SSIM for each sub333.35±309.1, respectively, PSNR 22.00±3.34
られる．DSC（式-4）は２値化画像の形の一致を評価して6が同一座標上に重なって存在するピクセル数を示す．以上の物理評価において，在するピクセル数を示す．以上の物理評価において，り評価対象領域を決定した．この手法は分割後8と考え，大津の二値化法により評価対象領域を決定した．この手法は分割後10像毎に最適な閾値（t）を決定する．また，視覚的にSSIM
region,
was added for visual evaluation.
and を評価するために，小23.78±2.56, MSSIM 0.68±0.10 and
化画像の評価対象領域の全ピクセル数，N（χ∩y）は両画像
7
画像生成に不必要な脳実質外の領域は評価対象から外して指標値を算出すべき
2
2
外の領域は評価対象から外して指標値を算出すべき
重みづけした和（式5）が最小になるように画9の各領域の強度分散（σ5）が最小になるように画
1 ，σ2 ）を重みづけした和（式11
領域毎のSSIM を画像化した独自のSSIM マップでも視覚的評価を加えた．
0.73±0.09, DSC 0.92±0.07 and 0.93±0.06, and
10)て存在するピクセル数を示す．以上の物理評価において，8と考え，大津の二値化法により評価対象領域を決定した．この手法は分割後により評価対象領域を決定した．この手法は分割後．また，視覚的にSSIM� を評価するために，小10像毎に最適な閾値（t）を決定する．また，視覚的にSSIM を評価するために，小����for�eachof��thethe fake_S was
22
実質外の領域は評価対象から外して指標値を算出すべき
12𝑆𝑆𝑆𝑆�� �5）が最小になるように画� 𝑦𝑦�� � 𝑦𝑦� � 1…（1）�𝑆𝑆��
10 log� assessments,
�…（2）
2
9
の各領域の強度分散（σ，σ）を重みづけした和（式5）が最小になるように画2
���
）を重みづけした和（式� SSIM を画像化した独自の SSIM マップでも視覚的評価を加えた．
���
2 SSIM マップでも視覚的評価を加えた．
の
11
領域毎の
more similar to the 40 min_S than to the 10法 10)により評価対象領域を決定した．この手法は分割後10像毎に最適な閾値（t）を決定する．また，視覚的にSSIM を評価するために，小�定する．また，視覚的にSSIMを評価するために，小
�
�
���
����
�
�
��
��
�
��
� �
� �
��
��
�
�𝑆𝑆���� 𝑦𝑦�
10log���
�…（3-2）12𝑆𝑆𝑆𝑆���𝑦𝑦�5）が最小になるように画�
𝑦𝑦�…（2）
…（1）
�𝑆𝑆��
����
10𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥log�� � � , 𝑦𝑦��…（2）13
𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥,
� ∑σ12，σ22）を重みづけした和（式
�����
��
� ��
� �� � �� � …（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆
11 マップでも視覚的評価を加えた．
領域毎の
SSIM
マップでも視覚的評価を加えた．
���� SSIM����������を画像化した独自の�
��
た独自の SSIM�����を決定する．また，視覚的にSSIM を評価するために，小�＊� ��� � �� ������� �� ��� ��� ���
� ��10 log ��� �…（2）��� 𝑦𝑦 ��� …（1）����∩�� �
�
12
𝑆𝑆𝑆𝑆�
𝑦𝑦
�
�𝑆𝑆��
�
∑
�
�
�
��
1）
�𝑆𝑆��
�
10
log
�
�…（2）
…（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆
�,𝑦𝑦…（3-2）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥
∑
13
𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥,𝑦𝑦� ��� �𝑡𝑡����, 𝑦𝑦� �…（3-2）
� 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥�� �𝑡𝑡�𝜎𝜎����…（5）
14 SSIM
�𝑆𝑆� マップでも視覚的評価を加えた．
� ���𝜎𝜎� �𝑡𝑡� � �� �𝑡𝑡�𝜎𝜎��� � …（4）
� ��
� ���
化した独自の� �𝑡𝑡�� �� � �� � …（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆� ��� ��� �� ������ ���

�

�

�

�

�

�

PSNR(dB)

MSE����� �� ��� ������ ���� �
� ��
� �
��
���∩��
���
…（1）
�𝑆𝑆��
����𝑡𝑡�10 log,�𝑦𝑦�����…（3-2）
�…（2）
�
15
1-4.
�統計画像による評価
� �𝑡𝑡�13∑���𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥,𝑦𝑦��…（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆� � �𝑡𝑡�, 𝑦𝑦� �…（3-2）∑…（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥
�𝑡𝑡�𝜎𝜎�𝑡𝑡�
�𝑡𝑡�𝜎𝜎
�
���
𝜎𝜎
�
�
�
�
…（5）
� 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥�� �𝑡𝑡�𝜎𝜎��� �𝑡𝑡�
…（5）
14
�𝑆𝑆�
�
…（4）
𝜎𝜎�� �𝑡𝑡� � �� �𝑡𝑡�𝜎𝜎� � ��� � ��� ��������� ��� ���
��
�
��
�
�
�
��� � ��� ���
123

DSC

16

MSSIM

I-IMP SPECT データは Three-dimensional stereotactic surface projections (3D� �11）�����∩����∑ �𝑡𝑡�𝜎𝜎
…（3-1）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆�𝑥𝑥15
� �𝑡𝑡�� …（4）
�
17
SSP)
解析を行い，
健常者に対して血流低下領域をで脳表画像上に描出
� , 𝑦𝑦� �…（3-2）
�𝑆𝑆���𝑡𝑡�𝜎𝜎𝜎𝜎�� �𝑡𝑡� � �� �𝑡𝑡�𝜎𝜎Z-score� �𝑡𝑡�𝜎𝜎� �𝑡𝑡� …（5）𝜎𝜎�� �𝑡𝑡�1-4.
� ��統計画像による評価
������� �𝑡𝑡� � ����� ���� ��� � 14��
� �𝑡𝑡� …（5）�� ���
(b)
＊
123
(a)
-dimensional
16
I-IMPsurface
SPECTprojections
データは(3DThree-dimensional stereotactic
surface projections(3D- 10min_S
18 stereotactic
させて診断されるのが一般的となっている．そこで，生成された
PNG
fake_S データを10min_S
fake_S
10min SPECT� �𝑡𝑡�
� �𝑡𝑡�
� �𝑡𝑡�
）15
1-4.
統計画像による評価11
�𝑡𝑡�𝜎𝜎�𝑡𝑡�𝜎𝜎
）
𝜎𝜎
�
�
�
�
…（5）
て血流低下領域を
Z-scoreで脳表画像上に描出
17SSP)
解析を行い，
健常者に対して血流低下領域を
Z-score で脳表画像上に描出����� 3D-SSP 解析を行い 40min_S，10min_S，fake_S
19
Dicom
形式に変換することでか
123
16
I-IMP SPECT
データはThree-dimensional
stereotactic surface projections(3DThree-dimensional
stereotactic
surfaceprojections(3Dっている．そこで，生成された
PNG
データを
18
させて診断されるのが一般的となっている．そこで，生成された
PNG
データを
20
らの Z-score map で比較した．なお，PNG から Dicom へ変換する際にはオリジ
11）
価
17
SSP)
解析を行い，
健常者に対して血流低下領域を
Z-score で脳表画像上に描出に対して血流低下領域を
Z-scoreで脳表画像上に描出
SSP 解析を行い40min_S，10min_S，fake_S
か
19
Dicom
形式に変換することで3D-SSP 解析を行い 40min_S，10min_S，fake_S
か
21
ナル
Dicom
画像と
PNG ファイルの信号値の比率から算出した128 倍を各ボク．Evaluation
1-4
by Statistical
Image
タは Three-dimensional
stereotactic
surfaceprojections(3D18
させて診断されるのが一般的となっている．そこで，生成された
PNG
データを的となっている．そこで，生成された
PNG
データをお，PNG からDicomへ変換する際にはオリジ
123I-IMP
20
らの
Z-scoremap data
で比較した．なお，PNG
から Dicom へ変換する際にはオリジ
22
セル値に乗算することで画像のカウントに近似させ,ヘッダ情報を付加
SPECT
are Dicom
generallyused for
常者に対して血流低下領域を
Z-score で脳表画像上に描出
19
Dicom
形式に変換することで3D-SSP解析を行い40min_S，10min_S，fake_S
かで 3D-SSP 21
解析を行い
40min_S，10min_S，fake_S
かルの信号値の比率から算出した
128
倍を各ボク
ナル
Dicom
画像と
PNG
ファイルの信号値の比率から算出した128 倍を各ボク
23
した.
Z-scoremap は 客three-dimensional
観 的 評 価 が 必 要 な た め Stereotactic
extraction
diagnosis
by performing(d)
一般的となっている．そこで，生成された
PNG
データを
(c)
＊
＊
20
らの
Z-scoreへ変換する際にはオリジmapで比較した．なお，PNG
から Dicomへ変換する際にはオリジ
12）た．なお，PNG
から
Dicom
11)
画像のカウントに近似させ,ヘッダ情報を付加
fake_S22
セル値に乗算することでDicom
画像のカウントに近似させ,ヘッダ情報を付加
fake_S
10min_S24
estimation(SEE)解析を加えた．SEE
はanalTalairach daemon10min_S
を用い３D-SSPの Zstereotactic
surfaceprojection(3D-SSP)ことで 3D-SSP
解析を行い
40min_S，10min_S，fake_S
かpaired t-test , * : p<0.01
21
ナル
Dicom
画像と
PNG
ファイルの信号値の比率から算出した
128
倍を各ボク
ァイルの信号値の比率から算出した
128
的
評 価 が 23
必 要ysisなた
たStereotactic
extraction
し.め Z-scoring
Z-scoremap
は倍を各ボク
客of観hypoperfusion
的評 価 が 必 要 な た め Stereotactic extraction
25
score
map
の各
pixel
Talairach
脳座標図譜に合致した座標情報に落とし込むこ
and
theを
areas
較した．なお，PNG
から Dicom へ変換する際にはオリジ）
22
セル値に乗算することでDicom
画像のカウントに近似させ,
12
com 画像のカウントに近似させ,ヘッダ情報を付加
Fig. 2 を用い３D-SSP
Theヘッダ情報を付加
evaluation results．SEE
は Talairach
daemonを用い３D-SSPの healthy
Z24
estimation(SEE)解析を加えた．SEE
は Talairach daemonの Z-of (a) MSE, (b) PSNR,
26とで
Brodmann野の分類に合わせた絶対評価を可能としている．
onbrain
surface
imagesforsubjects.
G ファイルの信号値の比率から算出した
128
倍を各ボク
(c)
SSIM,
and
(d)
DSC
are shown in graphs.
23
した.
Z-score
map
は
客
観
的
評
価
が
必
要
な
た
め
Stereotactic
extraction
観的評価
必 要 map
な たの各
め pixelStereotactic
extraction
脳座標図譜に合致した座標情報に落とし込むこ
25
score
を Talairach
脳座標図譜に合致した座標情報に落とし込むこ
3D-SSP
analysiswasperformedby
27 が Therefore,
2．結果
By image generation, fake_S was rated higher than 1012） ヘッダ情報を付加
で Dicom 24
画像のカウントに近似させ,
estimation(SEE)解析を加えた．SEE
は Talairach daemon を用い３D-SSP の Zえた．SEE
daemonを用い３D-SSPの Z-to Dicom
た絶対評価を可能としている．
26とでBrodmann野の分類に合わせた絶対評価を可能としている．
converting
the generated
PNG
data
min_S
a signiﬁcantdifference in all evaluations.
28は Talairach
各評価指標の結果をFig.2に示す．10min_Sと fake_Sのwith
MSE
平均値と標準偏
は客観的
評
価
が
必
要
な
た
め
Stereotactic
extraction
25
score
map
の各
pixel
を
Talairach
脳座標図譜に合致した座標情報に落とし込むこ
rach 脳座標図譜に合致した座標情報に落とし込むこ
27
2．結果
29
差はそれぞれ 540.79±458.02，333.35±309.1，PSNR 22.00±3.34，23.78±2.56，MSSIMを加えた．SEE
は Talairach
daemonを用い３D-SSP の Z26とでBrodmann野の分類に合わせた絶対評価を可能としている．
わせた絶対評価を可能としている．
す．10min_Sとfake_Sの MSE
平均値と標準偏28
各評価指標の結果をFig.2に示す．10min_Sとで各評価ともに
fake_S の MSE fake_S
平均値と標準偏◆ Journal300.68±0.10，0.73±0.09，DSC
0.92±0.07，0.93±0.06
では対応
of JART
Englishedition2024
58
Talairach 27
脳座標図譜に合致した座標情報に落とし込むこ
2．結果
35±309.1，PSNR
22.00±3.34，
23.78±2.56，
MSSIM
29
差はそれぞれ540.79±458.02，
333.35±309.1，
PSNR
22.00±3.34，
23.78±2.56，MSSIM
31のある t 検定にて有意差をもって 10min_S より 40min_S に類似した．Fig.3に類に合わせた絶対評価を可能としている．

������ ��� �original articles
Generation of standard time acquisition images from short time acquisition images of cerebral blood flow SPECT using deep learning

min_S with signiﬁcant differences in the corresponding t-tests. Fig. 3 shows pix2pix analysis images from Test_data. There are examplesof each condition: The upper panel shows No
abnormality (N.A), the middle panel shows Alzheimer's dementia (AD), and the lower panel
shows Right internal artery stenosis (R. IC).

N.A is shown as Decrease, indicating areas ofrelative hypoperfusion, and Increase, indicating areas of relative hyperperfusion. AD and
R.IC were displayed in comparison with Decrease. The selection criteria for cases were as
follows: the patients with clear areas of hypoperfusion in dementia or cerebrovascular disease and higher than average MSSIM in thebasal ganglia region were selected by referring
only to the 3D-SSP at 40 min_S. The SSIM map
shows low SSIM values for cold colors (blue)and high values for warm colors (yellow). In
MSE, 10 min_S shows 647.76, fake_S shows
293.38. In PSNR, they show 20.02 and 23.46,
respectively. MSE and PSNR for AD were from914.17 to 395.17 and from 18.52 to 22.16, respectively, and for R.IC from MSE 749.42 to
237.19 and from PSNR 19.38 to 24.38, showing
the same changes as for N.A. MSSIM changed
to higher values in all cases, from 0.63 to 0.75
for N.A, 0.63 to 0.73 for AD, and 0.64 to 0.72
for R.IC. In DSC, the values were 0.96 to 0.97
for NA, 0.95 to 0.95 for AD, and 0.94 and 0.95
for R.IC.

N.A

AD

R.IC

10min_S

40min_S

fake_S

SSIM map 10min_S

SSIM map fake_S

Fig. 3 The images show generated images andSSIM maps for three cases of no abnormality (Upper), Alzheimerʼs dementia (Middle),
and right internal artery stenosis (Lower).
The SPECT images of each case shown in the ﬁgure are
40 min_S, 10 min_S, and fake_S in the same slice. The
SSIM map shows 10 min_S and fake_S of the same slice
as SPECT.

Rt.LAT Lt.LAT

Rt.MED Lt.MED

Rt.LAT Lt.LAT

Rt.MED Lt.MED

Rt.LAT Lt.LAT

Rt.MED Lt.MED

Rt.LAT Lt.LAT

40min_S

40min_S

40min_S

40min_S

10min_S

10min_S

10min_S

10min_S

fake_S

fake_S

fake_S

fake_S

1(e)

Rt.LAT Lt.LAT

5
Rt.MED Lt.MED

Rt.LAT Lt.LAT(f)

Rt.MED Lt.MED

(i)

0

100

Rt.LAT Lt.LAT

Rt.MED Lt.MED

Rt.LAT Lt.LAT

40min_S

40min_S

40min_S

40min_S

10min_S

10min_S

10min_S

10min_S

fake_S

fake_S

fake_S

fake_S(g)(h)

Rt.MED Lt.MED(j)

Rt.MED Lt.MED

(l)

(k)

Fig. 4 Z-score map (e) ( f ) (g) (h) and SEE ( i ) ( j ) (k) ( l ) of the three cases in Fig. 3.
(e) ( i ): The indication of low blood ﬂow for N.A, ( f ) ( j ) : The indication of increased blood ﬂow for N.A,(g) (k) : The indication of low blood ﬂow for AD, (h) ( l ) : The indication of low blood ﬂow for R.IC.

Arts and Sciences ◆ 59

Fig. 4 shows the results of 3D-SSP Z-score

map and SEE analysis of the three cases in Fig.
3, which were analyzed using the normal database constructed at our institution. The Z-score
map of the 3D-SSP is displayed with a lower
limit of 1.0 and an upper limit of 5.0 as in thescale used for clinical diagnosis, and SEE isclassiﬁed by Lobule (Level 3) and displayed as
Extent ratio (%). In 10 min_S for N.A, the Zscore region was depicted with an extent ratioof 15% to 20% in the upper and lower temporal gyrus region in the Decrease and 15% to
55% in the right and left frontal and temporal
lobe regions in the Increase, on the other hand,that in 40 min_S and fake_S was not depicted.
In the AD patients, the Z-score regions weremore extensive in the fake_S than in the 40
min_S, and furthermore, those in the 10 min_S
were more extensive than in the others in allbrain regions. In the fake_S, the precuneus, aspeciﬁc area of hypoperfusion in AD, showed
an Extent ratio of 50%, but not in the fake_S. In
the R.IC, the left frontal region showed a Zscore with an Extent ratio of 20-50%, which
was not seen in the 40 min_S (SEE⇨).

3. Consideration
In short-time collected SPECT image which
includes much quantum noise, the effect of image quality improvement by deep learning is
the most expected point, and the MSE and
PSNR results show that the image quality is signiﬁcantly improved in fake_S compared to 10
min_S, and is closer to 40 min_S. The case images in Fig. 3 also show noise reduction in
fake_S compared to 10 min_S, which is consistent with the physical evaluation. The next issue is the similarity accuracy of signal information between corresponding voxels in the generated and reference images. In AI, it is common to evaluate similarity based on SSIM values, and Fukui 9) et al. refer to the index values
in the guidelines 13) for image compression ofdigitized documents. The guideline evaluates

60 ◆ Journal of JART English edition 2024

the value of the text ﬁle when it is converted
into an image. PSNR 30 to 40 [dB] and MSSIM
0.90 to 0.98 are considered to be “a level wheredegradation can be seen when enlarged,” andPSNR less than 30 [dB] and MSSIM less than
0.90 are considered to be “clearly degraded.”
The results of FAKE_S were not satisfactory because the degradation was clearly visible. When
we check the images with low MSSIM in Fig. 2,
a proportion of skull base sections which has
small parenchymal brain area that is depicted
as radiopharmaceutical uptake is little is large,
and the images with MSSIM 0.3 to 0.5 are majority, which is considered to be one of thereasons to degrade the evaluation value. Theseare predicted to have a signiﬁcant effect on
MSE and PSNR, and we believe that evaluation
excluding skull base images is necessary in the
future. Fig. 3 SSIM map shows that the MSSIM
increased by 16% in N.A, 13% in AD, and 11%
in R.IC at 40 min_S compared to 10 min_S. The
map also shows that the number of cold regions decreased, and it is possible to partiallyvisualize the similarity evaluation. Next, regarding the evaluation of the similarity of theZ-score map in all brain regions, the clinicaldiagnosis does not seem to differ signiﬁcantly
between the 40 min_S and fake_S Z-scoremaps in the validation case N.A. Decrease andIncrease, but in AD, there is failure of depiction on Rt.LAT precuneus region, and that is a
speciﬁc hypoperfusion region in AD, which inﬂuences the diagnosis. Also in R.IC, depictionof frontal brain region on Lt.LAT that is notdepicted in 40 min_S is observed. The DSC is
an image that evaluates the similarity between
binarized images, and there is no signiﬁcantdifference between 40 min_S, 10 min_S, andfake_S. We believe that the threshold setting in
the Otsu method was suitable for calculatingeach evaluation index. Finally, although pix2pix image generation could improve the image quality of 10 min_S, it is difﬁcult to generate a standard time distribution of cerebral perfusion for a short collection time. Therefore, itoriginal articles
Generation of standard time acquisition images from short time acquisition images of cerebral blood flow SPECT using deep learningis necessary to extend the collection time from
10min to ﬁnd a collection time when the relative count ratio between each voxel in thebrain parenchyma region is closer to 40 min,and then to train with the data.

4. Conclusion
Using pix2pix, an artiﬁcial intelligence-based
image generation model, we attempted to generate a standard SPECT image with 40 minutes
acquisition time from a 10 minutes acquisition
time of the original cerebral perfusion SPECT
image. The 3D-SSP analysis also showed thatthe generated images were more similar to thestandard images than the original images.
However, they were not at the level of clinicaluse as standard SPECT images.
Conflict of interest

There are no conﬂicts of interest to be disclosed by the ﬁrst author or co-authors.

References
1） Nakamura Y, Narita K, Higashi T, et al.: Diagnostic
value of deep learning reconstruction for radiationdose reduction at abdominal ultra-high-resolution CT.
Eur Radiol, 31(7): 4700-9, 2021.
2） Njeh I, Mzoughi H, Ben Slima M, et al.: Deep
Convolutional Encoder-Decoder algorithm for MRI
brain reconstruction. Med Biol Eng Comput, 59(1):85-106, 2021.

3） Kim M, Kim HS, Kim HJ, et al.: Thin-Slice Pituitary
MRI with Deep Learning-based Reconstruction:
Diagnostic Performance in a Postoperative Setting.
Radiology, 298(1): 114-22, 2021.
4） Park CJ, Chen W, Pirasteh A, et al.: Initial Experience
With Low-Dose 18F-Fluorodeoxyglucose Positron
Emission Tomography/Magnetic Resonance Imaging
With Deep Learning Enhancement. J Comput Assist
Tomogr, 45(4): 637-42, 2021.
5） O k a m o t o K , U s h i j i m a Y, O k a m u r a C , e t a l . :Measurement of cerebral blood flow using graph plot
analysis and I-123 iodoamphetamine. Clin Nucl Med,
27(3): 191-196, 2002.
6） Yamamoto Y, Onoguchi M, Wada A, et al.: Evaluationof Shortened Protocol of Graph Plot Method with
123
I-IMP. Jpan J.Radiol.Technol, 67(5): 524-33, 2011.
7） Phillip Isola, Jun-Yan Zhu, Tinghui Zhou, et al.: Imageto-Image Translation with Conditional Adversarial
Networks. Proceedings of the IEEE Conference on
Computer Vision and Pattern Recognition (CVPR),
1125-1134, 2017.
8） Diederik P. Kingma, Jimmy Ba: Adam: A Method for
Stochastic Optimization. Published as a conference
paper at ICLR, 2015.
9） Fukui R, Fujii S, Ninomiya H, et al.: Generation of
the Pseudo CT Image Based on the Deep Learning
Technique Aimed for the Attenuation Correction of the
PET Image. Jpan J.Radiol.Technol, 76(11): 1152-62,
2020.
10）Nobuyuki Otsu: A Threshold Selection Methodfrom Gray-Level Histograms. IEEE Transactions on
Systems, Man, and Cybernetics, 9(1): 62-66, 1979.
11）Minoshima S, Frey KA, Koeppe RA, et al.: A
diagnostic approach in Alzheimer ʼ s disease using
three-dimensional stereotactic surface projections offluorine-18-FDG PET. J Nucl Med, 36(7): 1238-48,
1995.
12）Mizumura S, Kumita S, Cho K, et al.: Developmentof quantitative analysis method for stereotactic brain
image: assessment of reduced accumulation in extent
and severity using anatomical segmentation. Ann Nucl
Med, 17(4): 289-95 2003.
13）Kobako Masahiko: Process to Standardization, A
Report by Committee of Standardization (3), Guidelinesof Image Compression for Digitized Documents,
Journal of image & information management, 50(5):21-24, 2011.

Arts and Sciences ◆ 61

Arts and Sciences
original articles

Received August 29, 2022 ; accepted May 24, 2023

MiSDO:The Open-source Radiation Dose Management System
SUGIMOTO Kohei1）, MATSUMOTO Masaki2）, OITA Masataka3）, FUJIWARA Yuta4）,
NAGASAKI Ryota5）, SHODA Takashi6）, KURODA Masahiro7）1）Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University/
Division of Imaging Technology, Okayama Diagnostic Imaging Center2）Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University/
Department of Radiological Technology, Ehime University Hospital
3）Faculty of Interdisciplinary Science and Engineering in Health Systems, Okayama University4）Division of Clinical Radiology Service, Okayama Central Hospital5）Department of Radiology Diagnosis, Aoki Internist and Pediatrics Clinic6）Department of Radiology, Kawasaki Medical School General Medical Center
7）Department of Radiological Technology, Faculty of Health Sciences, Okayama University

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 854: 29-35, 2023.
Key words: dose management system, open-source, digital imaging and communications in medicine,radiation dose structured report【Abstract】

All medical facilities with diagnostic imaging equipment in Japan must recently record and manage radiation doses.
Accordingly, a radiation dose management system (DMS) is essential for recording and managing radiation doses, and
it is difﬁcult to introduce in all medical facilities because of its high cost. In this study, we developed an open-source
DMS called “MiSDO” and verified its capability through simulations. The results showed that it could record andmanage radiation doses quickly and accurately. “MiSDO” is promising as free software to record and manage radiation
doses that anyone can use.

1. Introduction
The International Commission on Radiological Protection recommends establishing diagnostic reference levels (DRLs) to optimize radiation dose for imaging procedure 1). Over the
past decade, radiation dose optimization with
DRLs has been implemented worldwide 2-8).
Moreover, several reports suggest DRLs havecontributed to reducing radiation dose in clinical practices 9, 10). The ﬁrst step of radiation dose
optimization is to obtain representative doseindex values for each radiological examination
in medical facilities. There are two principal
approaches for collecting data: manual and automatic methods. Although manual data collection is simple, it has the problem of inaccurate
data collection11). Therefore, in recent years,
a method that considers the value calculated
from a dose management system (DMS) 12),62 ◆ Journal of JART English edition 2024

which can collectively manage radiation doses
from radiological examinations, as the representative value of the medical facility and comparing the value with DRLs would be suitablefor optimizing radiation doses 13).
However, because commercially available
DMSs are often expensive, there are problems
with accelerating their introduction in all medical facilities. Under these circumstances, Japanese Enforcement Regulations on the Medical
Care Act were revised in April 2020, making
the recording and managing radiation doses
mandatory for all medical facilities. Radiationdose recording is usually implemented by referring to the secondary capture output fromthe X-ray imaging modalities to the picturearchiving and communications system (PACS).
On the other hand, radiation dose management could be necessary to compare the representative dose index values of the facility with

original articles
MiSDO: The Open-source Radiation Dose Management System

DRLs, and consider what to do if the representative values exceed one. As mentioned above,
considering that manual recording of radiation
doses is inaccurate 11) and comparing values
calculated from DMS with DRLs as representative values are suitable 13), all medical facilities
in Japan would be better to install DMS.
To achieve a possible solution, we have developed an open-source DMS called “MiSDO”
that can record and manage radiation doses
for the X-ray imaging modalities such as computed tomography (CT), angiography, andnuclear medicine examinations (URL: https://github.com/dose-mmasaki/MiSDO_release).
Although there are several reports of developing in-house DMS systems for CT 14-21) andﬂuoroscopically guided intervention 20, 22-24) for
referring to radiation dose information in digital imaging and communications in medicine(DICOM) format data. There has been no free
DMS, including all modalities under the revised
Enforcement Regulations on the Medical Care
Act 14-24). In this study, we veriﬁed the operation of “MiSDO” using DICOM ﬁles retrieved
from diagnostic imaging modalities of several
manufacturers. Then, we simulated the recording and management of radiation dose using“MiSDO” and clariﬁed its usefulness.

2. Materials and Methods
2.1 Development environment and devices

The development environments were used
Visual Studio 2019 (Microsoft Corporation, WA,USA) as the integrated development environment, Python (version 3.7.8; Python Software
Foundation, DE, USA), and Visual C# (version
7.3; Microsoft Corporation) as the programming language, and SQLite as the database. Pydicom, a Python library, was used to process
DICOM ﬁles, including radiation dose structured report (RDSR). A computer with Windows 10 education operating system (Microsoft
Corporation), which has a single Intel core i53470S CPU 2.9-GHz processor and 4 GB RAM,was used to verify the softwareʼs operation. CT
systems used were SOMATOM Sensation 64(VB42B; Siemens, Munich, Germany), Discovery CT 750HD (17BW50.7B; GE Healthcare,
WI, USA), Aquilion NEW PRIME TSX-303A/
MW (7.0; Canon Medical Systems, Tochigi, Japan), and Aquilion 64 (3.10; Canon Medical
Systems). Inﬁnity Celeve-i INFX-8000C (N9;Canon Medical Systems), Symbia Dual Head
System (VB10B; Siemens), and Biograph Horizon (VJ21B; Siemens) were used as angiography, single photon emission CT (SPECT) andpositron emission tomography (PET)/CT systems, respectively.
2.2 Development of “MiSDO”
Figure 1A shows an overview of the system

conﬁguration of “MiSDO.” It consists of two
main modules for recording and managing radiation doses. The recording module consistsof “DoNuTS,” which extracts dose information from DICOM headers and RDSRs, and“ChuRROs,” which automatically extracts dose
information from secondary captures (only
Aquilion 64) with an optical character reader(OCR). This OCR algorithm adds the image
pixels in the column direction to obtain themarginal distribution. Then, we performed thepattern matching classiﬁcation between themarginal distribution and the previously registered information (Fig. 1B). The radiation dose
information of CT and X-ray angiography are
extracted almost equivalently to the DEN Dosesoftware 13). Radiopharmaceutical dose is also
extracted in nuclear medicine examinations,such as SPECT and PET. The management
module consists of programs for visualization and output functions using data stored
in the database. “MiSDO” was developed as aprogram that worked with these modules andcould operate through a graphical user interface.

Arts and Sciences ◆ 63

Fig. 1 Overview and details of the developed radiation dose management system.
(A) An overview of the system conﬁguration of “MiSDO.”(B) Details of the algorithm for the optical character reader function of “MiSDO.” Character
strings of secondary capture output from CT are acquired row by row, and the marginal
distribution added in the column direction is used for character classiﬁcation by patternmatching.

2.3 Operation validation of the developed
DMS

The recording and management modules of“MiSDO” were operationally validated. A water
phantom was scanned using one of the protocols routinely used in each imaging modality. Then, the RDSRs and secondary captures
were retrieved from the CT, X-ray angiography,
SPECT, and PET/CT devices in DICOM format. To verify the accuracy of OCR, randomly
selected ten protocols from the protocols
list used in clinical practice and scanned thephantom using the Aquilion 64. These DICOM
ﬁles were imported using “MiSDO” to conﬁrm
that they were working correctly. Also, we
simulated the recording and management of

64 ◆ Journal of JART English edition 2024

radiation dose from CT examinations. Referring to the report by Ogawa 25), the number ofCT examinations per day was assumed to be
25. Then, the RDSR ﬁle outputs from Aquilion
NEW PRIME TSX-303A/MW were duplicatedfor one day, one week, one month, six months,
and one year, respectively. The number ofthese data were 25, 175, 700, 4,375, and 8,750,
respectively. The volume CT dose index (CTDIvol) and the dose length product (DLP) of
the duplicated data were replaced with simulated data computed from regression equations created using patientsʼ height and weight.
“MiSDO” was used to store these data andmeasured the time required for analysis. The
median values of the replicated one-year dataoriginal articles
MiSDO: The Open-source Radiation Dose Management Systemwere compared with the values of the routine
chest CT scan for adults of the DRLs 2020 in Japan (CTDIvol = 13 mGy, DLP = 510 mGy･cm) 26).

3. Results
3.1 Operation validation
Figure 2 shows a screen capture of the de-veloped DMS. All radiation dose information
was extracted accurately without any errors
from DICOM ﬁles of one scan for each of thesix modalities (SOMATOM Sensation 64, Discovery CT 750HD, Aquilion NEW PRIME TSX303A/MW, Inﬁnity Celeve-i INFX-8000C, Symbia Dual Head System, and Biograph Horizon)
and secondary captures of 10 scans for one
modality (Aquilion 64).

Fig. 3 Double logarithmic plot of recording timefor extracting information from duplicatedradiation dose structured reports.
The time required for the Data analysis of 25 records
for assuming some daily examinations, 175 records forweekly, 700 records for monthly, 4,375 records for semiannually, and 8,750 records for annually were 14 sec onds (0.23 min), 103 seconds (1.72 min), 494 seconds(8.23 min), 4,923 seconds (82.1 min), and 10,243 seconds (170.7 min), respectively.

3.2 Processing time
Figure 3 shows the time it took “ MiSDO ”

to record the duplicated RDSR. The recording time increased as the number of data increased. The time required for 25 recordings
for the number of daily examinations and
8,750 recordings for annual examinations was
14 seconds (0.23 min) and 10,243 seconds(170.7 min), respectively.

3.3 Simulation of dose management
Figure 4 shows that the median CTDIvol and

DLP of the standard body weight extracted
from the duplicate RDSRs were 12.5 mGy and487.2 mGy･cm, respectively. These data assume a routine chest CT scan for adults, andthe corresponding values DRLs 2020 in Japan 26)
are 13 mGy and 510 mGy･cm, respectively.
The median values of the data simulated in thisstudy were lower than those in DRLs.

Fig. 2 Screen capture of the developed radiation dose management system after
extracting radiation dose information from multiple modalities.
Arts and Sciences ◆ 65

Fig. 4 Scatter plots and violin plots for CTDIvol and DLP simulated routine chest
CT scan for adults.
The left column shows the scatter plots, where the horizontal axis represents body massindex (BMI) and the vertical axis represents CTDIvol (ﬁrst row) and DLP (second row). The
right column shows violin plots of CTDIvol (ﬁrst row) and DLP (second row) for standard bodyweight (50-70 kg). Strip plots are shown within the violin plots. The dotted lines in the violin
plots are quartiles, representing the 25th, 50th, and 75th percentiles from the top, respectively. The median values of these data (12.5 and 487.2 mGy, respectively) are displayed in
the upper right corner.

4. Discussion
In this study, we veriﬁed that “MiSDO” could
accurately extract data necessary for recording
and managing radiation dose from multiple
manufacturersʼ DICOM ﬁles retrieved fromeach modality. Furthermore, the extracted data
were duplicated to simulate radiation dosemanagement. “MiSDO” has been able to extract
data quickly, revealing that it can accurately
process large amounts of data generated inclinical practice. “MiSDO” can easily calculate
representative dose index values and comparethem with DRLs, suggesting that the system canbe used as a tool to optimize radiation doses.
The developed DMS could extract information on one year of CT examination data
(8,750 records) in less than three hours. The

66 ◆ Journal of JART English edition 2024

program that reads the data necessary for dosemanagement only retrieves text data from the
DICOM ﬁle so that the data can be extracted
at high speed. The commercial DMS is designed to perform a DICOM query/retrieve on
the PACS at night time to get the data into the
DMS. “MiSDO” has been able to achieve shorttime processing even on the local PC used forthis simulation. Thus, we considered “MiSDO”
acceptable enough for use in a clinical practice where data is expected to be extracted atnight-time, similar to commercially available
DMSs. Because there are many CT scanners inJapan 28), manual storage of radiation dose data
is more time-consuming than in other countries. This issue may lead to prolonged workfor radiological technologists. “MiSDO” could
be an effective solution to this problem sinceoriginal articles
MiSDO: The Open-source Radiation Dose Management System

the mechanical recording of radiation dose
data can increase work efﬁciency and prevent
human error.
“MiSDO” has the following two strengths
compared to the previously reported in-housedeveloped DMSs. The First is that all “MiSDO”
source code is publicly available. Commercially available DMSs are guaranteed to work andare regularly inspected by the manufacturer.
However, it is not possible with a free DMS. If
the source code of the DMS is disclosed, theprogram errors can be addressed by reading
the source code. RADIANCE 14) was a visionary
open-source DMS; however, as of 2022, it isclosed to the public. DEN Dose 20) is also a free
DMS; however, the source code is not publicly
available. Although there are several reports ofother privately developed DMSs, the systems
are private 19), or even if the source code is publicly available, only a limited number of systems 21) are available in the supported modalities. In other words, “MiSDO” is the only opensource DMS that supports many modalities.
The second is the ability to achieve accurate
OCR for the Japanese. Compared to English,
Japanese is more challenging to apply for OCR
accurately due to the lack of spaces between
words and the fact that it has more than 3,000
character types. Interestingly, “MiSDO” could
read Japanese in secondary captured CT images with high accuracy. Since the secondary
captured image is digital data, the marginal distribution of characters and phrases is uniquelydetermined. Therefore, it could be achieved
with high accuracy by using a pattern-matching algorithm. To the best of our knowledge,
the only language supported by the OCR
functions of the free DMSs reported is English14, 15, 17, 21), and this capability is an advantage
when considering use in Japan.
A limitation of “MiSDO” is that it cannot connect with PACS. When using “MiSDO” to record
dose information, it is necessary to read a DICOM ﬁle from the PACS system or to connect aworkstation to the PACS and then process thedata with “MiSDO”. It is a signiﬁcant drawback
for ﬂuoroscopically guided intervention, where
the maximum skin dose needs to be calculated
immediately; however, almost free DMSs also
do not support this 27).

5. Conclusion“MiSDO” is a DMS that can realize free andaccurate recording and management of exposure doses. It is also the only free DMS compliant with the revised Japanese laws. “MiSDO”
is expected to solve problems when manually
recording and managing radiation doses.

Acknowledgments
We thank Mr. Eiji Ohnishi (Okayama Saiseikai General Hospital, Okayama, Japan) for hiscooperation in obtaining image data.
Conflict of interest

The authors declare that they have no conﬂict of interest.

References
1） Vañó E, et al.: ICRP publication 135: Diagnostic
reference levels in medical imaging. Ann ICRP, 46(1),1-144, 2017.
2） Foley SJ, et al.: Establishment of CT diagnostic
reference levels in Ireland. Br J Radiol, 85(1018),
1390-1397, 2012.
3） Fukushima Y, et al.: Diagnostic reference level ofcomputed tomography (CT) in Japan. Radiat Prot
Dosimetry, 151(1), 51-57, 2012.
4） Roch P, et al.: French diagnostic reference levels in
diagnostic radiology, computed tomography andnuclear medicine: 2004-2008 review. Radiat Prot
Dosimetry, 154(1), 52-75, 2012.
5） van der Molen AJ, et al.: A national survey on radiationdose in CT in The Netherlands. Insights Imaging, 4(3),383-390, 2013.
6） Saeed MK, et al.: Regional survey of image quality
and radiation dose in computed tomography
examinations in Saudi Arabia. Australas Phys Eng Sci
Med, 37(2), 279-283, 2014.
7） Sulieman A: Establishment of diagnostic reference
levels in computed tomography for paediatric patientsin Sudan: a pilot study. Radiat Prot Dosimetry, 165(14), 91-94, 2015.

Arts and Sciences ◆ 67

8） Kanal KM, et al.: U.S. diagnostic reference levels
and achievable doses for 10 adult CT examinations.
Radiology, 284(1), 120-133, 2017.
9） Matsunaga Y, et al.: Diagnostic reference levels andachievable doses for common computed tomography
examinations: Results from the Japanese nationwide
dose survey. Br J Radiol, 92(1094), 20180290, 2019.
10）Katsari K, et al.: Implementation of a computed
tomography dose management program across amultinational healthcare organization. Eur Radiol,31(12), 9188-9197, 2021.
11）Dickinson N, et al.: A comparison of manually
populated radiology information system digitalradiographic data with electronic dose management
systems. Br J Radiol, 93(1111), 20200055, 2020.
12）Gress DA, et al.: AAPM medical physics practiceguideline 6.a.: Performance characteristics of radiationdose index monitoring systems. J Appl Clin Med
Phys, 18(4), 12-22, 2017.
13）Osman ND, et al.: Radiation dose management in
CT imaging: Initial experience with commercial dosewatch software. J Phys Conf Ser, 1497(1), 012020,
2020.
14）Cook TS, et al.: Informatics in radiology: RADIANCE:An automated, enterprise-wide solution for archivinga n d re p o r t i n g C T r a d i a t i o n d o s e e s t i m a t e s .
Radiographics, 31(7), 1833-1846, 2011.
15）Shih G, et al.: Automated framework for digitalradiation dose index reporting from CT dose reports.
AJR Am J Roentgenol, 197(5). 1170-1174, 2011.
16）Christianson O, et al.: Automated size-specific CT
dose monitoring program: Assessing variability in CT
dose. Med Phys, 39(11), 7131-7139, 2012.
17）Sodickson A, et al.: Exposing exposure: Automatedanatomy-specific CT radiation exposure extraction for
quality assurance and radiation monitoring. Radiology,
264(2), 397-405, 2012.
18）Dave JK, et al.: Extraction of CT dose informationfrom DICOM metadata: Automated Matlab-based
approach. AJR Am J Roentgenol, 200(1), 142-145,
2013.

68 ◆ Journal of JART English edition 2024

19）Nitrosi A, et al.: Patient dose management solution
directly integrated in the RIS: “ Gray Detector ”
software. J Digit Imaging, 27(6), 786-793, 2014.
20）Dendo Y, et al.: Development of computer codefor dose management using DICOM radiation dose
structured report in X-ray computed tomography.
Medical Imaging and Information Sciences, 33(2), 4347, 2016.
21）Weisenthal SJ, et al.: Open-source radiation exposure
extraction engine (RE3) with patient-specific outlier
detection. J Digit Imaging, 29(4), 406-419, 2016.
22）J o h n s o n P B , e t a l . : S k i n d o s e m a p p i n g f o r
fluoroscopically guided interventions. Med Phys,
38(10), 5490-5499, 2011.
23）Borrego D, et al.: A hybrid phantom system for patientskin and organ dosimetry in fluoroscopically guided
interventions. Med Phys, 44(9), 4928-4942, 2017.
24）Borrego D, et al.: Physical validation of UF-RIPSA: A
rapid in-clinic peak skin dose mapping algorithm forfluoroscopically guided interventions. J Appl Clin Med
Phys, 19(3), 343-350, 2018.
25）Ogawa K: Study on the running condition and theoperation of CT in Saitama prefecture. Journal of
JART, 60(8), 904-909, 2013.
26）Japan Network for Research and Information on
Medical Exposure (J-RIME), et al. National diagnostic
reference levels in Japan (2020) -Japan DRLs 2020-.
[Accessed 21 May 2021] http://www.radher.jp/
J-RIME/report/DRL2020_Engver.pdf27）Malchair F, et al.: Review of skin dose calculation
software in interventional cardiology. Phys Med, 80,
75-83, 2020.
28）OECD: Computed tomography (CT) scanners(indicator). [Accessed 26 December 2022]

Arts and Sciences
original articles

Received September 2, 2022 ; accepted June 23, 2023

Effects of radioprotective equipment on radiation
exposure to the operator’s eye lens during computed tomography fluoroscopy-guided procedure
HASEGAWA Takaaki, M.D., Ph.D.1）, SHIMIZU Hidetoshi, R.T., Ph.D.2）,
CHATANI Shohei, M.D.1）, MURATA Shinichi, M.D.1）, HATTORI Hisashi, R.T.1）,
INABA Yoshitaka, M.D., Ph.D.1）
1）Department of Diagnostic and Interventional Radiology, Aichi Cancer Center Hospital2）Department of Radiation Oncology, Aichi Cancer Center Hospital

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 854: 44-49, 2023.
Key words: radiation exposure, CT ﬂuoroscopy, radioprotective equipment, eye lens【Abstract】
Purpose: To evaluate whether radiation exposure to the operatorʼs eye lens is reduced by radioprotective equipment ofshield and lead drape during computed tomography (CT) ﬂuoroscopy-guided procedures.
Materials and Methods: Radiation doses were measured using small optically stimulated luminescence dosimeters
outside and inside radioprotective glasses of the operator during 16 lung nodule localizations. Measurements were
performed under four settings: A) with radioprotective shield and lead drape; B) with radioprotective shield, without
lead drape; C) without radioprotective shield, with lead drape; and D) without radioprotective shield or lead drape.
The ﬂuoroscopy duration was compared between settings, with and without a shield, using Welchʼs t-test. Radiation
doses per procedure were compared among the four settings of radioprotective equipment using the one-way analysis
of variance.
Results: Mean duration of ﬂuoroscopy was signiﬁcantly longer in settings with shield (53.8 ± 5.5s for settings of A andB) than in those without shield (45.6 ± 2.6s for settings of C and D) (p = 0.005). Mean radiation doses were 26.0 ±4.9 µGy, 43.1 ± 3.5 µGy, 66.4 ± 3.5 µGy, and 79.1 ± 7.0 µGy outside the glasses, for settings A, B, C, and D, respectively,
and 11.9 ± 4.2 µGy, 20.9 ± 3.4 µGy, 30.9 ± 2.7 µGy, and 34.2 ± 3.6 µGy inside the glasses, for settings A, B, C, andD, respectively. Significant differences were detected among the four settings for the radiation dose both outside(p < 0.001) and inside (p < 0.001).
Conclusion: Radioprotective equipment reduces radiation doses to the operatorʼs eye lens during CT fluoroscopyguided procedures.

INTRODUCTION
The importance of reducing radiation exposure in medical staff has recently increased.
The International Commission on RadiologicalProtection has recommended an annual dose
limit to the eye lens of 20 mSv averaged overa deﬁned period of ﬁve years, with doses notexceeding 50 mSv in any single year 1）. The International Atomic Energy Agency has adopted
this new dose limit 2）. Thus, we must consider
radiation exposure to the eye lens during interventional radiology procedures.
Computed tomography (CT) ﬂuoroscopy is
one of imaging modality used during inter-

ventional radiology. It offers the advantage of
rapid and objective visualization of the puncture target 3，4）and is widely used in performing
procedures such as biopsy, ablation, and preoperative lung nodule localization 5-11）. However, this procedure has the strong drawbackof radiation exposure to both patients andmedical staff 3，9-12）. In particular, the eye lens ofoperators are exposed to relatively high radiation doses 11，12）.
Several methods to reduce operator radiation
exposure during CT ﬂuoroscopy-guided procedures have been reported. For example, theinstallation of a radioprotective shield in frontof the scan plane has been reported to reduce
Arts and Sciences ◆ 69

the radiation exposure to the operator 13，14）.
Placement of a lead drape over the patient toblock scattered radiation reaching the operator
has been shown to be an effective option 15-17）.
However, such results have been derived
from experimental studies using phantoms;
therefore, the extent to which radiation exposure could be reduced by these methods has
not been evaluated in clinical settings. In thisstudy, we measured doses to the eye lens received by the operator during CT ﬂuoroscopyguided procedures and evaluated the clinicalreduction in radiation doses to the operator using shields and lead drapes as radioprotective
equipment.

METHODS
Study design

Radiation doses were measured during preoperative localization of the lung nodules. This
procedure was chosen for the analysis because
the ﬂuoroscopy time was relatively short anddid not vary between sessions.
This study was approved by our institutional review board as a survey for operator
radiation exposure. Written informed consent
was obtained from the operator performing
the procedure before measuring the radiation
dose. Informed consent to perform lung nodule localization under CT ﬂuoroscopy, which
provides medical exposure, was obtained fromeach patient.

kyo, Japan). Subsequently, the needle wasadvanced to the target nodule and a mixture ofindigo carmine (Indigo Carmine; Daiichi Sankyo Co. Ltd., Tokyo, Japan) and lipiodol (Lipiodol; Fuji Pharma Co. Ltd., Tokyo, Japan) was
injected into the lung parenchyma while withdrawing the needle until lipiodol accumulation
reached the pleural surface on CT ﬂuoroscopy
images. A real-time 3 slices CT image was displayed by treading on the foot panel of theoperator. The fluoroscopic images were obtained with a tube voltage of 120 kV and a tube
current of 10 mA, and the duration of ﬂuoroscopy was recorded. The procedures were performed by an interventional radiologist (T.H.,
with approximately 10 years of experience ininterventional radiology). Measurements were
performed with four settings of radioprotective
equipment using a 0.5-mm lead shield (KYOWAGLAS XA; KURARAY Trading Co., Tokyo,
Japan) and a 0.25-mm lead drape (Smart light;
HOSHINA Co., Tokyo, Japan): A) with shieldand lead drape; B) with shield, without leaddrape; C) without shield, with lead drape; andD) without shield or lead drape. No signiﬁcantdifferences on body weight and body massindex of patients (p = 0.58) and tumor size
(p = 0.90) were detected by the one-way analysis of variance (ANOVA) between settings.

Measurement of radiation doses

Radiation doses were measured during 16
sessions of lung nodule localization between
November 2020 and January 2021. The procedure was performed percutaneously using
real-time CT ﬂuoroscopy (Aquilion LB; Canon
Medical Systems Corp., Otawara, Japan). Local
anesthesia was performed with 1% lidocaine(Xilocaine Injection Polyamp 1%; Aspen Japan
K.K., Tokyo, Japan) using a 6 cm 23-G needle(Terumo Cattelan Needle; Terumo Corp., To-

70 ◆ Journal of JART English edition 2024

Fig. 1 A radioprotective shield (asterisk) was set infront of the scan plane at settings A and B,
and a lead drape (arrow) was placed on thepatient outside the computed tomography
gantry at settings A and C.

original articles
Effects of radioprotective equipment on radiation exposure to the operator’s eye lens during computed tomography fluoroscopy-guided procedure

Table 1 Detail and result of the procedure of each radiation dose measurement setting
Case

Age

Body
Sex weight BMI
(kg)

Tumor
location

Tumor
size
(mm)

Body
position

76

M

Right lower

8

Prone

Duration
Radiation
Radiationof CT
dose outside dose inside
fluoroscopy the glasses the glasses
(sec)
(µGy)
(µGy)

Setting A
1

56.3

21.1

54.4

25.6

11.9

2

75

M

62.7

22.9

Right upper

5

Prone

57.0

27.3

11.9

3

73

F

57.4

24.5

Right upper

8

Prone

55.7

32.4

17.9

4

71

F

52.5

22.5

Right lower

6

Left decubitus

50.8

18.8

6.0

Setting B
1

69

M

51.8

20.2

Right upper

3

Left decubitus

58.4

43.5

25.6

2

64

M

63.7

21.5

Right upper

18

Prone

42.5

40.1

19.6

3

30

F

72.6

29.2

Left lower

6

Right decubitus

50.3

48.6

22.2

4

65

F

69.8

25.4

Right lower

7

Prone

61.4

40.1

16.2

Setting C
1

48

F

59.8

19.8

Right lower

3

Prone

47.9

70.8

33.3

2

65

F

49.3

22.8

Right upper

13

Left decubitus

41.9

63.1

28.1

3

61

F

55.6

23.2

Left upper

4

Supine

44.3

69.1

34.1

4

71

F

42.8

19.4

Right upper

10

Prone

48.0

62.8

28.3

Setting D
1

65

M

62.4

22.1

Left upper

9

Prone

44.3

78.4

30.7

2

71

F

42.8

19.4

Right upper

8

Prone

47.9

80.1

36.7

3

68

F

61.0

26.3

Right lower

11

Left decubitus

42.3

69.1

30.7

4

66

F

54.6

21.5

Right lower

7

Prone

48.6

88.7

38.9

BMI: body mass index

The radioprotective shield was set in front of
the scan plane, and a lead drape was placed on
the patient outside the CT gantry. Each setting
comprised four sessions of localization procedure.
The radiation dose was measured using
small optically stimulated luminescence dosimeters (OSLDs) (NanoDot; Nagase Landauer,
Tsukuba, Japan). These small OSLDs were
taped outside and inside the left surface of theradioprotective glasses, with the plane of thedosimeters facing the CT scan plane (Panoramashield; TORAY Industries, Tokyo, Japan).
Taped OSLDs were removed from the radioprotective glasses and the data were read using
a microSTAR reader (Nagase Landauer) immediately after each session.
Assessment

The duration of ﬂuoroscopy and the radiation dose of CT ﬂuoroscopy outside and insideA

B

Fig. 2 A) Locations of small optically stimulated
luminescence dosimeters (OSLDs) on theradioprotective glasses.
B) Small OSLDs were taped outside andinside the left surface of the radioprotective
glasses.
Arts and Sciences ◆ 71

the radioprotective glasses were measured.
Data are expressed as mean ± standard deviation. To evaluate the inﬂuence of the usage ofradioprotective shield on the ﬂuoroscopy duration, the duration was compared between settings with and without a shield using Welchʼs ttest. The radiation doses per procedure among
the four radioprotective equipment settings
were evaluated using the one-way ANOVA,
and the difference between each setting wascompared using Tukeyʼs multiple comparison
test. Statistical signiﬁcance was set at p < 0.05.
Statistical analyses were performed using acommercially available software (SPSS for Windows, version 24; IBM, Armonk, NY, USA).

A

B

RESULTS
Duration of fluoroscopy

Durations of fluoroscopy were 54.5 ± 2.3 s,
53.1 ± 7.4 s, 45.5 ± 2.6 s, and 45.8 ± 2.6 s forsettings A, B, C, and D, respectively. Mean duration of ﬂuoroscopy was signiﬁcantly longer
in settings with shield (53.8 ± 5.5 s at settings
A and B) than in those without shield (45.6 ±2.6 s at settings C and D) (p = 0.005).
Radiation dose

Radiation doses were 26.0 ± 4.9 µGy, 43.1
± 3.5 µGy, 66.4 ± 3.5 µGy, and 79.1 ± 7.0 µGy,
outside the radioprotective glasses, for settings A, B, C, and D, respectively, and 11.9 ±4.2 µ Gy, 20.9 ± 3.4 µ Gy, 30.9 ± 2.7 µ Gy, and34.2 ± 3.6 µGy, inside the radioprotective glasses, for settings A, B, C, and D, respectively.
Significant differences were detected among
the four settings for the radiation dose bothoutside (p < 0.001) and inside (p < 0.001) theradioprotective glasses by one-way ANOVA.
In the following Tukeyʼs multiple comparison
test, signiﬁcant differences were seen between
all settings at outside the glasses (A vs B:
p = 0.005, A vs C: p < 0.001, A vs D: p < 0.001,
B vs C: p < 0.001, B vs D: p < 0.001, C vs D:
p = 0.04) and all settings except between Set-

72 ◆ Journal of JART English edition 2024

Fig. 3 A) Estimated radiation doses outside
the radioprotective glasses. Radiation
doses were: A) 26.0 ± 4.9 µGy; B) 43.1
± 3.5 µ Gy; C) 66.4 ± 3.5 µ Gy; and D)
79.1 ± 7.0 µGy. The one-way analysis ofvariance revealed significant differencesamong settings (P < 0.001).
B) Estimated radiation dose inside theradioprotective glasses. Radiation
doses were: A) 11.9 ± 4.2 µGy; B) 20.9
± 3.4 µ Gy; C) 30.9 ± 2.7 µ Gy; and D)
34.2 ± 3.6 µGy. The one-way analysis ofvariance revealed significant differencesamong settings (P < 0.001).

tings C and D at inside (A vs B: p= 0.04, A vs C:
p < 0.001, A vs D: p < 0.001, B vs C: p = 0.02, B
vs D: p = 0.003, C vs D: p = 0.68).

DISCUSSION
This study showed that radioprotective
equipment comprising a shield and a leaddrape was effective in reducing radiation exposure to the eye lens of the operator during
clinical CT fluoroscopy-guided procedures.
These results support the concept that radioprotective equipment should be used during
CT fluoroscopy-guided procedures, as suggested in previously reported experimental

original articles
Effects of radioprotective equipment on radiation exposure to the operator’s eye lens during computed tomography fluoroscopy-guided procedurestudies 13-17）.
It has been reported that the occupationalradiation dose could be reduced by 71–97%
with a radioprotective shield or lead drape 14-17）
in a phantom study. However, radiation dose
was reduced up to 67% (1 - 26.0 µGy / 79.1 µGy)
in this study, even though both shield andlead drape were used. This suggests that thetheoretical maximum dose reduction could not
be achieved in a clinical setting. The reason
for this is unclear; however, the measurement
point might be one explanation. The measurement points close to the scan plane areassociated with more scattered radiation 16）. If
the measurement point of the phantom study
is closer to the scan plane than the eye position in clinical settings, the reduction in radiation dose by radioprotective equipment might
be overestimated. The reduced sensitivity of
OSLDs to the higher X-ray energy may be another explanation 18）. Nonetheless, we must pay
attention to reducing the occupational dose
as much as possible by using radioprotective
equipment during CT ﬂuoroscopy-guided procedures.
The fluoroscopy duration was significantly
longer when a radioprotective shield was used.
The movement of the operatorʼs arm was interfered with by the shield set in front of thescan plane, which might have prolonged theﬂuoroscopy time. Despite the longer ﬂuoroscopy time, the radiation dose was reduced
using a shield. However, shortening the duration of ﬂuoroscopy is important to reduce occupational exposure doses to medical staff andexposure to patients 19，20）. The use of curtaintype radioprotective equipment might also
be effective as a less obstructive option 17）;

however, comparisons of whether and how
such equipment might shorten the duration of
ﬂuoroscopy and reduce radiation doses have
yet to be performed. Further investigations are
required to determine which type of equipment is better.
This study has several limitations. First, radiation doses measured using small OSLDs wereenvironmental radiation doses; therefore, theresults did not entirely match the dose to theeye lens. However, the OSLDs were placednear the eye, and the results were thought torepresent doses close to the actual dose to theeye lens. Second, the sample size was small.
Third, tumor location was not matched between the groups. This may affect ﬂuoroscopy
duration and the distances between the scanplane and the operator. Further investigation
to evaluate the relation of them may help tovalidate the result of this study.
Conclusion

We measured the radiation doses to the operatorʼs eye lens during CT ﬂuoroscopy guided
procedures and showed that radioprotective
equipment of glasses, shield, and lead drape
reduces the radiation doses to the operatorʼs
eye lens during CT fluoroscopy-guided procedures. In particular, using both a shield andlead drape might be effective in maximizing
the full beneﬁt of all equipment.
Statement and Declarations

This work was supported by the Aichi Cancer Research Foundation.
The authors declare that they have no conﬂict of interest.

Arts and Sciences ◆ 73

References
1） International Commission on Radiological Protection(ICRP): ICRP Statement on Tissue Reactions/Early
and Late Effects of Radiation in Normal Tissues andOrgans—Threshold Doses for Tissue Reactions in a
Radiation Protection Context. ICRP Publication 118,2012. Available online: https://journals.sagepub.com/
doi/pdf/10.1177/ANIB_41_1-2 (accessed on 30 April
2022).
2） International Atomic Energy Agency (IAEA): Radiation
Protection and Safety of Radiation Sources:
International Basic Safety Standards; General Safety
Requirements Part 3. Available online: https://wwwpub.iaea.org/MTCD/Publications/PDF/Pub1578_
web-57265295.pdf (accessed on 30 April 2022).
3） Silverman SG, Tuncali K, Adams DF, Nawfel RD,
Zou KH, Judy PF: CT fluoroscopy-guided abdominalinterventions: Techniques, results, and radiation
exposure. Radiology, 212, 673-681, 1999.
4） Fu YF, Li GC, Cao W, Wang T, Shi YB: Computed
To m o g r a p h y F l u o r o s c o p y - G u i d e d V e r s u sConventional Computed Tomography-Guided Lung
Biopsy: A Systematic Review and Meta-analysis. J
Comput Assist Tomogr, 44(4): 571-577, 2020.
5） Shibamoto K, Mimura H, Fukuhara Y, Nishino K,
Kawamoto H, Kato K: Feasibility, safety, and efficacy
of artificial carbon dioxide pneumothorax for computed
tomography fluoroscopy-guided percutaneousradiofrequency ablation of hepatocellular carcinoma.
Jpn J Radiol, 39(11): 1119-1126, 2021.
6） Hasegawa T, Kuroda H, Sato Y, et al.: The Utility ofIndigo Carmine and Lipiodol Mixture for Preoperative
Pulmonary Nodule Localization before Video-Assisted
Thoracic Surgery. J Vasc Interv Radiol, 30(3): 446452, 2019.
7） Tomita K, Iguchi T, Hiraki T, et al.: Computed
Tomography Fluoroscopy-guided Core Needle Biopsyof Abdominal Para-aortic Lesions: A Retrospective
Evaluation of the Diagnostic Yield and Safety.
Interventional Radiology, 5(3): 128-133, 2020.
8） Iguchi T, Matsui Y, Tomita K, et al.: Computed
Tomography-guided Core Needle Biopsy for Renal
Tumors: A Review. Interventional Radiology, 2021.
doi: 10.22575/interventionalradiology.2020-0019.
9） Kim GR, Hur J, Lee SM, et al.: CT fluoroscopyguided lung biopsy versus conventional CT-guided
lung biopsy: a prospective controlled study to assessradiation doses and diagnostic performance. EurRadiol, 21(2): 232-239, 2011.

74 ◆ Journal of JART English edition 2024

10）K n o t t E A , R o s e S D , Wa g n e r M G , e t a l . : C T
Fluoroscopy for Image-Guided Procedures: Physician
Radiation Dose During Full-Rotation and Partial-Angle
CT Scanning. J Vasc Interv Radiol, 32(3): 439-446,
2021.
11）I n a b a Y, H i t a c h i S , Wa t a n u k i M , C h i d a K :Occupational radiation dose to eye lenses in CTguided interventions using MDCT-fluoroscopy.
Diagnostics 11(4): 646, 2021.
12）Kaartinen S, Husso M, Matikka H: Operatorʼs eye lensdose in computed tomography-guided interventions.
Eur Radiol, 31(6): 4377-4385, 2021.
13）Mahnken AH, Sedlmair M, Ritter C, Banckwitz R,
Flohr T: Efficacy of lower-body shielding in computed
tomography fluoroscopy-guided interventions.
Cardiovasc Intervent Radiol, 35(6): 1475-1479, 2012.
14）Haipt F, Kirsch M, Hosten N: Evaluation of a leaden
radiation protection barrier for dose reduction for thephysician during CT fluoroscopy-guided interventions.
Rofo, 182(6): 512-517, 2010.
15）Stoeckelhuber BM, Leibecke T, Schulz E, et al.:Radiation dose to the radiologist ʼ s hand duringcontinuous CT fluoroscopy-guided interventions.
Cardiovasc Intervent Radiol, 28(5): 589-594, 2005.
16）Nawfel RD, Judy PF, Silverman SG, Hooton S, Tuncali
K, Adams DF: Patient and personnel exposure during
CT fluoroscopy-guided interventional procedures.
Radiology, 216(1): 180-184, 2000.
17）Neeman Z, Dromi SA, Sarin S, Wood BJ: CT
fluoroscopy shielding: decreases in scattered radiation
for the patient and operator. J Vasc Interv Radiol,17(12): 1999-2004, 2006.
18）Al-Senan RM, Hatab MR: Characteristics of an OSLDin the diagnostic energy range. Med Phys, 38(7):4396-4405, 2011.
19）Li J, Udayasankar UK, Carew J, Small WC: CTguided liver biopsy: correlation of procedure time andradiation dose with patient size, weight, and lesion
volume and depth. Clin Imaging, 34(4): 263-268,
2010.
20）Pradella M, Trumm C, Stieltjes B, Boll DT, Zech
CJ, Huegli RW: Impact factors for safety, success,duration and radiation exposure in CT-guided
interventions. Br J Radiol, 92(1099): 20180937, 2019.

Arts and Sciences
original articles

Received May 17, 2023 ; accepted September 4, 2023

Exploring the Significance of Subject Color Absorption and Indoor Lighting Interference inThree-Dimensional Surface Scanner ApplicationsSUZUKI Hidekazu, MSc.1）, SAITO Masahide, Ph.D.2）, UEDA Koji, RTT.3）,
KOIDE Tomoki, RTT.3）, SANO Naoki, Ph.D.4）, AIKAWA Yoshihito, Ph.D.4）,
ONISHI Hiroshi, Ph.D.5）

1）Department of Radiology, University of Yamanashi Hospital2）Medical Physicist, Department of Radiology, University of Yamanashi3）Department of Radiology, University of Yamanashi Hospital4）Department of Radiology, University of Yamanashi Hospital5）Doctor, Department of Radiology, University of Yamanashi

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 855: 25-31, 2023.
Key words: SGRT, Radiation Therapy, 3D surface scanner, Ambient light factor【Abstract】

There is a three-dimensional surface scanner that utilizes the reﬂection of red laser light as a device for surfaceguided radiation therapy. However, depending on the color of the object, sufficient reflected light might not be
obtained, and accurate surface recognition could be hindered by the contamination of ambient light similar to thereﬂected light, originating from indoor illumination. Therefore, this system aimed to elucidate how the recognition
capability is affected by the color of the target object and the ambient light.
Various hues, grayscale variations, and skin colors were employed to investigate whether recognition could beachieved by altering the color temperature and illuminance of the surrounding light. It was found that recognition
was not possible for colors that absorb red laser light, such as blue, green, black, and darker colors with insufﬁcient
reﬂection. Furthermore, while the impact of ambient illuminance was substantial, the inﬂuence of color temperature
was minimal.

1. INTRODUCTION
In radiotherapy, precise irradiation position
matching holds paramount importance, serving as a fundamental technique for achieving
high-precision radiotherapy outcomes 1). Currently, Image-guided radiation therapy (IGRT)
encompasses various methods, including the
2D-2D matching technique employing electronic portal imaging devices (EPID) and linac
graphs (LG), the 3D matching approach utilizing cone beam computed tomography (CBCT)
with kV X-rays for three-dimensional positioning. There is also a technique for the prostateand similar areas that uses an ultrasound probetransrectally for localization 2). However, thesemethodologies entail invasive procedures involving patient exposure to radiation.
Nevertheless, a recent advancement known

as surface guided radiation therapy (SGRT) has
emerged, enabling the acquisition of three-dimensional positional data of an objectʼs surface
by externally irradiating light and analyzing theresulting information. Within SGRT, body surface recognition primarily relies on three-dimensional scanner technology, employing
methods such as patterned light projection,
where a ﬁxed shape pattern like a triangle isprojected onto the object, capturing and analyzing its deformation via an optical camera toascertain three-dimensional shape and measure alterations. Notably, there are two primary
types: patterned light projection 3) and triangulation 4), each with distinct operational principles. While the laser-based method can depict
three-dimensional images over time by continuously irradiating a monochromatic laser
beam across a wide area and analyzing the reArts and Sciences ◆ 75

ﬂected light, it is susceptible to environmental
factors within the treatment room and the hueof the object being scanned. Speciﬁcally, ambient room illumination and the objectʼs color
may inﬂuence the collected data. Therefore,
the aim of this study is to elucidate the impactof treatment room conditions and object hue
on the body surface position data acquired bya non-contact laser-based 3D body surface
scanner (VOXELAN® HEV-600M/RMS, Electronics Research & Development Corporation,
Okayama, Japan; hereinafter referred to as
VOXELAN).

2. METHOD

Fig. 1 Overview of VOXELAN.
VOXELAN can grasp the three-dimensional shape by irradiating
the object with a red laser (two places on the left and right) fromthe ceiling suspended main body and continuously shooting thereﬂected light with the camera (center part) of the main unit. The
position displacement amount with the reference data can bedisplayed in a color map (upper left ﬁgure) or in a proﬁle (lower
left ﬁgure).

2-2 Recognition ability of an object (subject or
patient) in different hues and lightness

2-1 Equipment used:

The VOXELAN employed in this study is suspended from the ceiling and equipped with
two laser beams and a camera to capture reﬂected light. A red laser beam is emitted near
the isocenter (Fig. 1), with a distance of 1.6
meters to the isocenter and an elevation angleof 45 degrees. Continuously irradiating the redlaser, the system collects data to depict proﬁlesof three-dimensional changes over time.

We created the color sample sheets shown
below using a color printer (ColorMultiWriter
9100C: NEC, Japan), and evaluated their discriminative ability. To examine the inﬂuence ofhue, we selected 24 colors based on the RGB
color code (Fig. 2), and to investigate the effectof brightness, we classiﬁed 51 shades fromwhite (#FFFFFF) to black (#000000), fromwhich 25 shades were extracted (Fig. 3). Additionally, to consider the impact of skin color,we created 11 colors ranging from No. 25 toFig. 2 24-Color RGB Color Code for hue evaluation.

Fig. 3 25 Grayscale Codes for color brightness evaluation (including white and black additions).

76 ◆ Journal of JART English edition 2024

original articles
Exploring the Significance of Subject Color Absorption and Indoor Lighting Interference in Three-Dimensional Surface Scanner Applications

Fig. 4 How to find the recognition rate．
The recognition rate was measured using the VOXELAN proﬁle function. The blue line in the right ﬁgure indicates thereference position, while the red line indicates the position of the recognized object.

No. 35, which are the darkest on the skin chart
based on Von Luschanʼs chromatic scale 5).
VOXELAN measures the distance to the object
by emitting a laser beam from the main unit
mounted on the ceiling at an elevation angle of
45 degrees, and recognizes the three-dimensional
object using the triangulation method. Therefore,
even if an object on a horizontal bed reﬂects thelaser beam uniformly, if the object is large or located far away from the isocenter, the distancefrom the object to the detector will increase, andthe amount of light reﬂected and delivered to thedetector will change slightly, resulting in a change
in recognition performance. Using this phenomenon, the total length of the colored paper as theobject was measured from the proﬁle display,which is a function of the 3D body surface scanner used in this study, and the recognition rate

was calculated using Equation (1) (Fig. 4).
Recognition rate (%) = Recognized length (cm) /Total length of object (cm) ×100(%),…… (1)
2-3 Difference in recognition ability due to difference in ambient light illuminance:

VOXELAN measures distances based on reﬂected red laser light emitted by objects, capturing their three-dimensional shapes overtime. In radiotherapy rooms, patient positioning often utilizes in-room lasers, and dimmed
lighting is common to mitigate patient discomfort. Hence, ambient brightness might affect
VOXELANʼs recognition ability. Ambient brightness was measured using an illuminance meter(LightSpectrum Pro Ver. 4.3.0, iPhone 14.3: AM
Power Software, Italy), and illuminance varied for each colTable 1 Combination table for investigating the impact of differencesor temperature at the isocenterin illuminance on recognition accuracy.
surface as shown in Table 1.
Recognition rates were calculated using Equation (1) for the
25 grayscale shades used in
Method 2-2.
Table 2 Combination table for investigating the impact of differencesin color temperature on recognition accuracy.

2-4 Difference in Recognition
Ability due to Difference inAmbient Light Color Temperature:

As VOXELAN captures reﬂected light from a red laser,
Arts and Sciences ◆ 77

we examined the impact of incident red lightother than that emitted by the red laser fromthe main unit by varying the color temperatureof ambient light. Ambient lightʼs color temperature was adjusted using a smart LED bulb
(SwitchBot, Shenzhen, China), with variationfor each illuminance at the isocenter plane asshown in Table 2. Recognition rates were determined from Equation (1), and the color temperature component at the isocenter surface
was measured using a spectroradiometer(LightSpectrum Pro Ver. 4.3.0, iPhone 14.3: AM
Power Software).

3. RESULT
3-1 Effects of differences in hue and lightnessof the object (subject or patient):

Regarding hue variances, red (C1), yellow(C5), and peach (C21) demonstrated a 100%
recognition rate. However, green (C8) and purple (C18) exhibited an 80% recognition rate,
while dark green (C9), light blue (C13), andblue (C16) were not recognized (Fig. 5).
Grayscale lightness exhibited a 100% recognition ability for white, with sufﬁciently highlightness, while black, with low lightness, remained unrecognized. The recognition bound-Fig. 5 Differences in recognition due to differences in hue.

Fig. 6 Differences in recognition due to differences in skin color.

It could not be recognized by the hues of C9 to C17.

Colors darker than skin color number 29 are not recognized.

120%

120%

80%

1478 lx
727 lx

60%
40%
20%
0%

40

60

80

100

120

140

160

34 lx

60%
40%

100%

4639 lx

80%

40

60

80

100

120

140

Grayscale Number

160

G160

Grayscale number G40 to G160 weredivided into 25 pieces.

1787 lx

60%

0%

G40

120%

Recognition Rate

931 lx1290 lx80%

20%

Grayscale Number

695 lx2800 K40%
20%
0%4317 lx100%4158 lx

Recognition Rate

Recognition Rate

100%

3600 K

5600 K
40

60

80

100

120

Grayscale Number

140

160

Fig.7 The effect of differences in illuminance due to variations in the color

Fig. 7 The
effect of differencesin illuminanceto variations in the color temperatemperatureof ambient lighton recognitiondue
rates.
ture of ambient light on recognition rates.

78 ◆ Journal of JART English edition 2024

original articles
Exploring the Significance of Subject Color Absorption and Indoor Lighting Interference in Three-Dimensional Surface Scanner Applications

ary ranged from G120 to G60 on the grayscale
spectrum in Figure 3. Concerning skin color,
Von Luschanʼs chromatic scale No. 28 served as
the threshold, with darker skin tones remaining unrecognized. No. 28 on Von Luschanʼschromatic scale corresponds to Type V on theFitzpatrick Skin Type (Fig. 6).

limit at No. G65 with an illuminance of 4317 lx.
Moreover, image brightness decreased with
ambient light illuminance at 2800 K and 5600 K(Fig. 7).
3-3 Effect of ambient light color temperature:

Maintaining constant ambient illuminancewhile changing the color temperature did notalter the recognition rate, with threshold values
remaining nearly consistent (Fig. 8). However,lower color temperatures (2700 K) resulted in
the objectʼs edge displaying a higher position
than the reference, indicating increased lightentering the detector at that location (Fig. 9).

3-2 Effect of ambient light illuminance:

120%

120%

100%

100%

80%

5643 K3556 K

60%

Recognition rate

Recognition rate

Under ambient light with a color temperature of 3600 K and an illuminance of 34 lx, therecognition rate decreased from No. G140 andbecame unable to recognize at No. G95. As
ambient light illuminance increased, image
brightness decreased, reaching the recognition

40%2826 K

20%
0%

40

60

80

100

120

Grayscale Number

140

160

Recognition rate3639 K

2752 K

0%

40

60

80

100

120

140

160

Grayscale Number

G160

Grayscale number G40 to G160 weredivided into 25 pieces.

5730 K2745 K

700 lx40%1700 lx

4200 lx20%0%5559 K

40%

G40

100%

60%

3481 K

60%

20%

120%

80%

80%

40

60

80

100

120

Grayscale Number

140

160

effectcolortemperaturetemperature differences
duedueto variationsin ambient
Fig. 8 Fig.8
The Theeffectof ofcolor
differences
to variationsin ambient
light irradiance on recognition rates.
light irradiance on recognition rates.

Fig. 9 An example of how the color temperature of ambient light affected recognition．
Differences in ambient light color temperature caused image distortion at the edges of the reference
object. The red areas on the image indicate higher values compared to the reference position.

Arts and Sciences ◆ 79

4. DISCUSSION
4-1 Effects of hue and lightness:

VOXELAN identiﬁes objects by emitting a
red laser from the main unit installed on theceiling and capturing laser reﬂections with acamera. Consequently, objects not reﬂecting
the red laser cannot be recognized. When thereﬂected lightʼs color component reaches theeyes, itʼs perceived as the objectʼs color. Objects absorbing red light, such as green, blue,
and indigo, remain unrecognized.
Regarding color lightness, a scale from white
to black was utilized in this study. White reﬂects all colors of light, while black absorbs allcolors, making white recognizable but blacknot. Colors between white and black absorb
red light to varying degrees, leading to a recognition threshold at a certain lightness, as shown
in Result 3-1. As the object-detector distanceincreases, reﬂected light decreases, potentiallylowering the recognition threshold. Skin color
lacks a quantiﬁable threshold due to hue andlightness variations. Nevertheless, using Von
Luschanʼs chromatic scale and the Fitzpatrick
Skin Type, a threshold allowing 80% recognition based on these patterns was established.
SGRT has demonstrated efﬁcacy in irradiating breast cancer 4). however, concerns havebeen raised regarding diminished recognition
capability due to skin discoloration during irradiation. Yet, understanding the skin color
recognition threshold elucidated in this study
enables the assessment of SGRT continuity in
scenarios involving temporal skin discoloration, such as whole breast irradiation. Throughcomparison of discoloration severity with color
samples from Von Luschanʼs chromatic scale
and the Fitzpatrick Skin Type, SGRT viability
can be pre-assessed, even in an international
medical context where patients exhibit diverse
skin tones.
4-2 Effect of ambient light illuminance:

From Result 3-2, VOXELANʼs red laser, emit-

80 ◆ Journal of JART English edition 2024

ting at 680 nm, matches the detectorʼs measurement wavelength. Consequently, ambient
light of the same wavelength reaching the detector as reﬂected laser light is also captured,inﬂuencing data collection. As ambient lightincreases, reﬂected light from the object andthe recognition threshold decrease due to thepresence of ﬂuorescent lamps emitting light at
680 nm.
4-3 Effect of ambient light color temperature:

The study conﬁrmed that ambient light, including the 680 nm red laser component, affects recognition ability when mixed fromsources other than the emitting laser. Changes
in room light color for patient psychologicaleffects did not affect the red laser 6). Fluorescent lamps commonly used in treatment rooms
typically emit neutral light (5000 K). Results 3-3
indicated no recognition performance differences at various color temperatures. The examination of the wavelength components oflight at the color temperatures used in thisstudy revealed that at around 3000 K, whichcorresponds to warm white lighting, the yellow to red components are predominant, withfew blue and green components (Fig. 10). Additionally, for neutral light color at 5000 K anddaylight color at 6000 K, the blue, green, andred components are distributed almost evenly.
From these results, itʼs inferred that contamination aside from the red laser component is unaffected by ambient light color temperature but
depends on light intensity.
Moreover, observed ambient noise appears
caused by excessive red component entering
the detector, leading to misrecognition. Lower
color temperatures contain relatively more redcomponents, even at the same illuminationlevel, potentially mixing the 680 nm wavelength into the detector. Implementing ﬁlters
attenuating the 680 nm wavelength or reducing room illumination could mitigate misrecognition effects.

original articles
Exploring the Significance of Subject Color Absorption and Indoor Lighting Interference in Three-Dimensional Surface Scanner Applications

Fig. 10 Wavelength components of LED lighting.
The laser wavelength used by VOXELAN is 680 nm, so there is a high possibility of misrecognitionin the surrounding light with a color temperature of 2700 K, where components of that wavelength
are relatively prominent.

5. CONCLUSION
The VOXELAN HEV-600M 3D body surface
scanner utilized in this study demonstrated
compatibility with the lighting conditions typical of daily clinical practice. Nonetheless, given
its reliance on red light, consideration of boththe objectʼs color and ambient lighting hue isimperative. Additionally, the determination of
Von Luschanʼs chromatic scale No. 28 as theskin color recognition threshold for VOXELAN
signiﬁes a critical criterion for its future application.

6. CONFLICT OF INTEREST
The VOXELAN used in this study was borrowed from Hamano Engineering Co., Ltd. aspart of a commissioned research project.

ACKNOWLEDGMENTS
This study is the result of research funded by
the Japan Association of Radiological Technologistsʼ academic research grant. Additionally, I
presented part of the abstract of this study atthe 38th Annual Meeting of the Japan Association of Radiological Technologists held on September 17, 2022.

References
1） Dawson LA, et al.: Advances in Image-Guided
Radiation Therapy. J. Clin. Oncol. 25(8), 938-946,
2007.
2） Lachaine M, et al.: Intrafractional prostate motion
management with the Clarity Autoscan system. Med.
Phys. Int. 1(1), 72-80. 2013.
3） Bert C, et al.: A phantom evaluation of a stereovision surface imaging system for radiotherapy patient
setup. Med. Phys. 32(9), 2753-2762, 2005.
4） Freislederer P, et al.: Recent advances in Surface
Guided Radiation Therapy. Radiat. Oncol. 15(1), 187,
2020.
5） Gupta V, et al.: Skin typing: Fitzpatrick grading andothers. Clin. Dermatol. 37(5), 430-436, 2019.
6） Dalke H, et al.: Colour and lighting in hospital design.
Opt. Laser Technol. 38(4-6), 343-365, 2006.

Arts and Sciences ◆ 81

Arts and Sciences
note

Received July 21, 2021 ; accepted November 17, 2022

Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients withprostate cancer
SAITO Hitoshi, Ph.D., MIURA Shuta, SASAKI Hiroshi, SUZUKI Keiko
Department of Radiology, Akita Kousei Medical Center

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 848: 28-38, 2023.
Key words: MLC, Gamma pass rate, IMRT, Dose rate, Radiochromic ﬁlm【Abstract】

This study aimed to determine the optimum dose rate (DR) of intensity-modulated radiation therapy (IMRT) for
patients with prostate cancer in relation to the multileaf collimator (MLC) position errors based on the DR and gamma
pass rate (GPR). A gamma evaluation was performed using a 3% dose difference and 2 mm distance-to-agreement
criteria with a dose threshold of 10%. The MLC position error was measured using DynaLog files. The GPR was
measured using MapCHECK2 and EBT3. The delivery time decreased from 97 sec to 83 sec when the DR increased
from 500 to 600 monitor units per minute (MU/min). However, the difference between DR 500 and 600 MU/min was
not signiﬁcant ( p > 0.05). The MLC position errors increased with increasing DR but no signiﬁcant difference wasobserved in the maximum root mean square errors between the DRs of 300 and 400 MU/min, 400 and 500 MU/min,and 500 and 600 MU/min ( p > 0.05). The mean percentage GPRs of 97.6%, 96.2%, 97.0%, and 95.7% were observed
for the DRs of 300, 400, 500, and 600 MU/min, respectively, in EBT3. However, no signiﬁcant difference was observedin the GPRs of DRs 300, 400, 500, and 600 MU/min ( p > 0.05). The GPR of a DR 600 MU/min using EBT3 were at thevery limit of 95% criteria. Therefore, we suggested that a DR of 500 MU/min was the most acceptable rate considering
clinical safety.

Introduction
The intensity-modulated radiation therapy(IMRT) technique uses a multileaf collimator(MLC) to modify the beam fluence in thesame treatment ﬁeld in order to improve theconformity of the prescribed dose distribution
around the tumor region 1-5). This modulation
using MLC can be achieved using the sliding
window (dynamic MLC [DMLC]) technique.
DMLC is a treatment technique in which
both the dose rate (DR) and leaf velocity(LV) are continually adjusted by MLC shapes
when the beam is on. An increase in the
DR greatly reduced the delivery time 6，7) ,thus decreasing the burden on the patient;in particular, a longer delivery time causes
result in patient repositioning or movement
during a therapeutic session. However,increasing DR cause the faster LV, and a

82 ◆ Journal of JART English edition 2024

DR of 300 monitor units per minute (MU/
min) or 400 MU/min is routinely applied in
DMLC-IMRT because higher LV affects the
MLC position accuracy 8-10). Vorwerk et al. 9)
recommended that the DR for sliding window
IMRT should be 300 MU/min or 400 MU/min
for patients with prostate cancer according
to the dose volume histograms of the organs
at risk. Kaviarasu et al.10) examined the effectof DR on treatment accuracy using portal
dosimetry gamma evaluation (GE) and createda workflow for pretreatment IMRT quality
assurance (QA) using portal dosimetry with adefault DR of 400 MU/min for the approved
treatment plan. Thus, a higher DR of 500 or
600 MU/min was not applicable.
On the contrary, Ghasroddashti et al. 6)
conducted a survey of the relationship between
DR and the number of MUs; however, they
did not explicitly indicate which DR wasnote
Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients with prostate cancer

acceptable, and a higher DR will possibly
allow sufficient time to increase the numberof patients treated in a day. Furthermore,
Slosarek et al.7) suggested that the difference
between DRs of 100 MU/min and 600 MU/
min, measured using the radiation planningindex, was minor, and a low DR of 100 MU/
min did not have a significant impact on
the differences in treatment accuracy even iflarger MLC position errors occurred in DR 600
MU/min than that in DR 100 MU/min. Thesestudies can potentially apply a higher DR of
500 or 600 MU/min.
Although these studies evaluated dose
distribution using GE, few studies haveevaluated proportion of MLC position errors
in detail based on DR changes in the clinicalradiation plan. Furthermore, the optimal DR
has not been determined such as previous
studies 6-10). This study aimed to determine theoptimal DR in DMLC-IMRT for patients withprostate cancer in terms of relationship with
the MLC position errors according to the DR
and the inﬂuence of DR on dose distribution.

Materials and Methods
Patient data
Data of 15 patients with prostate cancer
treated using DMLC-IMRT in our institution
between June 2019 and January 2020 wereretrospectively obtained. Their median age
was 71 years (range, 56–81 years). According
to the Comprehensive Cancer Network Risk
classification for Prostate cancer (ver. 4,2018), four patients had low-grade prostatecancer and 11 had inter mediate-grade
prostate cancer 11). All patients were treated forprostate cancer with a dose of 76 Gy (2 Gy
per fraction) using a 7 ﬁeld IMRT with 10 MV
photon beams energy.
Computed tomography simulation anddelineation
Computed tomography (CT) axial scans witha slice thickness of 2.5 mm were performed forall patients using a 16 slice CT scanner (BrightSpeed Elite Pro Vision; GE Healthcare, USA).
The CT images were then transferred to atreatment planning system (TPS; Varian Medical
Systems, Palo Alto, CA, USA) for treatment
planning. The target volumes were contoured
by a physician. The clinical target volumes(CTVs) were the prostate, the proximal 1 cmof the seminal vesicle for intermediate-riskpatients, and the prostate for low-risk patients.
The planning target volumes (PTVs) consistedof the CTV with a posterior 5 mm margin anda 7 mm margin for other directions (superior,inferior, anterior, right lateral, and left lateral).
The prescribed dose was planned to be 95% of
the PTV.
Linear accelerator and treatment planning system
The treatment plans were calculated usinga Clinac iX (Varian Medical Systems) linear
accelerator equipped with a Millennium
120-leaf MLC (central: 20 cm of field, 5 mm
leaf width; outer: 20 cm field, 10 mm leaf
width) capable of IMRT delivery for different
DRs (300, 400, 500, and 600 MU/min). Allplans were created using Varian ʼ s Eclipse
TPS incorporating the Anisotropic Analytical
Algorithm version 13.6, and the associatedFig. 1 Flow of copied clinical plans for four DRs:
300, 400, 500, and 600 MU/min.
First, the clinical plan was copied, and optimization
process was not modiﬁed; second, the clinical plan waschanged based on the four DRs: 300, 400, 500, and 600
MU/min; and third, the leaf motion calculator was rerun foreach ﬁeld, and the dose distribution was recalculated infour copied plans.

Arts and Sciences ◆ 83

the clinical plan was changed based on the four DRs: 300, 400, 500, and 600 MU
3and third, the leaf motion calculator was rerun for each field, and the dose distrib
4
was recalculated in four copied plans.
5（第１に臨床計画をコピーし、最適化過程は変更しませんでした。第２に
6
は４つの線量率に基づいて変更した。第３にリーフモーション計算機で、
7
ィールドに対して再計算を行い、線量分布が４つのコピー計画により再計
Dosevolumehistgramparametersofthecopiedfourplans.
errors (0 –0.05, 0.05 –0.5, 0.5 –
1.0, and 1.0 –1.5 mm). The
8行った。
） （MU/min）
Doserate
2

Table1

Structure

Constrainttype

300

400

500

600

MLC position errors represent
80.33
80.34
80.34
80.35
Max（Gy）
the differences in the MLC
10
MLC position
error
Mean（Gy）
77.84
77.84
77.83
77.81
PTV
positions between the planned
The positional
accuracyof97.53
the DMLC was evaluated from a DMLC log (DynaLo
D99%（%） 11 97.46
97.49
97.52
and actual delivery positions.
12–14)
V76Gy（%）12 2.39
2.43MLC details
2.47
2.49
containing. These log
files contained DMLC delivery details rec
The analysis value of DynaLog
V70Gy（%）
8.43
8.45
8.47
8.49
13
every 50 ms to analyze the inaccuracyﬁlesin MLCmotion forasbanks
A and B. We ana
was expressed
the root
V65Gy（%）
11.06
11.08
11.10
11.12
Rectumthe log 13.39
files of all
IMRT copied
whilesquarechanging
onlyThethe RMSDRs using the Do(RMS).
V60Gy（%）14 13.36
13.40
13.42 plans mean
V50Gy（%）15 17.99
18.03
18.05
18.08
areSystems,
used to TX,
condense
v.6.8 FractionLab
software(Mobius errors
MedicalUSA). We assesse
V40Gy（%）
24.05
24.10
24.14
24.19
a
set
of
errorsintoasingle16
following factors: delivery time, number of MU, number of segments, and proport
8.80
8.80
8.76
8.76
V75Gy（%）
representative value 15) . The
MLC position
errors
V65Gy（%）17 16.41
16.42
16.41 (0–0.05,
16.41 0.05–0.5, 0.5–1.0, and 1.0–1.5 mm). The MLC po
Bladder
RMS errors are always greater
V40Gy（%）18 34.89
34.91
34.92
34.96 in the MLC positions between the planned anderrors represent
the differences
than or equal to the mean of
Dataarepresentedasmeanvalues.
delivery positions. The analysis value theof DynaLog
files ofwasas the root
PTV,planningtargetvolume 19
absolute value
theexpressed
errors.
20
square (RMS). The RMS errors are FractionLab
used to condense
software ais set
usedoftoerrors into a15)
leaf motion calculator21version
13.6 (Variancalculate
RMSareerrorsfor individual
leavesrepresentativevalue . The
RMStheerrorsalwaysgreater thanor equal to the me
Medical Systems). The22linearthe
accelerator
wasinfiles,
rangesofgantryanglesinfiles,
andabsolute value of the errors. FractionLab software is used to calculate theequipped with a maximum LV of 2.5 cm/sec.
entire leaf banks in a collection of files. For
23
errors for individual leaves
in files, ranges of gantry angles in files, and entire leaf
In addition, the number of segment settings fora set of n errors (differences between the set
24
in a collection of files. For a set of n errors (differences between the set and delDMLC-IMRT was automatically calculated inand delivered positions), the RMS errors were25
positions),theRMS
errorswere calculated
the following
the TPS. Clinical plans (DR 600 MU/min) were
calculatedusing the using
following
formula: formula:
26 400, 500, and 600
copied for four DRs: 300,
MU/min. Figure 1 shows the ﬂow of the fourᎂሺ୉୰୰୭୰ሻమ
27
RMS error ൌ ට௡copied plans. The optimal fluence patterns
determined during the
28 initial optimization
process were not modiﬁed, and the only DRs
29
Gamma evaluation (two-dimensional diode array detector)
were changed for all plans. Table 1 lists theGamma evaluation (two-dimensional diode30
To evaluate the influence of DRs on the dose distribution, all IMRT copied plans
dose volume histogram parameters for four
array detector)
31
measuredusing
MapCHECK2(Sun Nuclear
Corporation,
Melbourne,
FL, USTo evaluate
the influenceof DRs onthecopied plans. These parameters were much thecomparethe dose distributions
between all
theIMRT
calculated
measured
dose distribution,
copiedandplans
were doses; a GE
same values in spite of32
the differentDRs.
measuredusingand
MapCHECK2(Sun Nuclear
33
performed using a 3% dose
difference
2 mm distance-to-agreement
criteria w
FL, USA)
compareMLC position error
34
dose threshold (TH) of Corporation,
10% (3%/2 Melbourne,mm) to remove
the tonoise,
as recommended b
The positional accuracy of the DMLC was
the dose distributions between the calculated
35
American Association of Physicists in Medicine Task Group (AAPM TG) 2
evaluated from a DMLC log (DynaLog) fileand measured doses; a GE was performed
containing MLC details 12-14). These log files
using a 3% dose difference and 2 mm distance4
contained DMLC delivery details recorded
to-agreement criteria with a dose threshold
every 50 ms to analyze the inaccuracy in(TH) of 10% (3%/2 mm) to remove the noise,
MLC motion for banks A and B. We analyzed
as recommended by the American Association
the log files of all IMRT copied plans whileof Physicists in Medicine Task Group (AAPM
changing only the DRs using the DoseLab v.6.8
TG) 21 16，17). MapCHECK2 has a measuring
area of 26 cm × 32 cm that consists of 1,527
FractionLab software (Mobius Medical Systems,
solid-state SunPoint diode detectors with a
TX, USA). We assessed the following factors:
resolution of 0.8 mm × 0.8 mm, diagonaldelivery time, number of MU, number ofdetector spacing of 7.07 mm, and parallel
segments, and proportion of MLC position
984 ◆ Journal of JART English edition 2024

note
Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients with prostate cancer

detector spacing of 10 mm. MapCHECK2
was set up under an 8 cm water-equivalentphantom (Solid Water HE; GAMMEX-RMI,
Middleton, WI, USA) and placed in a planewith an isocenter. All treatment parametersin the copied plans were the same as thosein the clinical plan, excluding the gantry andcollimator angles set to 0 °for all ﬁelds. Before
the GE, MapCHECK2 was calibrated according
to the manufacturerʼs guidelines. A GE wasperformed at an absolute dose. The calculated
and measured dose distributions werecompared using the SNC Patients TM v. 6.7.4(Sun Nuclear Corporation). In addition, Woon
et al. 18) reported that the criterion of 3%/1
mm was the most sensitive gamma criterion
for MapCHECK2 to detect systematic MLC
errors. Therefore, we conducted a GE using
the criterion of 3%/1 mm in the additional
investigation.
Gamma evaluation (Film)
The radiochromic film used in this study
was a Gafchromic EBT3 (Inter national
Specialty Products, Wayne, NJ, USA) with sheet
dimensions of 20.3 cm × 25.4 cm. The film
was used according to the methods describedin the AAPM TG-55 report 19). To obtain thecalibration curve, the EBT3 ﬁlm was cut into
smaller pieces measuring 6 cm × 6 cm in size,and 12 of the smaller ﬁlms were selected. Eachpiece of ﬁlm was placed under a 10 cm solid
water phantom with a 10 cm space underneathto provide adequate backscatter, a field sizeof 10 cm × 10 cm, and a 90 cm source-tosurface distance. The ﬁlms were then irradiatedusing the Clinac iX linear accelerator with a
10 MV photon beam energy in the range of
0 MU to 500 MU (0, 10, 25, 50, 100, 150, 200,
250, 300, 350, 400, and 500 MU). To evaluate
the influence of DR on dose distributions,
the EBT3 film was sandwiched between I ʼ
mRT phantoms (IBA Dosimetry, GmbH,
Schwarzenbrunk, Germany) and placed in thesagittal plane at the center of the phantom

Fig. 2 Experimental set-up for film evaluation using
IʼmRT phantom.
To evaluate the influence of dose rate on the dose
distribution, the EBT3 ﬁlm was sandwiched between IʼmRT
phantoms and located in the sagittal plane at the centerof the phantom. Because sagittal plane could draw themost rectum which was organ at risk, we veriﬁed the dose
distribution using sagittal plane. We evaluated the dose
distribution at the center of the PTV.

(Fig. 2). After irradiation, the ﬁlms were kept ina box in order to protect them from ﬂuorescentlight for 24 h after irradiation exposure, and an
unexposed ﬁlm was scanned using a ﬂatbed
scanner (Epson Expression DS-G20000; Epson
Tokyo, Japan) in 48-bit RGB mode (red, 16bit color; green, 16-bit color; and blue, 16bit color) with a resolution of 75 dots/inch.
All treatment parameters in the copied plans
were the same as those in the clinical plan,
including the gantry and collimator angles. The
calculated and measured dose distributions
were compared using the DoseLab dosecomparison software ver.6.8 (Mobius Medical
Systems). A GE was performed with anabsolute dose using criteria of 3%/2 mm,
TH10%.
Dose rate dependence (preliminary experiment)
Actually delivered DRs of linear accelerator
were measured using two-dimensional (2D)
diode array detector (Profiler2 model1174;
Sun Nuclear Corporation). The measurement
were 20 cm × 20 cm open field size for
300 MU of 10 MV photon beams using
DRs of 300, 400, 500, and 600 MU/min. In
Arts and Sciences ◆ 85

addition, to verify the variations of radiation
output with DR in Clinac iX, a cylindricalion chamber (Farmer 30013; PTW GmbH,
Freiburg, Germany) and an electrometer(RAMTEC Smart; TOYO Medic, Tokyo, Japan)
were used. The measurements were madein water with a depth 10 cm and in an open
filed size of 10 cm × 10 cm for 100 MU of
10 MV photon beams using the DRs of 300,
400, 500, and 600 MU/min. The measurement
values for each DR were obtained from ten
measurements. Furthermore, we conﬁrmed the
DR dependence of MapCHECK2 by measuring
100 MU in 10 cm × 10 cm open ﬁelds with 10
MV photon beams in the same setup (under an
8 cm solid water).
Statistical analysis
A comparison of Dynalog files for MLC
position errors between the four copied
plans was performed by repeated-measures
ANOVA or the Friedman test and post hoccomparisons with Bonferroni/Dunn ʼ s test
or Steel –Dwass test. Statistical significancewas set at P < 0.05. All statistical analyses
were performed using Excel 2015 software(Microsoft, Redmond, WA, USA) with the
add-in software application Statcel4 (OMS
Publishing Inc. Tokyo, Japan).

Results
In the preliminary experiment
Table 2 shows the results of actually
delivered DRs. The actually delivered DR of
600 MU/min was slightly lower than that ofnominal value. Delivery beams for other DRs(400, and 500 MU/min) measured by Proﬁler2
were the equivalent magnification values as

Fig. 3 Results of the dose rate (DR) dependence
for ion chamber and MapCHECK2.
The output of the Clinac iX with 10 MV photon beams
measured by the ion chamber was quite constant for thisrange of DRs with the maximum variation of 0.04% for the
DR of 600 MU/min (normalized with the DR of 300 MU/min). The response of the MapCHECK2 increased withincreasing DR value with a maximum variation of 0.4%.

nominal values normalized with a dose rate of
300 MU/min. Figure 3 shows the results of DR
dependence for ion chamber and MapCHECK2
in the preliminary experiment. The outputof the machine with a 10 MV photon beamenergy measured by the ion chamber wasquite constant for this range of DRs with amaximum variation of 0.04% for DR of 600
MU/min (normalized with a DR of 300 MU/min). The response of MapCHECK2 increased
with increasing DR value, with a maximum
variation of 0.4%, which is equivalent andcomparable to the value of 0.21%–0.35% fromprevious studies 20，21).
MLC position error
Tables 3 and 4 show the differences in the
DRs analyzed based on the MLC position
errors in this study. Table 5 shows the resultsof the statistical analysis of MLC position
errors. The delivery time decreased from 97
sec to 83 sec when the DR increased from500 to 600 MU/min. However, the difference

Table 2 Results of actually delivered dose rates of linear accelerator
Dose rate（MU/min）

300

400（×1.33）

500（×1.67）600（×2.0）

Proﬁler2（pulse/sec）

180

240（×1.33）

300（×1.67）

350（×1.94）

The number in parentheses indicated the magniﬁcation values normalized with a dose rate of 300 MU/min.

86 ◆ Journal of JART English edition 2024

note
Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients with prostate cancer

between DR 500 and 600 MU/min was
not significant ( p > 0.05, Table 4). The MU
values normalized with a DR of 300 MU/
min were expressed as a percentage increase
in increased DRs, and gains of 3.12% wereachieved for 400 MU/min, 6.47% for 500 MU/
min, and 9.80% for 600 MU/min; however,no signiﬁcant difference was observed in therespective comparisons ( p > 0.05, Table 4).
No signiﬁcant differences were also observed
between the DRs of 300 and 400 MU/min, 400
and 500 MU/min, and 500 and 600 MU/min
for the number of segments ( p > 0.05, Table 3).

Expressed in terms of percentage increased
in MUs per 100 MU/min increase DR, weobserved gains of approximately 3.3% which
was approximately the same and comparable
to the value of 4.1% from a previous study 6).
The number of MUs and segments increased
with increasing DR but MU per segment
was slightly lower with increasing DR (Table3). Moreover, no significant difference wasobserved in the maximum RMS between theDRs of 400 and 500 MU/min, and 500 and 600
MU/min ( p > 0.05, Table 4).
The proportion of MLC position errors in

Table 3 Results of MLC position errors based on the dose rates.
Delivery time（sec）
Monitor unit（MU）
Segment
MU per segment
Leaf speed Minimum（cm/sec）
Leaf speed Maximum（cm/sec）
Mean RMS error（mm）
Max RMS error（mm）
MLC bank A
0-0.05 mm（%）
0.05-0.5 mm（%）
0.5-1.0 mm（%）
1.0-1.5 mm（%）
MLC bank B
0-0.05 mm（%）
0.05-0.5 mm（%）
0.5-1.0 mm（%）
1.0-1.5 mm（%）

300 MU/min

400 MU/min

500 MU/min

600 MU/min

151.85 ± 21.64
757.27 ± 108.49
668.27 ± 51.10
1.13
0.20 ± 0.06
2.10 ± 0.08
0.18 ± 0.03
0.47 ± 0.07

116.82 ± 15.89
780.87 ± 107.73
696.87 ± 63.63
1.12
0.24 ± 0.06
2.20 ± 0.07
0.23 ± 0.03
0.54 ± 0.07

97.22 ± 12.75
806.27 ± 106.41
735.33 ± 65.83
1.09
0.28 ± 0.07
2.24 ± 0.08
0.27 ± 0.03
0.59 ± 0.07

83.71 ± 10.66
831.47 ± 106.43
770.07 ± 65.70
1.08
0.33 ± 0.09
2.26 ± 0.07
0.30 ± 0.03
0.64 ± 0.08

41.53 ± 13.58
54.74 ± 14.13
3.47 ± 2.52
0.24 ± 0.37

36.51 ± 13.45
57.32 ± 13.14
5.49 ± 3.73
0.55 ± 0.57

33.16 ± 13.26
57.99 ± 15.03
7.96 ± 5.03
0.89 ± 0.76

30.58 ± 13.01
57.47 ± 16.35
10.32 ± 5.68
1.36 ± 0.94

42.39 ± 12.43
54.25 ± 12.63
3.13 ± 2.27
0.22 ± 0.35

36.58 ± 12.97
57.53 ± 13.13
5.08 ± 3.22
0.52 ± 0.56

33.02 ± 12.87
58.72 ± 13.56
7.23 ± 4.03
0.83 ± 0.73

30.49 ± 12.15
58.90 ± 13.44
9.43 ± 4.89
1.28 ± 0.98

Data are presented as mean ± standard deviation.
MLC, multi leaf collimator; RMS, root mean square.

Table 4 Results of DynaLog files based on the dose rates.
Analysis of variance
Data

Deliverytime
2.84E-33

Monitorunit
4.12E-38

Segment

Leaf speed
Minimum
Maximum
3.22E-07
1.02E-06

p -value
1.17E-65
Post hoc comparisonscomparison
Leaf speed
Delivery
MonitorSegment
time
unit
Dose rate 1
Dose rate 2
Minimum
Maximum
300
400
**
n.s.
n.s.
n.s.
*
500
**
n.s.
*
*
**
600
**
n.s.
**
**
**
400
500
**
n.s.
n.s.
n.s.
n.s.
600
**
n.s.
*
*
n.s.
500
600
n.s.
n.s.
n.s.
n.s.
n.s.
Analysis of variance was calculated using repeated measures of analysis of variance or the Friedman test.
The Bonferroni/Dunnʼs test or Steel–Dwass test was used for post hoc comparisons. n.s., not signiﬁcant; *,p < 0.05; **, p < 0.01.

Arts and Sciences ◆ 87

Table 5 Results of the statistical analysis of MLC position errors.
Analysis of variance
Leaf positionp -value
Post hoc comparisons

Mean
RMS
error
7.66E-44

Max
RMS
error
2.70E-32

0-0.05 mmbank Abank B

0.05-0.5 mm

0.5-1.0 mm

1.0-1.5 mmbank Abank Bbank Abank Bbank Abank B

6.91E-66 2.92E-104 2.33E-12

1.10E-17

5.46E-66

1.2E-65

4.4E-60

2.7E-60Max
Mean
0-0.05 mm
0.05-0.5 mm
0.5-1.0 mm
1.0-1.5 mm
RMS
RMS
Dose rate 1 Dose rate 2 errorbank A bank B bank A bank B bank A bank B bank A bank B
error
300
400
**
n.s.
**
**
n.s.
n.s.
**
**
**
**
500
**
**
**
**
n.s.
*
**
**
**
**
600
**
**
**
**
n.s.
*
**
**
**
**
400
500
**
n.s.
n.s.
n.s.
n.s.
n.s.
**
**
**
**
600
**
**
**
**
n.s.
n.s.
**
**
**
**
500
600
*
n.s.
n.s.
n.s.
n.s.
n.s.
**
**
**
**
Analysis of variance was calculated using repeated measures of analysis of variance or the Friedman test. The Bonferroni/
Dunnʼs test or Steel–Dwass test was used for post hoc comparisons. n.s., not signiﬁcant; *, p < 0.05; **, p < 0.01. MLC,
multi leaf collimator; RMS, root mean square.
comparison

approximately > 90% of the total errors in theDRs 300, 400, 500, and 600 MU/min in banks
A and B were within 0–0.05 mm and 0.05–0.5
mm (Table 3). No significant difference wasobserved in the MLC position errors between
the DRs of 300 and 400 MU/min, 400 and
500 MU/min, 400 and 600 MU/min, and 500
and 600 MU/min in banks A and B (range
0.05–0.5 mm) ( p > 0.05, Table 5). In addition,
no signiﬁcant difference was observed in the
MLC position errors between the DRs of 400
and 500 MU/min, 500 and 600 MU/min inbanks A and B (range: 0 mm –0.05 mm) ( p> 0.05, Table 4). Furthermore, no significant
difference was observed in the Max RMS
errors between 300 and 400 MU/min, 400 and
500 MU/min, and 500 and 600 MU/min ( p >0.05, Table 5). On the contrary, MLC position
errors of the all comparisons in banks A and
B (range: 0.5–1.0 mm and 1.0–1.5 mm) were
statistically differences. ( p < 0.05, Table 5).
Gamma evaluation
Figure 4 shows the mean values of gamma
pass rates (GPRs) for MapCHECK2 and EBT3
according to DRs. The mean percentage GPRsof 99.6%, 99.5%, 99.4%, and 99.5% wereobserved for the DRs of 300, 400, 500, and
600 MU/min, respectively, in MapCHECK2.
The mean percentage GPRs of 97.6%, 96.2%,

88 ◆ Journal of JART English edition 2024

Fig. 4 Gamma pass rates (GPRs) for MapCHECK2and EBT3 according to the varying dose
rates (DRs).
The mean percentage GPRs of 99.6%, 99.5%, 99.4%,
and 99.5% were observed for the DRs of 300, 400, 500,
and 600 MU/min, respectively, with the gamma criteria of
3%/2 mm in MapCheck2. The mean percentage GPRs of
97.6%, 96.2%, 97.0%, and 95.7% were observed for theDRs of 300, 400, 500, and 600 MU/min, respectively, withthe gamma criteria of 3%/2 mm in EBT3.

97.0%, and 95.7% were observed for theDRs of 300, 400, 500, and 600 MU/min,
respectively, in EBT3. Based on the GE of
EBT3 ﬁlms, the GPR of a DR of 600 MU/min
was lowest than that of other DRs. However,no signiﬁcant difference was observed in the
GPRs of DRs 300, 400, 500, and 600 MU/min( p > 0.05).
Figure 5 shows the mean values of GPRs
with the most sensitive criterion 3%/1 mm
for MapCHECK2 according to DRs. The mean
percentage GPRs of 90.3%, 89.8%, 89.6%, andnote
Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients with prostate cancer

Fig. 5 Gamma pass rate (GPR) with the most sensitive
criterion 3%/1 mm for MapCHECK2 18）.
The mean percentage GPRs of 90.3%, 89.8%, 89.6%,
and 89.1% were observed for the DRs of 300, 400, 500,
and 600 MU/min, respectively, with the gamma criteria of
3%/1 mm in MapCHECK2.

89.1% for DRs of 300, 400, 500, and 600 MU/
min, respectively, were observed (Fig. 5). The
GPRs decreased with increasing DR; the GPRof a DR of 600 MU/min was lowest value
as well as in EBT3. However, no significant
difference was observed in the GPRs of DRs
300, 400, 500, and 600 MU/min ( p > 0.05).

Discussion
In this study, we evaluated the MLC
position errors between the planned andactual delivery positions using DynaLog ﬁles.
These log ﬁles of the delivered IMRT containsignificant information used to assess theroutine IMRT QA and are commonly used forpatient-specific IMRT QA22，23). Furthermore,these log ﬁles are a promising tool for IMRTQA automation that reduces the time spent
on IMRT QA and can be used to analyze
the entire IMRT day-to-day delivery 24). In
this study, DynaLog ﬁles were considered toreﬂect the accuracy of the MLC position, andour results were highly reliable.
The number of MUs increased with increasing
DR ( Table 3 ), suggesting a larger numberof small MU segments. Previous studies
demonstrated that a small MU segment may
result in delivery inaccuracy in IMRT 25-27).
Huang et al. 28) reported that the presenceof small MU segments has a strong impact
on GPRs. However, these studies did notinvestigate a small MU segment with MUs
fewer than 1. Therefore, small MU segments
had a little effect on the GPRs in this study
because the MU per segment value was muchthe same based on the DR ( Table 3 ). In acomprehensive multicenter study, Kerns etal.29) revealed that the parameters, including
gantry angle, number of beam holdoffs, andnumber of segments, commonly thought toaffect MLC performance were found to haveno such effect. Therefore, we considered that
increasing the number of small MU segments
had no effect on the GPRs and MLC position
errors.
A patient-speciﬁc QA for IMRT is extremely
important for ensuring the quality of carefor patients with cancer during radiotherapy.
Various methods, including the use of anion chamber, 2D array detectors, and anelectronic portal imaging device (EPID),
have been employed during pretreatment
veriﬁcation to detect possible errors between
the calculated dose and the measured
dose 30-32). The MapCHECK2 used in this study
has a detection accuracy and a stability of
GPR equivalent to those of MatriXX (ionchamber 2D array) and EPID 33). MapCHECK2
showed that a systematic MLC error of up
to 0.5 mm was not detected with a gamma
criterion of 3%/1 mm 18); in this study, almost
all MLC position errors in banks A and B were
within 0–0.05 mm and 0.05–0.5 mm (Table 3).
Therefore, MapCHECK2 with a GE of 3%/2
mm could not detect a slight difference in thedose distribution according to the differencein DRs (Fig. 4). However, the GPRs decreased
with increasing DR using criteria of 3%/1 mm(Fig. 5). Previous studies were demonstrated
that 1 mm MLC position error produced about
5% errors in dose delivery and decreasedin average GPRs 34，35). We considered that
decreasing GPRs were influenced by MLC
position errors within 0.5–1.0 mm and 1.0–1.5
Arts and Sciences ◆ 89

mm (Table 5) .
By contrast, Gafchromic films were
designed for IMRT and QA because they
have high resolution and can detect slightdifferences in the dose distribution 36 ，37) .
Furthermore, Marroquin et al. 38) evaluatedthe uncertainty in an EBT3 film dosimetry
system, including the dynamic reproducibility,
uniformity, and orientation. They noted thathigher uncertainties were found because of
the relative orientation of the film and theuniformity in the response of the scanner.
However, they reported that one muststrictly control the position and orientationof the ﬁlm, so that the total uncertainties are
considerably reduced. We considered that
the GE using EBT3 had a little uncertainty
because we performed the film analysis in
the same position on the scanner and in thesame orientation. In addition, Borca et al.39)
evaluated DR dependence in IMRT (6 MV and
15 MV) among various DRs (100, 300, and 600
MU/min). In another study by Ataei et al.40),
DR dependence (6 MV and Co-60 gammarays) was observed between DRs of 200 and
400 cGy/min. These studies found that DR
dependence was not significantly different
between the EBT3 ﬁlms. Therefore, results of
the GE using the EBT3 ﬁlms were not affectedby the difference in DRs, and the decreasein the GPR with increasing DR in EBT3 wasconsidered to mainly reﬂect the inaccuracy of
MLC position errors according to the DRs.
Vo r w e r k e t a l . 9 ) r e c o m m e n d e d t h a tmechanical and technical aspects limit for
the LV of 2.5–3.0 cm/sec and for the DR of
300 –400 MU/min should be respected forprostate patients. In addition, we consideredthat MLC position errors were less in the sameDRs because maximum LV was 2.5 cm/sec
in our study. Furthermore, Kaviarasu et al.10)
indicated that some fields of a DR 500 MU/
min showed the worse gamma value than DR
400 MU/min. They discussed that increasing
the DR increased the number of control points

90 ◆ Journal of JART English edition 2024

per min and increased the complexity of the
MLC delivery, but they did not investigate theMLC. In addition, average gamma values weresame values for 400 and 500 MU/min, andthe maximum gamma value of a DR 400 MU/
min was slightly better (0.08 point) than thatof a DR 500 MU/min, and difference of point
absolute dose using ion chamber showed that
< 1% mean deviation for 400 and 500 MU/
min. These results showed that there were few
difference between the DR 400 and 500 MU/
min same as our study. More importantly, we
considered that intrafractional displacement of
the prostate during IMRT had a greater effecton dose distribution than slightly difference of
MLC position errors between the DR 400 and
500 MU/min. Previous studies demonstrated
that the average 3D displacements of
intrafraction prostate were approximately
2 –3 mm according to the immobilization
system and duration of radiotherapy 41，42) .
Furthermore, Kontaxis et al.43) reported thatthe average drops in D99% coverage due todisplacement of the intrafraction prostate for
the PTV and CTV during radiation delivery
were 11% and 2.1%, respectively, using
combined 1.5T magnetic resonance imaging
and a linear accelerator system. Therefore, we
considered the inﬂuence for dose distribution,
the delivery time should be as short as
possible.
These results indicated that a DR of 500 or
600 MU/min was the acceptable rate whenreducing the delivery time. However, nosignificant difference was observed between
DR 500 and 600 MU/min for the delivery time
(Table 4). Those causes were considered that
actually delivered DR of 600 MU/min wasslightly lower than that of nominal value. In
addition, the GPRs of a DR 600 MU/min waslarger decreased compared to DR 400 and 500
MU/min using MapCHECK2 with a gamma
criterion 3%/1 mm (Fig. 5). Furthermore, theGPR of a DR 600 MU/min using EBT3 were atthe very limit of 95% criteria deciding by TG

note
Consideration of the optimum dose rate in intensity-modulated radiation therapy for patients with prostate cancer

218 17) (Fig. 4). Therefore, we suggested that a
DR of 500 MU/min was the most acceptable
rate considering clinical safety.
With regard to the limitations, according toour analysis, the MU values in DMLC-IMRT
increased with increasing DR. The usage ofgreater MUs results in an increase in scatteredradiation and radiation leakage, causing
secondary malignancies 44-46). In addition, thetransmitted radiation dose, which depends
on the transmission through the leaves, isalso higher 47) and consequently increases theintegral dose to the organ at risk because ofinter- and intraleaf transmission leakage andscatter. Decreasing these radiation doses isimportant for the protection of organs at risk
and in normal tissues. However, we did notconsider these inﬂuences in terms of radiation
exposure in this study.

Conclusion
We considered the inﬂuence of DR on the
MLC position errors and GPR and found thata DR of 500 MU/min was the most acceptable
rate when reducing the delivery time while
maintaining the MLC positional accuracy and
GPR.

Conﬂict of interest
The authors declare that they have noconﬂict of interest.

Statement of human rights
This study was approved by the Ethics
Committees of Akita Kousei Medical Center(approval No. 2020-155).

References
1） Ezzell GA, et al.: Guidance document on delivery,
treatment planning, and clinical implementation of
IMRT: Report of the IMRT Subcommittee of the AAPM
Radiation Therapy committee. Med Phys, 30, 20892115, 2003.
2） Bortfeld T: IMRT: A review and preview. Phys Med
Biol, 51(13), R363-379, 2006.
3） Staffurth J: A review of the clinical evidence for intensity-modulated radiotherapy. Clin Oncol, 22(8), 643-657.
4） Bortfeld TR, et al.: X-ray ﬁeld compensation with multileaf collimators. Int J Radiat Oncol Biol Phys, 28(3),723-730, 1994.
5） Mell LK, et al.: Intensity-Modulated Radiation Therapy
Use in the U.S., 2004. Cancer, 104(6), 1296-1303,
2005.
6） Ghasroddashti E, et al.: Clinical consequences ofchanging the sliding window IMRT dose rate. J Appl
Clin Med Phys, 13(4), 4-12, 2012.
7） Slosarek K, et al.: Beam rate inﬂuence on dose distribution and ﬂuence map in IMRT dynamic technique.
Reports of practical oncology and radiotherapy, 17,
97-103, 2012.
8） Intensity modulated radiation therapy collaborative
working group: Intensity-modulated radiotherapy: current status and issues of interest. Int J Radiat Oncol
Biol Phys, 51, 880-914, 2001.
9） Vorwerk H, et al.: Impact of different leaf velocities anddose rates on the number of monitor units and thedose-volume-histograms using intensity modulated
radiotherapy with sliding-window technique. Radiat
Oncol, 31(3), 2008.
10）Kaviarasu K, et al.: Impact of dose rate on accuracyof intensity modulated radiation therapy plan delivery
using the pretreatment portal dosimetry quality assurance and setting up the workﬂow at hospital levels. J
Med Phys, 40(4), 226-232, 2015.
11）National Comprehensive Cancer Network Website.
https://www.nccn.org/professionals/physician_gls/
pdf/prostate.pdf. Accessed 17 October 2022.
12）Calvo-Ortega JF, et al.: A Varian DynaLog ﬁle-based
procedure for patient dose-volume histogram-based
IMRT QA. J Appl Clin Med Phys, 15(2), 4665, 2014.
13）Osewski W, et al.: Clinical examples of 3D dose distribution reconstruction, based on the actual MLC
leaves movement, for dynamic treatment techniques.
Rep Pract Oncol Radiother J Gt Cancer Cent Poznan
Pol Soc Radiat Oncol, 19(6), 420-427, 2014.
14）Kumar R, et al.: Quick, efﬁcient and effective patientspecific intensity-modulated radiation therapy quality
assurance using log ﬁle and electronic portal imaging
device. J Can Res Ther, 13(2), 297-303, 2017.
15）Klein EE et al.: Quality assurance of medical accelerators: Recommendations of AAPM Task Group No.
142. Med. Phys, 36(9), 2009.
16）Low DA, et al.: Evaluation of the gamma dose distribution comparison method. Med phys, 30, 24552464, 2003.
17）Miften M, et al.: Tolerance limits and methodologies
for IMRT measurement-based veriﬁcation QA: Recommendations of AAPM Task Group No. 218. Med.
Phys, 45(4) 2018.
18）Woon W, et al.: A study on the effect of detector resolution on gamma index passing rate for VMAT and IMRTQA. J Appl Clin Med Phys, 19, 2, 230-248, 2018.

Arts and Sciences ◆ 9119）Niroomand-Rad A, et al.: Radiochromic ﬁlm dosimetry:recommendations of AAPM Radiation Therapy Committee Task Group 55. American Association of Physicists in Medicine. Med Phys, 25, 2093-115, 1998.
20）Létourneau D, et al.: Evaluation of a 2D diode arrayfor IMRT quality assurance. Radiother Oncol, 70(2),199-206, 2004.
21）Khamfongkhruea C, et al.: Dosimetric evaluation ofradiation dose rate effect in respiratory gated intensity
modulated radiation therapy. Biomed Imaging Interv
J, 8(1), e5, 2012.
22）Litzenberg DW, et al.: Verification of dynamic andsegmental IMRT delivery by dynamic log ﬁle analysis.
J Apple Cline Med physics, 3, 63-72, 2002.
23）Defoor DL, et al.: Investigation of error detection capabilities of phantom, EPID and MLC log file based
IMRT QA methods. J Appl Clin Med Phys, 18(4), 172179, 2017.
24）Dinesh Kumar M, et al.: QA of intensity-modulated
beams using dynamic MLC log ﬁles. J Med Phys, 31,
36-41, 2006.
25）Xia P, et al.: Communication and sampling rate limitations in IMRT delivery with a dynamic multileaf collimator system. Med Phys, 29(3), 412-423, 2002.
26）Xia P, et al.: Point/counterpoint. Segmental MLC issuperior to dynamic MLC for IMRT delivery. Med
Phys, 34(7), 2673-2675, 2007.
27）Rangel A, et al.: Tolerances on MLC leaf position accuracy for IMRT delivery with a dynamic MLC. Med
Phys, 36(7), 3304-3309, 2009.
28）Huang L, et al.: Impact of small MU/segment anddose rate on delivery accuracy of volumetricmodulated arc therapy (VMAT). J Appl Clin Med Phys,
17(3), 203-210, 2016.
29）Kerns JR, et al.: A multi-institution evaluation of MLC
log ﬁles and performance in IMRT delivery. Radiation
Oncology, 9, 176, 2014.
30）Dong L, et al.: Patient-speciﬁc point dose measurement for IMRT monitor unit verification. Int J Radiat
Oncol Biol Phys, 56, 867-877, 2003.
31）Howell RM, et al.: Establishing action levels for EPIDbased QA for IMRT. J Appl Clin Med Phys, 9, 2721,
2008.
32）Agnew A, et al.: Monitoring daily MLC positional errors
using trajectory log ﬁles and EPID measurements for
IMRT and VMAT deliveries. Phys Med Biol, May 7,
59(9), N49-63, 2014.
33）Son J, et al.: A comparison of the quality assurance offour dosimetric tools for intensity modulated radiation
therapy. Radiol Oncol, 49(3), 307-313, 2015.

92 ◆ Journal of JART English edition 2024

34）LoSasso T, et al.: Physical and dosimetric aspectsof a multileaf collimation system used in the dynamic
mode for implementing intensity modulated radiotherapy. Med Phys, 25, 1919-1927, 1998.
35）Yan G, et al.: On the sensitivity of patient-specific
IMRT QA to MLC positioning errors. J Appl Clin Med
Phys, 10(1), 120-128, 2009.
36）Zeidan OA, et al.: Characterization and use of EBTradiochromic film for IMRT dose verification. Med.
Phys, 33(11), 4064-72, 2006.
37）Shimohigashi Y, et al.: Evaluation of a single-scan protocol for radiochromic ﬁlm dosimetry. J Appl Clin Med
Phys, 16(2), 412-424, 2015.
38）Marroquin EYL, et al.: Evaluation of the uncertainty
in an EBT3 ﬁlm dosimetry system utilizing net opticaldensity. J Appl Clin Med Phys, 17(5), 466-481, 2016.
39）Borca VC, et al.: Dosimetric characterization and useof GAFCHROMIC EBT3 film for IMRT dose verification. J Appl Clin Med Phys, 14(2), 158-171, 2013.
40）Ataei G, et al.: Evaluation of dose rate and photon
energy dependence of Gafchromic EBT3 film
irradiating with 6 MV and Co-60 photon beams. J
Med Signals Sens, 9(3), 204-210, 2019.
41）Xie Y, et al.: Intrafractional motion of the prostate
during hypofractionated radiotherapy. Int J Radiat
Oncol Biol Phys, 72(1), 236-46, 2008.
42）Mostafaei F, et al.: Preliminary clinical evaluation of
intrafraction prostate displacements for two immobilization systems. Cureus, 12(9), e10206, 2020.
43）Kontaxis C, et al.: Delivered dose quantification in
prostate radiotherapy using online 3D cine imaging
and treatment log ﬁles on a combined 1.5T magnetic
resonance imaging and linear accelerator system.
Phys Imaging Radiat Oncol, 15, 23-29, 2020.
44）Hall EJ: Intensity-modulated radiation therapy,
protons, and the risk of second cancers. Int J Radiat
Oncol Biol Phys, 65, 1-7, 2006.
45）Hall EJ, et al.: Radiation-induced second cancers:
The impact of 3D-CRT and IMRT. Int J Radiat Oncol
Biol Phys, 56, 83-88, 2003.
46）Purdy JA: Dose to normal tissues outside the radiation therapy patientʼs treated volume: A review ofdifferent radiation therapy techniques. Health Physics,
95, 666-676, 2008.
47）Schmidhalter D, et al.: Leaf transmission reduction
using moving jaws for dynamic MLC IMRT. Med Phys,34, 3674-3687, 2007.

Arts and Sciencesmaterial

Received June 26, 2022 ; accepted January 6, 2023

Effect of luminance non-uniformity caused byaged deterioration of a medical liquid-crystal display for low-contrast detectability
TAKARABE Shinya1），2）, TAKAHASHI Keita1）, AKAMINE Hiroshi1）,
AWAMOTO Shinichi1）, OGAWA Kazuhisa1）, KATO Toyoyuki1）
1）Division of Radiology, Department of Medical Technology, Kyushu University Hospital2）Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 848: 49-54, 2023.
Key words: Liquid-crystal display, Aged deterioration, Luminance uniformity, Contrast-detail phantom,

Image quality ﬁgure (IQF)【Abstract】

The purpose in this study is to examine the effect of the luminance non-uniformity caused by the aged-deteriorationof medical liquid-crystal displays (LCDs) for the low contrast detectability using a contrast-detail phantom. Two
medical LCDs of the same-type with different operating times were used. The ﬁrst was operated for 38,000 h (ageddeterioration LCD) and the second for 200 h (non-deterioration LCD). These LCDs were calibrated to the grayscale
standard display function with a maximum luminance of 170 cd/m2. Contrast-detail images acquired under thesame exposure conditions were displayed on each LCD and an observer study was performed by ten radiological
technologists. The average image quality ﬁgures of the aged-deterioration and non-deterioration LCDs were 74.2 and
70.4, respectively and a signiﬁcant difference was seen ( p = 0.036). Our results indicated that the luminance nonuniformity caused by aged-deterioration of the LCD may affect the low contrast detectability.

1 Introduction
In the past decade, liquid-crystal displays(LCDs) with cold-cathode fluorescent lamp
(CCFL) backlights have increasingly been
used, replacing the use of cathode ray tube
monitors in medical settings as soft copy
reading devices. However, according toinvestigations in Japan regarding the quality
control of LCDs, the rate of performing quality
control was low, implying that LCDs withdegraded quality may be used in hospitals.1)
Aged-deterioration of LCDs can lead to adecrease in the maximum luminance (Lmax),change in chromaticity, and luminance nonuniformity.2) Takahashi et al. examined therelationship between the Lmax and operatingtime of the display backlight over a threeyear period for 249 LCDs (initial Lmax setting:
240 cd/m 2 , color temperature: 7,500 K,(RadiForce ® RX210), EIZO Co., Ishikawa,Japan).3) They reported that the Lmax of 39 of
the LCDs were less than 170 cd/m2 becauseof aged-deterioration. 3) Akamine et al.
examined the color temperature of two same
type LCDs (RadiForce® RX210) with different
operating times (under 10,000 hours and over
20,000 hours). They reported that the color
temperature was different between these
LCDs due to deterioration of phosphor in the
CCFL and color ﬁlter.4)
There is a case study report that display
performance will degrade with increasing timein use, which in turn may degrade diagnostic
performance. 5) To the author ʼ s knowledge,
there are no previous reports in the literature
regarding the effects of luminance nonuniformity, caused by the deterioration of
the medical LCD, on soft copy reading. We
assumed that the luminance non-uniformity
may affect the low-contrast detectability. Asa preliminary study for exploring the effects
Arts and Sciences ◆ 93

(a)(a)Aged-deterioration
Aged-deteriorationLCD
LCD(ADLCD)(ADLCD)(a)(b)(b)Non-deterioration
Non-deteriorationLCD
LCD(NDLCD)(NDLCD)(b)

Fig. 2 Test patterns used in this study. (a) and

Fig. 2 Test patterns used in this(b)study.
(a) and (b) are TG18-UNL80 test pattern and
are TG18-UNL80 test pattern and thetestpatternmodifiedfrom
TG18-UNL80
pattern,respectively.
Fig.LCDs
1 The
type
LCDstimes
with displayed
different
original testtest
patternmodifiedfrom TG18Fig.
Fig.11The
Thesamesametype
type
LCDs
with
withsame
different
different
operation
operation
times
displayedidentical
identicaluniform
uniformtesttestoperation
displayed
identical
uniform
patterns.
patterns.The
Theoperating
operatingtimes
times
of
of(a)
(a)andandtimes(b)(b)werewere
about
about38,000
38,000andand200200
hours,
hours,respectively.
respectively.
test-patterns.
The(a)
AAluminanceluminancenon-uniformity
non-uniformity
waswasobserved
observedfor
forthetheoperating
LCD
LCDwithwithatimes
alongerlongerof
operation
operation
time.
time.
and (b) were about 38,000 and 200 hours,
respectively. A luminance non-uniformity
was observed for the LCD with a longer
operation time.

of the LCD luminance non-uniformity, weused the contrast-detailed (CD) phantom
and compared the low-contrast detectability
for two same type LCDs with different
operating times. The purpose of this study
was to examine the effect of luminance nonuniformity caused by aged-deterioration forthe detectability of low-contrast signals.

2 Materials and Methods
A case study approach was used to perform
a physical evaluation and observer study for
medical LCDs (RadiForce® RX210, EIZO Co.)
Two same type color LCDs with different
operating times were used in this study. The
first was operated for about 38,000 hours[aged-deterioration LCD (ADLCD)] and thesecond for about 200 hours [non-deterioration
LCD (NDLCD)] ( Fig. 1 ). Both LCDs were
calibrated to the grayscale standard display
function (GSDF) with a Lmax of 170 cd/m2 byusing a quality-control software (RadiCS ®,EIZO Co.) and a near-range luminance meter(RadiCS® UX1 Sensor, EIZO Co.).
First, we measured the luminance uniformity

94 ◆ Journal of JART English edition 2024

UNL80 test pattern, respectively.

and variation of the luminance for the physicalevaluation of the LCDs before performing anobserver study to evaluate the low-contrast
detectability of the LCDs.
2.1 Measurement of luminance for physicalevaluation

In terms of the luminance non-uniformityof medical LCDs, American Association of
Physicists in Medicine (AAPM) Task Group 18(TG18) required that to measure luminance ofﬁve points in the test pattern displayed on an
LCD (Fig. 2 (a)).6) However, such test pattern
cannot evaluate the entire screen. Therefore,
an original test-pattern was modified basedon the TG18-UNL80 test pattern. The test
pattern had the same pixel value as the
TG18-UNL80 test pattern and was divided
into 48 measurement regions (Fig. 2 (b)); theluminance was measured corresponding toeach rectangular region. The original testpattern was displayed on the LCDs andthe luminance was measured by use of atelescopic-type luminance meter (LS-100 ®,Konica Minolta Co., Ltd., Tokyo, Japan). The
distance between the LCD and luminancemeter was 150 cm. The ambient light at thecenter of the LCD measured by an illuminancemeter (ANA-F9®, Tokyo Koden Co., Tokyo,

material
Effect of luminance non-uniformity caused by aged deterioration of a medical liquid-crystal display for low-contrast detectability

Japan) was 0.1 lux. Luminance measurement
in a telescopic-type luminance meter isaffected by stray light.7, 8) To minimize the lightemission from outside the focused area on thetelescopic-type luminance meter, the regionof the test pattern outside the measurement
area was covered by solid fiberboard. The
luminance was measured three times. The
luminance uniformity is given by
Luminance uniformity = (Lmmax - Lmmin) /(Lmmax + Lmmin) × 200;(1)where Lm max and Lm min are the measured
maximum and minimum luminance including
the reflected luminance. The luminance
uniformity is calculated using only the Lmmax
and Lmmin. To evaluate the luminance variation
for the whole monitor screen, we also
calculated the standard deviation (SD) of theluminance measured at 48 regions. Similarly,
we measured luminance uniformity and the
SD using TG18-UNL80 test pattern.
2.2 Observer study using CD phantom

LCDs was calibrated GSDF with a Lmax of 170
cd/m2. The illuminance of the center of these
displays were set to 350 lux. This illuminancedetermined based on the actual measured
illuminance at the center of this ADLCD,
which was used in the clinical practice. The
window level and window width were set to
512 and 1024, respectively. Ten radiological
technologists (1−11 years of experiences)
participated in the observer study. They could
observe the CD images at any distance, foras long as needed. Each observer recorded
the depth at which each signal size in the
CD phantom could be recognized with 50%
confidence. The image quality figure (IQF)
was calculated from individual observer databy the following equation;
IQF = ∑i=15
i=1 (Ci · Di,th),(2)

where Ci represents the depth value (contrast)of the object (visible hole) in the column (i),and D(i,th) denotes the corresponding smallest
visible diameter (threshold diameter) in thecolumn (i). A small IQF value indicates highdetectability with a low-contrast signal.9–11)
A paired t-test analysis was performed to
examine the mean differences of IQF values
between ADLCD and NDLCD.

The observer performance test was carriedout with a CD phantom (Kyoto Kagaku
Co., Ltd., Kyoto, Japan).9) The CD phantom
had signals (concave signals) of diameters
ranging from 0.3 to 8.0 mm in 15 steps anddepths from 0.3 to 8.0 mm in 15 steps. For
the three largest diameters, there was a single
X-ray
tube
signal in the center, similar to conventional
CD phantoms. However, four-point selective
CD phantoms were used for the remaining
signals, comprising a signal in the centerand in one of the corners. Three CD images
SID: 124 cm
were acquired. The exposure condition was
Lucite phantom
80 kV, 400 mA, and 25 ms and geometries
are shown in Fig. 3. A computed radiography
CD phantom(CR) system (IP: ST-VN, IP reader FCR 5000®,
Anti-scatter grid
Fujifilm Co. Tokyo, Japan) was used for the(ratio 8:1, 40 lines/cm)
Detector
X-ray detector. The CD images in DICOM
format were displayed on both the ADLCD Fig. 3 Geometries
CD with 7-cm-thickness
lucitephantoms.
Fig. for3 acquiring
Geometries
for acquiringCDwith 7-cmand NDLCD. The display function of thesethickness lucite phantoms.

Arts and Sciences ◆ 95

3 Results

The results of the measured luminanceusing our original test pattern are shown in
Figs. 4 (a and b). Table 1 provides the valuesof Lmmax, Lmmin, luminance uniformities, andSD of the luminance value using the original
test pattern. The luminance uniformities
of ADLCD and NDLCD were 77.8% and25.4%, respectively. The ADLCD displayed(a)(b)
a significant non-uniformity. The SDs of theFig. 4 Luminance values (cd/m2 ) measured using
measured luminance for the ADLCD andthe original test pattern (Fig. 2 (b)). (a) and (b)NDLCD were 9.30 and 3.15,
respectively.
the luminancecorresponding
to (Fig. 2 (b)). (Fig. 4 Luminance values (cd/m2)aremeasured
usingvalues
the original
test patternsmall
rectangularregionsoftheoriginal
test
There was a signiﬁcant difference
the SDs values corresponding to small rectangular regions of the original te
are theinluminancepattern (Fig. 2 (b)) displayed on the ADLCD(Fig.2(b))
displayedon the ADLCD
and NDLCD, respectively.
p
between the ADLCD and NDLCD (F-test,
and NDLCD, respectively.
< 0.01). On the other hand, for using TG18UNL80 test pattern, the luminance uniformities
Table 1 Results of physical evaluation for ADLCD
and NDLCD using the original test patternof ADLCD and NDLCD were 23.2% and10.6%, respectively. The SDs of the measured
ADLCD
NDLCD
luminance for the ADLCD and NDLCD were2
Lm max84.8 cd/m
78.1 cd/m2
5.12 and 2.5, respectively. There was not a
Lm min37.3 cd/m2
60.5 cd/m2
signiﬁcant difference in the SDs between the
Luminance uniformity
77.8%
25.4%
ADLCD and NDLCD.
SD of luminance value
9.30
3.15
For the observer performance test, the IQF
SD; standard deviation, ADLCD; aged-deterioration LCD,
NDLCD; non-deterioration LCD
values of the ADLCD and NDLCD were 74.2 ±14.7 and 70.4 ± 14.4, respectively. There was astatistical difference in the IQF values for the
ADLCD and NDLCD (Fig. 5) (paired t-test, p =0.036).

4 Discussion
We measured the luminance uniformity as
physical evaluation and IQF as low contrast
detectability, using two same type LCDs
with different operating times in order toinvestigate the effect of luminance nonuniformity due to aged-deterioration of the
medical LCD.
For both test patterns (TG18-UNL80 test
pattern and the original test pattern), theluminance uniformity of the ADLCD waspoorer than that of the NDLCD because of
the degradation of the backlight or impurities
contained in the liquid crystal component

96 ◆ Journal of JART English edition 2024

Aged-deterioration LCD(ADLCD)

Non-deterioration LCD(NDLCD)

Fig. 5 Comparison of image quality figures (IQF)
Fig.5 Comparisons of image quality figures (IQF) between agedbetween
deterioration
LCD andaged-deterioration
non-deterioration LCD. LCD and nondeterioration LCD.

( Fig. 4 and Table 1 ). The criteria for theacceptance test of the luminance uniformity
showed that the value of luminance uniformity
should be within 30%.6, 12) When TG18-UNL80
test pattern was used, the results of both
ADLCD and NDLCD were within this referencematerial
Effect of luminance non-uniformity caused by aged deterioration of a medical liquid-crystal display for low-contrast detectability

value (23.2% and 10.6%, respectively). On theother hand, when our original test pattern wasused, the results of only ADLCD exceeded
this value (Table 1). The SD of the ADLCD
was significantly higher than that of the
NDLCD when the original pattern was used.
This is because by increasing the number ofmeasurement points for the luminance of theentire screen, the variation in luminance ofthe entire screen (non-uniformity), measured
more accurately compared to using TG18UNL80 test pattern.
There was a statistically signiﬁcant difference
between the ADLCD and NDLCD with thesame Lmax (170 cd/m2) for IQF values (Fig. 5).
We estimated that the reason for the higher
IQF values of the ADLCD was because theregion with the non-uniformity, in particular
the black spot overlapping the signals of the
CD phantom, resulted in low detectability of
the low contrast signals.
In this study, we did not evaluate thechromaticity of the monitor in detail. Krupinski
et al. reported that there is no significant
difference in the diagnostic ability of breast
biopsy virtual slide regions of interest forcalibrated color LCDs and uncalibrated color
LCDs.13) In our study, we calibrated the LCDs
before the experiment and it is consideredthat the change in chromaticity has lessinﬂuence on the detectability of simple signals
using monochrome images.
Only one LCD was used as the ageddeterioration sample; however, to ourknowledge, there are no reports in theliterature regarding the effects of luminance
non-uniformity caused by the ageddeterioration of the LCD. This study revealed
that the non-uniformity of the LCD may
degrade the detectability of the low contrast
signals.
By measuring the luminance uniformity
regularly, degradation in low contrast
detectability due to aged-deterioration canbe detectable, however determining theluminance uniformity is difficult because
the use of telescopic-type luminance meters
for measuring luminance uniformity is time
consuming, and scientiﬁc-grade 2D luminancecolorimeters are too costly for most users in
hospitals. Practical and easier methods such as
using commercially available digital cameras14),
should be contained in constancy tests incertain guidelines and regular measurementsof the luminance uniformity is required.6, 12)

5 Conclusion
Because of either the degradation of thebacklight or impurities contained in the liquid
crystal component, the luminance uniformityof ADLCD (77.8%) was degrade compared
to NDLCD (25.4%). There was a statisticallysignificant difference between the ADLCD
and NDLCD with the same Lmax (170 cd/m2)
for low contrast detectability (paired t-test,
p = 0.036). The detectability of low-contrast
signals may be lower due to the effects ofluminance non-uniformity caused by theaged-deterioration of the LCD.

Acknowledgments
The authors are grateful to all members indivision of radiology, department of medical
technology, Kyushu university hospital whose
comments made enormous contribution tothis study.

Funding
This research did not receive any specific
grant from funding agencies in the public,commercial, or not-for-proﬁt sectors.

Declarations Conﬂicts of interest
Not applicable.

Arts and Sciences ◆ 97

Ethics approval
The observers of this study were explained
about the outline and purpose of the study, themethod of the experiment, and the possibilityof presenting the results of the experiment at
academic conferences and papers.

Informed consent
Not applicable.

References
1） T Shibutani, et al.: Current Situations and Problems of
Quality Control for Medical Imaging Display Systems.
Japanese Journal of Radiological Technology, 71(4);356-361, 2015. (Japanese)
2） N. Hashimoto: Image display devices (3): LCD
Monitor (Lecture of JSRT Member). Japanese Journalof Radiological Technology, 59(1); 21-28, 2003.
(Japanese)3） K Takahashi, et al.: Effective luminance deteriorationof medical liquid crystal displays in clinical use.
Radiological Physics and Technology, 10; 382-386,
2017.
4） H Akamine, et al.: Chromaticity and correlated color
temperature of the white point in medical liquid–
crystal display. Medical Physics, 39(8); 5127-5135,
2012.

98 ◆ Journal of JART English edition 2024

5） LJ Caffery, et al.: The effect of time in use on thedisplay performance of the iPad. British Journal ofRadiology, 89(1063); 20150657, 2016.
6） E. Samei, et al.: Assessment of display performancefor medical imaging systems. Report of the American
Association of Physicists in Medicine (AAPM) Task
Group 18, AAPM On-line Report No. 03, Med Phys,
2005.
7） J Morishita, et al.: Effect of test patter ns on
measurement of the luminance of LCD devices by useof a telescopic-type luminance meter. Radiological
Physics and Technology, 1; 95-99, 2008.
8） T Shiiba, et al.: Effects of ambient-light correction
in luminance measurements of liquid-crystal display
monitors by use of a telescopic-type luminance meter.
Radiological Physics and Technology, 3; 65-69, 2010.
9） T MAO, et al.: Manual: contrast-detail phantom Artinis
CDRAD type 2.0. St. Radboud, The Netherlands:
Project Quality Assurance in Radiology, Department ofRadiology, University Medical Center Nijmegen, 1998.
10）M. McEntee, et al.: A comparison of low contrast
performance for amorphous Silicon/caesium iodide
direct radiography with a computed radiography: A
contrast detail phantom study. Radiography, 13; 8994, 2007.
11）S. Hatanaka, et al.: Comparison of viewing angle andobserver performances in different types of liquidcrystal display monitors. Radiological Physics andTechnology, 2; 166-174, 2009.
12）Japan Industries Association of Radiological
Systems (JIRA): Japanese Engineering Standardsof Radiological Apparatus (JESRA) X-0093*B-2017
quality assurance guideline for medical imaging
display systems. JIRA, Tokyo; 2017.
13）E. A. Krupinski, et al.: Observer Performance Using
Virtual Pathology Slides: Impact of LCD Color
Reproduction Accuracy. Journal of Digital Imaging,25(6); 738-743, 2012.
14）K Kawamoto, et al.: A method for evaluating
luminance non-uniformity of displays by use of acommercially available digital camera. Radiological
Physics and Technology, 10; 409-414, 2017.

Arts and Sciencesmaterial

Received June 17, 2022 ; accepted January 6, 2023

Effective scan parameter setting of Quiet Suitecombined readout segmented multi-shot EPI DWI(qRESOLVE) for decrease of image distortion andacoustic noise with a 3T MRI scanner
KOBAYASHI Yoshikazu1）, KANDA Toshimitsu2）, SAITO Yoko3）
1）ShinSapporo neurosurgical hospital / Hirosaki University Graduate School of Health Sciences, Radiologic technologist2）ShinSapporo neurosurgical hospital, Radiologic technologist
3）Department of Radiation Science, Hirosaki University Graduate School of Health Sciences, professor, Medical doctor

Note: This paper is secondary publication, the ﬁrst paper was published in the JART, vol. 70 no. 850: 34-44, 2023.
Key words: Quiet Suite combined readout segmented multi shot EPI DWI (qRESOLVE), image distortion,

acoustic noise, echo spacing, parallel imaging factor【Abstract】

The purpose of this study was to determine effective scan parameter settings for decreasing image distortion andacoustic noise by scanning phantoms with various parameters using the Quiet Suite combined readout segmented
multi-shot echo planar imaging (qRESOLVE) with a 3T MRI scanner. The distortion rate of the slit area in the phantom
was calculated in the phantom experiment. Furthermore, peak sound pressure levels were calculated. The results
showed that with a decrease in echo spacing (ES) and ﬁeld of view (FOV), for a thin slice thickness, an increase in
the parallel imaging factor (PIF) and matrix size (MS) were effective for decreasing image distortion (p<0.017). To
decrease acoustic noise, an increase in ES, number of segments (SEG), repetition time (TR), and FOV, and a decrease
in PIF and MS, were effective (p<0.017). With respect to routine clinical examinations, a decrease in ES and anincrease in PIF were effective for decreasing image distortion, and with an increase in ES, a decrease in PIF and SEG
were effective for decreasing acoustic noise.

Introduction
Diffusion-weighted imaging (DWI) using
single-shot echo planar imaging (EPI) is
useful for the diagnosis of acute cerebral
infarction and brain tumors. However, it has
the disadvantages of causing signiﬁcant image
distortion and very loud acoustic noise 1).
Image distortion may degrade the diagnostic
accuracy, and loud acoustic noise causes
discomfort and anxiety in patients. Moreover, adecrease in acoustic noise is important to avoid
hearing impairment. Siemens Healthineers
has developed readout segmented multi-shot
EPI DWI (RESOLVE：readout segmentationof long variable echo-trains) as an imaging
method to improve image distortion. RESOLVE
is a new multi-shot EPI DWI that segments
the readout direction in k-space. RESOLVE

decreases the readout time in k-space, whichallows short echo spacing, and can be usedin conjunction with parallel imaging methods.
In addition, parallel imaging methods canbe used to decrease dephasing and image
distortion 2) . However, RESOLVE has the
disadvantages of loud acoustic noise resulting
from the fast switching of the gradient fieldand short echo spacing. Recently, RESOLVE
with the Quiet Suite method (qRESOLVE)
was developed to decrease discomfort andavoid hearing impairment during routine
c l i n i c a l e x a m i n a t i o n. q R ESOLV E i s a neffective sequence that achieves silence byautomatically optimizing the shape of thegradient ﬁeld (the angle of the gradient ﬁeld
is decreased) 3，4). In this study, a phantom wasscanned with various qRESOLVE parameters,
and effective parameter settings for decreasing
Arts and Sciences ◆ 99

image distortion and acoustic noise were
investigated.

Materials and Methods
1. Equipment

An MRI scanner (MAGNETOM Skyra syngo
VE11 3.0T (Siemens Healthineers)) was used.
The coil was a 20 channels head/neck coil
(Siemens Healthineers). A spherical phantom(Siemens Healthineers：D165 {1.25gNaS04 ×
6H20}) and Japanese Industrial Standards (JIS)phantom (Nikko Finds Industries：95-1108Ztype) were used.

to decrease sampling error, and the averagevalue was calculated.
Distortion rate(%) = (Wq/Wt) × 100 ‥‥ (1)where Wq is the slit width measured by
qRESOLVE and Wt is the slit width measured
by T 2WI. As shown in Fig. 1 , Wt and Wq
were measured by drawing a straight line
perpendicular to the slits at both ends. The
closer the distortion rate is to 100, the lessimage distortion is present.
4. Examination of acoustic noise
4.1. Peak sound pressure level

2. Scan parameters

In qRESOLVE, the echo spacing (ES),parallel imaging factor (PIF), number ofsegments (SEG), phase partial fourier (PpF),
repetition time (TR), matrix size (MS), slice
thickness (ST), and ﬁeld of view (FOV) werevaried. The scan parameters are listed in Tables
1-1 through 1-8. The center of the phantom
was set to the isocenter, and the scan plane
was a transverse section. The phase encoding
direction was set to the left-right direction,
motion probing gradient (MPG) pulses wereapplied in three axes, and a monopolar threescan trace was used in diffusion mode. The
parallel imaging method used was generalized
auto-calibrating partially parallel acquisitions(GRAPPA) 5).

A spherical phantom was scanned
using qRESOLVE ( Tables 1-1 through 1-8 )with various scan parameters to measureacoustic noise. The measurement positionof acoustic noise ( ● ) is shown in Fig. 2. The
measurement time was set to 1 min (because
the scan time for DWI using single-shotecho planar imaging used in routine clinicalexamination is approximately 1 min). The
maximum value during the measurement
period was used as the peak sound pressurelevel (Lpeak) (dB). Scans were performed 10
times to decrease sampling error, and theaverage value was calculated. An acoustic
sound measurement system (Kenneth Inc.：
YC-30) was used. The settings of the acoustic
noise measurement system are as follows :the frequency-weighting characteristic was

3. Examination of distortion rate

The distortion rate is generally calculatedusing the area method 6). However, in thisstudy, ST, MS, and FOV also varied, and theimage could not be subtracted. Therefore, thedistortion rate was deﬁned as in Eq. (1), basedon a report by Kajisako et al.7) qRESOLVE withvarious scan parameters (Tables 1-1 through1-8) were evaluated in comparison with T2weighted images (T 2WI) ( Table 2). The slit
area in the JIS phantom was imaged for bothsequences. Scans were performed 10 times

100 ◆ Journal of JART English edition 2024

Fig. 1 Slit width measuring method
Straight lines were drawn at the slits on both ends ; Wt
was measured on T2WI, and Wq was measured using
qRESOLVE.

material
Effective scan parameter setting of Quiet Suite combined readout segmented multi-shot EPI DWI (qRESOLVE) for decrease of image distortion and acoustic noisewith a 3T MRI scanner

Table 1-1 Imaging parameters of qRESOLVE withvarious ES values
ES (ms)

0.5

0.6

0.7

TR (ms)

0.78

0.94

Table 1-4 Imaging parameters of qRESOLVE withvarious PpF values
1

PpF

4500

Off

TE (ms)

83

92

100

107

122

127

TE (ms)Band width (Hz/pixel)

620

465

372

318

250

228

Band width (Hz/pixel)

220×220

FOV (mm)

7/8

TR (ms)122

101
220×220

FOV (mm)5

Slice thickness (mm)5

Slice gap (%)

20

Slice gap (%)

20

192×192

192×192MS

number of excitations

1

number of excitations

SEG

7

PIF

PIF

GRAPPA 2

SEG

7

PpF

Off

ES (ms)

0.94

1
GRAPPA 2

Fat suppression

CHESS

Fat suppression

CHESS

b-factor (s/mm2)

0, 1000

b-factor (s/mm2)

0, 1000

on

Reacquistion mode

Reacquistion mode
FilterFilter

Raw filter, Distortion Correction (2D), Prescin Normalize

Table 1-2 Imaging parameters of qRESOLVE withvarious PIF values
PIF

2

3

TR (ms)81

250

Slice thickness (mm)
MS

6/8

4500

on
Raw filter, Distortion Correction (2D), Prescin Normalize

Table 1-5 Imaging parameters of qRESOLVE withvarious MS values

4

128×128MS

4500

160×160

TR (ms)192×192

226×2264500

TE (ms)

122

94

81

TE (ms)

94

108

122

137

Band width (Hz/pixel)

250

260

277

Band width (Hz/pixel)

275

256

250

240

220×220

FOV (mm)

220×220

FOV (mm)Slice thickness (mm)5

Slice thickness (mm)5

Slice gap (%)

20

Slice gap (%)

20

number of excitations

1

192×192MS
number of excitations

1

SEG

7

SEG

7

PIF

GRAPPA 2

ES (ms)

0.94

ES (ms)

PpF

Off

PpF

0.94
Off

Fat suppression

CHESS

Fat suppression

CHESS

b-factor (s/mm2)

0, 1000

b-factor (s/mm2)

0, 1000

Reacquistion modeon

Reacquistion mode

FilterTable 1-3 Imaging parameters of qRESOLVE withvarious SEG values
SEG

Filter

Raw filter, Distortion Correction (2D), Prescin Normalize

35

TR (ms)7

9

Table 1-6 Imaging parameters of qRESOLVE withvarious TR values
11

4500

TR (ms)4030

TE (ms)TE (ms)

122

122

122

122

122

Band width (Hz/pixel)

Band width (Hz/pixel)

521

326

250

207

176

FOV (mm)

FOV (mm)Slice thickness (mm)Slice gap (%)
MS
number of excitations
PIF

on
Raw filter, Distortion Correction (2D), Prescin Normalize

220×2205
20
192×192

4500

5000
250
5

Slice gap (%)

20MS

192×192
1

1

SEG

7

GRAPPA 2

PIF

GRAPPA 2

ES (ms)

0.94

ES (ms)

PpF

Off

PpF

0.94
Off

Fat suppression

CHESS

Fat suppression

CHESS

b-factor (s/mm2)

0, 1000

b-factor (s/mm2)

0, 1000

Reacquistion modeon

Reacquistion mode

Filter

Raw filter, Distortion Correction (2D), Prescin Normalize

Filter6000

220×220

Slice thickness (mm)number of excitations

5500

122

on
Raw filter, Distortion Correction (2D), Prescin Normalize

Arts and Sciences ◆ 101

Table 1-7 Imaging parameters of qRESOLVE withvarious FOV values
100×100 150×150

FOV (mm)
TR (ms)

122
277

260

Slice thickness (mm)

250

241

237

5

Slice gap (%)

20

4.5m

192×192MS
number of excitations

1

SEG

7

PIF

GRAPPA 2

ES (ms)

0.94

PpF

Off

Fat suppression

CHESS

b-factor (s/mm2)

0, 1000

Reacquistion mode
Filter250×250 300×300

4500

TE (ms)Band width (Hz/pixel)

200×200

on
Raw filter, Distortion Correction (2D), Prescin Normalize

Fig.２

Table 1-8 Imaging parameters of qRESOLVE withvarious ST values
ST (mm)

1

3

5

TR (ms)4500

TE (ms)122

Band width (Hz/pixel)
FOV (mm)Slice gap (%)
MS
number of excitations

250
220×220

1
7
GRAPPA 2
0.94
CHESS

b-factor (s/mm2)

0, 1000

Filtermaximum and minimum of Lpeak using various
parameters and Eq. (2) 8) :Off

Fat suppression
Reacquistion mode

The black dot ( ● ) shows the measurement position for

20

PIF
PpF

10

The black dot (●)
showsnoise
the measurement
positionanalysis.
for acoustic
noise and time waveform
acoustic
and time waveform
The distancefrom
thecenterofthegantrywasapproximately
4.5
m and 4.5 m and wasanalysis. The distance from the center of the gantry was approximately
was located outside the five Gaussian lines (gray lines).
located outside The
the five
Gaussian lines (gray lines) . The height of the measurement point
height of the measurement point was 1.3 m above thewas 1.3m aboveground.
the ground.

192×192

SEG
ES (ms)7

Acoustic
noise andnoisetime waveform
Fig. 2 Acoustic
and time measurement
waveform position
measurement positiononSound pressure level (dB) = 20log 10 (A/Ao)‥‥‥‥ (2)

Raw filter, Distortion Correction (2D), Prescin Normalize

Table 2 Imaging parameters of T2WI

where A is the observed value and Ao is thereference value (20 × 10-6 [Pa]).

T2WI
TR (ms)4500

TE (ms)88

Band width (Hz/pixel)

193

FOV (mm)Slice gap (%)
MS
Slice thickness (mm)number of excitations
PIF

220×22020
192×192
5
1
no usedES (ms)9.8FilterDistortion Correction (2D), Prescin Normalize

set to C, and the time-weighting characteristic
was set to Fast. Furthermore, we calculated
the sound pressure level (dB) between the

102 ◆ Journal of JART English edition 2024

4.2. Time waveform analysis

The spherical phantom was scanned by
qRESOLVE with various scan parameters(Tables 1-1 through 1-8) to analyze the time
waveform of acoustic noise. The recording
position of acoustic noise ( ● ) is shown in
Fig. 2. The recorded data was transferred to apersonal computer (Microsoft Surface Pro3),and the time waveform was analyzed. A
recording device for acoustic noise (TASCAM
Inc.：DR-05X) was used. Frequency analysis
software (NCH software Inc.：WavePad audio
editing software) was used.

material
Effective scan parameter setting of Quiet Suite combined readout segmented multi-shot EPI DWI (qRESOLVE) for decrease of image distortion and acoustic noisewith a 3T MRI scanner

5. Statistical analysis

The distortion rate and acoustic noise (Lpeak)obtained from the phantom experiment were
evaluated to determine signiﬁcant differencesusing the Friedman test. The signifacance level
was set at 5%, and it was corrected using the
Bonferroni method for multiple comparisons.
EZR 9) was used for statistical analysis.

Results

Table 3-1 Distortion rate with various ES values
ES (ms)

0.5

0.6

0.7

0.78

0.94

1

distortion rate (%)

115.8

118.3

121.3

123.4

128.2

130.6

Table 3-2 Distortion rate with various PIF values
PIF

2

3

4

distortion rate (%)

121.0

114.1

111.2

Table 3-3 Distortion rate with various SEG values
SEG

3

5

7

9

11

distortion rate (%)

119.2

119.2

119.2

119.3

119.3

Table 3-4 Distortion rate with various PpF values

1. Examination of distortion rate
1-1. Distortion rate with various ES values

The distortion rates with various ES values
are listed in Table 3-1 . The distortion rateincreased with an increase in ES. There wasa significant difference between ES values(p<0.008).
1-2. Distortion rate with various PIF values

The distortion rates with various PIF values
are listed in Table 3-2 . The distortion rate
decreased with an increase in PIF. There wasa significant difference between PIF values(p<0.017).

PpF

Off

7/8

6/8

distortion rate (%)

120.9

121.5

123.6

Table 3-5 Distortion rate with various TR values
TR (ms)

4030

4500

5000

5500

6000

distortion rate (%)

120.9

120.9

120.9

120.8

120.9

Table 3-6 Distortion rate with various MS values
MS

128×128

160×160

192×192

226×226

distortion rate (%)

119.4

118.3

117.6

117.2

Table 3-7 Distortion rate with various ST values
ST (mm)

1

3

5

7

10

distortion rate (%)

113.0

114.4

118.4

120.2

123.0

Table 3-8 Distortion rate with various FOV values
FOV (mm)

100×100 150×150 200×200 250×250 300×300

distortion rate (%) not measured

113.6

118.4

123.5

128.7

1-3. Distortion rate with various SEG values

The distortion rates with various SEG values
are listed in Table 3-3. There was no change
in the distortion rate with an increase in
SEG. No significant difference was observed
between any of the SEG values (p>0.01).
1-4. Distortion rate with various PpF values

The distortion rates with various PpF values
are shown in Table 3-4. The distortion rate
decreased with a decrease in PpF. There wasa significant difference between any PpF
values (p<0.017).
1-5. Distortion rate with various TR values

The distortion rates with various TR values
are shown in Table 3-5 . No significant
difference was observed between the TR
values (p>0.01). TR did not affect the distortion

rate.
1-6. Distortion rate with various MS values

The distortion rates with various MS values
are shown in Table 3-6. The distortion rate
decreased with an increase in MS. There wasa significant difference between MS values(p<0.013).
1-7. Distortion rate with various ST values

The distortion rates with various ST values
are listed in Table 3-7 . The distortion rateincreased with increasing ST. There was asignificant difference between ST values(p<0.01).

Arts and Sciences ◆ 103

1-8. Distortion rate with various FOV values

The distortion rates with various FOV values
are listed in Table 3-8 . The distortion rateincreased with an increase in the FOV. There
was a significant difference between FOVvalues (p<0.013).
2. Examination of acoustic noise
2-1. Examination of Lpeak
2-1-1. Lpeak with various ES values

The results for Lpeak with various ES values
are shown in Table 4-1.With an increase in
ES, Lpeak decreased to 0.94 ms. There was asignificant difference between all ES values
except between 0.7 and 0.78 ms (p<0.008).
Using this result, the phantom experiment was
set to 0.94 ms (minimum value of Lpeak). There
was a level difference of 14.1 dB between
the maximum (with an ES of 0.5 ms) andminimum (with an ES of 0.94 ms). According
to Eq.(2), the sound pressure level with an ESof 0.5 ms was 5.1 times higher than that withan ES of 0.94 ms.
2-1-2. Lpeak with various PIF values

The results for L peak with various PIF
values are listed in Table 4-2. Lpeak increased
with increasing PIF. There was a significant
difference between PIF values (p<0.017).
There was a level difference of 1.6 dB
between the maximum (with a PIF of 4) andminimum (with a PIF of 2). According toEq.(2), the sound pressure level with a PIF of
4 was 1.2 times higher than that with a PIF of
2.
2-1-3. Lpeak with various SEG values

The results for Lpeak with various SEG values
are listed in Table 4-3. Lpeak decreased withincreasing SEG, and there was a significant
difference between SEGs values (p<0.01).
There was a level difference of 4.7 dB
between the maximum (with a SEG of 3) andminimum (with a SEG of 11). According toEq.(2), the sound pressure level with a SEG of

104 ◆ Journal of JART English edition 2024

Table 4-1 Lpeak with various ES values
ES (ms)

0.5

0.6

0.7

0.78

0.94

1

Lpeak (dB)

94.8

87.7

86.6

86.8

80.7

81.7

Table 4-2 Lpeak with various PIF values
PIF

2

3

4

Lpeak (dB)

82.2

83.2

83.8

Table 4-3 Lpeak with various SEG values
SEG

3

5

7

9

11

Lpeak (dB)

86.3

83.4

82.6

81.9

81.6

Table 4-4 Lpeak with various PpF values
PpF

Off

7/8

6/8

Lpeak (dB)

82.4

82.3

82.5

Table 4-5 Lpeak with various TR values
TR (ms)

4030

4500

5000

5500

6000

Lpeak (dB)

82.9

82.7

82.4

82.3

82.2

Table 4-6 Lpeak with various MS values
MS

128×128

160×160

192×192

226×226

Lpeak (dB)

82.1

82.1

82.8

82.5

Table 4-7 Lpeak with various ST values
ST (mm)

1

3

5

7

10

Lpeak (dB)

83.0

82.9

82.8

82.8

82.8

Table 4-8 Lpeak with various FOV values
FOV (mm)
Lpeak (dB)

100×100 150×150 200×200 250×250 300×300
82.9

82.7

82.4

82.3

82.2

3 was 1.7 times higher than that with a SEG of
11.
2-1-4. Lpeak with various PpF values

The results for Lpeak with various PpF values
are listed in Table 4-4. Lpeak showed almost nochange with decrease in PpF. There was no
signiﬁcant difference between any PpF values(p>0.017). There was a level difference of 0.2
dB between the maximum (with a PpF of 6/8)
and minimum (a PpF of 7/8) with various
PpF. According to Eq.(2), the sound pressurelevel with a PpF of 6/8 was 1.0 times higher
than that with a PpF of 7/8.
2-1-5. Lpeak with various TR values

The results for Lpeak with various TR valuesmaterial
Effective scan parameter setting of Quiet Suite combined readout segmented multi-shot EPI DWI (qRESOLVE) for decrease of image distortion and acoustic noisewith a 3T MRI scannerare shown in Table 4-5. Lpeak decreased slightly
with an increase in TR. There was a signiﬁcantdifference, except for between TR 5000 ms andTR 5500 ms and between TR 5500 ms and TR
6000 ms (p<0.01). There was a level differenceof 0.7 dB between the maximum (with a TRof 4030 ms) and minimum (with a TR of 6000ms) with various TR. According to Eq.(2), thesound pressure level with a TR of 4030 ms was
1.1 times higher than that with a TR of 6000
ms.
2-1-6. Lpeak with various MS values

The results for Lpeak with various MS values
are shown in Table 4-6. Lpeak increased slightly
with increasing MS. There was a significant
difference, except for between MS 128 × 128
and MS 160 × 160 (p<0.013). There was a level
difference of 0.4 dB between the maximum(with a MS of 192 × 192) and minimum(with MS values of 128 × 128 or 160 × 160).
According to Eq.(2), the sound pressure levelwith a MS of 192 × 192 was1.1 times higher
than that with MS values of 128 × 128 or 160
× 160.
2-1-7. Lpeak with various ST values

The results for Lpeak with various ST values
are shown in Table 4-7. Lpeak was not affectedby ST. There was no significant difference
between any ST values (p>0.01). There wasa level difference of 0.2 dB between the
maximum (with a ST of 1 mm) and minimum(with ST values of 5, 7, or 10 mm). According
to Eq.(2), the sound pressure level with a STof 1 mm was 1.0 times higher than that with
ST values of 5, 7, or 10 mm.
2-1-8. Lpeak with various FOV values

The results for Lpeak with various FOV values
are shown in Table 4-8. Lpeak decreased withincreasing FOV. There was a significant
difference, except for between FOV 200 × 200
mm and FOV 250 × 250 mm, and between
FOV 250 × 250 mm and FOV 300 × 300 mm(p<0.01). There was a level difference of 0.7
dB between the maximum (with a FOV of 100
× 100 mm) and minimum (with a FOV of 300
× 300 mm) with various FOV. According toEq.(2), the sound pressure level with a FOVof 100 × 100 mm was 1.1 times higher thanthat with a FOV of 300 × 300 mm.
2.2. Time waveform analysis

The time waveforms of acoustic noise
measured with changes in various parameters
are shown in Fig. 3-10. In the time waveform,
the horizontal axis represents time (ms), andthe vertical axis represents sound pressure(dB). Wada et al.10) reported that the amplitudeof the vertical axis of the time waveform
increases as the acoustic noise increases. The
results of this study showed that the amplitudeof the time waveform decreased with increasein ES, FOV, and SEG, and slightly decreased
with decreases in PIF and MS. The amplitudeof the time waveform showed little changewith any of the other parameters.

Discussion
Acoustic noise in MRI, especially in DWI
using single-shot echo planar imaging, is very
loud, and decreasing this noise is importantfor decreasing discomfort and anxiety during
routine clinical examinations and preventing
hearing impair ment. In this study, weinvestigated the parameters of qRESOLVE thatwere effective for decreasing image distortion
and acoustic noise.
First, we consider image distortion. With
respect to ES, the distortion rate increased
with an increase in ES. With an increase inES, the bandwidth (BW) was automatically
set to narrow, resulting in an increased phasedispersion and thus an increased distortion
rate. Regarding the PIF, the distortion rate
decreased with an increase in the PIF. Whenthe reading time was shortened in the phasedirection, the BW was automatically set to aArts and Sciences ◆ 105

Fig. 3 Waveforms of qRESOLVE with various ES
values (from left to right : 0.5, 0.6, 0.7, 0.78,
0.94, and 1.0 ms)

Fig. 7 Waveforms of qRESOLVE with various TR
values (from left to right : 4030, 4500,
5000, 5500, and 6000 ms)

Fig. 4 Waveforms of qRESOLVE with various PIF
values (from left to right : 2, 3, and 4)

Fig. 8 Waveforms of qRESOLVE with various MS
values (from left to right : 128 × 128, 160 ×
160, 192 × 192, and 226 × 226)

Fig. 5 Waveforms of qRESOLVE with various SEG
values (from left to right : 3, 5, 7, 9, and
11)

Fig. 9 Waveforms of qRESOLVE with various ST
values (from left to right : 1, 3, 5, 7, and
10 mm)

Fig. 6 Waveforms of qRESOLVE with various PpF
values (from left to right : Off, 7/8, and 6/8)

Fig. 10 Waveforms of qRESOLVE with various FOV
values (from left to right: 100×100, 150×150, 200×200, 250×250, and 300×300
mm)

wide range, resulting in suppressed dephasing
and thus a decreased distortion rate.
Concerning the SEG, with an increase in theSEG, the segment width decreased to divide
k-space, thus decreasing the readout time.
As a result, it is expected to be effective insuppressing dephasing and decreasing image
distortion. However, there was no signiﬁcantdifference in the distortion rate between
SEGs. With an increase in SEG, the reading
time of each SEG decreased, but the BW was
automatically set to a narrow range; thus, thedistortion rate was not change. With respect to
the PpF, the distortion rate decreased with anincrease in PpF. Blurring was suppressed andthe distortion rate decreased with an increasein the data filling of k-space, although the

BW and echo time (TE) did not change withan increase in PpF. Regarding the TR, thedistortion rate did not change with an increasein TR. The BW and TE did not change withincreasing TR. Concerning MS, the distortion
rate decreased with an increase in MS. The
BW automatically narrowed with an increasein MS, but the magnetic field deflection in
the voxel decreased, resulting in a decreased
distortion rate 11) . With respect to ST, thedistortion rate increased with increasing ST.
The BW did not change with the ST thickness,but the magnetic ﬁeld deﬂection in the voxel
increased, resulting in an increased distortion
rate 11). Regarding the FOV, the distortion
rate increased with increasing FOV. The BW
automatically narrowed with an increase in

106 ◆ Journal of JART English edition 2024

material
Effective scan parameter setting of Quiet Suite combined readout segmented multi-shot EPI DWI (qRESOLVE) for decrease of image distortion and acoustic noisewith a 3T MRI scanner

FOV, and the spatial resolution also increased.
Therefore, the ES, PIF, MS, ST and FOV
are effective parameters for decreasing thedistortion rate. However, in routine clinicalexaminations, MS, ST and FOV change thespatial resolution. Thus, the MS, ST and FOV
are not appropriate parameters. Furthermore,
it is appropriate to set PpF to “off ” to avoid
image distortion resulting from blurring.
Therefore, a decrease in ES and an increase
in PIF are effective for decreasing image
distortion.
Next, we consider acoustic noise. Concerning
ES, L peak decreased with an increase in ES.
The BW was automatically set to narrow withan increase in ES, resulting in a decrease in
the angle of the gradient field. With respect
to the PIF, Lpeak increased with an increase in
the PIF. The intensity of the blip applied in
the phase direction increased because of thewide interval of the collected data, resulting
in an increase in the angle of gradient field.
Regarding the SEG, L peak decreased withan increase in SEG. The BW automaticallynarrowed with an increase in SEG, resulting ina decrease in the angle of the gradient ﬁeld.
However, the scan time increased threefoldwith an increase in SEG (from a SEG of 3
to a SEG of 11) ; thus, parameter settings
with an increase in SEG should be avoided.
Concerning the PpF, L peak did not changewith increasing PpF. The BW and TE did notchange with increasing PpF. With respect
to the TR, L peak decreased slightly with anincrease in TR. It was assumed that the BW
and TE did not change, but acoustic soundwas slightly lower in the longer TR than in
shorter TR because the interval between
acoustic sounds was wide and less affectedby reverberation. Regarding the MS, L peakincreased slightly with an increase in MS. The
BW automatically narrowed and TE increased.
Generally, with a narrow in BW, resulting ina decrease in the angle of the gradient field
and the acoustic noise is small. However,

because the amplitude of the gradientincreased simultaneously, Lpeak was assumed
to be increase. Concerning the ST, Lpeak did
not change with the thickness of ST. The BW
and TE did not change with the thickness of
ST. With respect to the FOV, Lpeak decreasedslightly with an increase in the FOV. With anincrease in FOV, the BW was automatically
set to narrow, resulting in a decrease in theangle of the gradient field. We calculated
the sound pressure level difference between
the maximum and minimum values of L peakwith various parameters using Eq.(2). The
maximum value of Lpeak was 5.1 times higher
than the minimum value in ES, 1.1 times
higher for FOV, 1.7 times higher for SEG, and
1.2 times higher for PIF. This suggests thatan increase in ES is the most effective way todecrease acoustic noise. Individual differencesin hearing are common. A decrease inacoustic noise is considered important toprevent hearing impairment. Furthermore,time waveform analysis of acoustic noise
showed that an increase in ES, FOV and SEG,
and a decrease in PIF and MS, are effective fordecreasing the acoustic noise. Therefore, theeffective parameters for decreasing acoustic
noise are ES, PIF, SEG, TR, MS, and FOV.
However, in routine clinical examinations,an increase in SEG prolongs scan time andincreased the possibility of artifacts caused bybody motion. Therefore, a parameter settingwith an SEG of 9 or higher is not appropriate.
With an increase in TR, the scan timeincreases and the image contrast changes,
while with an increase in MS, ST, and FOV,
the spatial resolution changes, so they are notappropriate parameters. Therefore, an increasein ES and SEG and a decrease in PIF are
effective for decreasing acoustic noise. ES, PIF,
and MS are common parameters employedfor decreasing image distortion and acoustic
noise. However, an increase in ES decreases
acoustic noise and increases image distortion,
whereas a decrease in PIF and MS decreases
Arts and Sciences ◆ 107

acoustic noise and increases image distortion.
Therefore, there is a trade-off relationshipin the parameter setting, and further study
is required. In the future, to determine theoptimal scan parameter setting for decreasing
image distortion and acoustic noise, we plan
to evaluate the head MRI images of healthy
volunteers.

Conclusion
In qRESOLVE, a decrease in image distortion
was achieved with a decrease in ES and FOV,a thin slice thickness, and an increase in PIF
and MS (p<0.017). Furthermore, a decrease inacoustic noise was achieved with an increasein ES, SEG, TR, and FOV and a decrease in
PIF and MS (p<0.017). However, in routine
clinical examinations, a decrease in ES andan increase in PIF are effective for decreasing
image distortion, and with an increase in ES,
and an increase in SEG and a decrease in PIF
are effective for decreasing acoustic noise.

Conﬂict of interest
The author has no conflict of interest to
declare.

Funding
The author received no speciﬁc funding forthis work.

Acknowledgements
I would like to thank Professor Yoko Saito
for her warm guidance and encouragement.
I would like to express my sincere
appreciation.

108 ◆ Journal of JART English edition 2024

References
1） M. E. Bastin: Correction of eddy current-induced
artefacts in diffusion tensor imaging using iterative
cross-correlation. Magn Reson Imaging, 17(7), 10111024, 1999.
2） D. A. Porter, et al.: High resolution diffusion-weighted
imaging using readout-segmented echo-planar
imaging, parallel imaging and a two-dimensionalnavigator-based reacquisition. Magn Reson Med,
62(2), 468-475, 2009.
3） O. Martin, et al.: Acoustic-noise-optimized diffusionweighted imaging. Magn Reson Mater Phy, 28, 511521, 2015.
4） R. Julie, et al.: Quiet Diffusion-Weighted Head
Scanning: Initial Clinical Evaluation in Ischemic Stroke
Patients at 1.5T. J. MAGN. RESON. IMAGING, 44(5),1238-1243, 2016.
5） M. A. Griswold, et al.: Generalized Autocalibrating
Partially Parallel Acquisitions (GRAPPA). Magn Reson
Med, 47(6), 1202-1210, 2002.
6） Y. Kaneko, et al.: Using the area mismatch with
SE images to evaluate the distortion of EPI. Japan
Journal of Magnetic Resonance in Medicine, 36(3),98-105, 2016.
7） M.Kajisako, et al.: Experience with Siemensʼ RESOLVE(readout segmented EPI DWI). Rad Fun,10(5), 11-14,
2012.
8） K. Kuno, et al.: Acoustic noise measurement andevaluation/dB and LAeq. Tokyo, Japan, Gihoudo
publishing co., 28-31, 2006.
9） Y. Kanda : Investigation of the freely available easyto-use software “EZR”(Easy R)for medical statistics.
Bone Marrow Transplantation, 48, 452-458, 2013.
10）T. Wada, et al.: Analysis of the acoustic sound in
MRI. Oto-Rhino-Laryngology, Tokyo, 42(1), 131-135,
1999．
11）T. Aoki, et al.: 3-Tesla MR Imaging of the pelvis.
Japanisch-Deutsche Medizinische Berichte, 52(1), 4752, 2007.

Regulations and Requirements for Submissions to the
Journal of the Japan Association of Radiological Technologists
Submission Regulations
Revised: April 1, 2013
October 30, 2013
February 20, 2016
April 20, 2019
October 3, 2020
July 9, 2022
December 3, 2022
Objective

Article 1. These regulations are based on the operations defined in Article 4 of the articles on theincorporation of the Japan Association of Radiological Technologists (hereafter “theAssociation”). They stipulate the criteria for submissions to the Journal and informationalmagazines published by the Association (hereafter “the Journal, etc.”).
Eligibility

Article 2.
2-1. Only members of this association are allowed to submit articles to the associationʼs journal, etc.
2-2. However, the following requirements must be met in order to submit articles:(1) Students of radiologic technology schools who have a member of this association as a coauthor.
(2) Individuals with a foreign nationality who hold a radiologic technologist license.
(3) Non-members other than the above may submit articles by paying half of the association
membership fee per article as a submission fee.
2-3. The submission fee stated in the preceding paragraph 3 will not be refunded regardless ofwhether the article is accepted or not.
2-4. Co-authors do not need to pay the submission fee.
Copyright

Article 3. The copyright of the published manuscript is based on rules regarding the management of theworks of the Society.
Obligations

Article 4.
4-1. The topic of submitted manuscripts must belong to a relevant domain to technologies forprevention, diagnosis, and treatment related to radiation therapy, and manuscripts must be
unpublished.
4-2. Submitted papers, whether for fundamental or applied research, must sufficiently consider
bioethics, and authors must bear the ultimate responsibility for their content.
4-3. Fabrication, forgery, plagiarism, violation of the law, and other forms of wrongdoing are notallowed in submissions.
4-4. If the author has already reported similar content to that of the published manuscript or
submitted it to another journal, the author is required to explain the difference from themanuscript in a separate document.
4-5. The author must disclose all information regarding conflicts of interest.
4-6. The author shall be held accountable for any misconduct regarding the content of the
publication, and the Society shall not be involved at all.
Submissions

Article 5. The types of accepted submissions are categorized as follows:(1) Original articles
Highly original research papers with clear objectives and conclusions.
(2) Review articles
Articles systematically summarizing a specific research domain from a particular perspective.
(3) Rapid communications
Reports of original research that must be published rapidly.
(4) Reports
Surveys of significance to the study of radiological technology or reports of interesting andRegulations and Requirements for Submissions ◆ 109

important cases.
(5) Notes
Articles on the development or evaluation of new equipment, techniques, products, etc.
(6) Technical material
Compilations of survey data or technical aspects, or anything that can serve as a reference forresearch and technology.
(7) Overview articles
A compilation of technologies, principles, or basic elements with reference to the literature.
However, what was explained in the development and use of equipment and software constitutes
a technical explanation.
(8) Miscellaneous
Other items approved by the editorial committee for publication, such as lecture transcripts, courses
published as journal articles, and newspaper/magazine articles that were not published in Issues 1–7.
How to submit

Article 6.
6-1. Use the online posting system.
6-2. The author shall save the duplicate data of the submitted manuscript until the publication decision.
Formatting

Article 7. The explanation of the manuscript shall be provided according to the submission procedure
specified separately.
Reception of submissions

Article 8. The reception date shall be the date on which the editorial board has determined to comply
with this regulation.
Review

Article 9.
9-1. Received manuscripts will be reviewed carefully and impartially by peer-reviewers selected by
the editorial committee.
9-2. Peer reviews are limited to two times. However, in the case of Article 5, items 7 and 8, in
principle, peer review is not performed.
9-3. The acceptance or rejection of the manuscript will be decided by the editorial committee inconsideration of the opinions of the reviewers, and the date will be the final acceptance date.
Corrections

Article 10.
10-1. In principle, the author must proofread the manuscript up to twice and return it by thedesignated date. If the deadline is breached, the school will be completed with the proofreadingof the editorial board.
10-2. The correction of words and plates that were not included in the manuscript is not allowed.
Printing

Article 11.
11-1. 20 copies of the papers published in the Journal, etc., will be presented to their authors as anoffprint.
11-2. The authors must bear the expenses of any additional offprints. If additional offprints are
required, they must be requested by the time corrections are submitted.
Revision or repeal of regulations

Article 12.
12-1.
12-2.
12-3.
12-4.
12-5.
12-6.

This regulation will come into effect on April 1, 2012.
This regulation will come into effect on April 1, 2016.
This regulation will come into effect on April 20, 2019.
This regulation will come into effect on October 3, 2020.
This regulation will come into effect on July 9, 2022.
This regulation will come into effect on December 3, 2022.

110 ◆ Journal of JART English edition 2024

Requirements for Submissions to the
Journal of the Japan Association of Radiological Technologists
Revised: February 20, 2016
April 20, 2019
October 3, 2020
July 19, 2023

Based on Article 7 of the Submission Regulations of the Japan Association of Radiological Technologists,
the following guidelines must be followed for manuscript submission:
1. How to write original articles, reviews, breaking news, reports, notes, materials, and explanations
1) Title and abstract
Enter the following items in the online posting system.
①List the authorʼs name, institution, affiliation and occupation, and contact information, and selectthe field of expertise. The authorʼs qualifications should be as specified in the submission guidelines.
②Select the type of post.
③Provide the title in both Japanese and English, and include information about the co-authors. List
the co-authors in the order of authorship. If a co-author is not a radiological technologist, their
qualifications should be as specified in the submission guidelines.
④Summarize the abstract in Japanese and English within 300 characters (words).
⑤Enter the keywords in English. Keywords should be in noun forms and should be limited to five.
2) Text and figures/tables
Create the main text, including figures and tables, in a single file. Additionally, prepare figures andtables as separate files and submit them.
①The manuscript should be in Japanese or English.
Create the document using Word with A4 paper size. Use Mincho font for Japanese text and Times
font for English text, both at 12 points. Set the line spacing to 18 points. Leave a margin of at least
2 cm on all sides (top, bottom, left, and right).
②The specified number of pages and excess page costs of the manuscript are as shown in thefollowing table.
Type of submission
Original articles
Review articles
Rapid communications
Reports
Notes
Technical material
Overview articles
Technical overview articles
Miscellaneous

Number of pages (as published)
8
8
3
3
8
8
8
4–6
2 (strictly enforced)

Fee for additional pages¥10,000 per pageNone

③As a general rule, academic terms should conform to Cabinet Notification No. 2 and JIS.
④The unit of quantity is the International System of Units (SI).
⑤Include page numbers and line numbers in the main text.
⑥Use “，” and “．” for punctuation.
⑦Use full-width characters for Katakana and half-width characters for English letters and numbers.
⑧The main text should be structured with headings such as Introduction, Methods, Results,

Discussion, Conclusion, and References.

⑨For equipment, include the generic name, model, manufacturer, city, and country.
⑩Number the equations.
⑪The figures and tables created as separate files from the main text are of higher resolution and canbe subjected to secondary processing in production.

⑫Number the figures and tables.
⑬Ensure that all figure and table numbers are referenced in the main text.
⑭For academic papers, write the titles of figures and tables, as well as the text within the tables, inEnglish.
⑮Provide Japanese explanations for figures and tables.
⑯When reproducing figures and tables, clearly indicate the source and ensure that the author has
obtained permission from the original source.
Regulations and Requirements for Submissions ◆ 111

3) References
References should be listed in the order in which they appear, with the numbers in parentheses atthe end of the referenced text.
The notation format is as follows.
①For magazines
Author names: Title (article title) Magazine name (abbreviation), volume, first-last page, year of
publication.
②For a book
Author names: Book title, First-last page, publisher, year of publication.
③If there are two or more authors, enter only the first author and enter “other” and “et al.”4) Trademark name
If a trademark name is required, write the trademark name in both parentheses after the common
name and add Ⓡ.
5) Acknowledgments
Create a separate file from the main text for the acknowledgments.
2. Submission of copyright transfer agreement(1) The first author and co-authors must agree to the contents of the copyright transfer agreement as
specified in the copyright regulations.
(2) The copyright transfer agreement should be as specified in the copyright regulations, and thedesignated form available on the societyʼs website must be used.
(3) The copyright transfer agreement must be signed by the first author and co-authors, and provided
when the manuscript is submitted.
3. About secondary publication(1) Obtain approval from the editorial departments of both the first and second journals.
(2) The period until the secondary publication should be decided through discussions between theeditorial departments of both parties and the author.
(3) Secondary publications of treatises are intended for different types of readerships.
(4) The secondary publication of a treatise should faithfully reflect the content of the first treatise.
(5) Specify the source of the original treatise.
(6) Specify in the title that it is a secondary publication.
4. About technical commentary requested by the editorial board
The structure of the document should generally follow the sections (1) to (9) below.
(1) Abstract (100-150 words in Japanese and English)(2) Keywords (3 words)(3) Introduction:(4) Purpose of explanation (overview)(5) Main paper(6) Comparison and consideration with previous research (development technology)(7) Clinical usefulness(8) Conclusion(9) References

112 ◆ Journal of JART English edition 2024

Journal of JART–English edition 2024–

June 12, 2024
Issuer: Ueda Katsuhiko
Publisher: The Japan Association of Radiological Technologists
22F Mita Kokusai Building. 1-4-28,
Mita, Minato-ku, Tokyo. 108-0073
TEL: +81-3-4226-2211 FAX: +81-50-3153-1519
https://www.jart.jp
・Published by The Japan Association of Radiological TechnologistsⒸ2024, Printed in Japan.

The Japan Association of Radiological Technologists
https://www.jart.jp