2021
Journal of— E n g l is h e d i t io n —2120

The Japan Association of Radiological Technologists

Journal of21

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
Foreword

3

Regarding Publication of the English Edition
UEDA Katsuhiko, President, The Japan Association of Radiological Technologists

History

4

History of The Japan Association of Radiological Technologists (JART)

6material

Arts and Sciences

Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison ofDecision-Making Processes between MR Imaging Duty and Other Alternative Duties
MAEYATSU Humio, YAMAGUCHI Sayaka, YAMAGUCHI-SEKINO Sachiko, HIKICHI Takeo

18

original articles

Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging
OKANO Kazuto

28

original articles

The Usefulness of Bone Suppression Image-Based Temporal Subtraction Processing for the
Improvement of Lung Nodule Detection on Chest Radiograph Images
SAKURAI Noriko, TAKAHASHI Shingo, TAKAHASHI Daishi, KODAMA Naoki

36

original articles

New Quantitative Calculation method of Contrast Values in Slot Scan ImageICHIKAWA Shigeji, KUMAGAI Kanami, SATOH Yasutaka, NONAKA Takashi, NAKAMURA Yutaka

45material

Invention of Surface Contamination Screening Method in a Nuclear Disaster –Segment Method–
TAJIMA Naoto, OISHI Kotaro, HAMADA Junji, AIGASE Ayuko, INOUE Haruyuki, NUMATA Kyoichi, HASHIMOTO Terumi, WATANABE Hiroshi

51material

Effectiveness of the Assistance in Image Interpretation Using the Image Reproduction Functionin Radiography
YAMASHITA Tatsuya

56

original articles

Long Term Characteristics Change of n-type Semiconductor Rectal Dosimeter
YASUI Ken’ichiro, SHIINOKI Takehiro, TAKAHASHI Wataru, OKIMOTO Yoshinori, SUMIKAWA Tetsuo, NAKAMURA Masatoshi

64

original articles

71

original articles

Standardization of a Daily Inspection Protocol for Angiography System
SUZUKI Keiko, HOSOKAWA Seiki, HAGIHARA Yoshiaki, ITO Makoto, KOMATSU Yuki

Survey of the relationship between radiological technology students’ modalities of interestand their level of understanding of technical terms –Questionnaire survey of RT students–
NAKAYA Koji, MUTO Hiroe, MATSUURA Kanae

79

original articles

Effects and Limitations of Visceral Fat Area Evaluation and Written Instruction by X-ray Computed
Tomography
MIZUI Masato, KASAI Chika, SENDA Yutaka, TASHIRO Takao

86

original articles

Basic Evaluations of JIS Certified Radiation Protection Eyewear for Eye Lenses Using Different
Evaluation Methods
KATO Kyoichi, KITTAKA Daisuke, YASUDA Mitsuyoshi, NAKAMURA Tokiko, SATO Hisaya, SUZUKI Shoichi

Contribution

95

Global Extension of Medical Technologies: What can Radiologic Technologists do for Global Health?

99

Regulations and Requirements for Submissions to the Journal of the Japan Association ofRadiological Technologists

KONO Yuzuru

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 2021

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 the latter half of 2021, the needle insertion for examinations of contrasting of the examination
for CT, MRI, Ultrasound and Radioisotope will be further 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 2021

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

2008

2009

Renaming as public interest incorporated association JART“ Presentation of the Medical Exposure
Guidelines (Reduction Targets)” for patients

Start of the Radiological Technologists Liability Insurance System

Launch of the Radiological Technologists
Liability Insurance System with participationby all members

2013

Enactment of X-Ray Week
Relocation of offices to the World Trade
Center Building in Tokyo2014

Launch of the radiation exposure advisor
certification system

Staging of a joint academic conference between Japan, South Korea, and Taiwan
Revision of the Medical Exposure Guidelines

2015

Establishment of the committee on Autopsy
imaging (Ai)2017

Launch of the Team Medicine Promotion
Conference, with the President of JART as its
representative2018

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

Registration of transition to a public interest
incorporated association (April 1)th

Event to mark the 65 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

Revision to the national examination for radiological technologists

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

2019

2020

2021

Event to commemorate the 120th anniversaryof the discovery of X-rays
Event to mark the 70th anniversary of founding and transition to a public interest incorporated association (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
Partial revision of the designation regulation
for radiological technologist training school

History of JART ◆ 5

Arts and Sciencesmaterial

Received January 16, 2019 ; accepted May 31, 2019

Analysis of Facility Policy on Allocating Pregnant
Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty
and Other Alternative Duties
MAEYATSU Humio1）, YAMAGUCHI Sayaka1）, YAMAGUCHI-SEKINO Sachiko2）,
HIKICHI Takeo3）
1）Department Radiology, Miyagi Kosei Association Izumi Hospital2）Work Environment Research Group, National Institute of Occupational Safety, Japan3）Department Radiology, Hirose Hospital

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 809: 14-23, 2020.
Key words: MRI workers, Pregnant Staff, Safety management【Abstract】

Previous studies (Yamaguchi: JJMRM, 38, 2018) have observed variations in assignment of pregnant workers tomagnetic resonance imaging (MRI) duty. This study analyzed background factors of the 7.6% “Proactive Personnel
Placement” from the previous research. “Workersʼ personal attributes” and “workplace characteristics” were rarely
involved. However, “physical loads” played an important role. When MRI work was regarded as an alternative work
placement, “exposure protectability” and “flexible work arrangements” were considered critical, and reduction of thephysical load for workers was an option. Concerns regarding exposure (residual risk) warranted precaution. Providing
information on the elements of concern is important while assigning MRI work placement.

Introduction
Magnetic resonance imaging (MRI) is a medical imaging modality that actively uses non-ionizing radiation (NIR: radio waves with wavelengths of 0.3 THz or less, infrared rays, visible
light, and some ultraviolet rays). A survey conducted in 2017 revealed that women accounted for ≥30% of MRI equipment operators 1).
Similar to other modalities, life events such as
pregnancy and childbirth must be consideredwhile assigning MRI scan duty.
MRI operators are routinely exposed to moderate to severe static magnetic fields (SMFs)
from the MRI equipment, ranging from a minimum of several tens of gauss (G) up to around1 T upon entering the scan room 3), 4). The operators are also exposed to weak pulsed fields
and high-frequency electromagnetic fields ofseveral tens of MHz when they enter the room

6 ◆ Journal of JART English edition 2021

during data acquisition. The MRI scan duty
also involves physical tasks, such as transporting the imaging coil or assisting patient transfer, as in other modalities. Extensive researchhas been conducted on the effects of NIR from
MRI scans, such as the effect on reproduction
and development, ranging from the cellular to
the animal level, through epidemiological research. To date, a clear effect of SMF on development and reproduction has not been reported 5), 6), 7), 8). Further, there is no uniform opinion
regarding MRI scan duty for pregnant operators, even at a global level. Government or
academic bodies in each country mainly advisethat “pregnant operators should not enter theroom while scanning is in operation” 5), 6), 9) ;however, the reality is that operating standards
differ at the hospital level 10).
It was assumed that conditions would be
similar in Japan. Based on the characteristics ofmaterial
Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

the MRI scan duty 1), our group hypothesizedthat two factors could be contributing towards
the discrepancies in deployment policies. The
first was the inability to eliminate the remaining risk associated with the uncertainty concerning the hazardous effect of NIR (especiallystrong SMFs) on reproduction and development, which was named “Differences in awareness about NIR.” The second was the attitude
toward safety regarding handling of physicalload, such as patient transfer and coil installation. This factor was named as “Considerations
regarding the working conditions.”
In a previous study, the authors developed aquestionnaire on the aforementioned hypotheses, which set five categories of questions.
Four of them were raised from the factor “Differences in awareness about NIR,” namely, 1:“Interest,” 2: “Concerns of adverse health effects,” 3: “Ease of Protection from exposure,”and 4: “Temporal symptoms caused by nonionizing radiation,” which are known to bepresent near the MRI equipment 11), 12). The final
one was 5: “Physical load” and it reflected the“Considerations regarding the working conditions” factor of the hypothesis. The questionnaire was sent to 5,769 facilities nationwide in
November 2017. The questionnaire responses
revealed that the policies on allocation of MRI
scan duty to pregnant operators vary in Japan1).
The majority of the responses stated that operators had a “less-promoted allocation pattern” (52.6%), indicating a tendency to refrainfrom allocating these duties to pregnant women. The authors investigated background factors for “less-promoted allocation pattern” using the decision tree analysis and logistic regression analysis and reported that the respondentsʼ sex and age are considerable factors
added to the aforementioned two hypothesizedfactors 2).
In contrast, the results of the questionnairealso showed that 7.6% of respondents stated“proactive personnel placement.” This allocation pattern essentially increases the number of

allocations compared before pregnancy. Investigating background factors that affect this typeof selection may provide supporting material
for pregnant employees and also provide information for a flexible system of allocation.
Furthermore, “proactive personnel placement”
may indicate that MRI scans are treated as alternative work duties for pregnant employees;
therefore, comparing the reasons for selection
with other modalities will lead to the proposalof rational alternative work duties for pregnant
employees.
Thus, this study focused on “proactive personnel placement” where an increase was reported in the number of allocations after pregnancy and examined background factors involved in the selection of this option. First, weinvestigated the background factors underlying
selection. Second, regarding the decision of alternative duties, factors affecting the selection
were analyzed by comparing the case of MRI
scan duty and other duties. Third, we classified
free responses on allocation policies and discussed the contents to further deepen our understanding of the allocation situation.

Methods
1. Questionnaire distribution and collection

The protocols have already been reported in
our previous study 1). Specifically, we created alist of facilities to be surveyed, based on the listof facilities with MRI equipment installed, according to the 2017 Data Book of Medical Devices and Systems. The survey was conductedwith personnel responsible for the MRI scanduty. The questionnaire was sent to 5,769 facilities on the above list on November 7, 2017.
Among the facilities, 5,763 were set as the total
number of facilities, excluding six facilities
where the questionnaire was not delivered.
The questionnaire comprised four sections: I)
Basic Information, II) General Matters Relating
to Employee Pregnancy, III) Policies Regarding
MRI Examination Duties During Pregnancy,
Arts and Sciences ◆ 7

Matters Considered in MRI Examination Duties,
and Concepts of Alternative Duties During
Pregnancy, and IV) Opinions on Non-ionizing
Radiation in General and Future Policies on MRI
Examination Duties during Pregnancy. There
were 34 questions (in sections I to IV) and freecomments (in section V). The response deadline was set at approximately 3 weeks after therecipient had received the questionnaire. Finally, the valid response rate was 36.0%, with 2,072
valid responses, after excluding 31 completely
blank non-response questionnaires from thecollected questionnaires.
2. Classification of allocation policy and datasets
The policy for allocation of MRI work topregnant employees was recoded into threegroups based on the responses: proactive personnel placement (n=157, 7.6%), maintained
status quo (n=679, 32.8%), and less-promoted
allocation pattern (n=1,088, 52.5%), and datasets were created with “proactive personnel
placement” set to 1, and the rest being set as 0.
If the respondents answered as “others (questions did not match the actual situation in thefacility)” we asked for specific reasons and feasible content in the free responses (n=485).
The free responses were classified based on
the strength of allocation awareness, as follows: “Aggressive arrangement,” “Continual arrangement,” “Principle allocation in consideration,” “Appropriate response on the consent
of the person,” and “Other allocation arrangement.”
3. Question classifications

The definitions of the questions are based on
our previous studies 1), 2). The analysis set included only typical answers. Other responses,
including free comments, were excluded fromthe analysis.
a) Personal attributes and facility characteristics
There were five items for the respondentsʼ
personal attributes: “Sex,” “Age,” “Years of em-

8 ◆ Journal of JART English edition 2021

ployment,” “Years of employment at the present
institute,” and “Deciding for allocation.” There
were 13 items for the facility characteristics:“Type of institute,” “Number of beds,” “Type of
MRI scanner,” “Number of modalities at the institute,” “Female ratio (at the department),” “Female ratio (at MRI scan duty),” “Allocation pattern (at the department),” “Work overtime,”“Hours of employment per week,” “Staff sufficiency,” “Allocation pattern (at MRI scan duty),”“Occurrence of additional support at MRI scanduty,” and “Number of MRI examinations permonth.”b) Opinions on NIR
Opinions on NIR were classified into four
items: “Interest,” “Concern of adverse health effects,” “Ease of protection from exposure,” and“Temporal symptom caused by non-ionizing
radiation.” For “Interest,” the degree of interest
was set as “High,” “Low,” and “Not interested”
based on the combination of the level of interest and acquisition of safety information. In
this study, the target of “Interest” was legislation and guidelines on NIR emitted from home
appliances. “Concern of adverse health effects”
was classified into four items: “No,” “Feel necessary for precautionary action,” “Yes,” and“Not a basis for the decision.” “Ease of protection from exposure” was classified into three
items: “Easy,” “Not easy,” and “Not basis for thedecision.” “Temporal symptom caused by nonionizing radiation” was set as “Experienced andfamiliar with the occurrence mechanism,” “Experienced but not familiar with the occurrence
mechanism,” “Not experienced but familiar
with the occurrence mechanism,” and “Neither
experienced nor familiar with the occurrence
mechanism.”c) Opinions on physical load
For questions regarding measures adopted
for physical work owing to patient transfer andcoil setting, three items were included to define the concept of physical load: “Low or reducible,” “High or not-reducible,” and “Not abasis for the decision.”material
Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

4. Factors for selecting alternative work duties

Factors for selecting alternative work duties(except for MRI scan duty) were set as “Ease ofprotection from exposure,” “Reduction of physical load,” and “Adoption of work role”. Differences in factors underlying the selection were
examined and compared with those of selection in MRI scan duty. For MRI scan duty, thefactors for “Ease of protection from exposure”
and “Reduction of physical load” were inferredfrom the work options as described below.
Work options were classified into the following five groups: “Access restriction during dataacquisition (NIR1),” “Reduction of physiological load (PL),” “Simultaneous selection of NIR1
＋PL (NIR1+PL),” “Access restriction for MRI
scan room (NIR2),” and “No given option(None).” The answer NIR1+NIR2 was merged
into NIR2, as the NIR2 includes strong access
restriction to the MRI room and covers the situation of NIR1. The reasons for adoption of thework role were derived from the related questions in the questionnaire.
Each facility entered a maximum of four reasons for the three candidates on alternative
work duties other than MRI. Thus, all three responses for the 2,072 facilities were merged(N=6,216, including non-responses and invalid
responses) and analyzed. Answers selecting
MRI scan duty as alternative work were excluded; however, they were still analyzed as
described above. The selection status of theaforementioned three reasons for selection
was derived from the applicable questions in
the questionnaire.
5. Analysis

SPSS 22 (IBM corp, Armonk, NY, USA) wasused as the analysis software, and the statisticalsignificance was set at p <0.05. The association
between personal attributes and facility characteristics and opinions on NIR and physical load
was examined using Fisherʼs exact test and chisquared test after cross-tabulation. Backgroundawareness of NIR protection and opinions on

physical load were investigated based on the
responses in the related sections of the questionnaire. The relationship between exposure
protection, physical load, and working status
was examined using correspondence analysis
for alternative work duties besides MRI scan
after primary tabulation.

Results
1. Investigation of the background factors forselecting “proactive personnel placement”

The results of the cross-tabulation of personal attributes and facility characteristics in theselection of “proactive personnel placement”
are shown in Table 1. A significant difference
was seen only in the number of examinations
per month, and the breakdown revealed an increase in the selection rate in facilities that performed 500‒999 examinations per month.
Women and younger individuals tended to select this option; this preference was not statistically significant. Therefore, the contribution of
personal attributes and facility characteristics is
considered to be limited.
Table 2 shows the differences in awarenessof NIR and considerations based on working
status in the selection of “proactive personnel
placement.”
A significant difference was observed for all
factors other than “Temporal symptoms caused
by non-ionizing radiation” (χ2 test, df=2 or 3;
the p-value was p <0.05 for “Interest” andp <0.0001 for all others). In terms of “Interest,”
the respondents who selected “proactive personnel placement” selected the “not interested”
response more frequently. The most common
response for “Concern of adverse health effects” was “No (46.3%),” which reflects a mindset that stems from the fact that reports regarding adverse effects on development and reproduction are lacking.” The frequency of thisanswer among this group was more than twice
the percentage from the “others” group (21.9%).
The frequency of the response “Feel necessary
Arts and Sciences ◆ 9Table 1 Results of cross-tabulation of personal attributes and facility characteristics. Invalid responses were
excluded from the summary.
Promoted allocation
pattern (n=157)n%Others(n=1,915)
n
%

n

%

Total

Sex N.S.
Male
FemaleTotal
Age N.S.
20-29
30-39
40-49
50-59
>60
Total
Years of employment N.S.
<9
10-19
20-29
>30
Total
Years of employment at the present institute N.S.
<9
10-19
20-29
>30
Total
Making decision for allocation N.S.
No
Yes
Total
Type of institute N.S.
University hospital
Public hospital
Other hospital
Others
Total
Number of beds N.S.
<99
100-199200-299300-399>400
Total
Type of MRI scanner N.S.
0.5 T MRI scanner (only)
1.5 T MRI scanner (only)
1.5 T and 3 T MRI scanner
3 T MRI scanner (only)
Others
Total
Number of modalities at the institute N.S.
<= 5
6-8
9-10
11+
Total
Female ratio (at the department) N.S.
<= 16.7
16.8-25.0
25.1-37.5
37.6+
Total

10 ◆ Journal of JART English edition 2021

129
28
157

82.2%
17.8%
100.0%

1,541
220
1,761

87.5%
12.5%
100.0%

1,670
248
1,918

87.1%
12.9%
100.0%

11
50
52
37
7
157

7.0%
31.8%
33.1%
23.6%
4.5%
100.0%

81
454
618
515
92
1,760

4.6%
25.8%
35.1%
29.3%
5.2%
100.0%

92
504
670
552
99
1,917

4.8%
26.3%
35.0%
28.8%
5.2%
100.0%

24
50
51
32
157

15.3%
31.8%
32.5%
20.4%
100.0%

216
623
545
369
1,753

12.3%
35.5%
31.1%
21.0%
100.0%

240
673
596
401
1,910

12.6%
35.2%
31.2%
21.0%
100.0%

55
50
40
12
157

35.0%
31.8%
25.5%
7.6%
100.0%

621
605
349
181
1,756

35.4%
34.5%
19.9%
10.3%
100.0%

676
655
389
193
1,913

35.3%
34.2%
20.3%
10.1%
100.0%

82
68
150

54.7%
45.3%
100.0%

904
734
1,638

55.2%
44.8%
100.0%

986
802
1,788

55.1%
44.9%
100.0%

3
41
112
1
157

1.9%
26.1%
71.3%
0.6%
100.0%

84
490
1,146
41
1,761

4.8%
27.8%
65.1%
2.3%
100.0%

87
531
1,258
42
1,918

4.5%
27.7%
65.6%
2.2%
100.0%

54
35
20
22
26
157

34.4%
22.3%
12.7%
14.0%
16.6%
100.0%

641
386
236
199
288
1,750

36.6%
22.1%
13.5%
11.4%
16.5%
100.0%

695
421
256
221
314
1,907

36.4%
22.1%
13.4%
11.6%
16.5%
100.0%

35
84
29
7
1
156

22.4%
53.8%
18.6%
4.5%
0.6%
100.0%

342
1,009
264
94
50
1,759

19.4%
57.4%
15.0%
5.3%
2.8%
100.0%

377
1,093
293
101
51
1,915

19.7%
57.1%
15.3%
5.3%
2.7%
100.0%

39
52
39
27
157

24.8%
33.1%
24.8%
17.2%
100.0%

460
575
399
333
1,767

26.0%
32.5%
22.6%
18.8%
100.0%

499
627
438
360
1,924

25.9%
32.6%
22.8%
18.7%
100.0%

33
31
41
28
133

24.8%
23.3%
30.8%
21.1%
100.0%

374
367
364
382
1,487

25.2%
24.7%
24.5%
25.7%
100.0%

407
398
405
410
1,620

25.1%
24.6%
25.0%
25.3%
100.0%

material
Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

Female ratio (at MRI scan duty) N.S.
<= 17.14
17.15-29.41
29.42-44.44
44.45+
Total
Allocation pattern (at the department) N.S.
Fixed
Rotation (2-3 modalities)
Rotation (all modalities)
Others
Total
Work overtime N.S.
Yes
No
Others
Total
Hours of employment per week N.S.
<39
40-49
50-59
60-64
>65
Total
Staff sufficiency N.S.
SufficientPartially insufficientInsufficient
Total
Allocation pattern (at MRI scan duty) N.S.
Fixed
Not fixed (a part of the rotation pattern)
OthersTotal
Occurrence of additional support at MRI scan duty N.S.
Frequently
Occasionally
RarelyNone
Total
Number of MRI examination per month p <0.05<499
500-999>1,000
Total

34
26
35
25
120

28.3%
21.7%
29.2%
20.8%
100.0%

320
346
313
359
1,338

23.9%
25.9%
23.4%
26.8%
100.0%

354
372
348
384
1,458

24.3%
25.5%
23.9%
26.3%
100.0%

21
55
63
11
150

14.0%
36.7%
42.0%
7.3%
100.0%

312
561
643
198
1,714

18.2%
32.7%
37.5%
11.6%
100.0%

333
616
706
209
1,864

17.9%
33.0%
37.9%
11.2%
100.0%

126
27
2
155

81.3%
17.4%
1.3%
100.0%

1,382
349
20
1,751

78.9%
19.9%
1.1%
100.0%

1,508
376
22
1,906

79.1%
19.7%
1.2%
100.0%

40
104
9
2
1
156

25.6%
66.7%
5.8%
1.3%
0.6%
100.0%

329
1,261
134
17
11
1,752

18.8%
72.0%
7.6%
1.0%
0.6%
100.0%

369
1,365
143
19
12
1,908

19.3%
71.5%
7.5%
1.0%
0.6%
100.0%

87
58
11
156

55.8%
37.2%
7.1%
100.0%

910
637
196
1,743

52.2%
36.5%
11.2%
100.0%

997
695
207
1,899

52.5%
36.6%
10.9%
100.0%

25
109
16
150

16.7%
72.7%
10.7%
100.0%

354
1,150
203
1,707

20.7%
67.4%
11.9%
100.0%

379
1,259
219
1,857

20.4%
67.8%
11.8%
100.0%

51
45
39
20
155

32.9%
29.0%
25.2%
12.9%
100.0%

479
574
438
236
1,727

27.7%
33.2%
25.4%
13.7%
100.0%

530
619
477
256
1,882

28.2%
32.9%
25.3%
13.6%
100.0%

107
42
7
156

68.6%
26.9%
4.5%
100.0%

1,297
312
139
1,748

74.2%
17.8%
8.0%
100.0%

1,404
354
146
1,904

73.7%
18.6%
7.7%
100.0%

Table 2 Relationship between selection of allocation policies and their reasons. Considerations based on respondentsʼ awareness of nonionizing radiation and work situation in the selection. Invalid responses
were excluded from the summary. Chi-squared test.

“Interest”

p <0.05“Concern of adverse healtheffects”

p <0.0001

High
Low
Not interested
Total
No
Feel necessary forprecautionary action
Yes
Not basis for decision
Total

Promoted allocation
pattern (n=157)
n
%
39
25.5%
93
60.8%
21
13.7%
153
100.0%
68
46.3%

Others(n=1,915)
n
%
390
22.7%
1,201
69.8%
129
7.5%
1,720
100.0%
370
21.9%

n
429
1,294
150
1,873
438

%
22.9%
69.1%
8.0%
100.0%
23.8%

Total

63

42.9%

1,082

63.9%

1,145

62.3%

1
15
147

0.7%
10.2%
100.0%

77
163
1,692

4.6%
9.6%
100.0%

78
178
1,839

4.2%
9.7%
100.0%

Arts and Sciences ◆ 11

“Ease of protection fromexposure”

Easy

62

41.1%

467

28.2%

529

29.3%

p <0.0001

Not easy
Not basis for decision
Total
Experienced and familiar
with the occurrence
mechanism
Experienced but notfamiliar with the occurrence
mechanism
Not-experienced but
familiar with the occurrence
mechanism
Neither experienced norfamiliar with the occurrence
mechanism
Total
Low or reducible
High or not-reducible
Not basis for decision
Total

15
74
151

9.9%
49.0%
100.0%

448
740
1,655

27.1%
44.7%
100.0%

463
814
1,806

25.6%
45.1%
100.0%

34

22.2%

383

22.0%

417

22.0%

23

15.0%

272

15.6%

295

15.6%

31

20.3%

403

23.1%

434

22.9%

65

42.5%

686

39.3%

751

39.6%

153
113
11
23
147

100.0%
76.9%
7.5%
15.6%
100.0%

1,744
660
515
487
1,662

100.0%
39.7%
31.0%
29.3%
100.0%

1,897
773
526
510
1,809

100.0%
42.7%
29.1%
28.2%
100.0%“Temporal symptom caused
by non-ionizing radiation”

N.S.

“Physical load”

p <0.0001

Table 3 Rates of work options in the promoted allocation pattern. NIR1 or 2 represents consideration of “easeof exposure protection,” whereas PL shows the consideration of “reduction of physiological load.”
NIR = Non-Ionizing radiation; PL = Physical load.
Given work options

Abbreviations

Access restriction during data acquisition(Protect from exposure to time-varying and radio frequency electromagnetic fields)

NIR1

Reduction of physiological load

n

%
13

8.3

PL

14

8.9

NIR1+PL

16

10.2

Access restriction for MRI scan room
(Protection from static magnetic field exposure)

NIR2

62

39.5

No given option

None

40

25.5

12

7.6

157

100.0

NIR1+PL

No responses or invalid answers
Total

for precautionary action” was 42.9%. When
“Protection from Exposure” was considered a
problem, answers were divided into two majorgroups: 41.1% responded that it is easy to formulate measures for NIR exposure during
work; however, 49.0% responded that selection of this factor was not a basis for the decision. Regarding “Physical load,” 76.9% of respondents who selected “proactive personnel
placement” answered that the physical load issmall (or it is possible to assign personnel toreduce the load), which was higher than thenumber of respondents who selected this answer in the “others” group (39.7%).

12 ◆ Journal of JART English edition 2021

2. Factors for selecting alternative work duties– Comparison of MRI scan duties (proactive
personnel placement) and another modality
selection

Factors for selecting alternative work duties(“Ease of protection from exposure,” “Reduction of physical load,” “Adoption of work role”)
were compared to the factors for selecting MRI
scan duties (Tables 3 ‒ 5, Fig.1). The status offactors for selecting MRI scan duties as alternative work are shown in Table 3 and Fig.1. As
described in the methods, “Ease of exposure
protection” and “Reduction of physical load”
were investigated based on the status of granting work options (Table 3).
Overall, 25.5% of respondents were notgranted any particular work options, while thematerial
Analysis of Facility Policy on Allocating Pregnant Staﬀ for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

Figure 1 Rates of “adoption of work role” in the promoted allocation pattern.

remaining 66.9% were granted some kind ofwork option. The summative total of work options based on the premise of exposure avoidance (NIR1, NIR1+PL, NIR2) was 58.0%. In
contrast, work options that considered PL alone
accounted for 8.9%.
The reasons for selection relating to “Adoption of work role” for the group that implemented “proactive personnel placement” are illustrated in Fig.1. Type 1 corresponds to “Adoption of work role: easy,” Type 2 corresponds to“Adoption of work role: difficult,” Type 3 corresponds to “To prevent ionizing-radiation exposure,” Type 4 corresponds to “Absence of alternate duties,” Type 5 corresponds to “Other,”and Type 6 corresponds to “Not a basis for thedecision.” The selection rate for type 1 (46.5%),
type 2 (3.2%), type 3 (65.6%), type 4 (6.4%),
type 5 (0.6%), and type 6 (7.0%) included multiple answers.
These results suggest that “Ease of protection
from exposure” is a clear countermeasure, although the countermeasures for “Reduction ofphysical load” alone are infrequently applied.
The results also suggested that Types 1 and 3
are the main factors to be considered for the
adoption of work roles.
The frequency of and reasons for selectionof alternative work duties for pregnant employees are shown in Tables 4 and 5. Computed tomography (CT) was the alternative

work duty most often selected for pregnant
employees, and the reasons included “Ease ofprotection from exposure” and “Reduction ofphysical load,” while “Adoption of work role”
was not prioritized. The second most commonly selected reason for the selection was “reduction of physical load,” with the person being
assigned to reception duties or analysis of
medical information.
These options account for ≥ 8.0% of the seven duties listed in Table 4 (CT, receptionist,
general radiography, bone density scans, ultrasound, mammography, and X-ray TV), andwere examined by corresponding analysis tovisualize the relationship with factors affecting
selection (Fig.2). Figure 2 illustrates the strengthof the association between these three factors
and the selected factors. The closer the plot
position to the factor, the stronger the association between the selected item and factor. For
example, Table 5 shows that the answer ʻgeneral radiographyʼ is at the first position for“Adoption of work role” (54.6%), seventh position for “Ease of protection from exposure”(82.5%), and twelfth position for “Reduction ofphysical load” (51.4%), therefore, it is easy toTable 4 Selection rate for alternative work duties
for pregnant employees. (Reference) 810
for MRI scanning.
Alternative duty during the pregnancy

n

%

CT

865

20.8

Receptionist, analysis of medical
information, office works

646

15.6

Radiography

599

14.4

Bone density test

577

13.9

Ultrasound

410

9.9
9.3

Mammography386

X-ray TV; Fluoroscopy

370

8.9

Fundus examination

77

1.9

Radiation therapy

72

1.7

Other

69

1.7

Angiography

35

0.8

Mobile C-arm

23

0.6

Nuclear medicine

14

0.3

Mobile X-ray

8

0.2

Total

4,151 100.0

Arts and Sciences ◆ 13

Table 5 Reasons for choosing alternative work duties for pregnant employees. % indicates the value for the
total of each duty. The total percentage is not displayed in the table; it exceeds 100% because of themultiple choice format.
Alternative duty during
the pregnancy
CT
Receptionist, analysisof medical information,
office works
X-ray imaging
Bone density test
UltrasoundMammography
X-ray TV; Fluoroscopy
Fundus examination
Radiation therapy
Other
Angiography
Mobile C-arm
Nuclear medicine
Mobile X-ray
Total

Ease of protection
from exposure

Reduction ofphysical load

Adoption of work
role

66

%
7.6%

Number of
selection(see in Table 4)
n
865

33.6%

24

3.7%

646

54.6%
32.1%
23.9%
43.3%
33.8%
22.1%
22.2%
39.1%
22.9%
30.4%
21.4%
50.0%

52
6
16
9
17
2
7
15
2
2
0
0
218

8.7%
1.0%
3.9%
2.3%
4.6%
2.6%
9.7%
21.7%
5.7%
8.7%
0.0%
0.0%

599
577
410
386
370
77
72
69
35
23
14
8
4,151

n
770

%
89.0%

n
633

%
73.2%

n
334

%
38.6%

438

67.8%

545

84.4%

217

494
508
282
358
331
51
63
39
33
15
9
2
3,393

82.5%
88.0%
68.8%
92.7%
89.5%
66.2%
87.5%
56.5%
94.3%
65.2%
64.3%
25.0%

308
507
318
264
327
69
43
38
30
6
12
4
3,104

51.4%
87.9%
77.6%
68.4%
88.4%
89.6%
59.7%
55.1%
85.7%
26.1%
85.7%
50.0%

327
185
98
167
125
17
16
27
8
7
3
4
1,535

Figure 2 Results of correspondence analysis
among seven alternative work duties andselection reasons. Office work: Receptionist, analysis of medical information,
office works. X-ray: X-ray imaging. US:
Ultrasound. MMG: Mammography. X-ray
TV: Fluoroscopy.

predict that general radiography has a strong
association with “Adoption of work role” only.
In contrast, the answer ʻX-ray TVʼ is at the third
position for “Ease of protection from exposure”(89.5%), second position for “Reduction ofphysical load” (88.4%), and sixth position for“Adoption of work role” (33.8%), which sug-

14 ◆ Journal of JART English edition 2021

Othersngests an association with “Ease of protection
from exposure” and “Reduction of physicalload.” Thus, to visualize the relationship between selected alternative duties and these factors, the results are displayed on a two-dimensional diagram, as shown in Fig.2. As predictedfrom Table 5, general radiography was plottedclosest to “adoption of the work role,” demonstrating the strong association between these
two elements, while there is an association between CT and mammography and “Ease ofprotection from exposure,” while bone density
scans, X-ray TV, and ultrasounds demonstrated
a strong association with “Reduction of physical load.”
3. Summary of classification of free comments
Table 6 shows a summary of the 485 freecomments that described the specific reason
and the selected “not applicable” for the policies regarding assignment of MRI scan duties
for pregnant employees. Based on the content
of the free comments, 30.0% of pregnant employees are actively allocated, continue allocation, or are usually allocated to MRI while considering the situation. In contrast, 21.0% of responses were left up to the judgment of thematerial
Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

Table 6 Summary of classification and content of a free comments
The allocation situations to
the MRI scan duties① Youre facility
implementation content② Opinions on place①＋② Total

Aggressive arrangement

2

0.6%

5

3.1%

7

1.0%

Continual arrangement

41

12.7%

20

12.3%

61

13.0%

Principle allocation inconsideration

52

16.1%

24

14.7%

76

16.0%

Appropriate response on
consent of the person

68

21.1%

33

20.2%

101

21.0%

Other allocation
arrangement

69

21.4%

26

16.0%

95

20.0%

Other

76

23.6%

28

17.2%

104

21.0%

Request

14

4.3%

27

16.6%

41

8.0%

Total

322

100.0%

163

100.0%

485

100.0%

individual. Furthermore, 20.0% of responses
were classified as transfers to other duties.
Combining these two made up a total of 41.0%
of responses that were classified as “careful ornegative placement.” Twenty-nine percent of
the responses were classified as “others,” including requests from the staff. The summaryof free comments shows that a high percentageof people are cautious about placement or
have a negative opinion based on general unease regarding NIR exposure (residual risk).

Discussion
This study examined the influence of awareness of NIR (work options: NIR1 or NIR2) orconsiderations based on differences (work option: PL) in the decision-making process for assignment of MRI scan duties to pregnant employees. In addition, the effects of personal
attributes and facility characteristics of respondents were investigated. The data from Table 1
shows that “proactive personnel placement”
tends to be more common among women in
their 20s and 30s, although this observation is
not statistically significant. These results demonstrate that career development is prioritizedamong the younger generation and women. It
is assumed that these results reflect the awareness of professional employees and may show
a more rational attitude of pregnant workers
accepting risk communication for MRI scan du-ties. However, analysis of “less-promoted allocation pattern” showed a significantly highnumber of men and older respondents 2). This
result may reflect concerns about the lack ofclear guidelines on the safety management of
NIR duties for pregnant employees amongmen, especially those from older age groups. It
is assumed that these respondents prioritize
avoidance of risk owing to pregnant women
performing MRI scan duties and managementof workplace organization management.
Furthermore, the number of MRI scans was
the only facility characteristic with a significant
difference, with higher levels of “proactive personnel placement” in the group that performed
500‒999 scans per month, than in the groupthat performed 1000+ scans monthly (Table 1,
p <0.05). Based on the number of MRI scans
per unit, large-scale facilities are assumed tofall in the 1000+ group, while medium-scale
facilities with two MRI equipment are assumed
to fall in the 500‒999 group. Alternatively, thenumber of scans is presumed to reflect thescale of the facility (department), and in themedium-sized facility group, the options for alternative work duties are affected by the environment and conditions related to the work
roles. In a previous study, the ratio of “lesspromoted allocation pattern” (59.0%) was highest in the medium-sized facility group as wellas “proactive personnel placement” compared tothe small-scale and large-scale facility groups 2).
Arts and Sciences ◆ 15

Thus, the characteristics of facilities at this scale
indicate the diversity of alternative work options.
Regarding the concern of adverse health effects as background factors in selecting “proactive personnel placement,” the most common
response for selection was “No,” (46.3%) (Table2). However, a high percentage of respondents(42.9%) stated that they “Feel necessity for precautionary action.” This might be reflected in
the results regarding work options (Table 3), as
the total work options (NIR1, NIR1 + PL, NIR2),
including access restrictions to the exposuresource, were high (58.0%). This was also observed in free comments as a high percentage(70.0%) of the combined response rate of careful/negative opinions in allocating pregnant
employees and other/requests for allocation.
Given that the “Ease” of exposure protection
accounts for 41.1% of the reasons for selection(Table 2), it is assumed that countermeasures
to enable protection against risks are more frequently selected. This suggests that measures
like access restriction (NIR1 or NIR2) are incorporated as a means of controlling the exposure(58.0%, a total percentage of NIR1, NIR1+PL,
NIR2 in Table 3).
However, 49.0% of respondents stated thatthe ease of controlling protection against exposure to MRI scans is “Not a basis for the decision;” therefore, these respondents may consider physical load as a priority factor. Focusing on “Physical loads” as a background factor
for allocation, the highest reason was “low or
reducible (76.9%)” indicating that this may be
the main factor in the decision of alternative
work placement (Table 2). On the contrary,
only 8.9% of respondents added that they selected work options only in response to PL(Table 3). However, based on the conditions ofother work options, physical loads were reduced by imposing access restrictions to the
MRI scan room (NIR2: 39.5%) and simultaneous additional access restrictions during scanning (NIR1 + PL: 10.2%). This also implies that
it is easy to reduce the physical load through a

16 ◆ Journal of JART English edition 2021

set of measures combined with NIR protection
measures. These results suggest that personal
attributes and facility characteristics are rarely
involved as background factors for selecting
active personnel placement; however, there isa relationship between differences in awareness of NIR and considerations based on work
situations as hypothesized in the present study.
In particular, “Physical load” plays an importantrole in the selection of “proactive personnel
placement.”
As shown in Table 4, seven jobs (CT, reception work, general radiography, bone density
tests, ultrasound, mammography, and X-rayTV) accounted for the majority of allocated duties. However, when the factors affecting selection were examined with correspondence
analysis (Fig.2), the characteristics of the reason for selection differed depending on theequipment. CT, which was the most common
selection, emphasized “Ease of protection fromexposure” and as a work option, it is similar to
MRI scan duty considering the rate of exposure
avoidance (58.0%). MRI scan duty may also be
selected as it prevents exposure to X-rays (Table 3, Fig.1). Regardless of the exposure source,
the selection process for CT and MRI scan duty
is similar. However, selection for MRI scansemphasizes both “Ease of protection from exposure” and “Adoption of the work role,” suggesting that the selection characteristics differ
from those of CT, which is strongly associatedwith “Ease of protection from exposure,” andgeneral radiography, which is strongly associated with “Adoption of the work role.” Further,selection of alternative duties such as reception
work or analysis of medical information isstrongly associated with “reduction of physicalload” (Tables 4 and 5). However, this may also
be related to the gestation period, from thepoint of view of maternity protection, considering that physical load is a common and prioritized factor considered while selecting alternative work.

material
Analysis of Facility Policy on Allocating Pregnant Staff for MR Imaging Duty: Comparison of Decision-Making Processes between MR Imaging Duty and Other Alternative Duties

Conclusion

Acknowledgments

This study considered the background factors for the selection of “proactive personnel
placement,” which increases the number ofplacements to MRI scan duties after reporting apregnancy, focusing on differences in awareness about NIR and considerations based on
work situations.
Results showed that although there was little
involvement of personal attributes and facility
characteristics, there was a relationship between
differences in awareness of NIR and considerations based on work situations. “Physical load”
was a particularly important selection factor,
and it was a common factor with the groupthat selected alternative work assignments other than MRI scan duties. There was also a difference in awareness of “residual risk” owing
to the general unease regarding MRI scans, andthis was a factor where there were different
views. For MRI scans, the issue seems to bedisseminating information on the residual risk
as a precautionary measure.

This research was conducted jointly with thefollowing five organizations: The Japanese Society for Magnetic Resonance in Medicine, theJapan Association of Radiological Technologists, the Japanese Society of RadiologicalTechnology, the Osaka Association of Radiological Technologists, and the Miyagi Association of Radiological Technologists. The Japanese Society of Radiological Technology extended their cooperation after distributing thequestionnaire. This study was conducted as
special research: research and study on nonionizing radiation exposure in medical facilities
with an operating expenses subsidy from theJapan Organization of Occupational Healthand Safety, National Institute for Occupational
Safety and Health (P-29-01).
We would like to express our sincere gratitude to Shuhei Izawa, Tsukasa Doi, Hideki Fujita, Shinya Imai, Manabu Akahane, and RuiSheng Wang, who provided support for conducting and creating the questionnaire.

References

8） World Health Organization: Environmental Health Criteria 232 Static Fields, 1-351, 2006.
9） Grainger D, et al.: (MHRA), Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use.
Ed March, 1-85. Medicines and Health Care Products
Regulatory Agency, 2015.
10）De Wilde JP; Rivers AW, Price DL: A review of thecurrent use of magnetic resonance imaging in pregnancy and safety implications for the fetus. Prog Biophys Mol Biol, 87(2-3): 335-353, 2005.
11）International Commission on Non-Ionizing Radiation
Protection: ICNIRP guidelines for “limiting exposure
to electric fields induced by movement of the humanbody in a static magnetic field and by time-varying
magnetic fields below 1Hz ” ,. Health Phys, 106(3):418-425, 2014.
12）Yamaguchi S, et al.: Questionnaire survey on work in
MR testing clinics. special research report (SRR). National Institute of Occupational Safety and Health, 44,
71-82, 2014.

1） Yamaguchi-sekino S, et al.: Survey of Facility Policyon Allocating Pregnant Staff for MR Imaging Duty and
the General Attitude to Nonionizing Radiation in Japan. Jpn J Magn Reson Med, 38(4): 103-119, 2018.
2） Yamaguchi S, et al.: Analyses of background factors
on allocating MRI scan work to pregnant employees.
J Occup Saf Health, 12(1): 3-12, 2019.
3） McRobbie DW: Occupational exposure in MRI. Br J
Radiol, 85(1012): 293-312, 2012.
4） Yamaguchi-Sekino S, et al.: Occupational exposurelevels of static magnetic field during routine MRI examination in 3T MR system. Bioelectromagnetics,
35(1): 70-75, 2014.
5） Temperton DH: Pregnancy and Work in Diagnostic
Imaging Departments, 2nd ed. British Institute of Radiology, 1-11, 2008.
6） Expert Panel on MR Safety et al.: ACR guidance document on MR safe practices: 2013. J Magn Reson
Imaging, 37(3): 501-530, 2013.
7） Kanal E, et al.: Survey of reproductive health amongfemale MR workers. Radiology, 187(2): 395-399, 1993.

Arts and Sciences ◆ 17

Arts and Sciences
original articles

Received January 30, 2019 ; accepted September 27, 2019

Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging
OKANO Kazuto
Dept. of Radiological Sciences, School of Health Sciences, International University of Health and Welfare

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 812: 13-20, 2020.
Key words: Radiological Technologists, Medical Imaging, Healthcare resources, Regional uneven distribution【Summary】

The purpose of this study was to address regional uneven distribution of healthcare resources related to medical
imaging. We measured Giniʼs coefficient and the coefficient of variation based on the “Survey of Medical Institutions ”(number of Radiological Technologists, Serial angiography, Mammography, RI exam, PET, CT, MRI, 3D image
processing) to compare potential regional differences. In addition, we evaluated regional features using a hierarchicalcluster analysis. Our study reveals that the number of “Radiological Technologists ” presented a lower regional
difference compared to physicians, as opposed to “Medical imaging ” that presented a higher regional difference thanphysicians. Furthermore, our study classified all 47 prefectures into seven clusters that describe and define the featuresof each region. We suggest that the results of this study will be useful for the efficient planning and improvement of
the medical care provision system in each prefecture.

1. Background and purpose
One of the most challenging and worrisome
issues in Japan involves the potential shortageof doctors, nurses, and healthcare workers dueto the so-called “2025 Problem” associated withJapanʼs aging population. More specifically, thisproblem refers to Japanʼs declining birthrate
and aging population, which is expected tocause a rapid increase in the number of elderly
people and a significant change in the demographic structure of Japan in 2025. As a countermeasure, the Ministry of Health, Labor andWelfare (MHLW) has recently established the“Investigative commission about the demand of
the healthcare worker ” in 2015 to discuss theoutlook for supply and demand of healthcare
workers. Consequently, the objective of thiscommission was to introduce efficient measures
to ensure supply and demand, thus combating
regional uneven distribution of healthcare
workers 1). Radiological technologists were notinitially included in this greater discussion as astudy group. Recently, however, the number ofradiological technologists has been increasing

18 ◆ Journal of JART English edition 2021

due to the establishment of new radiological
technologistsʼ school. Therefore, this triggered
the implementation of various surveys andstudies that have evaluated the supply and demand situation of radiological technologists.
The supply and demand of each category of
medical workers has been thoroughly investigated, and necessary measures have been taken based on the operation of healthcare delivery system. In fact, there is a significant number of research papers and reports publishedthat assess the supply and demand among
physicians and nurses. In contrast, there are
only a few studies focusing on the supply anddemand of radiological technologists. Kodama
estimated the future demand for radiological
technologists as a function of their available
numbers and the number of hospitals, basedon statistical data from the Medical Institution
Survey and hospital reports 2). As a result, theauthors identified that the demand for radiological technologists was expected to decrease
following the peak year of 2008 2). In addition,
Muto investigated the demand for radiological
technologists and their respective salary sys-

original articles
Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging

tem based on related job-opening information,
reported the current and future demand for radiological technologists 3, 4). We have also conducted a secondary analysis based on statistical
data from medical facility surveys and hospital
reports, and reported on the supply and demand situation of radiological technologists
engaged in CT scanning and their future projections 5). As a result, it was feared that thedemand for radiological technologists would
decrease because the number of CT would decrease along with the decrease in medical demand 5). However, many reports on the supply
and demand of radiological technologists do
not engage into a meaningful and efficient discussion to provide a comparison of their supply and demand with that of physicians andnurses. However, the extent of this research
topic involves the whole of Japan, and, to ourknowledge, there is no research report evaluating the uneven distribution of Japanʼs regions.
In this study, we investigate the regional uneven distribution in the provision of diagnostic
imaging based on the Medical Institution Survey. The purpose of this study was to identify
the regional uneven distribution in radiological
technologists and diagnostic imaging devices,and to use this study for the introduction andsubsequent establishment of a medical careprovision system.

2. Subjects and methods
2-1 Subjects

The data used in our analysis involved eight
distinct items of the static/dynamic survey of
medical institutions report, published by the
MHLW, in 2017 6). These eight items used in thesurvey of medical institutions are the following:
the number of “Radiological Technologists,” thenumber of institutions for “Serial angiography ”
and “3D image processing,” and the number ofdevices for “Mammography,” “RI exam,” “PET,”“CT,” and “MRI ”. More specifically, “PET ” wasdefined as the total number of “PET ” and “PETCT ” examinations, “CT ” was defined as the total number of “multi-slice CT ” and “other CT ”
examinations; whereas, “MRI ” was defined as
the total of “3.0T or more,” “1.5T or more andless than 3.0T,” and “less than 1.5T ” examinations. Furthermore, the data used to describe
and define each item involve the total of “hospitals ” and “medical clinics ” included in thisreport. Each item was then expressed as per
100,000 population using the data for eachprefecture of the population estimates published by the Ministry of Internal Affairs andCommunications in 2017 7). Finally, we refined
our data according to each prefecture so as torepresent the number of physicians per 100,000
population, as shown in the Survey of Doctors,
Dentists, and Pharmacists, 2016 8).
2-2 Giniʼs coefficient and coefficient of variation

In this study, the Giniʼs coefficient and thecoefficient of variation (CV), were measured
and compared to identify potential regional
differences. Giniʼs coefficient is defined as theratio of the area enclosed by the Lorenz curve
and the equal distribution line to the area below the equal distribution line, and is calculated from the following equation (1).
1Giniʼs coefficient = ── ∑ni=1 ∑nj=1|yi - yj| … (1),2n2 ȳ
where n is the number of prefectures, and yrepresents the data for each prefecture. Giniʼscoefficient is a number between 0 and 1, and ahigher value indicates greater regional differences. The CV is an index shows the extent ofvariability of the data, and is calculated fromthe following equation (2):σ× 100 … (2),CV = ─
ȳ

where σ is the standard deviation of each
item. Higher values of the CV indicate greater
regional differences.

Arts and Sciences ◆ 19

2-3 Regional difference index and Hierarchicalcluster analysis

In this study, the “regional difference index”
was evaluated by dividing the data for each
item over the national average for each prefecture. The overall evaluation was based on the
average of the “regional difference index” ofeach item. Furthermore, a hierarchical cluster
analysis was performed using itemized “regional difference indices” in order to categorize the respective prefectures. The Ward method was then used as the cluster merger method. The distance between the objects used forclassification is the Eugrid square distance. Statistical analysis was performed using the SPSS
Statistics 25 software.

3. Results
3-1 Descriptive Statistics, Giniʼs coefficient,and coefficient of variation

The descriptive statistics, Giniʼs coefficient,and CV for each item are shown in Table 1 andFig.1. Giniʼs coefficient and CV of the “radiological technologist ” were 0.08 and 12.0, respectively, and are slightly lower than the values obtained for physicians (0.10 and 16.3, respectively). Therefore, it can be suggested thatthe regional difference is small. In contrast,
Giniʼs coefficient and CV for “diagnostic imaging system” was the highest the “PET ” item (Gi-Fig.1 Result of Giniʼs coefficient and Coefficientof variation（CV）

20 ◆ Journal of JART English edition 2021

niʼs coefficient: 0.20, and CV: 37.1). The following with the next highest values were “RI exam”(0.18, 30.3), “CT ” (0.17, 30.0), “MRI ” (0.15, 25.3),“Serial angiography ” (0.15, 24.5), “3D imaging”(0.14, 23.3), “Mammography ” (0.13, 21.6). Giniʼscoefficient and CV for “diagnostic imaging system” were higher than those of “physician” andthe regional difference was large.
3-2 Regional difference index by prefecture

The regional difference indices for each itemby prefecture are shown in Table 2, and thehighest and lowest prefectures for each item
are summarized in Table 3. There were many
prefectures in Western Japan that exceeded thenational average such as Oita (124.9), Kagoshima (123.9), Kochi (122.3), and Toyama (115.2).
However, the regional difference index for“Radiological Technologist ” was the highest in
the Hokkaido region (127.3, i.e., 56.4 people/100,000 population). On the other hand,
Saitama had lowest regional difference index
for “Radiological Technologist ” (75.5, i.e., 33.4
people/100,000 population). Consequently, ourfindings suggest that the regional difference index is about 1.7 times higher in Hokkaido thanin Saitama. Finally, many prefectures in EasternJapan had a significantly lower regional difference index compared to the national averagesuch as Saitama (75.5), Chiba (81.5), andKanagawa (77.9).
In addition, the regional difference index for“Serial angiography ” was the highest in Kagoshima with 151.6 (2.46 facilities/100,000
population). The prefectures with the next
highest values were Kagawa (146.5), Saga
(142.1), Ehime (140.0), and Tottori (130.8).
Similar to the findings of the “RadiologicalTechnologist ” item, there were many prefectures in Western Japan that exceeded the national average. In contrast, the regional difference index for “Serial angiography ” was thelowest in Saitama (52.3, i.e., 0.85 facilities/
100,000 population). Therefore, it is shownthat the regional difference index was approxi-

original articles
Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging

Table 1 Number of health resources related to medical imaging（per 100,000 Population）
Prefecture

Num ber ofR adiologicalT echnologists

Num ber of
S er ial
angiogr aphy

Hokka ido
Aomori
I wa teMiya giAkita
Ya ma ga ta
F ukushima
I ba ra ki
T ochigi
Gunma
S a ita ma
Chiba
T okyoK a na ga wa
Niiga ta
T oya ma
I shika wa
F ukuiYa ma na shi
Na ga noGifu
S hiz uoka
Aichi
Mie
S higaK yotoOsa kaHyogo
Na ra
W a ka ya ma
T ottori
S hima ne
Oka ya ma
Hiroshima
Ya ma guchi
T okushima
K a ga wa
E himeK ochiF ukuokaS a gaNa ga sa ki
K uma moto
Oita
Miya z a ki
K a goshima
Okina wa
Avera geS . D.
minimumma ximum
Gini's
CV

56. 4
43. 0
37. 9
40. 4
43. 8
43. 1
44. 5
40. 5
41. 8
44. 9
33. 4
36. 1
43. 2
34. 5
41. 3
51. 0
47. 6
50. 5
36. 5
42. 4
43. 2
39. 8
40. 1
38. 2
37. 8
45. 5
45. 8
42. 9
43. 3
47. 3
41. 1
44. 4
50. 4
42. 3
43. 4
47. 8
48. 4
43. 5
54. 2
47. 4
48. 1
45. 2
47. 5
55. 4
50. 0
54. 9
42. 4
44. 3
5. 3
33. 4
56. 4
0. 08
12. 0

2. 09
1. 41
1. 04
1. 29
1. 10
1. 54
1. 49
1. 35
1. 23
1. 79
0. 85
0. 98
1. 12
0. 99
1. 28
1. 99
1. 92
1. 67
1. 58
1. 78
1. 69
1. 44
1. 01
1. 67
1. 49
1. 50
1. 43
1. 54
1. 41
1. 80
2. 12
1. 61
1. 31
1. 66
1. 88
1. 75
2. 38
2. 27
2. 10
1. 84
2. 31
1. 99
1. 59
2. 00
2. 11
2. 46
1. 46
1. 62
0. 40
0. 85
2. 46
0. 15
24. 5

Num ber of
Mam m ogr aphy

Num ber ofR I exam( scintigr am )Num ber of
PE T

Num ber ofCT

Num ber of
MR I

Num ber of
3 D im age
pr ocessing

Num ber ofdoctor s

3. 23
2. 03
0. 66
15. 9
8. 2
2. 69
248. 7
4. 23
1. 25
0. 47
15. 7
6. 9
3. 13
209. 0
3. 03
1. 43
0. 56
13. 9
8. 0
2. 15
207. 5
2. 93
1. 46
0. 47
9. 6
5. 8
1. 81
242. 6236. 0
4. 52
1. 71
0. 20
10. 8
6. 3
2. 31
5. 26
1. 36
0. 36
11. 0
6. 2
2. 09
233. 3
3. 88
1. 01
0. 53
12. 2
5. 4
2. 13
204. 5
2. 49
0. 66
0. 17
10. 9
5. 6
2. 14
189. 8
3. 47
0. 87
0. 41
11. 0
5. 2
2. 66
228. 8
3. 98
1. 33
0. 61
12. 4
5. 9
2. 50
234. 9
2. 72
0. 63
0. 26
8. 2
3. 9
1. 55
167. 0
3. 17
0. 82
0. 34
7. 9
4. 7
1. 76
196. 9
3. 48
1. 14
0. 43
8. 2
4. 4
1. 84
324. 0
2. 58
0. 84
0. 24
6. 8
3. 7
1. 51
213. 0
4. 46
1. 76
0. 31
10. 8
5. 8
2. 12
205. 5
3. 98
1. 80
0. 47
14. 1
7. 1
1. 99
256. 6
3. 92
2. 09
0. 96
12. 4
7. 5
3. 05
295. 8
3. 85
1. 80
0. 77
13. 4
7. 8
2. 44
256. 0
3. 89
1. 22
0. 49
10. 7
6. 2
2. 19
239. 8
4. 05
1. 06
0. 58
11. 5
5. 1
2. 36
236. 1
3. 64
1. 49
0. 65
12. 8
5. 7
2. 24
215. 5
2. 97
1. 03
0. 57
9. 8
5. 3
2. 15
207. 8
2. 88
0. 93
0. 48
9. 4
4. 8
1. 74
218. 6225. 7
3. 83
1. 00
0. 56
11. 1
5. 2
1. 83
2. 55
1. 34
0. 50
7. 8
4. 3
3. 26
231. 4
3. 54
1. 23
0. 50
9. 1
4. 7
2. 62
334. 9
2. 89
0. 90
0. 53
9. 9
4. 6
2. 28
283. 1
3. 18
1. 18
0. 55
10. 8
5. 0
2. 34
253. 2
2. 82
1. 04
0. 59
9. 8
4. 8
2. 52
251. 3
4. 44
1. 27
0. 32
17. 1
6. 1
2. 75
300. 6
4. 96
1. 77
0. 53
13. 1
5. 0
2. 83
316. 7
4. 23
2. 04
1. 17
12. 6
5. 7
2. 77
286. 2
3. 83
1. 15
0. 63
14. 4
6. 1
2. 67
312. 0
4. 14
0. 95
0. 46
13. 8
7. 0
2. 79
265. 6
5. 50
1. 66
0. 58
16. 6
6. 9
3. 54
259. 3
5. 25
1. 08
0. 40
22. 9
7. 0
2. 69
333. 3
4. 86
1. 65
0. 52
16. 8
10. 0
3. 72
289. 4
4. 03
1. 91
0. 88
16. 2
8. 1
3. 01
272. 4
3. 08
1. 12
0. 70
23. 4
10. 8
3. 50
315. 7
3. 50
1. 35
0. 47
13. 3
6. 6
2. 49
313. 4
5. 10
0. 73
0. 24
16. 4
8. 6
3. 03
287. 1
4. 43
0. 89
0. 44
16. 0
6. 6
3. 55
308. 6
4. 48
1. 13
0. 40
17. 2
7. 6
2. 66
294. 8
5. 90
1. 13
0. 43
19. 9
8. 1
2. 60
278. 4
3. 67
1. 65
0. 64
17. 3
8. 1
3. 03
251. 3
4. 24
1. 60
0. 43
21. 1
9. 5
4. 24
272. 5
3. 40
0. 83
0. 35
9. 8
5. 5
2. 15
250. 8
3. 84
1. 28
0. 51
13. 1
6. 3
2. 54
256. 5
0. 83
0. 39
0. 19
3. 9
1. 6
0. 59
41. 9
2. 49
0. 63
0. 17
6. 8
3. 7
1. 51
167. 0
5. 90
2. 09
1. 17
23. 4
10. 8
4. 24
334. 9
0. 13
0. 18
0. 20
0. 17
0. 15
0. 14
0. 10
21. 6
30. 3
37. 1
30. 0
25. 3
23. 3
16. 3
" S eria l a ngiogra phy" a nd " 3D ima ge processing" is the number of fa cilities.

mately 2.9 times higher in Kagoshima than in
Saitama.
The regional difference index for “Mammography ” was the highest in Oita with (153.8, i.e.,
5.90 units/100,000 population). The prefectureswith the next highest values were Yamaguchi(143.1), Yamagata (137.1), Tokushima (136.7),
and Saga (132.8). Conversely, the regional difference index for “Mammography ” was thelowest in Ibaraki (64.8, i.e., 2.49 units/100,000
population). Therefore, it is shown that the regional difference index was approximately 2.4
Arts and Sciences ◆ 21

Table 2 Regional difference index of each prefecture
P re fe cture

R adiologicalT echnologist

S er ial
angiogr aphy

Mam m ogr aphy

R I exam( scintigr am )

PE T

CT

MR I

3 D im age
pr ocessing

over allevaluation

Hokka ido
Aomori
I wa teMiya giAkita
Ya ma ga ta
F ukushima
I ba ra ki
T ochigi
Gunma
S a ita ma
Chiba
T okyoK a na ga wa
Niiga ta
T oya ma
I shika wa
F ukuiYa ma na shi
Na ga noGifu
S hiz uoka
Aichi
Mie
S higaK yotoOsa kaHyogo
Na ra
W a ka ya ma
T ottori
S hima ne
Oka ya ma
Hiroshima
Ya ma guchi
T okushima
K a ga wa
E himeK ochiF ukuokaS a gaNa ga sa ki
K uma moto
Oita
Miya z a ki
K a goshima
Okina wa

127. 3
97. 0
85. 4
91. 1
98. 8
97. 2
100. 591. 4
94. 3
101. 3
75. 5
81. 5
97. 4
77. 9
93. 2
115. 2107. 5114. 0
82. 2
95. 6
97. 4
89. 9
90. 5
86. 1
85. 2
102. 7103. 496. 9
97. 6
106. 792. 8100. 1113. 895. 5
97. 8
107. 8109. 398. 2122. 3106. 9108. 5102. 0107. 1124. 9112. 8123. 995. 7128. 5
86. 8
63. 8
79. 6
68. 0
95. 0
91. 7
83. 1
75. 6
110. 0
52. 3
60. 2
69. 1
61. 2
78. 8
122. 5118. 2102. 897. 3
109. 8104. 388. 8
62. 2
102. 7
91. 6
92. 4
88. 0
95. 2
86. 8
110. 8130. 898. 9
80. 8102. 4115. 8107. 8146. 5140. 0129. 4113. 4142. 1122. 997. 7123. 0130. 1151. 689. 7

84. 2
110. 178. 9
76. 2
117. 7137. 1101. 064. 8
90. 5
103. 7
70. 9
82. 6
90. 5
67. 1
116. 0103. 6102. 2100. 3101. 3105. 4
94. 7
77. 3
75. 1
99. 8
66. 4
92. 2
75. 3
82. 8
73. 4
115. 8129. 1110. 399. 7
107. 7143. 1136. 7126. 6105. 080. 3
91. 3
132. 8115. 4116. 6
153. 895. 7110. 588. 4158. 197. 5111. 7114. 0133. 0106. 0
78. 6
51. 2
67. 7
103. 3
49. 0
63. 6
88. 5
65. 5
137. 5140. 2163. 0140. 094. 7
82. 6
116. 4
80. 6
72. 5
77. 9
104. 7
95. 9
69. 8
92. 0
80. 9
98. 9
137. 9159. 289. 9
74. 3
129. 683. 9128. 9148. 587. 3105. 3
56. 7
69. 0
88. 3
87. 9
128. 8124. 664. 8129. 992. 7110. 1
93. 5
39. 7
71. 7
104. 934. 1
80. 7
120. 9
51. 3
66. 4
84. 9
47. 4
61. 0
93. 5
189. 4152. 196. 0114. 2127. 9112. 894. 5
109. 797. 8
98. 8
105. 2107. 7117. 262. 7104. 9230. 6124. 390. 7114. 279. 7102. 1173. 7138. 3
92. 8
47. 9
87. 5
78. 3
85. 7
126. 985. 0
68. 4

121. 6120. 1105. 9
73. 6
82. 8
83. 8
93. 3
83. 2
83. 9
95. 1
62. 3
60. 4
63. 0
51. 7
82. 2
107. 794. 5101. 9
81. 6
87. 5
97. 7
75. 0
71. 4
84. 8
59. 4
69. 3
75. 8
82. 1
74. 8
130. 9100. 095. 9110. 1105. 0126. 4174. 7127. 9123. 7178. 6101. 7125. 1122. 4131. 5151. 8131. 8161. 174. 6129. 1109. 0126. 191. 3100. 1
97. 7
85. 8
88. 1
81. 7
93. 7
61. 3
74. 0
69. 3
59. 1
91. 4
112. 4118. 7123. 9
98. 1
80. 0
89. 8
83. 1
75. 5
82. 6
68. 3
74. 9
72. 3
79. 1
76. 3
97. 1
78. 4
90. 1
97. 1
110. 2108. 7110. 8158. 7127. 6170. 7104. 1136. 4104. 0120. 1127. 8127. 9149. 987. 7105. 8123. 2
84. 7
71. 2
90. 9
82. 1
83. 6
84. 4
104. 6
98. 4
60. 8
69. 3
72. 6
59. 3
83. 3
78. 3
120. 1
96. 0
86. 1
92. 9
88. 2
84. 6
68. 5
72. 2
128. 1103. 0
89. 7
92. 3
99. 3
108. 3111. 4109. 2105. 2109. 9139. 4105. 9146. 5118. 3137. 897. 9119. 4139. 5104. 8102. 5119. 3167. 084. 5123. 1104. 5
95. 8
86. 3
91. 4
96. 3
92. 4
72. 5
84. 9
103. 3
60. 4
69. 7
79. 4
61. 2
92. 9
109. 2126. 7116. 492. 2
96. 0
102. 0
86. 5
76. 3
89. 5
87. 7
91. 2
84. 9
91. 0
88. 3
103. 9110. 7124. 3102. 699. 5121. 9113. 4130. 8129. 4130. 6101. 7108. 6107. 8105. 6119. 7121. 7134. 2
81. 7

times higher in Oita than in Ibaraki.
The regional difference index for “RI exam”
was the highest in Ishikawa (163.0, i.e., 2.09
units/100,000 population). The prefectures with
the next highest values were Shimane (159.2),
Hokkaido (158.1), Ehime (148.5), and Toyama(140.2). In contrast, Saitama had the lowest re-

22 ◆ Journal of JART English edition 2021

gional difference index for “RI exam” (49.0, i.e.,
0.63 units/100,000 population). Therefore, it isshown that the regional difference index wasapproximately 3.3 times higher in Ishikawa
than in Saitama.
Moreover, Shimane had the highest regional
difference index for “PET ” (230.6, i.e., 1.17

original articles
Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging

Table 3 Regional difference of health resources related to medical imaging
HighestOverallLowestRegionaldifferences

Regionaldifferences ratio

Kagoshima

134.2

Saitama

60.4

73.8

2.22

Hokkaido

127.3

Saitama

75.5

51.8

1.69

Kagoshima

151.6

Saitama

52.3

99.3

2.90

Oita

153.8

Ibaraki

64.8

88.9

2.37

RI exam（scintigram）

Ishikawa

163.0

Saitama

49.0

114.0

3.33

PET

Shimane230.6

Ibaraki

34.1

196.5

6.76

CT

Kochi

178.6

Kanagawa

51.7

126.9

3.46

MRI

Kochi

170.7

Kanagawa

59.1

111.6

2.89

Kagoshima

167.0

Kanagawa

59.3

107.7

2.82

Radiological Technologist
Serial angiography
Mammography

3D image processing

Regional differences ＝ Highest - Lowest
Regional differences ratio ＝ Highest / Lowest

units/100,000 population). The prefectureswith the next highest values were Ishikawa(189.4), Ehime (173.7), Fukui (152.1), and Kochi (138.3). In contrast, Ibaraki had the lowest
regional difference index for “PET ” (34.1, i.e.,
0.17 units/100,000 population). Therefore, it isshown that the regional difference index wasapproximately 6.8 times higher in Shimane
than in Ibaraki.
Kochi had the highest regional difference index for “CT ” and for “MRI ” (178.6, i.e., 23.4
units/100,000 population, and 170.7, i.e., 10.8
units/100,000 population, respectively). With
respect to “CT,” the prefectures with the next
highest values were Tokushima (174.7), Kagoshima (161.1), Oita (151.8), and Miyazaki(131.8), whereas Kagawa (158.7), Kagoshima(149.9), Saga (136.4), and Hokkaido (129.1)
were the prefectures with the next highest values for “MRI.” In contrast, Kanagawa had thelowest regional difference index for both “CT ”
and “MRI ” (51.7, i.e., 6.8 units/100,000 population, 59.1, i.e., 3.7 units/100,000 population,
respectively). Therefore, it is shown that theregional difference indices for “CT ” and “MRI ”
were approximately 3.5 and 2.9 times higher in
Kochi than in Kanagawa, respectively.
Furthermore, Kagoshima had the highest regional difference index for “3D image processing” (167.0, i.e., 4.24 facilities/100,000 popula-tion), followed by Kagawa (146.5), Nagasaki(139.5), Yamaguchi (139.4), and Kochi (137.8).
In contrast, Kanagawa had the lowest regional
difference index (59.3, i.e., 1.51 facilities/100,000
population, approximately 2.8 times lower thanKagoshima.
Overall, the highest regional difference index was in Kagoshima (134.2) followed by
Kagawa (130.8), Kochi (130.6), Ehime (129.4),
and Ishikawa (126.7). Conversely, Saitama had
the lowest overall evaluation of regional difference index (60.4). The prefectures with an
overall evaluation of the regional difference index of 80 or less were Tokyo (79.4), Aichi(76.3), Ibaraki (72.5), Chiba (69.7), and Kanagawa (61.2).
3-3 Hierarchical cluster analysis

As a result of a hierarchical cluster analysis,
we classified the 47 prefectures into sevenclusters. The dendrogram is a tree diagram thatshows how individuals are clustered together
in a cluster analysis (Fig.2). The mean item
value for each of the seven clusters is shown in
Table 4. We designated the cluster with thehighest mean value in the regional difference
index for each item as Cluster 1, and in descending order from Cluster 1 to Cluster 7.
Cluster 1 consisted of 3 prefectures: Kagawa,
Kochi, and Kagoshima. Cluster 1 was characArts and Sciences ◆ 23

Table 4 Average of regional difference index to each cluster
PrefectureRadiological
SerialRI exam
Mammography（scintigram）
Technologist angiography

PET

CT

MRI

3D imageprocessing

Cluster 1

Kagawa, Kochi, Kagoshima

118.5

142.5

105.8

113.6

108.5

155.9

159.8

150.4

Cluster 2

Ishikawa, Shimane, Ehime

101.9

119.0

105.8

156.9

197.9

104.7

112.1

115.8

Cluster 3

Hokkaido, Toyama, Fukui, Tottori,
Yamaguchi, Miyazaki

110.0

121.8

109.3

139.1

120.3

114.9

113.4

108.4

Cluster 4

Aomori, Wakayama, Hiroshima,
Tokushima,
Saga, Nagasaki, Kumamoto, Oita

106.2

111.7

123.6

82.1

78.2

132.7

114.4

114.2

Cluster 5

Akita, Yamagata, Niigata

96.4

80.6

123.6

125.5

57.4

82.9

96.4

85.4

Cluster 6

Iwate, Miyagi, Fukushima, Gunma,
Tokyo, Yamanashi, Nagano, Gifu,
Shizuoka, Aichi, Mie, Shiga,
Kyoto, Osaka, Hyogo, Nara,
Okayama, Fukuoka

95.8

90.4

88.1

92.2

106.3

83.5

86.0

89.9

Cluster 7

Ibaraki, Tochigi, Saitama, Chiba,
Kanagawa, Okinawa

86.0

70.3

77.4

60.3

58.1

69.3

75.3

77.2

Fig.2 Dendrogram

24 ◆ Journal of JART English edition 2021

terized as a region with abundant healthcare
resources that greatly exceeded the national
average for all items, especially for “Serial angiography,” “CT,” and “MRI ”.
Cluster 2 consisted of 3 prefectures: Ishikawa, Shimane, and Ehime. Cluster 2 was characterized as a region with abundant healthcare
resources, where all items were higher than
the national average, and where the “RI exam”
and “PET ” were particularly high.
Cluster 3 consisted of 6 prefectures: Hokkaido, Toyama, Fukui, Tottori, Yamaguchi, andMiyazaki. Cluster 3 was characterized as a region with abundant healthcare resources where
all characteristics exceed the national average.
Cluster 4 consisted of 8 prefectures: Aomori,
Wakayama, Hiroshima, Tokushima, Saga, Nagasaki, Kumamoto, and Oita. Cluster 4 wascharacterized by a lack of healthcare resources
for nuclear medicine examinations, with “RIexam” and “PET ” below the national average.
Cluster 5 consisted of 3 prefectures: Akita,
Yamagata, and Niigata. Cluster 5 was characterized by prefectures where the scores for“Mammography ” and “RI exam” were signifi-

original articles
Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging

cantly higher than the national average, whereas the scores for “PET ” were significantly lower.
Cluster 6 consisted of 18 prefectures: Iwate,
Miyagi, Fukushima, Gunma, Tokyo, Yamanashi,
Nagano, Gifu, Shizuoka, Aichi, Mie, Shiga,
Kyoto, Osaka, Hyogo, Nara, Okayama, and Fukuoka. Cluster 6 was characterized by a wellbalanced region with efficient healthcare resources.
Cluster 7 consisted of 6 prefectures: Ibaraki,
Tochigi, Saitama, Chiba, Kanagawa, and Okinawa. Cluster 7 was characterized as a region
with poor healthcare resources, falling below
the national average in all categories.

4. Discussion
In this study, we evaluated potential regional
differences using Giniʼs coefficient and CV
based on the number of “radiological technologists” and the number of “diagnostic imaging
devices” reported in the Medical Institution Survey. We also categorized regional characteristics in healthcare resources related to medical
imaging using a hierarchical cluster analysis.
Our results show that both Giniʼs coefficientand the CV for “radiological technologist ” werelower than those for “physician” with low regional differences. On the other hand, both coefficients for each diagnostic imaging device
were higher than those for “physician,” withhigh regional differences. In particular, “PET ”
exhibited the largest regional differences among
all the diagnostic imaging devices investigatedin this study. Regional uneven distribution is
influenced by medical demand, demographic
structure, and geography 9). Therefore, we had
assumed that the healthcare resources related
to medical imaging, especially in prefectureswith low population density such as Hokkaido, would have been high nationwide. However, in order to provide high-quality healthcare in all prefectures, diagnostic imaging devices and radiological technologists are need-ed, even in small population prefectures.
Therefore, we expect that eliminating regional
uneven distribution will be a very challenging
and difficult issue.
Saitama, Chiba, and Kanagawa, which havea low overall regional difference index, have
limited healthcare resources for their populations. In particular, it was identified that Saitama and Chiba lack both healthcare resources
related to medical imaging, but also healthcare
resources such as physicians, nurses, and hospitals 10). Till now, there are two prevalent reasons that explain why the scarcity of healthcare resources in Saitama and Chiba has not
had a major impact on the respective populations. The first reason is that the populations
are still relatively young and disease prevalence is low. The second reason is that a significant portion of these populations work in
Tokyo, therefore, they often choose to go to a
medical institution in Tokyo, should they fall
sick 10). According to the statistical survey of the
daytime population of Tokyo in the 2015 census, the population inflow to Tokyo was
936,100 people from Saitama, 716,881 people
from Chiba, and 1,068,505 people from
Kanagawa. Overall, this number comes to approximately 2.9 million people, when including the population inflow from other prefectures 11). Consequently, the daytime populationof Tokyo increases by approximately 2.4 million people, even after subtracting population
outflow from Japanʼs capital city. Therefore,
the overall regional differential index using thedaytime population would be significantly
higher in Saitama, Chiba, and Kanagawa prefectures than the results found in this study.
Similarly, if we calculate the overall regional
difference index of Tokyo on the basis of its
daytime population, then it would be significantly lower than the results provided in thisstudy. As a result, it is necessary to calculate
the overall regional difference index that considers not only the population but also thecharacteristics of the region, such as the dayArts and Sciences ◆ 25

time population. The medical demand is expected to increase in Saitama, Chiba, andKanagawa in the future for two reasons 10). The
first reason is the rapid increase in aging populations, whereas, the other reason is the increase in the use of local medical institutions
due to retirement. Therefore, it is necessary toconsider both the inflow and outflow of the
population when planning and improving the
medical care provision system for medical imaging. In Okinawa, where the aging rate is thelowest in Japan, the overall regional difference
index is bound to be higher than the results
shown in this study. Similarly, in Akita, where
the aging rate is the highest in Japan, the overall regional difference index is slightly lower
than the national average. However, if the calculations are based on the aging rate, the overall regional difference index will further decrease, and the region will seem to have scarce
healthcare resources. Therefore, it is necessary
to consider not only the results of this study,
but also the inflow/outflow of populations,and the aging rate in order to plan and improve the medical care provision system.
A hierarchical cluster analysis enabled us toclassify our data into 7 clusters, thus providing
us with a greater insight regarding their characteristics. The regional difference indices inclusters 1 and 3 were above the average for all
items included, i.e., indicate prefectures with
abundant healthcare resources. Nuclear medicine examinations with “RI exam” and “PET ”
had a significant impact on this classification.
Cluster 2 indicates prefectures where nuclear
medicine examinations were abundant, whereas cluster 4 indicates prefectures where nuclear
medicine examinations were poor. Furthermore, cluster 5 indicates prefectures that areabundant in “RI exam” but poor in “PET.” All 18
prefectures included in cluster 6 were average
and well-balanced prefectures with well-developed healthcare resources. We suggest that
Cluster 6 could be helpful in terms of planningand improving the medical care provision sys-

26 ◆ Journal of JART English edition 2021

tem. In all six prefectures of cluster 7, healthcare resources were generally scarce. These
prefectures were in fact the bottom three prefectures in the overall regional difference index (Saitama, Chiba, and Kanagawa), Ibaraki,
Tochigi, and Okinawa. Therefore, we suggestthat it is necessary to review the medical careprovision system for medical imaging after assessing future changes in medical demand suchas population inflow/outflow and aging rate.
Currently, each prefecture is planning a
medical care provision system that considers
the characteristics of each prefecture. In addition, shared use of diagnostic imaging devices
is being promoted in order to provide efficient
medical care. Therefore, it is necessary to planand improve the medical care provision system
by not merely considering individual hospitals
but the entire prefecture. The results of thisstudy are extremely useful for the development of the medical care provision system ineach prefecture. However, the development of
the medical care provision system requires
more detailed data analysis of secondary medical areas. Here, the secondary medical area
could be a medical administration area set foreach large city or wide area municipality in theregional healthcare plan. For example, in Tochigi prefecture, there are six medical regions:“North,” “West,” “Utsunomiya,” “East,” “Ryomo,”
and “South,” and there are multiple medical regions in each prefecture. In addition, the development of this system requires continuous
research.
Furthermore, there is no gold standard thatdefines the required number of radiological
technologists. Therefore, it is difficult to understand the potential excess and/or lack of radiological technologists. This study is a relative
survey of the presence or absence of regional
uneven distribution in healthcare resources related to medical imaging. Therefore, the excess
and/or lack of radiological technologists is not
captured. It can be inferred that the factors
causing regional differences include medical

original articles
Regional Uneven Distribution of Healthcare Resources Related to Medical Imaging

demand, demographic structure, and geographical conditions. In the future, detailed
factor analysis of the excess and/or lack of radiological technologists and regional uneven
distribution must be an essential issue to consider.

5. Conclusion
In this study, we evaluated regional uneven
distribution and used a hierarchical cluster
analysis to categorize each item based on thenumber of radiological technologists and thenumber of diagnostic imaging devices reported

References
1） Investigative commission about the demand of thehealthcare worker: The minutes of meeting, December 10, 2015.
https://www.mhlw.go.jp/stf/shingi/other-isei_315093.
html
2） Naoki Kodama, et al.: Study of the demand for radiological technologists. Japan Society of Education forRadiological Technologist, vol.1, No.1, 13-18, 2009.
3） Hiroe Muto, et al.: Employment environment of Radiological Technologists. Journal of Japanese Association of Radiologic Technologist, vol.64, No.776, 2532, 2017.
4） Hiroe Muto, et al.: Survey research on the current
situation of supply and demand of Radiological Technologists and future demand and work environment
improvement. Journal of Japanese Association of Radiologic Technologist, vol.66, No.795, 17-25, 2019.
5） Kazuto Okano: Study of the future demand forecast
for radiological technologists working in CT scan. The
Journal of health and welfare statistics, vol.65, No.13,
40-45, 2018.
6） The Ministry of Health, Labour and Welfare: Static/
Dynamic Survey of Medical Institutions and Hospital
Report, 2017.

in the medical institutions survey. Giniʼs coefficient and the CV underline that the regional
differences were lower for radiological technologists compared to physicians, whereas theregional differences were larger for diagnostic
imaging devices than for physicians. The results of this hierarchical cluster analysis showedthat the 47 prefectures could be classified into
seven clusters with distinct and well-defined
characteristics. We hope that the results of thisstudy will be used for the efficient planningand improvement of the medical care provision system in each prefecture.

http://www.mhlw.go.jp/toukei/list/79-1.html
7） Statistics Bureau, Ministry of Internal Affairs and Communications: Prefecture of the Population Estimates,
2017.
https://www.stat.go.jp/data/jinsui/2017np/index.html
8） The Ministry of Health, Labour and Welfare: Survey ofPhysicians, Dentists and Pharmacists 2016.
http://www.mhlw.go.jp/toukei/list/33-20.html
9） Koichiro Mori: How much is the regional difference inhealth care? Data analysis in units of secondary medical areas. [Hospital Edition]. Japan Medical Association Research Institute working paper, No.216.
http://www.jmari.med.or.jp/download/WP216.pdf
10）Tai Takahashi, et al.: Current status and future of
regional medical care provision systems. -Data collection by prefecture and secondary medical area
(2014)-. Japan Medical Association Research Instituteworking paper, No.323.
http://www.jmari.med.or.jp/research/working/wr_553.
html11）Statistics Division, Bureau of General Affairs, Tokyo:
Survey of the daytime population of Tokyo, 2015.
http://www.toukei.metro.tokyo.jp/tyukanj/2015/tj15index.htm

Arts and Sciences ◆ 27

Arts and Sciences
original articles

Received March 29, 2019 ; accepted November 29, 2019

The Usefulness of Bone Suppression Image-Based
Temporal Subtraction Processing for the Improvement of Lung Nodule Detection on Chest
Radiograph Images
SAKURAI Noriko1）, TAKAHASHI Shingo2）, TAKAHASHI Daishi2）, KODAMA Naoki1）
1）Faculty of Medical Technology, Niigata University of Health and Welfare
2）Faculty of Health and Welfare, Takasaki University of Health and Welfare

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 812: 21-27, 2020.
Key words: Digital Chest X-Ray Images, CAD, Temporal Subtraction Processing, Bone Suppression Processing, Im-proved Detection【Summary】

Chest X-ray (CXR) is the most commonly used diagnostic examination in lung cancer screening. The temporalsubtraction (TS) processing of CXRs using computer-aided diagnosis (CAD) software is a technique in which aprevious CXR is used to enhance evaluation of changes in an intervening time. However, if the superpositioning of
the two images is not accurate, excessive misregistration artifacts will make it difficult for radiologists to differentiate
between true changes and simple artifacts. In this study, we aimed to use bone suppression (BS) processing as amethod to reduce artifacts when detecting a lesion became difficult due to the occurrence of artifacts between two
images. The contrast-to-noise ratios (CNRs) of TS processing images with and without BS processing were calculated
and compared based on several types of positions including anterior inclination, lateral inclination, right anterior
oblique (RAO), and left anterior oblique (LAO). Our results showed that CNRs were significantly improved with BSprocessing.

1. Introduction
According to the Ministry of Health, Labor,and Welfare 2018, cancer is the leading causeof death in Japan. Lung cancer is increasing inincidence in both males and females 1). Currently, greater emphasis is given on preventive
medicine for the early detection and treatmentof lung cancer.
Lung cancer screening is generally performed with sputum examination and chest
radiography, although high-performance computed tomography (CT) is also widely used. CT
screening is usually used for treatment determination. Sputum examination is performedon high-risk patients with a history of smoking;however, chest radiography is critical for the
early detection of lung cancer. Chest radiography can be promptly and effortlessly performed and has the advantages of low cost and28 ◆ Journal of JART English edition 2021

low exposure to radiation. More than 80 different lesions have been shown to exist in thelung, and images may additionally include thepresence of overlapping ribs and normal tissue, making the detection of pale, small, andearly lesions of lung cancer challenging. Approximately 95% of missed lung cancer lesions
overlapped with the ribs and clavicles 2).
Research and development of computer-aided diagnosis (CAD) using artificial intelligence
technology have been employed in the field of
diagnostic imaging. However, the reading efficiency and diagnostic accuracy must be improved. Temporal subtraction (TS) processingof chest radiographs involves superimposing
two images of the same person, one from thepast and one from the present; then, the changes over time are identified. This is known as acomputer-aided detection system, which identifies lesions and presents the results for assess-original articles
The Usefulness of Bone Suppression Image-Based Temporal Subtraction Processing for the Improvement of Lung Nodule Detection on Chest Radiograph Images

ment. TS processing is useful to improve thevisibility of lesions that overlap with normal
tissue and may be overlooked by doctors 3), 4).
In TS processing, two images of the same
patient, one current image and one past image,acquired with digital radiography and computed radiography are subjected to differential
processing. Specifically, to superimpose thetwo images, first, a global matching process isperformed on the past image to roughly matchthe thorax. Second, a local matching process
corrects the distortion of the lung structure.
This two-step nonlinear image superimposition process emphasizes the shades thatchanged over time 5). The artifacts are reducedwith nonlinear image deformation, which isuseful for detecting changes over time 6). However, removing sharp linear artifacts in the ribedges and fine artifacts in the pulmonary vessels is complex as artifacts may persist evenafter performing the imaging deformations 7).
Thus, TS greatly affects the reproducibility of
past and current images 8). If the superimposition of the two images in a chronological sequence is not accurate, strong artifacts will appear in the entire lung field, which will interfere with image reading.
In the present study, we employed a method
to improve lesion detection in cases of poor
detection due to artifacts triggered by a misalignment between two images. Although there
have been reports on improvement of lesion
detection by modifying the algorithm of TS
processing systems 7), the use of both TS andbone suppression (BS) processing has notbeen reported. The BS process is a CAD application for chest radiographs. This CAD application depresses the signals of the ribs andclavicles from the lung field and can be generated as a single image 9). The detection rate oflesions is improved by enhancing visibility
with BS processing, even for radiologists who
are not specialists in chest radiology 10). Previous reports have demonstrated that BS processing is not significantly affected by position-

ing 11). In the present study, BS processing wasused as a preprocessor for TS processing, andTS images were generated for both the pastand present images. We compared the effect oflesion detection on TS images generated fromthe original and BS images using physical evaluation.

2. Materials
The present study used the radiographic system, Radnext 50 (Hitachi Medical Corporation),and the flat panel detector (FPD) [AeroDR(A50C-50438) by Konica Minolta, Inc. NEOVISTA I-PACS EX (A791-0304)] for TS and BS processing. Kyoto Kagaku Co., Ltd. N-1 LUNGMAN was used for the chest phantom. ImageJ(1.50i) was used for statistical analysis of thecontrast-to-noise ratio (CNR) region of interest(ROI).

3. Methods
In this study, for investigating the effect ofpositioning on the CNR in TS processing images, we calculated the CNR for each angularchange in positioning using images of a chest
phantom with an attached simulated nodule.
Additionally, we calculated and compared the
CNRs of TS images generated from the original
and BS images to determine whether BS processing improved detection of poor lesions
when artifacts occurred due to mispositioning.
For TS images after BS processing, the latter
was performed on the reference image and allcomparison images with varying positioning
angles, which were differentially processed.
Subsequently, the mean and standard deviation of the CNR of TS images with and without
BS processing, as well as the improvement rateof the CNR, were calculated. We also performed a significant difference test for TS images with and without BS processing using theMann-Whitney U test for CNR. The significancelevel was set at 5%.
Arts and Sciences ◆ 29

3-1 N-1 LUNGMAN

In this study, experiments were conductedusing images of a simulated nodule mounted
in the lung field of a chest phantom. This
phantom was composed of a soft tissue substitute and artificial bone with an absorption rate
similar to that of the human body. The phantom had simulated blood vessels arranged in
the lung field. Therefore, the concentration
changes were the same as observed in the human body. The inner structure of the lung field
was detachable, and a simulated lesion wasplaced inside.

nodule as visually recognized using ImageJ(1.50i). Figure 2 illustrates S was set as the inner signal region. The donut-shaped background region outside the nodule was set as B.
The size of the background region B was set to
5 mm in width, which ensured that the characteristics of the lung fields would not be lost.

i n n e r s i g n a l r e g i o n . T h e d o n u t - s h ap e d b a c k g r o u n d r e g i

n o d u l e wa s s e t a s B . Th e s iSz e o f t h e ba c k g r o u n d r e g i o n

3-2 Simulated nodules

A simulated nodule with a diameter of 1 cm
and a CT value of 50 HU was used. Figure 1
illustrates nodules were attached to the left under the clavicle, left heart edge, right middle
lung field, or right hilar area.

B
mm in width, which ensured that the characteristics ofw o u l d n o t b e l o s t . [ I n s e r t Fi g . 2 ]①

Figure 2 The position of the region of interest③④②

Figure 1 Mounting position of the simulated nodule: 1) left under the clavicle; 2) left edgeof the heart; 3) right lobumediusu, middle
lobe; and 4) right hilus pulmonis

3-3 CNR

The CNR of the simulated nodules was calculated as quantitative evaluation of the physical characteristics of the visibility of lesion
shadows on TS images.
We defined the boundaries of the simulated

30 ◆ Journal of JART English edition 2021

��� �|���� � ���� |���

where Save is the average luminance value inthe signal region, Bave is the average luminancevalue in the background region, and Bsd is thestandard deviation of the background lumiw
he r e value.
S a v e i sSincet h e thea v e valuer a g e lof
u mCNRi n a nflcuctuatede va l u e i n t h e s i g n a l
nancedepending on the ROI, the average of the two
measurements was used for analysis.

the average luminance value in the background region,
3-4 Reference and comparison images
The displacement of positioning was evaluat-

ed by focusing on the angle of displacements t a n da r d de vi a t i o n o f t he b a c k gr ou n d l u m i na n c e v afrom the posterior-anterior (PA) direction, which
is often used in lung cancer screening, and wasassessed in the following directions: anteriortilt, right anterior oblique (RAO), left anterior
oblique (LAO), right-lateral flexion, and left lat-15

original articles
The Usefulness of Bone Suppression Image-Based Temporal Subtraction Processing for the Improvement of Lung Nodule Detection on Chest Radiograph Images

eral flexion. The comparison images were processed by differentiating the images with different positioning angles. The comparison image was shifted from the reference image by– 9°in each direction in 1°increments. If a1°
nodule was not correctly positioned or theedges of the simulated nodule were indistinguishable from the surrounding artifacts, theROI could not be identified; therefore, we
compared the data up to the angle at which all
the simulated nodules could be measured.
3-5 TS and BS processing

The processing was executed on the I-PACS
EX screen. The processed images were automatically generated with the output in approximately 1 s. An initial display image was used.

4. Results
Figure 3 illustrates the graphs of CNR show-

ing the changes in the positioning of TS images
with and without BS processing. In the anterior
tilt TS images without BS processing, simulated
nodules two, three, and four could not be, and all the simulated nodules
measured at 5°
above 6°could not be measured. In TS images
with BS processing, simulated nodule two, and simulated
could not be measured at 5°. In thenodule four could not be measured at 6°
RAO TS images without BS processing, simulated nodule four could not be measured at 5°,
and simulated nodule two could not be measured at 6°. In the TS images with BS processing, all the simulated nodules could be measured at all angles. In the LAO TS images without BS processing, simulated nodules two and. In TS images
four could not be measured at 5°with BS processing, all simulated nodules
could be measured at all angles. At both rightand left lateral flexion, all the simulated nodules could be measured up to 9°in the TS images with and without BS processing.
All the simulated nodules were measured in
all positions up to 4°as CNRs. Table 1 illustrates

the means, standard deviations, and improvement rates of the CNRs of simulated nodules
one to four in the TS images with and without
BS processing. In the anterior tilt, RAO, and
LAO, the improvement in CNR was higher for
TS images with BS processing than for those
without BS processing in the simulated nodule.
In the anterior tilt position, improvement in the
CNR was 10.2% in simulated nodule one; however, the highest was in simulated nodule threeat 51.0%. In RAO and LAO, simulated nodule
three was low at approximately 10%; however,simulated nodule four was the highest at 34.7%
and 61.6%. The improvement rates for rightand left lateral flexions were low, with some
nodules showing a negative improvement rate.
Even after TS processing alone, the CNR was
stable and relatively high and was detected ataround 2.0.
Figure 4 illustrates the mean and standard
deviation of the CNR of TS images with andwithout BS processing. There was a significant
difference in the anterior tilt, RAO, and LAO.
There was no significant difference between
the right and left lateral flexions.

5. Discussion
Chest X-ray (CXR) imaging is an excellent
examination method as it has the advantagesof low cost, easy to use, and low exposure
dose, despite the considerable amount of information obtained. However, reading CXR images is highly cumbersome for radiologists,
who must take multiple pictures in a short period, to minimize misdiagnosis. TS processing
can improve detection as it allows instantaneous visualization of changes in lesions overtime 12). However, artifacts occur when there isa misalignment between the two images due tothe influence of the reproducibility of the pastand current images. This artifact makes it difficult to distinguish between detection of changes over time and simple artifacts 13). The mainfeatures of the artifacts are the linearity of theArts and Sciences ◆ 31

0.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②

Nodule③

Angle

Nodule④CNR(a)－ 1
3.50
3.00

CNR

3.00

1.00
2.50
0.50
2.00

1.50

0.00
1.50

1.00

1.00

0.50

0.50
０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②

Angle

Nodule③

Nodule④

CNR

CNR

3.00

2.00
3.50
1.50
3.00
1.00
2.50
0.50
2.00
0.00
1.50

０° １° ２° ３° ４° ５° ６° ７° ８° ９°

1.00

Nodule①

Angle

Nodule④

CNR

Nodule③

Nodule①(ｂ )－ 1

Nodule②

Angle

Nodule③(a) － 2

Nodule④(a)－ 2

1.50
3.50
1.00
3.00
0.50
2.50
0.00
2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°1.50

Nodule①

0.00
3.50

Nodule②

Angle

Nodule③

Nodule④

3.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②

Angle

Nodule③

Nodule④(b) － 2 ( ｂ ) － 2

2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°(c)－ 1

22

2.50

2.00
3.50

1.50
3.50
1.00
3.00
0.50
2.50
0.00
2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°

1.50
3.00

1.50

Nodule①

1.00
2.50

1.00

0.50
2.00

0.50

0.00
1.50

0.00
3.50

Nodule③

Nodule④

0.50
0.00

3.50

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②

Nodule③

Angle

CNR

(a)－ 2

2.50

1.00

CNR

Nodule②

Angle

Nodule④22(c) － 1 ( c ) － 1

Nodule②

3.00

Nodule③

Nodule④(ｂ )－ 2

2.50

0.00
2.50
2.00
1.50

Nodule②

Nodule③

Nodule④

0.00
3.50

０° １° ２° ３° ４° ５° ６° ７° ８° ９°

3.00

Nodule①

Nodule②

Nodule③

Nodule④０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②24

Angle

Nodule③

Nodule④(e)－ 1０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①23(d) － 1( d ) － 1

Nodule②

Angle

Nodule③

Nodule④(d) － 2(d)－ 2

Angle

Nodule④

3.50
3.00
2.50

2.50
2.00

2.00

(c)－ 2

1.50

1.50
3.50
1.00
3.00
0.50
2.50
0.00
2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°1.50

Nodule①

0.50

0.00

Angle

0.50

Angle

Nodule③(c)－ 2

0.50

1.00

1.00

Nodule②(c) － 2

1.00

Nodule①(d)－ 1

0.50
3.00

1.50
3.50
1.00
3.00
0.50
2.50
0.00
2.00
1.50

Nodule④

1.00
3.50

2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Angle

Nodule③０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

1.50

Angle

Nodule②23

2.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

3.00
2.50

CNR

CNR

Nodule②

3.00

CNR

3.00

(b) －(1ｂ ) － 1

3.50 Nodule①

CNR

Nodule④０° １° ２° ３° ４° ５° ６° ７° ８° ９°

0.50

0.50

CNR

Angle

Nodule③

1.00

CNR

CNR

2.50

Nodule②

0.00
3.50

2.00

3.50

0.00

０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

2.50(a) － 1( a ) － 1

CNR

1.50
3.00

2.00

0.00

CNR

2.00
3.50

2.50

CNR

CNR

2.50
3.50

1.00

25

0.50

Nodule②

Nodule③

Angle

Nodule④24(e) － 1( e ) － 1

0.00
０° １° ２° ３° ４° ５° ６° ７° ８° ９°Nodule①

Nodule②

Nodule③

Angle

Nodule④(e) － 2( e ) － 2

0.00

Figure 3 Graphsof CNRs showing changes in the positioning of TS images with and without BS processing
０° １° ２° ３° ４° ５° ６° ７° ８° ９°
Angle(a) Anterior tilt Nodule①(b) Right Nodule②
anterior oblique(c) Left anterior oblique (LAO) (d) Right lateral flexion
Nodule③(RAO)Nodule④
1. TS images without BS processing 2. TS images with BS processing

32

◆

CNR

(d)－ 2
3.50

Journal of JART English edition 2021
3.00
2.50
2.00

26

(e) Left lateral flexion

original articles
The Usefulness of Bone Suppression Image-Based Temporal Subtraction Processing for the Improvement of Lung Nodule Detection on Chest Radiograph Images

Table1 Values of CNRs for each simulated nodule on
temporal subtraction images with and withoutbone suppression(a) Anterior tilt(b) Right anterior oblique (RAO)(c) Left anterior oblique (LAO)(d) Right lateral flexion(e) Left lateral flexion
Simulated
NoduleAve/Std

①

Ave

②

Std

Ave

③

Std

Ave

④

Std

Ave

Std

TSI
without BS 1.51 0.11 1.11 0.88 1.37 0.47 1.50 0.28
TSIwith BS
Improvementrate（%）

1.66 0.05 1.49 0.65 2.07 0.24 2.08 0.28
10.2

34.5

51.0

38.1

（a）

Simulated
NoduleAve/Std

①

Ave

②

Std

Ave

③

Std

Ave

④

Std

Ave

Std

TSI
without BS 1.45 0.20 1.71 0.57 1.62 0.21 1.37 0.25
TSIwith BS
Improvementrate（%）

1.78 0.12 1.96 0.46 1.75 0.36 1.84 0.32
22.8

14.7

8.3

34.7

③

④

（b）

Simulated
NoduleAve/Std

①

Ave

②

Std

Ave

Std

Ave

Std

Ave

Std

TSI
without BS 1.27 0.24 1.19 0.81 1.69 0.09 1.20 0.46
TSIwith BS
Improvementrate（%）

1.79 0.24 1.36 0.73 1.87 0.11 1.94 0.54
40.3

14.2

10.1

61.6

③

④

（c）

Simulated
NoduleAve/Std

①

Ave

②

Std

Ave

Std

Ave

Std

Ave

Std

TSI
without BS 1.82 0.20 1.86 0.63 1.94 0.15 1.77 0.18
TSIwith BS
Improvementrate（%）

1.98 0.27 1.91 0.56 1.87 0.46 2.43 0.38
9.2

2.8

-3.7

37.2

③

④

（d）

Simulated
NoduleAve/Std

①

Ave

②

Std

Ave

Std

Ave

Std

Ave

Std

TSI
without BS 2.12 0.38 1.98 0.49 1.97 0.17 2.01 0.43
TSIwith BS
Improvementrate（%）

2.05 0.30 2.28 0.23 2.29 0.22 2.17 0.27
-3.3

15.1
（e）

15.9

Figure 4 Comparison of CNRs for TS images withand without BS processing of four positions. Mean value and standard deviation of
the CNR8.4

rib edges and the complexity of fine pulmonary vessels.
In this study, we generated artifacts by shifting the positioning of the comparison image by
1°in the forward-leaning, RAO, LAO, right-lateral bending, and left lateral bending positions
against the reference image. The results weredivided into two groups: anterior tilt, RAO and
LAO, and right and left lateral flexions.
Although the variations in CNR were large
for deviations to the right and left lateral bends,
the superposition of TS processing was sufficient to produce TS images with few artifacts. These were two-diwithin a range of up to 9°
mensional misalignments in the X and Y axes,
occurring by the rotation of the FPD with thefront surface of the chest attached. The misalignment was corrected with the global matching process of TS processing and was detectedby TS processing alone. Therefore, the CNR
did not improve, even for TS images with BSprocessing.
In contrast, in the cases of an anterior tilt,
RAO, and LAO, a part of the body is separated
from the FPD and is displaced not only in the
X-Y axis but also in the Z-axis. Although acomplex warping process was performed in
the local matching after the global matchingprocess, it was inadequate to cope with theincreasing displacement of the body. Therefore, artifacts and simulated nodules appearedin the TS images, where the edges cannot be
Arts and Sciences ◆ 33

seen beyond 5°. In this case, we first generated
BS images, followed by the TS images. All thesimulated nodules were measured up to 9°in
the RAO and LAO positions. In the anterior tilt
position, simulated nodules one and three. Simulated nodules
were measured up to 9°, withtwo and four could be measured up to 4°
no significant differences between TS images
with and without BS processing. The calculated anterior tilt of 4°was defined as a state inwhich the panel and body were 3 cm apart at
the lower end of the FPD. Although it is possible in elderly patients with bent hips, it isconsidered to be no problem in medical examinations.
The Mann-Whitney U test demonstrated that
there was a statistically significant difference in
the CNR values for the anterior tilt, RAO, and
LAO positions between the TS images with andwithout BS processing. For the artifacts causedby three-dimensional misalignment, the CNR
was improved by generating a BS processed
image first, followed by a TS image. Consequently, the detections of all simulated nodules
in the anterior tilt, RAO, and LAO positions
were improved.
The improvement rate for CNRs was higher
than 30% in the hilar area. This area contains a
mixture of two complex artifacts: linear ribedges and fine pulmonary vessels. The results
suggested that the rib shadows in the entire
lung field were attenuated by the BS and TS
processes. The complex superposition process
was reduced by combining the artifacts into asingle factor, and the CNR was improved.
However, the templates of the TS treatment superposition also included the thorax and pulmonary vessels of normal tissue and the ribs.
Nevertheless, the possible reduction of accuracy with the weakening of the ribs has notbeen tested. Areas with many vessels can be
accurately superimposed on the ribs when
they are weakened; however, they may not bealigned as the number of vessels decreases.

34 ◆ Journal of JART English edition 2021

In the case of poor lesion detection due toartifacts caused by the inadequate superimposition of past and current images, we read theTS images automatically generated using picture archiving and the communication system.
However, in this study, as a method to improve
lesion detection in clinical practice, we demonstrated that TS processing after BS processing
using two images improved lesion detection.
The diagnostic accuracy of TS images is expected to improve with improvement in thedetection capability.
In the present study, we focused on the angle in the upright frontal PA direction, often
used in medical examinations. However, sincevarious imaging methods are used in clinicalexaminations, the associated discrepancies
must be evaluated. In the future, we must investigate the effect of Z-axis misalignment on
the magnification rate and radiograph centerline, as well as respiratory misalignment andother lesions that are limited by phantom experiments. The variety in lesions must be studied in the future. Additionally, we assessedboth physical and visual evaluations, such asreceiver operating characteristic observer experiments, for maximizing its use in clinicalpractice.

6. Conclusion
In TS processing, artifacts tend to appear due
to the mismatch of past and current images,
which further complicates the temporal changes of lesions. In the present study, the nodules
were unable to cope with three-dimensional
misalignment, reducing the detectability of thenodules. Using BS processing in advance improved the CNR and was useful for nodule detection.
Acknowledgments

We would like to thank Editage (www.editage.com) for English language editing.

original articles
The Usefulness of Bone Suppression Image-Based Temporal Subtraction Processing for the Improvement of Lung Nodule Detection on Chest Radiograph Images

References
1） Ministry of Health, Labour and Welfare (MHLW): Demographic statistics, 2018.
2） Priya Kumar Shah, et al.: Missed non-small cell lungcancer: radiographic findings of potentially resectablelesions evident only in retrospect. Radiology, Vol 226,
No 1, 235-241, 2003.
3） Kakeda S, et al.: Improved detection of lung nodules
by using a temporal subtraction technique. Radiology,
Vol 224, No 1, 145-151, 2002.
4） Okazaki H, et al.: Improved detection of lung cancer
arising in diffuse lung diseases on chest radiographs
using temporal subtraction. Academic Radiology, Vol
11, No 5, 498-505, 2004.
5） Kobayashi T. Temporal Subtraction processing aimed
at hospital-to-clinic use. The Journal of Japan Association of Radiological Technologists, Vol 62, No 747,
87-89, 2015.
6） Katsuragawa S, et al.: Comparison of the quality of
temporal subtraction images obtained with manualand automated methods of digital chest radiography.
Journal of Digital Imaging, Vol 12, No 4, 166-172,
1999.
7） Sugimoto A, et al.: Development of temporal subtraction method for chest radiographs by using pixel
matching technique. Nihon Hoshasen Gijutsu Gakkai
Zasshi, Vol 69, No 8, 855-863, 2013.

8） Kano A, et al.: Digital subtraction technique between
temporally sequential chest screening Images. Konica
Technical Report, Vol 8, 65-68, 1995.
9） Kobayashi T, et al.: Development of bone suppression processing as an application of computer aided
detection of nodules in chest radiographs. Konica Minolta Technology Report, Vol 12, 71-76, 2015.
10）Kodama N, et al.: Effectiveness of bone suppression
imaging in the diagnosis of tuberculosis from chest
radiographs in Vietnam: An observer study. Clinical
Imaging, Vol 51, 196-201, 2018.
11）Sakurai N, et al.: Study of profile analysis on the simulated tumor and visibility evaluation in lung area using
Bone Suppression processing. The Journal of Japan
Association of Radiological Technologists, Vol 64, No
781, 21-27, 2017.
12）Okazaki H, et al.: Improved detection of lung cancer
arising in diffuse lung diseases on chest radiographs
using temporal subtraction. Academic Radiology, Vol
11, No 5, 498-505, 2004.
13）Sakai S, et al.: Evaluation of the image quality of temporal subtraction images produced automatically in a
PACS environment. Journal of Digital Imaging, Vol 19,
No 4, 383-390, 2006.

Arts and Sciences ◆ 35

Arts and Sciences
original articles

Received April 23, 2019 ; accepted August 30, 2019

New Quantitative Calculation method of Contrast
Values in Slot Scan ImageICHIKAWA Shigeji1），2）, KUMAGAI Kanami1）, SATOH Yasutaka1）,
NONAKA Takashi1）, NAKAMURA Yutaka1）
1）Department of Radiology, Fussa Hospital2）Graduate School of Health Science, Suzuka University of Medical Science

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 813: 14-21, 2020.
Key words: long length radiography, slot scan image, contrast, blur
【Summary】

The slot scan technology for long-length radiography installed in the fluoroscopic imaging equipment performs
continuous radiographing while the X-ray tube and the light-receiving unit simultaneously move in parallel, creating along-length image. The disadvantage is that the exposure while moving creates a blurred image looking with reduced
contrast, contributing to low image quality. Although the cause is related to the combination of exposure time andtube voltage, the conventional contrast improvement method cannot be applied due to the influence of blurring, andthere is no physical evaluation report, only a visual evaluation report.
In this study, we analyze the blur part and propose a method to calculate the source of the new concept of contrast
quantitatively.

BackgroundLong-length radiography systems aimed atfull spine imaging and full leg imaging is classified into the general X-ray radiography equipment and the fluoroscopy radiography equipment.
The general X-ray equipment includes a system in length of which the X-ray tube and thelight-receiving unit move in parallel (Fig.1 a1),
the X-ray tube inclines (Fig.1 a2), and images
are taken at a time in light irradiation field(Fig.1 a3).
The fluoroscopy radiography equipment includes a system in which the X-ray tube andlight-receiving surface move in parallel (Fig.1b1), images are taken in the large field of view,
and images are taken in sequence while moving (Fig.1 b2). It is introduced and operated
according to the circumstances of each hospital.
The light-receiving surface changed fromanalog to digital computed-radiography (CR)and flat-panel detector (FPD), and the image

36 ◆ Journal of JART English edition 2021

a1 a2 a3
b1

b2

Fig.1 Long length radiographic system(a1), (a2), (a3) : X-ray general radiographic system(b1), (b2) : Fluoroscopic radiographic system

quality improved digital image processing.
FPD system can output the Ⅹ-ray signal as adigital signal in real-time. It is characterized byimages with a large field of view, less distortion, a broad dynamic range, and high detective quantum efficiency. Therefore, it has apossibility to reduce radiation dose.
In contrast, the slot scan technology for long

original articles
New Quantitative Calculation method of Contrast Values in Slot Scan Image

a

b

c

Fig.2 Image creation process with slot scan technology (from exposure to image creation)(a) Image Acquisition (b) Stitching (c) Long length image

images in FPD-mounted fluoroscopy X-ray radiology equipment makes the examinationeasy for patients because it takes only 1–2 minfrom radiation to the end of image processing.
It is good for throughput with easy handling,
fast processing of images, and short examination time (Fig.2) 1-3).
The imaging method continuously irradiates
an X-ray beam with a slit-shaped (2 or 4 cm)
collimator, produce more than 10 images, andmake one long-length image.
Since an X-ray beam radiates vertically toward an object, it has a constant scale with lessdistortion.
Consequently, in the field of orthopedics, it
is often used to measure alignment and evaluate a patientʼs condition before and after operation 4, 5). It is also applied to leg angiography
in the field of surgery due to its continuous
imaging 6).
The imaging method is that the X-ray tube
and the light-receiving part (FPD, 17 × 17inch) simultaneously move from the head tothe foot side at a constant speed (HS mode:
150 mm/sec, HQ mode: 75 mm/sec) and havea slit shape (HS mode: 4 cm, HQ mode: 2 cm),
irradiates an X-ray beam from a collimator forcontinuous exposure.
The tube voltage can output from 60 to 130
kV with a exposure time of 1.0 –20.0 msec. The
modes available include three-way, 110 cm,
120 cm, or 150cm on source image receptor
distance. Slit images become one long image
through superposition. The image mode has
the HS mode, which is standard image quality,
and the HQ mode, which is high quality (Table1). The tube voltage (kV), tube current (mA),and exposure time (s) must be set manually
because the automatic exposure control cannot be used. Because an X-ray is radiated whilemoving, this results in blurred and low-quality
images (Fig.3). A picture taken in a moving
vehicle may be blurred in normal mode but
can be taken when in an almost stationary state
at a short exposure speed.
Thus, this image is slightly or strongly

Table 1 Exposure techniques with slot scan technology (2 types)
Tube current [mA] : 400 mA (constant)Mode

Moving Speed[mm/sec]

HS

150

HQ

75

Slit width[cm]

Tube voltage[kV]

Exposure time
[msec]

SID
[cm]

4

60 1301.0 20.0

110/120/150

260 1301.0 20.0

110/120/150

Arts and Sciences ◆ 37

(CNR), and some method must be considerednecessary in capturing slot scan images.
In this study, we suggest methods that evaluate the contrast in slot scan images quantitatively by analyzing the blur it produces.

1. Methods
1-1 Definition of contrast in slot scan images
1-1-1 Difference between general radiographic
images and slot scan images
Fig.3 Features of slot scan images (blurred image)
Blur appears in the x-ray tube traveling direction

blurred, leading to a degree of contrast. Similarly, the slot scan images can be stationary ata short exposure speed.
However, it is necessary to increase the tube
voltage because the image quality decrease depending on the exposure speed. Based onthese findings, it is important to consider the
tube voltage and not only the exposure speed
to take fine slot scan images. Due to the influence of blurring, a highly accurate physicalevaluation, such as the contrast noise ratio

Images contain motion elements and are expressed as a blur since the X-ray tube and imaging unit continuously radiate an X-ray beam
while moving in slot scan images. In the area
indicated by the arrows in Fig.4, the concentration of contrast rapidly changes in still images,
but it changes by gradation in the blur of slot
scan images. Furthermore, when the range isbroad the image is difficult to observe. Whenthe range is narrow it is easy to observe theimage, which is almost stationary. This blurred
range is observed like low contrast images dueto the vague concentration of contrast (Fig.5).
We define this as the contrast in visual effects.
1-1-2 The feature of slot scan images

Regarding the blurring in slot scan images,
the width of the blur can be improved byshortening the imaging time. On the otherFig.4 Difference between still image andblurred image
Still image: Concentration boundary is clear (sharp)
Blurred image: Concentration boundary is unclear(slightly change)

38 ◆ Journal of JART English edition 2021

Fig.5 Difference of blurred size
The size of the blur is affected by the exposure time(a) Large blur image, exposure time is long(b) Middle blur image, exposure time is middle(c) Small blur image, exposure time is short

a

b

c

original articles
New Quantitative Calculation method of Contrast Values in Slot Scan Image

hand, the apparent contrast is also affected byimage quality caused by the tube voltage.
Therefore, the tube voltage must also be considered.
The relationship between image and X-ray
dose can be expressed as the photo effect (P.
E.) in the following equation:
P.E = V n・I・t / r 2 ............ (1),where V is the tube voltage, n is the tube
voltage index (2–6), I is the tube current, t
is the imaging time, and r is the distance.
Equation (1) shows that when the imaging
time (t) is shortened, the image effects can be
kept constant by increasing the tube voltage(V), and the image effects can be maintained at
a constant level. However, when the tube voltage (V) is increased, the image changes in decreasing contrast, owing to the change in the
X-ray image quality. This is the case for bothgeneral radiographic imaging and slot scan imaging.
In general radiographic imaging, decreasing
the tube voltage and extending the imaging
time improves the contrast. On the other hand,the contrast does not improve in slot scan imaging. This is because extending the imaging
time increases the blur and decreases the contrast in visual effects. If the imaging time isshortened, the amount of blur is reduced, andthe contrast tends to improve. However, when
the tube voltage increases, the contrast drops
due to changes in the X-ray image quality.
Thus, there is a contradictory relationship between the imaging time and tube voltage withrespect to the change in image quality. To improve the image quality of slot scan images, it
is insufficient to decrease the blur width; however, it is also necessary to consider the X-ray
image quality caused by the tube voltage. Sincea change in the blur is affected by both theimaging time and the tube voltage, we define
this change as the amount of blur.
Therefore, it is assumed that an optimal com-bination of the imaging time and tube voltage
can maintain an optimal visual contrast in slot
scan images.
1-1-3 Analysis of the amount of blur (contrast invisual effects)
The profile curve (image) of the blurred area
is measured from an image obtained by slot
scan imaging (Fig.6a). While the density of astill image abruptly changes, the density (signal value) of a slot scan image gradually changes due to the effect of blurring, showing a
curve like that of an X-ray (Fig.6b). The curveis characterized by a slight curve at first, reaching a maximum near the center and reverting
to a slight curve.
Next, the rate of change is calculated by differentiating the values obtained from the profile curve. As shown in Fig.6c, the calculated
values are graphed as a spike-shaped graph forthe still image and a mountain-shaped graphfor the slot scan image.
From both graphs, the height value can beconsidered the value when the concentration
change is at the maximum, defined as the contrast in the still image, and the contrast in a

Fig.6 Contrast analysis methoda(a) measurement range on the chart(b) profile curve by imagej(c) rate of change curve (differential)bcArts and Sciences ◆ 39

visual effect is the contrast in the slot scan image. We define the contrast value in a visual
effect as the Cp (contrast peak value) value.
Since the Cp value varies with the combinationof imaging time and the tube voltage, it can be
regarded as one of the image quality evaluation parameters. By using the method described above, the best value of contrast in visual effect is obtained from the combination ofimaging time and tube voltage, and the imaging conditions (imaging time and tube voltage)at that time are considered to be the optimal
imaging conditions for slot scan images.

at 400 mA.
The measurement was performed three times
each and the average value was obtained. Table 2 shows the imaging conditions.
Note) The SS value is defined as a value that isinversely proportional to the incident X-ray
dose, as 200 when the incident X-ray is 1mR.
1-3-3 Imaging

The slot scan radiography (11 ways) was
performed in an HS mode with the upper endof the phantom as the imaging start point and1-2 Equipment and materials- Fluoroscopy equipment: FPD-mounted X-ray
fluoroscopy equipment: SONIAL VISION G4 (Shimadzu Corporation)- Phantom: Water phantom (ph-40) 40 × 40 cm(Kyoto Science)- Ⅹ Line chart: R-1 fluoroscopy chart- Analysis tool: Image-J 1.48 (2014)
1-3 Acquisition of captured images
1-3-1 Preparing materials

The simulated materials for slot scan imaging
were made in a tough water phantom (hereafter called a phantom) with thickness as follows: 10, 15, and 20 cm. An X-line chart for thecontrol of fluoroscopy imaging accuracy (hereafter called an X-line chart) was placed on thephantom. Figure 7 shows the layout.
1-3-2 Imaging conditions

There are 11 imaging conditions in combining the tube voltage with the imaging time andwas described as follows: 70 kV–25.0 msec, 75
kV–20.0 msec, 80 kV–16.0 msec, 85 kV–12.0
msec, 90 kV–8.0 msec, 95 kV–5.6 msec, 100
kV–3.6 msec, 105 kV–2.5 msec, 110 kV–1.8
msec, 115 kV–1.4 msec, and 120 kV–1.0 msec.
Regarding the setting, in order to obtain thesame image effect, the digital value (SS value)
was set under the condition of 400 (within ±15%), and the tube current was kept constant

40 ◆ Journal of JART English edition 2021

Fig.7 Arrangement of image acquisition(phantom and x-ray chart)(a) Phantom on the top of which the X-ray chart ispositioned(b) Illustrated arrangement of phantom and X-ray chart

Table 2 Imaging condition
Each combination of tube voltage and exposure time keeps almost same SS value
Tube voltage (kV)Exposure Time (msec)

70
75
80
85
90
95
100
105
110
115
120

25.0
20.0
16.0
12.0
8.0
5.6
3.6
2.5
1.8
1.4
1.0

a
b

original articles
New Quantitative Calculation method of Contrast Values in Slot Scan Imagetion of the X-ray tube (Fig.9 a, b).
1-3-6 Rate of change measurement

The measured profile curve was converted
into a numerical value, and differential processing was then performed to obtain the rateof change (Fig.9c).
1-3-7 Calculation of the Cp value

Fig.8 Scanning direction of slot scan technique

From the change in rate measurement results
obtained in 1-3-6, the maximum Cp value wasobtained for each phantom thickness.

The arrow shows the scanning direction

2. Results
the lower end as the end point. Figure 8 shows
the imaging situation. The X-ray chart is arranged so that the slit is perpendicular to theadvancing direction of the tube.
1-3-4 Measurement data

Since the image obtained from the slot scan
imaging is subjected to frequency processing,such as dynamic range compression after
stitching processing, the projected image (rawimage) before processing was used for measurement.
1-3-5 Image analysis

2-1 Change to Cp value of the tube voltage
Figure 10 shows the Cp value for each imag-

ing condition at each phantom thickness. It became a mountain-shaped graph for each phantom thickness. In addition, the Cp value wasdifferent among the phantoms. Specifically, an
increase in phantom thickness causes the Cp
value to shift to the high voltage side, and theCp value becomes 440.499 for a phantom
thickness of 10 cm, 236.242 for 15 cm, and96.830 for 20 cm. As for the value, an increasein phantom thickness results in a lower optimum Cp value. Table 3 shows the Cp values
for each imaging condition.

Figure 9 shows the measurement processing

method. Using the widest slit at the top of the
X-ray chart, profile curves were measured in
the scanning direction for adjacent parts withdifferent densities (blurred parts) in the direc-

2-2 Blur width in X-ray chart
Fig.11 shows the slot scan image of the X-ray

chart. In the region of 0.5 LP/mm, the blurwidth is large and non-identifying at the tube

Fig.9 Measurement of the contrast peak value (Cp) from the slot scan image

a

b

c

(a) X-ray chart (Black frame: Profile measurement area)(b) Profile curve (c) Rate of change (differential data of profile curve)

Arts and Sciences ◆ 41

Table 3 Contrast peak value (Cp) measurement
resultTube Exposure
voltagetime[kV][msec]

70
75
80
85
90
95
100
105
110
115
120

Fig.10 Variation of Cp value with exposure
condition

25.0
20.0
16.0
12.0
8.0
5.6
3.6
2.5
1.8
1.4
1.0

Cp Value
10 cm

15 cm

20 cm

145.716
197.639261.348335.359390.654440.499426.030
395.724308.392
308.392
257.41771.84491.250125.428164.965
192.634230.378236.242212.733
179.988172.301
148.79826.38026.62737.12152.49070.16778.00292.06096.83078.28974.02562.5350.5 LP/mm ➡

70 kV︲25 msec

80 kV︲16 msec

90 kV︲ 8 msec

100 kV︲3.6 msec 110 kV︲1.8 msec 120 kV︲1.0 msec

Fig.11 X-ray chart image (10 cm) according to the difference of imaging conditions

voltage of approximately 70–80 kV. On theother hand, at a tube voltage of 110–120 kV,
since the exposure time was shortened, theblur width reduced, and the identification capability improved.
2-3 Imaging conditions and Cp value

The optimal combinations of imaging conditions were, 95 kV–5.6 msec at a phantom thickness of 10 cm, 100 kV–3.6 msec at 15 cm, and105 kV–2.5 msec at 20 cm. The more the phantom thickness increased, the more it shifted tothe high tube voltage and the short time exposure side. Also, in each phantom, the Cp value
tended to be higher in the high tube voltageshort time imaging range of approximately
95–105 kV than in the low tube voltage-longtime imaging range of approximately 70–80 kV(Table 4).

3. Discussion
Table 4 Imaging condition with optimum Cp value
Phantom thickness[cm]

Exposure condition[kV‑msec]

10

95 kV‑5.6 msec

15

100 kV‑3.6 msec

20

105 kV‑2.5 msec

42 ◆ Journal of JART English edition 2021

3-1 On existence of Cp value

Regarding the optimal measurement of Cp
value, it became a graph with a mountainshaped peak in each phantom. For still images,
the lower the voltage showed a higher contrast, and the lower contrast at a higher voltage

original articles
New Quantitative Calculation method of Contrast Values in Slot Scan Image

3-3 Features of Cp value (Part 2 the viewpoint

tend to decrease at a constant rate. On theother hand, the slot scan image had a low Cp
value in the low tube voltage range, and better
results were shown in the high tube voltage
range. It is presumed that the quality of image
will improve by shortening the imaging time,
because the improvement of the identification
capability in the short time imaging-high tube
voltage range was also recognized as shown in
the X-ray chart in Fig.10. However, despite theshortest imaging time, the Cp value did notshow the best value because it is affected by
the radiation quality caused by the tube voltage (Fig.10). From the above, it seems that theCp value is related to both the imaging time
and tube voltage.

In general X-ray photography, when thephantom thickness is 10–20 cm, the standard
tube voltage used is approximately 70–90 kV,
but the 95–105 kV obtained in this study tended to be high. Therefore, slot scan photography is performed continuously using a narrowcollimator with a width of 4 cm. For this reason, the generation of scattered X-rays is minimized even in a high voltage range. It is considered that the effect of scattered X-rays on
the contrast is insignificant even in a relatively
high tube voltage range.
This is considered to be a structural featureof the slot scan technology.

3-2 Characteristics of Cp value (Part 1)

3-4 Validity of evaluation by Cp value

The Cp value tends to be high in the hightube voltage range, but the Cp value changes
depending on the phantom thickness. As thephantom thickness changed from 10 to 20 cm,
the optimum exposure conditions changed
from 95 kV–5.6 msec to 105 kV–2.5 msec. Thisis the same as the general X-ray imaging area
and is similar to the fact that a low voltage is an
optimum condition for thin subjects and thatthe thicker the subject, the higher the voltage
range. Regarding the exposure time, the factthat the exposure time was different depending on the phantom thicknesses suggests thatthe optimum Cp value cannot be determined
only by the exposure time. Inferring from theapparent contrast, in the case of a thin phantom, the Cp value changes predominantly inthe tube voltage, and it is considered that the
exposure time predominates as the thickness
increases. This is considered to be a characteristic of the change in the apparent contrast in aslot scan image. Furthermore, in clinical practice, the thickness of the subject varies fromperson to person, so it is possible to estimate
the setting of the optimum conditions according to thickness.

In this study, the Cp value was assumed tohave the best visual contrast among the combination of exposure time and the tube voltage.
In order to maintain the same image effect, theimaging conditions were set by estimating theSS values, and the results were measured for
11-way different images, changing the longtime exposure to low voltage to short time exposure to high voltage. In other words, it isconsidered that the image obtained from the
maximum Cp value is the image that maintains
the best apparent contrast, while the width ofblurring is caused by the exposure time, and
the X-ray imaging quality is caused by the tube
voltage change. In the slot scan image, different Cp values were shown for changes in exposure time, tube voltage, and phantom thickness, indicating that the amount of blur changes at a constant rate with respect to thesechanging factors. The obtained Cp value isconsidered to be a quantitatively changed value. From the above, it is considered that thequantitative calculation of the contrast in theslot scan image was suggested.

of slot scan technology)

3-5 Possibility of Cp value

Since the automatic exposure control cannot
Arts and Sciences ◆ 43

be set in the slot scan technology, it is difficult
to set the optimum exposure conditions. As aresult, it is known that there are a few facilities
that take pictures due to the excessive dose. In
the future, based on this result, we consider
the possibility of quantitatively calculating thesuperiority or inferiority of image quality, including the possibility of CNR measurement.
The slot scan technology produces an image
that contains a negative factor called a blur.
However, the whole spine imaging is performed in all age groups, and includes highly
radiosensitive areas, such as the mammary
spine and gonads. Nowadays, a single examination includes the standing (anterior-posterior
and lateral) and the recumbent imaging, andregular (follow-up) imaging with overall doses
from other modalities will require radiation in
the future. It has the potential to increase therisk of disability and increase the risk of cancer. Under such circumstances, this study
makes it possible to approach dose evaluationand provide a foothold for dose reduction 7, 8).
We believe that the quantitative analysis ofblurred images obtained in this study can beapplied to the analysis of blurring and moving
images, such as moving images and pulse fluo-

References
1） Koichi Shibata: Development of applications for videocompatible FPD systems. Japanese Journal of Radiological Technology, 65, 821-828, 2009.
2） Kimiya Noto, et al.: Optimization of X-ray conditions
for full spine X-ray examinations in slot-scan digitalradiography. Nihon Hoshasen Gijutsu Gakkai Zasshi,
67(11), 1438-1442, 2011.
3） Nobuto Handa: Experience using the slot scan function in X-ray TV system. MEDICAL NOW, 65, 19-22,
2009.
4） Kazuya Goto: The clinical experience of slot imaging
in the SONIALVISION safire II and its usefulness in thelower limb region. MEDICAL NOW, 65, 23-26, 2009.

44 ◆ Journal of JART English edition 2021

roscopy. We proposed a method to analyze
image blurring using slot scan technology andproposed a quantitative calculation method inimage quality contrast.

4. Limit
In this study, we proposed a method toquantitatively analyze the blurring factors inslot scan images. However, we have not examined the evaluation of clinical images, and theindication for test images remains unknown.

5. Conclusions
Images obtained from the slot scan technology are blurred. By analyzing the blurring, weestablished a new method to calculate the apparent contrast (Cp value) quantitatively.

6. Acknowledgments
I would like to thank Professor Koichi Shibata of the University of Suzuka Medical Science and the Department of Medical Technology of the Public Fussa Hospital for their cooperation in this study.

5） Takahide Okamoto: Experience using slot radiography
in SONIALVISION safire17-application to bone extension in the lower limb. MEDICAL NOW, 68, 6-10, 2010.
6） Shigeji Ichikawa: Experience with slot scan radiography–attempts to perform a lower-limb angiography-.
MEDICAL NOW, 66, 31-35, 2009.
7） Law M, et al.: Cumulative radiation exposure and Associated cancer risk estimates for scoliosis patients:
Impact of repetitive full spine radiography. Eur J Radiol, Mar, 85(3), 625-8, 2016.
8） Grieser T, et al.: Radiation dose reduction in scoliosis
patients: low-dose full-spine radiography with digitalflat panel detector and image stitching system. Rofo,
Jul, 183(7), 645-9, 2011.

Arts and Sciencesmaterial

Received May 10, 2019 ; accepted November 29, 2019

Invention of Surface Contamination Screening
Method in a Nuclear Disaster –Segment Method–
TAJIMA Naoto1），2）, OISHI Kotaro1），3）, HAMADA Junji 1），3）, AIGASE Ayuko1），3）,
INOUE Haruyuki 1），4）, NUMATA Kyoichi 1），3）, HASHIMOTO Terumi 1），5）, WATANABE Hiroshi 6）1）Nuclear Accident Screening (Support) Team2）Department of Radiological Technology, Yokosuka Municipal Hospital3）Department of Radiology Center, Yokosuka Kyosai Hospital4）Health Promotion Division, Yokosuka City Health Center5）Department of Radiology, Saiseikai Yokohamashi Tobu Hospital6）School of Radiological Sciences, Faculty of Health Science, Gunma Paz University

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 813: 22-26, 2020.
Key words: nuclear disaster, screening, survey meter, radiation external exposure, surveyor【Abstract】

The conventional manual for surface contamination screening method following a nuclear disaster dictates that therequired screening processes should last for 3 minutes. However, the manual did not describe the specific procedurethat should be followed. As a result, surveyors performed many unnecessary operations, which, in turn, facilitatedincreased fatigue and exhaustion. Therefore, the Yokosuka and Miura Radiological Technologistsʼ Association special
dispatch team for nuclear disasters devised the segment method with the purpose to screen populations at a rateof 3 minutes per person. The segment method divides the whole body into six regions and screens in one-stroke
sketch manner. As a result, we were able to clarify the precise time allocation and to stabilize the operation speed.
Furthermore the segment method is easy to operate, prevents potential errors or omissions in the screening areas, andalso reduces the physical burden on the surveyor.

Introduction
The general anxiety regarding a nuclear disaster increased in Japan after the Tokai Village
JCO critical accident on September 30, 1999 1).
Yokosuka City has been a port of call for nuclear vessels of the US Navy since 1966 2), anda nuclear fuel processing plant was built in
1967. Therefore, nuclear disaster crisis awareness is acute, and safety measures against possible nuclear disasters are necessary in Yokosuka, especially since the Yokosuka Port was
designated as the home port of a nuclear-powered aircraft carrier in 2008 3).
The Yokosuka and Miura Radiological Technologistsʼ Association, a regional organizationof the Kanagawa Association of RadiologicalTechnologists, organized the Nuclear Accident
Screening Support (NAS) Team in 2004. This
team aims to conduct radioactive contamination screening, which is a necessary protective

measure in the event of a nuclear disaster. The
team was organized with the request of the
Yokosuka Medical Association, and its core
members are radiological technologists certified by the Japan Association of RadiologicalTechnologists (JART). The conventional manual for screening of surface contamination ofpeople affected by a nuclear disaster 4) statesthat “screening is completed within 3 minutes.”
However, there are no details provided regarding the screening process, thus, the speed andmoves tend to be ad hoc. Consequently, thisambiguity is bound to induce prominent issues
when unnecessary moves are performed, which
can in turn render the process as significantly
more time-consuming than what was anticipated but also result in surveyorʼs exhaustion.
Another manual 5) describes the speed withwhich the probe should move and a rough order of the body parts to be measured. However, the precise time that is required to screen
Arts and Sciences ◆ 45

the total body is not provided. Therefore, inthis article we report a screening method that
we developed where “screening of one personin 3 minutes” can be certainly implemented.

1. Methods (design guidelines)
The following design guidelines were used
to standardize a consistent screening method
for a single person over 3 minutes. The segment method was designed based on the following guidelines:① Clarifying the time allocation② Stabilizing operation speed③ Simple operation④ Preventing omissions in screening regions⑤ Alleviating physical burden on the surveyor
1-1. Clarifying time allocation and stabilizing
operation speed

To clarify the time allocation and stabilize
the operation speed, the total body surface
was split into six segments for screening. Eachsegment and its screening time are shown in
Fig.1 6).
The first segment involves the front of thehead, face, neck, and shoulder, whereas thesecond segment includes the front of the upper body, including the upper limbs. Furthermore, the third and fourth segments include

the front of the lower body and the rear of thehead and upper body, respectively. Finally, thefifth and sixth segments involve the rear of thelower body, including the sole of the shoes,
and regions that need additional care, such as
the palm and back of the hands, respectively.
The regulated screening time for each segment
is 20, 40, 30, 30, 30, and 30 seconds, respectively, which collectively results in a total screening time of 3 minutes.
1-2. Simple operation and preventing omissionsin screening regions
Fig.2 shows the screening method devel-

oped. To ensure that this operation will be
simple and to prevent omissions in screening
regions, a one-stroke sketch procedure is adopted where scanning is performed sideways
toward the lower body. Subjects place their
upper limbs toward their bodies and bend theback of their hands slightly forward. The surveyor screens sideways in one stroke from faceto right shoulder, right side of the head, top of
the head, left side of the head, and left shoulder. Consequently, the surveyor screens thefront of the upper body, including the upper
limbs and palm of the hands, and then thefront of the lower body while squatting. The
sides of the upper limbs are screened together
with the front during this procedure. Screening

Fig.1 Screening time for each segment

46 ◆ Journal of JART English edition 2021

material
Invention of Surface Contamination Screening Method in a Nuclear Disaster ‒Segment Method‒

2. Results
2-1. Clarifying the time allocation and stabilizing the operation speed

Fig.2 Screening method for the front and bothsides of the bodyis continuously performed from the upper half
to the lower body and along both sides toward
the toes.
Following screening of the front of the body,subjects are asked to turn around. The surveyor screens their lower body, including the soleof the shoes, and their upper body, and then
their head while standing up. Finally, subjects
are asked to raise both their hands, and thescreening process then focuses on the innersides of the upper limbs, both armpits, bothsides of the belly, and then on the regions thatneed additional care, such as the palm and theback of the hands, as necessary (Fig.3).

Conventional screening methods did notprovide any predetermined details or protocols
regarding the screening procedure, and the
speed and moves tend to be ad hoc. Therefore,
the precise definition and designation of thetime required for screening each segment clarified the time allocation and stabilized the
speed with which the survey meter should
move. An easy-to-understand video describing
the procedure is provided at the Yokosuka andMiura Radiological Technologistsʼ Association
website 6).
2-2. Simple operation and preventing omissions in screening regions

A one-stroke survey meter operation results
in a simple and efficient screening process
where all necessary areas of the human bodyto be scanned are covered, while at the sametime eliminating any unnecessary operations.
Three members of the NAS team participatedin the first dispatch team of the JART responding to the Great East Japan Earthquake and thenuclear disaster at the Fukushima Daiichi Power Plant of Tokyo Electric Power on March 11,2011 (Fukushima nuclear accident). However,Fig.3 Screening method for the rear and other parts of the bodyArts and Sciences ◆ 47

the on-site screening level in this disaster relief
mission was significantly altered. The affectedarea was substantially larger, and the number
of affected individuals was so immense thatthe individual scanning process should havebeen completed in approximately one and ahalf minutes, as opposed to the conventional 3
minutes. Adjustment to these requirements dictated the use of the one-stroke segment method that doubled the screening speed in an efficient manner. The 3-minute segment method
has a screening speed of approximately 3 ‒6cm/s, whereas the one and a half-minute method can screen twice as fast, i.e., 6 ‒12 cm/s
(Fig.4).
2-3. Alleviating physical burden on the surveyor

The conventional screening manual did notelaborate on the exact body region that needs
to be screened nor did it provide any instructions regarding the order of screening thatneeds to be followed. Therefore, the surveyor
had to squat several times when moving thesurvey meter up and down. Prior to the Fukushima nuclear accident, the segment method
required screening in a one-stroke direction,
thus the number of squats was reduced to only
two. However, two squats per screening induced a prominent burden on the surveyors
because the number of affected individuals in

the evacuation zone of the Fukushima nuclear
accident was significant high. As a result, basedon our experiences from the Fukushima nuclear accident, the initial screening of the fifth
segment and then of the fourth segment while
standing up manages to reduce the number ofsquats to one, thereby further reducing theburden on the surveyor. The one-squat method was then defined as the segment method.

3. Discussion
The segment method has demonstrated its
applicability and flexibility in nuclear disastersituations. However, contamination from the
Fukushima nuclear accident can be described
as an exceptional situation, thus the segment
method should, in principle, be performed
over 3 minutes, as outlined in the manual. The
screening level required for a whole-body decontamination process was elevated for theevacuation zone of the Fukushima nuclear accident, and contamination levels requiring simplified decontamination 7), namely partial wipeoff decontamination, were easily detectable.
The survey meter reading started to increase
even before initiating any measurements to determine the decontamination level, and all individuals successfully participated in the “oneand a half-minute method” scanning process in

Fig.4 Segment method ‒ One and a half-minute version

48 ◆ Journal of JART English edition 2021

material
Invention of Surface Contamination Screening Method in a Nuclear Disaster –Segment Method–

Table 1 Screening results from the first dispatch team

the Fukushima nuclear accident. The first dispatch team of the JART managed to screen
5,021 residents affected by the Fukushima nuclear accident over a period of 5 days, from the16th to 20th of March, 2011 (Table 1) 8).
Among the 12 surveyors, five individuals,i.e., three NAS team members and two members of the Kanagawa Prefecture Radiation
Safety Manager Committee that worked together with the NAS team had already practiced in
the segment method. More specifically, eachsurveyor had screened approximately 80 people based on a simple average. Continuous
squatting during this process can be extremely
straining, thus the standardization of the screening method minimized the number of squats
performed and reduced the inflicted burden
on the surveyors. In addition to those dispatched by the JART, surveyors in the NASteam conducting screening for the Fukushima
nuclear accident included two individuals dispatched from hospitals and two individuals
that were requested by the Ministry of Health,
Labor and Welfare. A nuclear power plant accident, as in this case, where the extent of theaffects population requiring screening is verylarge, translates into a situation where one surveyor is responsible to screen a high numberof people over several consecutive days. Therefore, the significance of the segment method
was that it demonstrated its applicability andusefulness in terms of reducing the burden on
surveyors.

4. Conclusions
We developed a segment method that provides solid instructions for screening individuals in case of a nuclear disaster, such as a nuclear power plant accident, in the future. The
whole body is divided into six regions (segments) and it is screened in a one-stroke
sketch. The advantages of this procedure arethat it clarifies time allocation, stabilizes theoperation speed, it is easy to operate, prevents
potential errors or omissions in screening regions, and alleviates the physical burden on
the surveyor. This segment method demonstrated its ability but also its flexibility in termsof reducing the screening times in the Fukushima nuclear accident, where the scale andratio of screening had significantly changed.
Arts and Sciences ◆ 49

Moreover, the segment method contributes toa distinct burden reduction of the surveyors
conducting screening processes that need toinclude greater populations. Therefore, thesegment method should be adopted as a standard screening procedure in case of a nuclear
disaster.

Acknowledgements
We deeply thank the members of the Yokosuka and Miura Radiological Technologistsʼ Association and the Kanagawa Prefecture Radia-

References
1） Tokushi Shibata: Tokai-mura Nuclear accident. Journalof the Physical Society of Japan, 55, 579-586, 2000.
2） Yokosuka City Base Countermeasures Division: Yokosuka City and Bases. 6, 136-154, 2000.
）
3 National Liaison Committee that does not allow thenuclear-powered aircraft carrier Yokosuka homeport:
The danger of the nuclear-powered aircraft carrier Yokosuka homeport in Tokyo Bay. Shinsensha, 1, 8-9,
2008.
4） Hisayoshi Kondo: Nuclear disaster and Radiation
Emergency Medical-Evacuation shelter relief activi ties-2003 Yokosuka City Medical Association disaster
relief training materials. 2003.

50 ◆ Journal of JART English edition 2021

tion Safety Manager Committee, who provided
continuous guidance to the authors, upondrafting this paper.
The abstract of this paper was presented in
the 27th Japan Conference of RadiologicalTechnologists (2011, held at Aomori) and received an award of excellence. As a consequence, the Japan Association of RadiologicalTechnologists recommended us to write thispaper. The contents of this paper were alsopresented in the 19th International Society ofRadiographers and Radiological Technologists
World Congress (2016, held at Seoul).

5） Nuclear Safety Research Association: Radiation Emergency Medical Basic Course I Text. 3, 14-15, 2008.
6） Yokosuka Miura Association of Radiological Technologists: Radiation Emergency Medical NAS team. Segment method manual. 2015.
http://ymart.jp/nas (Reference 2019.8.25)
7） Katsunori Yamada, et al.: Survey of Radiation Protection Creiteria Following the Accident at the Fukushima
Dai-ichi Nuclear Power Plant. JAEA-Review 2013-033,
6, 2013.
8） Japan Association of Radiological Technologists: Response to the Great East Japan Earthquake - Initiatives
for the Fukushima Dai-ichi Nuclear Power Plant Accident - Interim Report. 8, 2011.

Arts and Sciencesmaterial

Received September 13, 2019 ; accepted December 20, 2019

Effectiveness of the Assistance in Image Interpretation Using the Image Reproduction Function inRadiography
YAMASHITA Tatsuya
Meiseikai Shiokawa Clinic

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 816: 15-18, 2020.
Key words: assistance in image interpretation, double-check, image reproduction function【Summary】

In recent years, through questionnaire surveys, the importance of radiographic assistance in interpretation for
medical examinations and emergency care has become clear. However, there have been no reports on radiographic
assistance in interpretation in general imaging in daily practice, where it is considered to be the most frequently
used. Therefore, we constructed a radiographic assistance in interpretation for general imaging, using the image
reproduction function. As a result, we could prevent the oversight of abnormal findings in three cases out of a totalof 57 cases, in which image replication was performed within 1 year, from September 1, 2017 to August 31, 2018.
These facts suggest that the radiographic assistance in interpretation provided by medical radiologists, who use theimage reproduction function, also plays a role in double-checking general imaging work in daily practice, revealing its
usefulness.

Introduction
In recent years, although the sophisticationand specialization of medical care have increased, a critical shortage of physicians has
become a challenge.
Therefore, in April 2010, the Director of the
Ministry of Health Labor and Welfare of the
Health Policy Bureau notified regarding thepromotion of medical team 1).
In accordance with this, “it should be encouraged to utilize radiologists clarifying thatthey can assist in the reading of diagnostic images and provide explanations and consultations about radiological examinations” the law
was amended to make recommendations forthe active use of the radiologists and expansion of their duties.
Accordingly, the studies on the assistance inimage interpretation by radiologists, questionnaires on such assistance, and their usefulness
had been conducted 2-6).
Although we are a clinic with beds that do

not provide emergency care and medical examinations, we have experienced requests forimaging advice from the requesting physiciansin the course of our daily general radiology
work, and we became aware of the need forassistance in image interpretation of generalimaging.
However, the reports have been on reports ofgastrointestinal contrast imaging, ultrasonography, mammography, etc., and holiday and nocturnal computed tomography (CT) and magnetic resonance imaging (MRI) in the field of
emergency medicine 2-6), the assistance in image interpretation by radiologists in the field ofgeneral radiography in daily practice has notbeen reported.
In this study, we reported the usefulness ofimage replication as a method of assistance inimage interpretation for general radiography.

Equipment
The image processing equipment Console
Arts and Sciences ◆ 51

(a)

(b)

Fig.1 The explanation for the image reproduction function(a) Not using the reproduction function(b) Using the reproduction function

Advance (DR-ID300CL [Version 10]. Fujifilm)
was used.

What is image replication function?
Image replication function creates an imageof unique identifier (UID) that is different fromthe original image. The replicated and original
images are processed by a radiologist andstored as separate images in picture archiving
and communication system (PACS).
In traditional image processing, the original
image is overwritten by the processed image

52 ◆ Journal of JART English edition 2021

because the UID are the same (Fig.1-a).
However, in the image replication function,
the replicated image is given a new UID and
can be displayed as a different image than theoriginal (Fig.1-b).

Methods
Arrangements for the use of image replication
function

To avoid an unnecessary increase in thenumber of images due to replication and thetime required for physicians to check the im-material
Eﬀectiveness of the Assistance in Image Interpretation Using the Image Reproduction Function in Radiographyages, we discussed with our full-time physicians (N=2) and determined for image replication as follows.
1. A lesion contrary to the patientʼs complaint(non-examining side).
2. Neoplastic lesions (soft tissue masses, bonetumors, etc.), and foreign bodies.
3. An oversight at another hospital (Radiographs at other hospitals were diagnosed as
normal; however, our radiographs demonstrated a lesion).
4. The presence of a lesion at a distance fromthe painful area.
The images were replicated for these four
items, and the images were processed according to the purpose of each item (for example,
magnification of the lesion site by partial cropping, the addition of markers to the lesion, andadjustment of the density of soft tissue conditions).

Results
1. Classification and calculation of cases with image replication

A total of 57 cases were replicated during theperiod from September 1, 2017, to August 31,
2018, and tumor lesions and foreign bodies
were the most common items (46 cases). The
least common item was an oversight at anotherhospital (2 cases) (Fig.2).
2. The predicted number of missed imaging diagnoses in the absence of assistance in image
interpretation by replication image

The number of missed cases avoided by theassistance in image interpretation with the image replication feature was 3 out of 57 cases
per year.
3. Evaluation of the assistance in image interpretation with image replication

1. Classification and calculation of the cases withimage replication

The number of cases of image replication
during a year from September 1, 2017, to August 31, 2018, when this system was first implemented, was classified into the above categories (1‒ 4) and calculated.
2. The predicted number of missed imaging diagnoses in the absence of assistance in image
interpretation by replication image

With the help of our full-time physicians(N=2), we calculated the number of cases possibly missed in the absence of image replication.

Our full-time physicians (N=2) had the following opinion on the use of image replication
to assist in image interpretation.
1. Lesion recognition and explanation of thelesion to the patient became easier.
2. The time and effort required for image manipulation (density adjustment and magnification) on PACS were reduced.
3. Reduced the risk of missed lesions.
The following evaluations and opinions were
given.
Typical clinical examples of image replica-

3. Evaluation of the assistance in image interpretation with image replication

Our full-time physicians (N=2) were asked toevaluate and give their opinions on the use of
the image replication function to the assistancein image interpretation for 1 year.
Fig.2 Number of cases of image reproduction
Arts and Sciences ◆ 53

Fig.3 A case of a contralateral lesion
Chief complaint: right hip joint pain

Fig.4 Lesions in areas away from the pain site
Chief complaint: inside left knee paintion are shown in Fig.3 and 4.
Fig.3 demonstrates hyperpenetration in theleft femur (white circles in the figure) opposite
to the site of the chief complaint on the right
hip pain, which is replicated, cut out, and enlarged.
In Fig.4, a patient complained of medial left
knee pain; however, since a neoplastic lesion(white circle in the figure) was observed on
the fibula, the image was replicated, cut out,
and enlarged.

Discussion
In the past, these cases of image replication
required the physician to change the windowlevel and window width and to enlarge the image for a patient explanation, which made the54 ◆ Journal of JART English edition 2021

physicianʼs work more complicated. However,if the radiologist uses the image replication
function to change the window level and window width to suit the patientʼs needs, the physician can eliminate the procedure and reducethe burden of examination work.
Also, the most important aspect of the assistance in image interpretation was the oversightof abnormal findings. The failure to recognize
abnormal findings accounts for approximately
80% of diagnostic imaging errors 7).
In our hospital, to prevent errors in imaging
diagnosis, if an abnormal finding is foundwhen the radiologist takes pictures or confirms
images, the radiologist goes to the examination
room or confirms with the physician over the
telephone.
However, in a small facility, a single physician needs to examine and treat patients byhimself, which often results in a lack of communication and work stagnation.
However, since the start of the image replication function, the physician can check the images added by image replication and contact
the radiologist in charge only when necessary
to confirm the abnormal findings.
From these observations, it is considered thatthe pickup of abnormal findings by the image
replication function by radiologists can efficiently double-check to prevent oversight, and
it is an important factor in reducing diagnostic
imaging errors 2, 3).
Additionally, this kind of assistance in general radiography may promote the importanceof recruiting radiologists in small facilities that
do not have large equipment (e.g., CT, MRI),
that do not provide nighttime or emergency
care.

Conclusion
The assistance image interpretation in general radiography using the image replication
function was useful for preventing oversightand improving work efficiency.

material
Effectiveness of the Assistance in Image Interpretation Using the Image Reproduction Function in Radiography

References
1） The Director of the Ministry of Health Labor and Welfare of the Health Policy Bureau notified regarding thepromotion of medical team, No. 0430 No. 1, date April
30, 2010.
2） Kato, Kyoichi: 2. Assistance in reading in the field of
diagnostic imaging: Current status and future plans.
INNERVISION, 28(6), 41-44, 2013.
3） Kato, K.: 1. General comments on the radiologistʼs
auxiliary reading duties. INNERVISION, 28(7), 60-62,
2013.
4） Takashima, Yuko: 3. Reading assistance and the roleof radiologists in the field of medical examinations:

Reading assistance that can be implemented today to
improve the accuracy of examinations. INNERVISION,
28(7), 66-68, 2013.
5） Sakashita K.: 2. The role of radiographers in emergency medicine: From the perspective of the Japan
Accreditation Board for Emergency Radiographers.
INNERVISION, 28(7), 63-65, 2013.
6） Ichikawa H, et al.: The effect of CT interpretation assistance by radiological technologists in off hours
emergency medical care. JJSEM, 17(4), 535-542,
2014.
7） Berlin L: Defending the “missed” radiographic diagnosis. AJR, 176(2), 317-322, 2001.

Arts and Sciences ◆ 55

Arts and Sciences
original articles

Received July 18, 2019; accepted February 27, 2020

Long Term Characteristics Change of n-type
Semiconductor Rectal Dosimeter
YASUI Kenʼichiro1）, SHIINOKI Takehiro2）, TAKAHASHI Wataru3）, OKIMOTO Yoshinori1）,
SUMIKAWA Tetsuo1）, NAKAMURA Masatoshi1）1）Department of Radiological Technology, Yamaguchi Prefectural Grand Medical Center2）Department of Radiation Oncology, Yamaguchi University Graduate School of Medicine3）Osaka Branch, TOYO MEDIC Co., Ltd

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 816: 19-26, 2020.
Key words: semiconductor, n-type silicon, irradiation history, brachytherapy, rectal dosimeter【Abstract】

Semiconductor rectal dosimeters are useful for patient monitoring during brachytherapy. Many authors havereported a variety of characteristics such as a decrease in sensitivity with irradiation history. Additional characteristics
such as the dose rate dependence, dose per pulse dependence, sensitivity variation with temperature, dose linearity,and directional dependence have also been reported. However, the trend of these characteristics with irradiation
history has not been well investigated. Approximately three years have passed since we introduced a new n-typesilicon semiconductor rectal dosimeter in our hospital. Therefore, the purpose of this study is to investigate sensitivity,
dark current noise, dose rate dependence, sensitivity variation with temperature of the semiconductor rectal dosimeter,and changes in the characteristics with brachytherapy irradiation history.
An n-type silicon semiconductor rectal dosimeter system (Intracavitary Detector IDF-5 channels) was used in thisstudy. Measurements were performed with a High Dose Rate (HDR) Iridium-192 brachytherapy source. The radiation
source was placed between the semiconductor detector and the Farmer-type ion chamber in a water phantom system.
The ratio of the reading by the semiconductor dosimeter to the absorbed dose by the Farmer chamber as a reference
was defined as the sensitivity index value of the semiconductor. Several characteristics were investigated by evaluating
their sensitivity index.
For all the channels, the relative sensitivity decreased to approximately 0.92 – 0.95, with an irradiation history of
approximately 200 Gy. Dark current noise values tended to converge towards zero according to the irradiation history.
Dose rate dependence for HDR source strength was not observed, and it was not related to the irradiation history.
Although there was sensitivity variation with temperature, it was small after irradiation history.
The identified characteristics may affect the actual measurement results. However, when sensitivity calibration is
performed under appropriate conditions, they can be effectively used for rectal dose monitoring during brachytherapy.

1. Introduction
Real-time monitoring of rectal dose is essential for intracavitary brachytherapy in thetreatment of gynecological malignancies 1).
Monitoring is used to ensure that the treatment
is accurately performed with the intended dose
distribution. In addition, if administration differs from the intended dose and an unexpected dose increase to risk organs is identified, it
is possible to respond promptly 2), 3).
In our hospital, an n-type silicon semiconductor rectal dosimeter is used for real-timemonitoring. Semiconductor dosimeters provide real-time readout, high sensitivity, small

56 ◆ Journal of JART English edition 2021

dimensions, simple instrumentation and theabsence of bias voltages. As such, they are
well-suited for in-vivo measurements during
treatment 4).
However, as a physical phenomenon, whenradiation is incident on the detector, excessive
electron-hole pairs are created throughout thesemiconductor. Minority carriers (holes in ntype) are swept across the junction by built-in
potential and are measured by an electrometer.
The minority lifetime of the carriers affects
the sensitivity of semiconductors with irradiation history integrated dose, although this isdependent on the electrical properties of thesemiconductor crystal and adversely affects theoriginal articles
Long Term Characteristics Change of n-type Semiconductor Rectal Dosimeter

minority carrier lifetime 5)-7). These phenomena
in semiconductor dosimeters cause various
characteristics.
Previous studies on semiconductors 4), 8)-13)
have revealed that they exhibit a variety ofcharacteristics such as a decrease in sensitivity,
dose rate dependence, dose per pulse dependence, sensitivity variation with temperature,
dose linearity and directional dependence.
However, there is limited research on the dependence of the characteristics on the irradiation history with the exception of sensitivity
decrease 14).
Therefore, in this study, we investigatedcharacteristics that could be observed overthe long term, such as the sensitivity change
and the change in the dark current noise with
irradiation history. In addition, the dose ratedependence and its change, and sensitivity
variation with temperature and its change were
investigated for a semiconductor rectal dosimeter.

control system. A computerized control system is a combination of an adapter, personal
computer, and software. The reading value
was output in units of 16 bits ADU. ADU is ananalog-to-digital conversion unit that facilitates
the monitoring of ionization output using apersonal computer.
Fig.1 (a) shows the schematic of the experimental setup in a modification of the so-calledsandwich method 15). A water phantom system(IDF-Calibration Phantom, IBA) consisting ofwater cubes of 20 × 20 × 20 cm3 in size wasused. The Ir-192 source was sandwiched using

2. Materials and Methods
2-1 Experiment setup

The measurements were performed with aHigh Dose Rate (HDR) Iridium-192 (denotedhereafter as Ir-192) brachytherapy source(microSelectron-v2 HDR Ir-192; Nucletron B.V.,
Veenendaal, The Netherlands). The unit was
equipped with an Ir-192 source with an average apparent activity of 370 GBq. The source
was replaced approximately every six months.
A 5-channel n-type silicon semiconductor
dosimeter system (denoted hereafter as semiconductor dosimeter) is the subject of thisstudy. The semiconductor dosimeter was an
Intracavitary Detector IDF-5 (IBA Dosimetry,
Schwarzenbruck, Germany) and was connected to a DPD12pc electrometer (IBA) to measure the dose. It consists of a flexible probe
structure and rectal interstitial type with fivesemiconductors channels placed 20 mm apart.
The probes were connected to a computerized

(a)
(a)

(b)
(b)

(a)

(b)

Fig.1 A schematic diagram of the experimental
setup, (a) coronal plane and (b) axial plane.
The two detectors were positioned in a water phantom with sleeves at a distance of 8
cm on either side of the Ir-192 source. The
water phantom temperature was maintainedusing heated water.
Arts and Sciences ◆ 57

14

pressure, ion recombination, and polar

15

the

16

Ir-192 sources, as indicated in the wor

17

the semiconductor detector and Farmer-typeionization chamber (PTW-30013, Freiburg, 1 8
Germany). As shown in Fig.1 (b), both detectors were fixed using a poly-methyl methacry- 1 9late (PMMA) sleeve. Both sleeves were located20
in a phantom system with a separation of 8
cm each from the Ir-192 source. The phantom 2 1
was immersed in a water bath heated by aheater. This allowed the preset temperature
to be maintained with an accuracy of 0.2 C.
For all measurements, a current was applied 1hour before the start of the measurement andpre-irradiation was performed for 15 minutes
immediately before the measurement.
All measurements were read simultaneously
by the semiconductor and the farmer as a reference. The ratio of the reading by the semiconductor dosimeter to the absorbed dose by
the Farmer chamber as a reference was definedas the sensitivity index value. This is the same
principle of diode sensitivity calibration 16).

beam

quality

conversion

factoral 15).

in the work by Araki et al 15).
R Raactuali sactualt h e readinga c t u froma l r thee a semiconding from the sc t uisa ltheductor dosimeter with the background subdosimeter with the background subtra
tracted.
������� � ���� � ����������� (3)(3)

R Rr raws originalt h e o rrawi g ireadingn a l randa w Rbackgroundreading anda wis itheis the background noise. Rbackground was measured as dark current noise without a radiation
source. It was measured for 15 minutes in thesame manner as the radiation source.
6

2-3 Evaluated characteristics

The following four characteristics were examined in this study.
2-3-1 Sensitivity change with the irradiation
history

Sensitivity change with irradiation history
was examined using SI over a three-year period
and assessed as a relative value with the first SI
value at the introduction of the semiconductor
SI hwas1
p r e Sensitivitys e t t i mindex
e wanda s Ir-192
1 5 dosimetrym i n u t e s ( m a xdosimeteri m u m settim). Te measured at theto e1.00.
2-2
mwe a irradiated
w
5for
m15
im
u
m
t
i
m
e
)
.
1 1 p Bothr epsreedetectors
ts etti mt ei weres a1s 5 1 minui tnmineust e(sm a( mxtimeiamx of
u
m
t
i
m
e
)
.
T
h
eT h eintroduction and thereafter
periodically2measurements were repeated three times and thewith an Ir-192 radiation source, as shown inapproximately every six weeks. The irradiationrem
2 2m e ma se ua rs eum
n tesn t ws e rwee r ree pr ee ap teeadt e tdh rt eher e tei mt ei ms e as n da n tdh et h e.
Tominimizetheinfluenceofthetranhistory
recordedFig.1
3
b a c k g r o u n d w a s m e a s u r e d a s d a r k c u r r e n tall nirradiatedo i s e doses in clinicalr no dupresetnw
d a timews was
d s a ds a use
r ck uexperiments.
3 3sitionb a cbkatime,
gc rkoguthes amema se15ua rsminutes
eudr e ardka andrc ruernr te n nt o insoe i s e
4w i t h o u t time).
a r a Thed i a measurementst i o n s o u r c weree.
(maximumii ao tn
i osno us ro cuerwas
4 4repeated
w i twhiot uh
to ua ttimes
r aa drandiaadtthe.c e .
threebackground2-3-2 Change of dark current noise with the5
Referring to equation [14], for diode sensitivity
measured as dark current noise without a rairradiation history
5 5 R e fReerfrei rnrgi n tg o t eo q ue aq tui ao tni o [n1 4[ ]1, 4 ]f ,o r f o dr i oddi eo d se e ns se int si iv ti it vy i t ydiation6
c a l i b source.
ration,thesensitivityiThen d ebackgroundx( d e n waso t e dmeasured as dark
Referringsource. As
ri aequation
h ediode
6 6c alci ab lriabttoo tni ,o n , [14],t h etfors e nssensitivse int si iv ti it vy i t ycurrent
i n di en noise
xd e x without( d e( nd oe taneoradiation
dt e d
7
S
I
)
i
s
e
x
p
r
e
s
s
e
d
a
s
:
h
e
r
e
a
f
t
e
r
a
s
ity calibration, the sensitivity index (denotedshown in equations (1) and (3), dark current
et aeSIfrt ears aSsI )S Ii s) ie sx pe rx epsrseesds eads :a s :7 7hereafterh e rheear fas
noise was measured each time SI was mea������) is expressed as:
8
.
(
1
)
�� � ������
������
����������
�� ������ �����
sured. Similar to the sensitivity change, dark� ������
8 8 �� ���������
. (1)( 1. ) ( 1 )� ������
����� ������ ������
����� �����
������
9� ����� i s d e t e r m i n e d f r o m F a r m e r s currenta b s o noiser b e dchanges
d o s eweret o observed with ra������� �����
e ri nmefromi dn ef dFarmers
roF
maa re mrasb sa obhistory
eddo asd3-yearto
ab9 9 � ������
i s isidsdeterminede tdeertm
r o fmrFm
r sediation
rsboer dbover
eo st eo period.
�����10
w a t e doser w itot h
t h withe I rthe- 1Ir-192
9 2 ssource:
ource:
sorbedwater
In addition, R background/ R raw at each source
1 0 1 0w a w
t eart ewr i twhi tthh et hI er - I1r9- 21 9s2o us ro cuer: c e : strength was evaluated as a ratio of the dark�����11� ������
��� . (2) ( 2 )����� = �����
current to determine the effect of the dark cur������ ����������
������� �����=��������
1 1 1 1 � �����= ��
��� . ��� . ( 2 ) ( 2 )This is the12
MM i iss thet h echamberc h a m readingsb e r r e measured
a d i n g s withm e a s u r erent
d wnoisei t h ont hthee Isourcer - 1 9 strength.
2
1
2
M
i
s
t
h
e
c
h
a
m
b
e
r
r
e
a
d
i
n
g
s
m
e
a
s
u
r
e
d
w
i
t
h
t
h
e
I
r
1
9
2
12
M iIr-192
s t h source,e c h a whichm b e ris rcorrected
e a d i n gfors temm e a s u r eratiod wofi tthe
h tdarkh e current
I r - 1 9 to
2 the total reading
the
13
s
o
u
r
c
e
,
w
h
i
c
h
i
s
c
o
r
r
e
c
t
e
d
f
o
r
t
e
m
p
e
r
a
t
u
r
e
a
n
d
perature and pressure, ion recombination, andof the semiconductor dosimeter including the, hw
1 3 1 3 s o us ro cu17)
er, c e w
i chhi c h
i s i cs o rcroercrteecdt e df o r f o tr e mt ep m
e rpaetruart eu r ea n da n dkpolarity . Ir is the beam quality conversion
dark current noise, which indicates the degree14
p r e s s u r e , i o n r e c o m b i n a t i o n , a n d p o l a r i t y 1 7 ) . ��� i s
Ir-192i snot accuratelyi or ne csources,roem
c ob mbaiindicated, da npof
do luncertainty
paorliat ry i t1 y7if)1this
�i s is1 4 1 4factor
p r epsrfor
seusCo-60
rs eu, r ietoo, ni nas
tni ao tni ,o nan. 7 )�.value
��

��

15
the beam quality conversion factor for Co-60 toe aJARTmly i t cy o2021
r o -C6o0- 6 t0 o t o
1 5 1 558th◆
et hJournal
be e ab mq uEnglish
aq lui at editionnc vo en rvsei ro sni o fna cftaocrt o fro r f o Cof16
Ir-192 sources, as indicated in the work by Araki ets di incdaitceadt ei d1 6 1 6 I r - I1r9- 21 9s 2o us ro cuersc, e as ,s ai nn it nh et hweo rwko rbky bAyr aAkr ia ke ti e toriginal articles
Long Term Characteristics Change of n-type Semiconductor Rectal Dosimeter

quantified. The maximum source strength forthe three years holding the radiation source
was defined as 1.0 and compared.

3. Results
3-1 Sensitivity change with irradiation history[Fig.2 (a)–(e)] shows that sensitivity change

2-3-3 Dose rate dependence and its change

The dose rate dependence for the sensitivityof the semiconductor dosimeter was evaluated.
The SI investigated in the 2-3-1 study was evaluated for each dose rate. Furthermore, the firstyear of the evaluated three years was classified
as “Initial” and the third year as “Irradiated”.
The dose rate at the time of maximum source
strength for the three years holding the radiation source was defined as 1.0.

for the irradiation history for each semiconductor detector channel. The x-axis represents all
the irradiation history doses over a three-year
term. The y-axis represents the relative SI.
The scale of the x-axis varies from channel
to channel for clinical use, and the geometry is
shown in Fig.1. The SI decreased to approximately 0.92 – 0.95 with an irradiation history of
200 Gy. Notably, an initial exponential reduction was observed.

2-3-4 Sensitivity variation with temperature and3-2 Change of dark current noise with theits change

To investigate the sensitivity of the semiconductor dosimeter dependence on temperature,
SI was measured while changing the watertemperature. Using the geometry shown in
Fig.1, the temperature was set to 40, 38.5, 37,
35.5, 34 C with the body temperature set to
37 C 18). Temperature and pressure correction
was only performed for the farmer chamber
reading. The sensitivity at a temperature of
37 C was normalized to 1.00 and the correlation with the sensitivity to temperature wasobserved. The temperature coefficient, definedas (dSI/dT) where SI is the sensitivity index and
T is the temperature, was then determined via
linear regression of the data. The temperature
coefficient is expressed as 1%/ C as an SI increase per unit temperature.
This experiment was performed at the timeof the new introduction. This is defined as “Initial”. In addition, approximately 2 years after
the irradiation history, the experimental procedure was repeated at almost the same dose
rate. This is defined as “Irradiated”. The two
results were compared.

irradiation history

The change of the dark current noise of thesemiconductor dosimeter is shown in Fig.3.
The y-axis represents the dark current noise ata given time. With respect to the dark current
noise, individual differences among channelsof the semiconductor detector were observed.
Channel 3 had the highest dark current value.
Negative currents were observed in channels
2 and 4. The dark current noise for channel 5
only from the time of introduction was almost
zero. For the channels 1 – 4, the dark current
noise converged to 0 from the introduction
time.
Fig.4 shows the scatter plots of R background/
Rraw versus the relative source strength. Whenthe source strength was approximately 0.2,
the percentage of dark current noise was approximately 6%. When the source strength isapproximately 0.7 or more, it is 1% or less.
3-3 Dose rate dependence and its change[Fig.5 (a)–(e)] shows the result for the dose

rate dependence. The y-axis represents therelative SI and the x-axis represents the relative
dose rate. The white dots represent “Initial”,
and the black dots represent “Irradiated”. As arough estimate, the dose rate 1.0 corresponds
to approximately 6.85 Gy/h and the dose rate
Arts and Sciences ◆ 59

400
400

ry (Gy)ory (Gy)

600
600

ChannelChannel 5
3

400

ory
(Gy)
ry (Gy)600

Channel 5400

ory (Gy)

600

400

600

Channel123
ChannelChannel

1.00
1.00
1.00
0.95
0.95
0.95
0.90
0.90
0.90
0.85
0.85
0.85

0
00

200
200
200

400
400
400

Irradiation History (Gy)
Irradiation History (Gy)

1.05
1.05
1.00
1.00
0.95
0.95
0.90
0.90
0.90
0.85
0.85
0.85

(d)
(e)
(a)
(c)
(b)

0
0
0

200
200
200

400
400
400

Irradiation
History (Gy)
(Gy)
Irradiation
Irradiation History
History (Gy)

1.05
1.05
1.05
1.00
1.00
1.00
0.95
0.95
0.95
0.90
0.90
0.90
0.85
0.85

(c)
(d)
(e)

0
00

200
200
200

400
400
400

Irradiation History
History (Gy)
(Gy)
Irradiation

1.05

600
600
600

Channel 5

0.95
0.90

(e)

0

200

400

Irradiation History (Gy)600

Fig.2 (a)–(e) Sensitivity change with the irradiation
history

60 ◆ Journal of JART English edition 2021

0.85

Channel 5

Channel 3

200

400

600

Irradiation History (Gy)
0

100

200

300

400

500

Irradiation
History (Gy)Channel
4600

Channel 2

Fig.3 Change of dark current noise with the irradiation history

0.95
0.95

8.0%

0.90
0.90

1.00

Channel 2

Channel 4

0

-50

1.00
1.00

1.05
1.05

Channel2
Channel
1

50

0

1.05
1.05

6.0%

200

4.0%

Channel 1

Channel 2

Channel 4

Channel 5

400

0.0%

Channel 3

600
600

200
Irradiation
History400(Gy)
Irradiation History (Gy)2.0%

ChannelChannel 2
4

-2.0%
-4.0%

0.95

-6.0%

0.90
0.85

(d)
(b)

1.00

0.85

0.90

(b)

600
600
600

Channel 43Channel
5

0.95

0.85
0.85 0
(d) 0

600
600
600

Channel 1254ChannelChannel
3

1.00

(b)
Relative
RelativeSensitivity
SensitivityIndex
Index

Relative
RelativeSensitivity
SensitivityIndex
Index
Relative
Sensitivity
Index
Relative
Sensitivity
Index
Relative
RelativeSensitivity
SensitivityIndex
Index

Channel 13
Channel200

Irradiation History (Gy)

1.05
1.05

(c)
(b)
(a)

Relative
RelativeSensitivity
SensitivityIndex
Index
Relative
Sensitivity
Index

600

Relative Sensitivity Index

400

ory (Gy)0

Relative
Relative Sensitivity
Sensitivity Index

0.85

100

R background (ADU)

0.90

1.05

ܴܾܽܿ݇݃‫ ݀݊ݑ݋ݎ‬/ ܴ‫ݓܽݎ‬

0.95

Relative Sensitivity Index

1.00

(a)
Channel 1

Channel 1

0.0

0.2

0.4

0.6

0.8

1.0

Relative Source Strength

Fig.4 Ratio of dark current noise to source strength
0

200

400

Irradiation History (Gy)600

0.2 corresponds to approximately 1.45 Gy/h.
Channel 4
At dose rates in the range of 1.45 Gy/h to 6.85
1.00
Gy/h, there is no correlation between the dose
rate and SI both during the “Initial” and “Irra0.95
diated” term. Moreover, even when the term
0.90
and the term are compared, there was no clear
result that was common to all semiconductor
0.85
0
200
400
600
detectors
channels.
(d)
Irradiation
History (Gy)

Relative Sensitivity Index

Relative Sensitivity Index

1.05

1.05

3-4 Sensitivity variation with temperature andits change

As shown in [Fig.6 (a)–(e)], the results areplotted as the SI versus temperature. The white
dots represent the “Initial” whereas the black
dots represent “Irradiated”. For all semiconductor detectors channels, the temperature coefficient was 0.2 – 0.4%/ C at the initial stage ofintroduction. However, it was 0.1%/ C or lessafter the irradiation history.

original articles

ource
Strength)urce Strength)
ChannelChannel53
IrradiatedInitialdiateddiated
3025
0996

1.0
1.0

urce Strength)
Strength)urce

Channel 5diated0996

1.0

urce Strength)

0.93
0.93
0.93 0.0
0.0(d)(a) 0.0
(b)

(c)
(e)

1.07
1.07

1.00
1.00

0.93
0.93
0.93

(d)
(c)
(e)

0.0
0.0
0.0

1.00

(e)

0.0

0.99

◇ Initial◆ Irradiated0.05 %/C
0.93
0.93

◇ Initial
Initial◆IrradiatedIrradiated 0.39 %/C◆
Irradiated◇◆R² == 0.0226
0.0430R²===0.3025
0.01770.0345 R²
R²0.0002
R²

0.98

33

0.5
0.5
34

35

36

1.038
37 1.0

1.02
1.02

40

(b)
(d)

0.0
410.0

1.07
1.07

Channel 13
ChannelChannelChannel52341
ChannelChannel

1.01
1.01

39

IrradiatedIrradiatedIrradiated

1.00
1.00

1.00
1.00

Initial
Initial
Initial

0.99
0.99◇ Initial
Initial◆ IrradiatedIrradiated◇◆◇Initial
Initial0.05 %/C%/C
0.27 %/C%/C 0.05◇
Initial◆Irradiated◆IrradiatedIrradiated 0.39◇◆
◇R²
Initial◆Irradiated0.0345 R²
0.0002R² ===0.0226
0.0278R²
0.07030.0430R²===0.3025
0.0177R²
0.93
R² = 0.0168 R² = 0.0996
0.93
0.98
0.98
0.0
0.5
1.038
33 0.534
35
36
37 1.0
39
40
410.0
33
34
35
36
37
38
39
40
0.5
1.0
(c)
(b)
(d) 41

Temperture(C)
Relative
DoseRate
Rate(Source(SourceStrength)(a) Dose
Relative
Dose
Strength)
Relative
Dose
Rate(SourceStrength)Temperture(C)
Relative
Rate(SourceStrength)
1.02
1.02

ChannelChannel543
ChannelChannel1.07
5Channel
3

1.01
1.01
Irradiated

1.00
1.00

1.00

Initial

0.99
0.99

◇
◇Initial
Initial

0.27%/C%/C◇Initial
Initial◆IrradiatedIrradiated 0.21◇◆
0.0226 R² = 0.0703
0.3025
R²==0.0168
0.02780.98
R²
R² = 0.0996
0.98
33

34

35

36

37

38

◆
◆IrradiatedIrradiated
0.07
0.05%/C%/C
39

33 0.534
35
36
37 1.0
39
0.5
1.038
0.5
1.0
(e)
Temperture(C)(c) Dose
Temperture
Relative
Dose Rate
Rate (Source(SourceStrength)(C)
Relative
Strength)

Relative Dose Rate (Source Strength)

Channel 5

40
40

0.93
41 0.041(d)Channel 5

1.01
1.00
0.99
◇ Initial◆ Irradiated
0.98
R² = 0.0168 R² = 0.0996

(e)

33

34
0.5

35

◇ Initial◆ Irradiated0.21 %/C 0.07 %/C

36

37

38
39
1.0 (C)
Temperture

Relative Dose Rate (Source Strength)

Fig.5 (a)–(e) Dose rate dependence and its change

40

41

Irradiated1.00
Initial0.99◇ Initial◆ Irradiated0.05 %/C◇ Initial◆ Irradiated 0.39 %/C
R² = 0.0430 R² = 0.0177

0.98

33

0.5
34

35

36

37 1.0
38

1.02
1.02
1.02

ChannelChannel24

1.01
1.01
1.01

39

40

41

Channel 23
ChannelChannel1

Irradiated

1.00
1.00
1.00
Initial

0.99
0.99
0.99

◇ Initial◆ Irradiated◇ Initial◆ IrradiatedInitialIrradiated
0.05
%/C
0.27
%/C ◆◇◆ IrradiatedIrradiated◇◇ Initial
Initial
◆
0.09
0.28
%/C
0.05 %/C
%/C
0.39
%/C
R²
R² == 0.0703
0.0177R² == 0.0430
0.0278 R²
0.98
0.98
0.98
0.5
33
34
35
36
37 1.038
39
40
41
0.5 35
1.0
33
34
36
37
38
39
40
41
34
35 Temperture363738(c) 33(b)(C) 39 40 41(a) Dose
Relative
DoseRate
Rate(Source(SourceStrength)Temperture(C)
Relative
Strength)Temperture
(C)
1.02
1.02
1.02
1.02

Channel 5
Channel 24 Channel
Channel3
Channel 42
Channel 1

1.01
1.01
1.01
1.01

Irradiated

1.00
1.00
1.00
1.00

Initial

0.99
0.99
0.99
0.99
◇ Initial◇
Initial◇◇Initial
Initial
◇Initial0.21%/C◆IrradiatedIrradiated◇◇ Initial
◆
0.26
%/C
Initial
0.27
%/C
0.28
%/C
R² == 0.0278
0.0430 R²
R²==0.0703
0.0177 0.39 %/C
R²
0.98

0.98
0.98
33

34
0.5

35

36

37 1.038◆
Irradiated◆◆IrradiatedIrradiated◆Irradiated
0.07
%/C
0.10
%/C
◆
Irradiated
0.05
%/C
0.09
%/C
0.05 %/C
39

0.98 33
33 34
34 35
35 36
36 37
37 1.0
38 39
39
0.5
38
(e)
Temperture(C) 39(d)(c) Dose
33
34
35
36Strength)
37
38
(b)
Relative
Dose
Rate(SourceStrength)
Relative
Rate(SourceTemperture(C)
Temperture(C)(a)
Temperture (C)
1.02
1.02

40
40
40
40

41
41
41
41

Channel 45
Channel 4 Channel
Channel 3

1.01
1.01
1.00
1.00
0.99
0.99
0.99

◇
◇ Initial
Initial◇ Initial◇ Initial◆ Irradiated0.26
0.21
%/C
R² = 0.0278 R² = 0.0703 0.27 %/C

0.98
0.98
0.98 33
33(d) 33
(e)

34
0.5
34
34

◆
◆ IrradiatedIrradiated◆Irradiated
0.07
%/C
0.10
%/C
0.05 %/C

35
36
37
38
39
35
36
37 1.038
39
35 Temperture36
37
38(C) 39

Relative
Strength)(C)
Temperture(c) Dose Rate (Source
Temperture
(C)
1.02

40
40
40

41
41
41

Channel 5

1.01
1.00
0.99
0.98

(e)

◇ Initial◆ Irradiated0.21 %/C 0.07 %/C
33

34

35

36

37

38

Temperture (C)

39

40

41

Fig.6 (a)–(e) Sensitivity variation with temperatureand its change
Arts and Sciences ◆ 61

1.02
1.01
1.00
0.99
0.98

33

34

33
33

34
34

0.98
0.98 33
33

34
34

(b)
Relative
RelativeDetector
DetectorRespons
Respons

Relative
RelativeSensitivity
SensitivityIndex
Index

Initial
Initial
Initial

1.02

1.07

0.93

1.00
1.00

1.00

1.01

1.02
1.02
1.01
1.01
1.00
1.00
0.99
0.99
0.98
0.98

(d)
(b)
RelativeDetector
DetectorRespons
Respons
Relative

1.0
1.0

IrradiatedIrradiatedIrradiatedChannel 1

Channel 2(a)Temperture(C)
Relative Dose Rate (Source
Strength)

Relative Detector Respons

diateddiated
3025
.0002

1.07

Channel 1

Channel23
1
ChannelChannel

1.01

0.0

Relative
RelativeSensitivity
SensitivityIndex
Index

Initial
Initial

1.00
1.00
1.00

1.02

(a) Dose
Relative
Dose
Rate(SourceStrength)
Relative
DoseRate
Rate(Source(SourceStrength)Temperture(C)
Relative
Strength)

Relative Detector Respons

IrradiatedIrradiated

1.07
1.07
1.07

(b)

Relative Dose Rate (Source Strength)

Relative Detector Respons

Channel 3
1

(b)
(a)
(c)

0.0
0.0

Relative
Sensitivity
Index
Relative
Sensitivity
Index
Relative
Sensitivity
Index
Relative
Sensitivity
Index
Relative
Sensitivity
Index

ource Strength)

0.93
0.93

RelativeSensitivity
SensitivityIndex
Index
Relative

1.0

Relative Sensitivity Index

diated
.0002

0.93

1.0

Relative Sensitivity Index

1.00
1.00

Initial

0.5

Relative Detector Respons

Irradiated1.07

Relative
RelativeSensitivity
SensitivityIndex
Index

Channel 1

0.0

Relative
RelativeDetector
Detector Respons
Respons(a)◇ Initial◆ IrradiatedR² = 0.0345 R² = 0.0002

1.02

1.02
1.02
1.01
1.01
1.00
1.00
0.99
0.99

(d)
(b)
Relative Detector Respons

InitialRelative
Relative
Detector
Respons
RelativeDetector
DetectorRespons
Respons

1.00

1.00

Relative
Detector
Respons
Relative
Detector
Relative
DetectorRespons
Respons
Relative
Detector
Respons

Relative Sensitivity Index

Relative Sensitivity Index

Irradiated0.93

Relative Detector Respons

1.07

Channel 1

Relative
Detector
Respons
RelativeDetector
DetectorRespons
Respons
Relative

1.07

Relative Detector Respons

Long Term Characteristics Change of n-type Semiconductor Rectal Dosimeter

1.02
1.01
1.00
0.99
0.98

(d)

33

34

4. Discussion
Semiconductor dosimeters must be quantified under any clinical conditions for intracavitary brachytherapy to maximize their accuracy
and clinical utility. Without accurate sensitivity
calibration, it is not possible to determine if
a reading is due to abnormal dose values orother errors. In this study, we focused on thesensitivity and dark current noise, dose rate,
and temperature of the detector.
Regarding the decrease in the sensitivity associated with the irradiation, the result wasin agreement with previously reported findings 4)-7), 13), indicating an initial exponential
reduction, which subsequently slowed down.
From the experiments, it was determined that
there was the sensitivity decreased to approximately 0.92 – 0.95 with irradiation. According
to the guidelines of the American Associationof Physicists in Medicine (AAPM) task group
No.138, 3.4% of the total dose calculation uncertainty of high-energy HDR is recommended,
and a 5 – 8% decrease is not negligible because
it is higher than 19). Therefore, sensitivity calibration is required before use. Then, it is necessary to record the change in sensitivity overtime and observe that the sensitivity gradually
becomes moderate. To accomplish this, thehistorical irradiated dose delivered to the detector must be recorded if possible.
There are limited publications on dark current noise. In addition to the aforementioned
phenomenon that the sensitivity with the Ir192 source decreases with the irradiation history, the response to dark current noise also
decreases. It has been determined that somesemiconductor channels have a negative darkcurrent noise. In addition, when the source
strength was low, (i.e. before source replacement), the ratio of the dark current noise exceeded 6%, and it was not negligible, giventhat it exceeded the uncertainty 3.4% set by
the AAPM as in the aforementioned sensitivity
decrease. Depending on the treatment plan,

62 ◆ Journal of JART English edition 2021

the rectum may be far away from the iridium
source and there may be channels that receive
little or no radiation. Therefore, it is necessary
to quantify the zero signal as exactly zero.
Investigations at high dose rates of 60 Gy/h12)
were not feasible in this study. The dose ratedependence at rates from 1.8 Gy/h to 2.4 Gy/hhas been reported as negligible 13). In addition,
a dose rate dependence was not observedat dose rates of 1.4 Gy/h to 6.8 Gy/h in thisstudy. The results were the same for “Initial”
and “Irradiated”. As such, the decrease in thesource strength due to the decay of the Ir-192
source with an average apparent activity of
370 GBq can be interpreted as not affecting
the accuracy of sensitivity calibration. In otherwords, there was no dose rate dependence
and no change due to irradiation history.
In terms of the sensitivity variation with temperature, for the case of “Initial”, the result wasin agreement with reference 8)-11). Furthermore, it
was determined in this study that the tendency
becomes moderate with irradiation. Thus, it wasconsidered that temperature dependence reduced with irradiation. However, it was challenging to determine whether the temperature of theelement was owing to the temperature dependence of the electronic circuit system, and it can
only be considered to affect the final reading. In
actual clinical dose monitoring, the detector isinserted into the rectum. Therefore, it is desirable
to perform sensitivity calibration while accurately
maintaining the phantom temperature at 37 C,
especially when irradiation is initially low.
For all the characteristics of the semiconductor dosimeter, the results show that there are nolarge individual differences among the 5 channels. In actual clinical practice, there are cases
in which treatment is performed over multiple
fractions and the insertion position of each fraction into the rectum may be evaluated basedon the ratio of the measurement values of the 5channels. Therefore, the absence of individual
differences is a very important characteristic.

original articles
Long Term Characteristics Change of n-type Semiconductor Rectal Dosimeter

5. Conclusion
In this study, we examined characteristics
that were evaluated using a semiconductor
rectal dosimeter over a three-year period. The
sensitivity changed with irradiation history
and it was determined that there is a sensitivity variation with temperature, which changed
with irradiation history.
It should be noted these characteristics may
affect the actual measurement results. However, when sensitivity calibration is performed

References
1） Suzuki O, Yoshioka Y, Isohashi F, et al.: Effect of HighDose-Rate 192Ir source activity on late rectal bleeding
after intracavitary radiation therapy for uterine cervix
cancer. Int J Radiat Oncol Biol Phys, Aug 1; 71(5):1329-34, 2008.
2） Alecu R, Alecu M: In-vivo rectal dose measurementswith diodes to avoid misadministrations during intracavitary high dose rate brachytherapy for carcinomaof the cervix. Med Phys, May; 26(5): 768-70, 1999.
3） Tanderup K, Beddar S, Andersen CE, et al.: In vivo
dosimetry in brachytherapy. Med Phys, Jul; 40(7):070902, 2013.
4） Redaelli E: Characterization and failure analysis of X-ray
detector diodes. Master of Science Thesis, 123, 2014.
5） Osvay M, Tárczy K: Measurement of y-dose rates by
n- and p-type semiconductor detectors. phys stat sol,A, 27: 285-90, 1975.
6） Jie S: Fundamentals of diodes as radiation detectors –n type versus p type. Jpn J Med Phys, Apr; 37(Sup.
2): 1-6, 2017.
7） Rikner G, Grusell E: General specifications for silicon
semiconductors for use in radiation dosimetry. Phys
Med Biol, 32: 1109-17, 1987.
8） Van Dam J, Leunens G: Dutreix A: Correlation between temperature and dose rate dependence ofsemiconductor response; influence of accumulated
dose. Radiother Oncol, Dec; 19(4): 345-51, 1990.
9） Jursinic PA, Nelms BE: A 2-D diode array and analysis
software for verification of intensity modulated radiation
therapy delivery. Med Phys, May; 30(5): 870-9, 2003.
10）Saini AS, Zhu TC: Temperature dependence of commercially available diode detectors. Med Phys, Apr;
29(4): 622-30, 2002.

under appropriate conditions, it can be effectively used for rectal dose monitoring during
brachytherapy.

Acknowledgments
The authors would like to thank the members of my clinical institution for their technicalassistance with the experiments.
Conflict of interest

We have nothing to declare for this study.

11）Eveling JN, Morgan AM, Pitchford WG: Commissioning a p-type silicon diode for use in clinical electron
beams. Med Phys, Jan; 26(1): 100-7, 1999.
12）Grusell E, Rikner G: Radiation damage induced dose
rate non-linearity in an n-type silicon detector. Acta
Radiol Oncol, 23(6): 465-9, 1984.
13）Ghahramani F, Allahverdi M, Jaberi R: Dependency ofsemiconductor dosimeter responses, used in MDR/
LDR brachytherapy, on factors which are important inclinical conditions. Rep Pract Oncol Radiother, 13(1):29-33, 2008.
14）Jursinic PA: Implementation of an in vivo diode dosimetry program and changes in diode characteristics
over a 4-year clinical history. Med Phys, Aug; 28(8):1718-26, 2001.
15）Araki F, Ohno T, Kakei K, Kawamura S: Absorbed
dose-to-water measurement of an HDR 192Ir sourcewith Farmer ionization chambers in a sandwich setup.
Biomed Phys Eng Express, 1: 037002, 2015.
16）Report of Task Group 62 of the Radiation Therapy
Committee: Diode in vivo dosimetry for patients receiving external beam radiation therapy. 7-11, 25, 26, 2005.
17）Almond PR, Biggs PJ, Coursey BM, Hanson WF:
AAPMʼs TG-51 Protocol for clinical reference dosimetry of high-energy photon and electron beams. Med
Phys Sep, 26(9): 1847-70, 1999.
18）Sund-Levander M, Forsberg C: Normal oral, rectal,
tympanic and axillary body temperature in adult men
and women: a systematic literature review. Scand J
Caring Sci, Jun; 16(2): 122-8, 2002.
19）DeWerd LA, Ibbott GS, Meigooni AS: A dosimetric
uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No.138 and
GEC-ESTRO. Med Phys, Feb; 38(2): 782-801, 2011.

Arts and Sciences ◆ 63

Arts and Sciences
original articles

Received September 13, 2019 ; accepted March 27, 2020

Standardization of a Daily Inspection Protocol for
Angiography System
SUZUKI Keiko1），2）, HOSOKAWA Seiki 3）, HAGIHARA Yoshiaki 4）, ITO Makoto5）,
KOMATSU Yuki 6）1）Department of Radiology, Sasayama Medical Center Hyogo College of Medicine, Radiological Technologist2）Graduate School of Health Science, Suzuka University of Medical Science3）Department of Radiological Technology, Fukuoka School of Health Sciences, Radiological Technologist ph.D.
4）Department of Radiological Technology, Hyogo College of Medicine College Hospital, Radiological Technologist
5）Department of Central Radiology, Kindai University Hospital, Radiological Technologist
6）Department of Radiological Technology, Japan Community Health care Organization Osaka Hospital, Radiological Technologist

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 816: 27-32, 2020.
Key words: Angiography system, quality control, daily inspection, standardization【Abstract】

Around 10 years ago the Japan Medical Imaging and Radiological Systems Industries Association (JIRA) publisheda checklist to be followed at start-up and end-of-work of radiation-related equipment. However, recent angiographysystems are diversified in model and function, and there is a possibility that the daily inspection being performed as
per the published inspection table is insufficient. Upon investigating the daily inspection table of each facility, weobserved that 13.5% of the apparatuses use the JIRA inspection table, and the contents and quality of inspection are
diverse.
In this study, we developed a daily inspection table with respect to the currently used models and applications forthe purpose of correcting the disparity in daily inspection protocols among facilities and standardizing the daily quality
control of systems. We propose that incorporation and implementation of the inspection items described in this study
can improve the quality control output.

Introduction
Since the partial revision of the Medical Care
Act in April 2007 1), medical institutions are required to ensure the efficiency and safety ofmanagement systems for drugs and medical devices. Under this revision, the Japan Medical Imaging and Radiological Systems Industries Association (JIRA) has released information regarding the appropriate maintenance of radiationrelated systems, such as the inspection table 2)
and the guidelines for equipment delivery 3).
Since then, a study on inspection items forthe maintenance and safe use of cardiovascularimaging systems 4), and a specific guideline forthe use and maintenance of the examinationand treatment equipment in cardiovascularcare 5) have proposed distinct methods for startup and end-of-work inspections. However, in
recent years, angiography systems have become significantly diverse so as to include

64 ◆ Journal of JART English edition 2021

models equipped with computed tomographysystem (hereinafter IVR-CT), cone beam CT(hereinafter CBCT), and those compatible with
operating rooms (hereinafter hybrid). Therefore, each facility has been devising ways toreview and anticipate for items that are notspecifically presented in the JIRAʼs start-up andend-of-work inspection table. In this study, we
report the inspection table which we have devised according to the models currently in use.
Furthermore, we discuss and highlight its purpose that intends to rectify the current disparities observed among facilities by standardizing
the daily quality control procedures.

Materials and Methods
1. Collection of start-up and end-of-work inspection items

We collected inspection items from the startup and end-of-work checklist for angiography

original articles
Standardization of a Daily Inspection Protocol for Angiography Systemsystems used at each facility. All inspection
items were collected from checklists submitted
by candidates who took their 2017 certification
examinations through the Japan Professional
Accreditation Board of Radiological Technologist for Angiography and Intervention and applicants that are currently renewing their certifications. Next, we compared the collected inspection items with those of the JIRA.
2. Selection of start-up and end-of-work in-respective environment, system, peripherals,
and model. In addition, items in each category
were organized in a well-defined manner sothat they can be performed sequentially.
4. Consideration of a daily quality control

In addition to the items in our checklist, we
discussed the quality controls that users should
implement on a daily basis to identify potential
abnormalities of the equipment at an earlystage.

spection items

The inspection items were shortlisted basedon the guidelines for equipment delivery for
cardiovascular imaging systems 3) from among
the collected inspection items. For the start-up
inspection, we selected items that evaluatedthe operation and safety of each part of thesystem, which ensures that the dayʼs work canbe performed in a smooth and unhinderedmanner. For the end-of-work inspection, theselected items included cleaning and organizing systems contaminated with contrast media,
blood, and other substances, as well as records
of malfunctions and problematic issues that occurred while using the system. Consequently,
using the same criteria as described above, we
selected items related to the CBCT, IVR-CT,
and hybrid models, which are not listed in the
JIRA start-up and end-of-work checklist. We
excluded items that were difficult to standardize, such as items from the inspection tablethat are not common to all system manufacturers or items that have different inspection frequencies. These items were highlighted on theinspection table so that they can be performed
for each system as per the systemʼs requirement and configuration.
3. Development of the start-up and end-ofwork inspection table

The selected inspection items were divided
into two groups: the start-up inspection items
and the end-of-work inspection items. Bothgroups were further classified according to the

Results
1. Collection of start-up and end-of-work inspection items
We used 400 start-up and end-of-work inspection tables collected from 152 facilities.
Table 1 shows the number of inspection items
collected from each system and from the JIRA
start-up and end-of-work checklist. The breakdown of the number of systems is listed inTable 2. Our findings demonstrate that there
were 153 items for the start-up inspection and
72 items for the end-of-work inspection, including similar items. For the JIRA inspection
items, there were 30 items for the start-up inspection and 23 items for the end-of-work inspection. In addition, 54 of the 400 systems
used the entire JIRA inspection table or used
items extracted from it, thus accounting for13.5% of the total systems under considerationin this study.
In contrast, of the systems that did not use
the JIRA inspection table, 23 out of 28 (82.1%)
IVR-CT models (including two hybrid models
equipped with CT) had IVR-CT-specific inspection items added to the inspection checklist,and 21 out of 32 (65.6%) hybrid models had
hybrid-specific inspection items added. The
CBCT-specific inspection items were added in
11 out of 173 (6.4%) angiography systems, except for the systems used exclusively for cardiovascular imaging.

Arts and Sciences ◆ 65

Table 1 The number of collected inspection items
Collection source of inspection items

start-up
inspection
items

end-of-workinspection
items

Daily inspection table for each facility
angio

IVR-CT

HybridJIRAʼs daily
inspection table

total

environment

28

21

15

28

8

angiography system

64

52

53

64

16

peripherals

18

12

16

19

6

CBCT

4

1

3

4

‑

CT

‑

28

2

28

‑

Hybrid

‑

‑

10

10

‑

total

114

114

99

153

30

environment

19

15

17

19

8

angiography system

26

19

21

26

9

peripherals

16

13

13

16

6

CBCT

0

0

0

0

‑

CT

‑

8

2

8

‑

Hybrid

‑

‑

3

3

‑

total

61

55

56

72

23

Table 2 The breakdown of the number of systems by model
Model

angio (%)

IVR-CT (%)

Hybrid (%)

total (%)

The number of facilities

147

26

28

152

The number of systems

342 (85.5)

26 (6.5)

32 (8.0)400 (100)

The number of systems using JIRA checklist

46 (85.2)

2 (3.7)

6 (11.1)

54 (100)

The number of systems using other check lists

296 (85.6)

24 (6.9)

26 (7.5)346 (100)

The number of systems that perform specificinspection items

11 (20.0)

23 (41.8)

21 (38.2)

55 (100)

The number of apparatuses that have notundergone end-of-work inspection

42 (84.0)

6 (12.0)

2 (4.0)50 (100)

2. Selection of start-up and end-of-work inspection items

Based on the guidelines for equipment delivery for cardiovascular imaging system 3), 22
items were selected as the start-up inspection
items and 17 items were selected as the end-ofwork inspection items. We selected two items
for CBCT-specific, two items for hybrid-specific,
seven items for IVR-CT-specific models in thestart-up inspection, and five items for IVR-CTspecific models in the end-of-work inspection.
We employed the daily consistency test for
imaging display systems as a new item forstart-up inspection because this was a common
item in all systems under consideration in thisstudy. In addition, we adopted confirmation ofremaining hard disk capacity of the system, thenumber of protective aprons, cleaning, and the66 ◆ Journal of JART English edition 2021

number of radiographic aids and supplies solely at the end-of-work inspection to improvethe efficiency of the start-up inspection. Due tothe differences in necessity of daily inspection
and frequency of inspection among different
systems, warm-up and calibration of the X-ray
tube, proper operation of the emergency stop
button, brake test of the robotic arm, and calibration of the surgical bed were excluded fromstart-up and end-of-work inspection items.
3. Development of a start-up and end-of-workinspection table

The start-up inspection table is shown in
Fig.1, and the end-of-work inspection table isshown in Fig.2. The inspection items for CBCT,
hybrid, and CT models are designed to be performed additionally in each model. In contrast,

original articles
Standardization of a Daily Inspection Protocol for Angiography System

date

Start-up inspection
Air conditioning management of machine room and inspection room isdone. (temperature / humidity)
Checking the surveillance camera
Check microphone / intercom
environment
Operation check of oxygen, suction device, etc.

There is no obstacle in the operating range of the equipment, and it is in aﬁxed position.
Appearance check and cleaning of equipment
The “in use” indicator light is on when the unit is operating.
The system starts up normally and there is no error display.
Checking the display time
No abnormal noise or smell
Checking the operation of the support arm
Operation check of patient tableangiography
Operation check of X-ray aperture / ﬁlter / ﬁeld switchingsystemOperation check of touch sensor and irradiation prohibition switch
Operation check of ﬂuoroscopy and radiography (Including image
irregularities and artifacts)

peripherals

CBCT
HybridCT

Operation check of irradiation indicator
Operation check and remaining capacity check of external recording device(Constancy test of imaging display system)
The workstation starts up normally and there is no error display.
Operation and appearance check of contrast medium injector
There is no problem starting the HIS-RIS system.
Operation check of peripheral equipment related to inspection andtreatment
Rotating radiography operation checkConﬁrming image transfer operation to the workstation
Checking the multi-monitor connection and display
Check the placement and operation of the operating table
The system starts up normally and there is no error display.
No abnormal noise or smell
Gantry running / tilting operation check
Checking the lighting and displacement of the pointerX-ray tube warm-up
The phantom is scanned and there are no abnormalities in the CT and SD
values.
There is no artifact in the scanned phantom image.

inspector※Other inspection items recommended by the manufacturer should be performed as necessary.

Start-up inspection table
Fig.1Fig.1
Start-up
inspection table

excluding the above inspection items, all remaining items are designed to be performed in
exclusive cardiovascular imaging systems.
4. Consideration of an additional daily quality
control

From the collected inspection items, we
identified 57 of the 400 systems (14.3%) included in our study were checking and recording
the X-ray output conditions as an inspection
item. Since confirmation of the daily X-ray output reproducibility is an important item to ensure the stable operation of the system, we ex-amined whether this can be added to start-up
or end-of-work inspections as a quality control
item. As a result, we noticed that if “Operation
check of ﬂuoroscopy and radiography ” proposed in Fig.1 is performed at the time of startup inspection with a defined geometric arrangement, and then it can be used to assess
the consistency of the daily X-ray output. An
example of geometric arrangement is shown in
Fig.3. The recording of the X-ray loading factor
was separated from the start-up and end-ofwork inspection tables in another sheet. The
X-ray output recording sheet is shown in Fig.4.
Arts and Sciences ◆ 67

date

End-of-work inspection
Check the temperature and humidity in the inspection room

environment

There is no obstacle in the operating range of the equipment, and it is in aﬁxed position.
Conﬁrmation and replenishment of necessary items
There is no loss or damage to the radiographic aids.
Oxygen and suction device must be cleaned up.
Appearance check and cleaning of the system
The support arm is retracted.

angiographysystemNo abnormal noise or smell
Check if an error message is displayed
Transfer images / There are no unprocessed images.
Conﬁrmation of the remaining hard disk capacity
The system ends normally.
Contrast medium injector (cleaning and shut down)

peripherals

Conﬁrmation of normal shutdown of HIS-RIS system
Other equipment (cleaning and shut down)
X-ray protector (number / cleaning)Appearance check and cleaning of the system
The gantry is retracted.

CT

Transfer images / There are no unprocessed images.
Conﬁrmation of the remaining hard disk capacity
The system ends normally.

generalNo abnormality during inspection / Reporting and description when there isan abnormality
inspector※Other inspection items recommended by the manufacturer should be performed as necessary.

Fig.2 End-of-work inspection tablethat inspection
Fig.2 End-of-work inspection
table items and contents varied notremove patient
table from Field of
View

place thecopper plate

Fig.3 An example of geometric arrangement for
Fig.3X-ray
An example
geometric arrangement for X-ray
outputofcheck
output check

Discussion
The inspection items collected from thechecklist of each facility enabled us to identify

68 ◆ Journal of JART English edition 2021

only according to the model and purpose ofeach system, but also due to other potential
differences between the facilities. Therefore,
standardization of the inspection contents necessitated the establishment of items that werecommon to all angiography systems. Moreover, it was important to consider the items
designed to be performed according to thefunctions and purposes of use of the systems.
In addition, we decided to execute the inspection items listed in both, start-up and end-ofwork, inspection tables proposed by JIRA 2)
solely for the start-up or end-of-work inspection to improve efficiency based on the selection criteria shown in method 2. This is taking
into consideration the fact that the number ofinspection items is expected to increase withthe recent advancements in the functions of
the respective systems.
Since the start-up inspection is required tobe performed within a limited time before
commencing any task or emergency examina-

original articles
Standardization of a Daily Inspection Protocol for Angiography System

X-ray output check sheet
FoV

：

SID

：

phantom：inch

ﬂuoroscopy program：cm

radiography program：

mmCu

exposure time：sec＊ if you can't set exposure time,for DSA, record in "mGy/f" , for DA, record in "mGy/s".

fluoroscopy

dateradiography

tube
voltagetube
current

pulse
time

tube
voltagetube
current

pulse
time

air karma inspector

(kV)

(mA)

(ms)

(kV)

(mA)

(ms)

(mGy)*

note

Fig.4 Check sheet of X-ray output

tions, we investigated the time required to carrytion test. However, there are systems that canout the inspection of the environment, system,
display the test pattern only in service mode.
and peripherals, which are common items of
We believe that it is necessary to consider thisthe start-up inspection. The averagetime re-sheet ofissue
togetherwith manufacturers, and thus asFig.4 Check
X-ray
outputquired was 11 minutes and 45 seconds. We besess the means with which users can implelieve that “items that can be inspected in 10 toment appropriate monitor quality control.
We propose a record of the X-ray output as
15 minutes,” described in the main criterion for
selection of inspection items by the Safety Mana daily quality control item. This facilitates anagement Manual Preparation working group of
efficient quality assurance of the system as well
6),
JIRA are sufficient and can be implemented.
as early detection of potential abnormalities,
When selecting the inspection items, we embecause the daily variation of X-ray output valployed the daily monitor constancy test as one
ues can be graphed and analyzed by recordingof the start-up inspection items that is common
the X-ray output conditions in a separate table.
Image quality evaluations, such as spatial
to all systems. This is because regular inspecresolution and contrast resolution of images,
tion of the monitors is performed by each syswere also considered as an additional daily
tem manufacturer during maintenance and inquality control. However, it is difficult to enspection. However, the “Quality Assurance
7)(QA) Guideline for Medical Display Systems”
sure standardization because only certain farecommends that the constancy test for a medicilities have phantoms for image quality evalucal image display monitor used in diagnostic
ation. The “Evaluation and routine testing in
7)
medical imaging departments–Part 2-9: Conimaging should be performed on a daily basis .
Therefore, it is preferable that daily constancy
stancy tests–Equipment for indirect ﬂuoroscopy
test should be performed by the user.
and indirect radiography JIS4752-2-9 ” 8) states
Currently, each system can display the test
that “the frequency of constancy tests shall be
performed at least every three months in the abpattern that is used in the overall daily evaluaArts and Sciences ◆ 69

sence of information on the frequency of testing” 8). Therefore, it is necessary for each facility to have its own image evaluation phantoms
to supplement the inspections that cannot be
performed during the manufacturerʼs maintenance.

Conclusion
In this study, we propose a new daily inspection method for angiography systems. We
believe that the effective implementation ofdaily inspection items adapted as per the model and purpose of use can facilitate the efficientand appropriate equipment management ofeach device. In addition, the use of the proposed daily inspection is expected to standardize daily inspections and improve system management by users.

Acknowledgments

tivities of Japan Professional Accreditation
Board of Radiological Technologist for Angiography and Intervention (group leader: Keiko
Suzuki) in 2017 and 2018. We appreciate thecooperation of all the parties involved in thisstudy. We would also like to express our deepest gratitude to Naoki Moriyama of the National Hospital Organization, Kyoto Medical Center; Yoshiki Kawase of Osaka General Medical
Center; Jun Kobayashi of Kansai Rosai Hospital; Yutaka Kimura of National Hospital Organization, Osaka National Hospital; and YukariMoriyama of Higashi Takarazuka Satoh Hospital for their collaboration and assistance inwriting this paper, and to Professor Hiroe Mutoof the Department of Radiological Technology,
Faculty of Health Science, Suzuka University of
Medical Science for her advice. An executive
summary of this study was presented at the 34th
Japan Conference of Radiological Technologists (2018, Shimonoseki).

This study was conducted as part of the ac-

References
1） Ministry of Health, Labor and Welfare. “Enforcement of
the Act for Partial Revision of the Medical Care Act toEstablish a System to Provide Quality Medical Care”.
Ministry of Health, Labor and Welfare. 2007-03-30.
https://www.mhlw.go.jp/web/t_doc?dataId=00tb356
1&dataType=1&pageNo=1, (accessed 2020-12-04).
(Japanese).
2） Japan Medical Imaging and radiological Systems Industries Association. “Checklist of diagnostic imaging
system: Safety Management Information”. Japan Medical Imaging and radiological Systems Industries Association. 2007-12-05. http://www.jira-net.or.jp/anzenkanri/01_hoshutenken/01-03.html, (accessed 2020-1204). (Japanese).
）
3 Japan Medical Imaging and radiological Systems Industries Association. “Equipment Delivery Guidelines:
Safety Management Information”. Japan Medical Imaging and radiological Systems Industries Association.
2009-06-12. http://www.jira-net.or.jp/anzenkanri/01_
hoshutenken/01-01.html, (accessed 2020-12-04).
(Japanese).
4） Take Toshio, et al.: Standardization of cardiovascularimaging system management. Japanese Journal of

70 ◆ Journal of JART English edition 2021

Circulatory Technology. 2009, 21, p.5-10. (Japanese).
5） Kikuchi Makoto, et al.: Guidelines for usage and maintenance of equipment in cardiovascular diagnosis
and treatment (JCS 2009). Circulation Journal. 2009,
73(Suppl. III), p.1241-1321. (Japanese).
6） Japan Medical Imaging and radiological Systems Industries Association. “Checklist of diagnostic imaging
system: Safety Management Information”. Japan Medical Imaging and radiological Systems Industries Association. 2007-12-05. http://www.jira-net.or.jp/anzenkanri/01_hoshutenken/01-03.html, (accessed 2020-1209). (Japanese).
7） Japan Medical Imaging and radiological Systems Industries Association. “Quality Assurance (QA) Guideline
for Medical Display Systems (JESRA X-0093*B-2017)”.
Japanese Engineering Standards of Radiological Apparatus. 2017-07-20. http://www.jira-net.or.jp/publishing/jesra_public.html, (accessed 2020-12-09). (Japanese).
8） “Evaluation and routine testing in medical imaging departments – Part 2-9: Constancy tests – Equipment
for indirect radioscopy and indirect radiography”. JIS
handbook: 77 Medical Radiation. Japanese Standards
Association, ed. 2018, p.1730-1741. (Japanese).

Arts and Sciences
original articles

Received February 17, 2020 ; accepted July 29, 2020

Survey of the relationship between radiological
technology students’ modalities of interest andtheir level of understanding of technical terms– Questionnaire survey of RT students –NAKAYA Koji, MUTO Hiroe, MATSUURA Kanae
Department of Radiological Technology, Faculty of Health Science, Suzuka University of Medical Science, Teacher

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 816: 33-40, 2020.
Key words: radiological technology students, radiological technologist education, modalities of interest, questionnaire

survey【Abstract】
Purpose. This study aimed to investigate the relationship between studentsʼ modalities of interest in clinical practicaltraining during radiological technologist education and their degree of learning for those modalities. Methods.

The target is 2019 fourth-year students of Suzuka University of Medical Science. The same questionnaire survey
was administered to participating students before and after clinical training. In the first part of the questionnaire,
students ranked the modalities of radiological technologistsʼ duties by their level of interest. The second part of thequestionnaire assessed their learning level for each modality. In this study, the technical term for each modality waspresented individually, and participantsʼ level of understanding of these technical terms was defined as the learninglevel for that modality. Results. The modalities of the radiological technologistsʼ work in which students were mostinterested were general radiography, computed tomography, and magnetic resonance. The interest in these modalities
did not change between before and after clinical training. Studentsʼ learning levels were particularly high in themodalities of interest. Conclusion. We investigated changes in studentsʼ interest in modalities attributable to clinicalpractical training during radiological technologist education and identified the relevance of the degree of learning for
those modalities. We aim to use these data to inform educational improvements.

1. Introduction
In Japan, universities that train radiological
technologists provide fourth-year education.
In the Department of Radiological Technology at Suzuka University of Health Sciences,
all specialized subjects related to radiological
technologistsʼ clinical practice are acquired by
the end of the third year, and students thenadvance to the fourth year. During the fourthyear, students return to their hometown from
May to August, and are offered clinical training at a local hospital. Every year, all fourthyear students choose specialized subjects toguide their clinical practice. We were interested in studentsʼ perceptions relating to three
specific points. First, we assessed studentsʼinterest in modalities involved in the practiceof a radiological technologist during clinicalpractice after covering all specialized subjects
in on-campus training. Second, we evaluatedwhether studentsʼ modalities of interest hadchanged after they received clinical educationfrom radiological technologists during theirclinical training. Third, we investigated whether studentsʼ learning levels differed between
modalities of interest and those in which they
were not interested. We thought that as clinical training offers opportunity to understandthe importance of clinical work that cannot
be experienced through on-campus training1）,
there may be differences in studentsʼ modalities of interest between before and after clinical training. Clarifying these three points willbuild understanding of studentsʼ modalities ofinterest and weak parts of learning, which can
Academic Research Grant Report ◆ 71

be used to guide student education. Therefore,
the purpose of this study was to investigate therelationship between studentsʼ modalities ofinterest in clinical practical training and theirdegree of learning for those modalities.

2. Materials and Methods
2-1. Targets

The present questionnaire survey targeted2019 fourth-year students at Suzuka University
of Health Sciences, Department of RadiologicalTechnology Science (100 students: 69 men, 31
women). The questionnaire survey was conducted both before and after clinical training(two times in total). The questionnaire wascompleted via the campus portal system. All
personal information was anonymized and discarded. Informed consent was obtained fromall participating students. In addition, this study
was approved by the Ethics Committee of the
Suzuka University of Medical Science.
2-2. Survey items

The same questionnaire survey was administered before and after clinical training. The
first part of the questionnaire asked participating students to rank each modality based on
their interest. The six modalities representing
radiological technologistsʼ practice presented
in the questionnaire were: general radiography(GR), computed tomography (CT), magnetic
resonance (MR), nuclear medicine (NM), radiotherapy, and angiography. Mammography
and X-ray TV inspections were included in
GR. The work of radiological technologists
also involves ultrasound. However, ultrasoundwas excluded from the present survey because
there were many facilities where radiological
technologists did not perform ultrasound. We
also investigated the reason studentsʼ chose
their first-ranked modality using free description.
The second part of the survey covered studentsʼ learning level in relation to each modal-

72 ◆ Journal of JART English edition 2021

ity. In this study, the technical term for each
modality was presented individually, and studentsʼ level of understanding of these technicalterms was used to define their learning level
for that modality. To extract the terminology ofeach modality, we first set the difficulty level of
explaining the terminology of each modality inthree levels: easy, normal, and difficult. Of thethree difficulty levels, in this study, we adopted
technical terms extracted as “normal” as questionnaire material. For each technical term,
students who could explain that term chose“A”, students who knew the term but could not
explain it chose “B”, and students who did notknow the term chose “C”. The technical terms
presented by each modality are shown in Table
1. The terminology was determined throughconsultation with faculty members in each specialized field, and technical terms with roughly
the same level of difficulty were extracted.
2-3. Data processing

The modalities of interest were scored basedon studentsʼ ranking. The scores for each modality are shown in Table 2. The score for each
modality was calculated as the total score rate(%) of each modality by the following equation(1).

This total score rate was compared among
modalities and for each modality before andafter clinical training. Based on the learninglevel for each modality as recorded in the surveys, the recognition level and level of understanding of technical term for each modality
were calculated using formulas (2) and (3).

original articles
Survey of the relationship between radiological technology studentsʼ modalities of interest and their level of understanding of technical terms–Questionnaire survey of RT students–

Table 1 Technical terms presented for each modality
modality

terminology

general radiography computed tomography
(GR)
(CT)
Jacobi line

nuclear magnetic
resonance (NMR)

nuclear medicine(NM)maximum intensity

diffusion weighted

autoradiography tissue maximum ratio

projection (MIP)

image (DWI)

radiation therapy(ARG)

angiography

seldinger(TMR)

Table 2 Conversion of ranking to points
Rank

1st place

2nd place

3rd place

4th place

5th place

6th placeScore

6 point

5 point

4 point

3 point

2 point

1 point

The levels of recognition and understandingfor each modality were compared for each modality and any changes before and after clinicaltraining were evaluated. We also investigatedstudentsʼ free descriptions for the top threemodalities of interest.

GR, 1.3% for CT, 20.5% for MR, 12.7% for NM,
16.2% for radiotherapy, and 12.8% for angiography. The top three modalities of interest for
students both before and after clinical practicewere CT, MR, and GR, in that order.
3-3. Learning level for each modality
Figure 2 shows the results for the recognition

2-4. Statistical analysis

The Pearson chi-square test was used for statistical analysis of significant differences fromthe results of questionnaire surveys before
and after clinical training. Using this significant
difference test, the recognition level of technical term before and after clinical training wascompared. In addition, we compared the levelof understanding of technical term before andafter clinical training.

3. Results

level of technical term for each modality before and after clinical training. Before clinicaltraining, the recognition level of technical term
for each modality were 91.9% for GR, 100%for CT, 100% for MR, 97.0% for NM, 97.0% forradiotherapy, and 51.5% for angiography. Afterclinical training, the recognition level for technical term for each modality were 97.9% for
GR, 100% for CT, 100% for MR, 97.0% for NM,
97.0% for radiotherapy, and 90.7% for angiography. There was a significant difference in therecognition level of GR before and after clini-

3-1. Survey collection rate

3-2. Modalities of interest ranking
Figure 1 shows the results of the total score25

20

ܶ‫( ݁ݐܽݎ ݁ݎ݋ܿݏ ݈ܽݐ݋‬%)FIGURE 1
The questionnaire response rate before clinical training was 99% (69 men, 30 women), andthe response rate after clinical training was
97% (67 men, 30 women).

15

Before clinical training
After clinical training

10

rate for each modality before and after clinical training. The total score rates before clinical training were 20.7% for GR, 21.9% for CT,
Each modality
21.6% for MR, 11.9% for NM, 15.6% for radioof the total score rate for each modality before and after clinical training
therapy, and 8.4% for angiography. The FIGURE
total 1. Results
Figure 1 Results of the total score rate for eachscore rates after clinical training were 16.5% formodality before and after clinical training
5

0

GR

CT

MR

NM

radiotherapy angiography

Academic Research Grant Report ◆ 73

3

FIGURE 32

FIGURE 3
*
***

***

***

***

100

***

80

***

݄ܶ݁
‫݈݁ݒ݈݁ ݊݋݅ݐ݅݊݃݋ܿ݁ݎ‬݄ܶ݁‫݃݊݅݀݊ܽݐݏݎ݁݀݊ݑ‬݈݁‫(݈݁ݒ‬%)
(%)

80

***

60

***

***
***

60

Before clinical training
After clinical training

40

20

0

***

݄ܶ݁ ‫( ݈݁ݒ݈݁ ݃݊݅݀݊ܽݐݏݎ݁݀݊ݑ‬%)100

Before clinical training
After clinical training

40

20

GR

CT

MR

NM

0

radiotherapy angiography

Each modality
Eachmodality2.
recognitionof technicalofterms
FIGUREof levelunderstanding
technical terms
Figure 3.2 Comparison
Comparison
ofofrecognitionof technicalfor each modality before and after clinical training

terms for each modality before and after
clinical training

The Pearson
Pearson chi-squarechi-square test
test waswas used
used forfor thethe significancesignificance test.
test.
The
*: p <p 0.05,***: p < 0.001***:< 0.001

The Pearson chi-square test was used for the significance test.
* : p < 0.05, *** : p < 0.001

cal training ( p < 0.05). In addition, there was asignificant difference in the recognition level ofangiography before and after clinical training( p < 0.001).
Figure 3 shows the results for the level ofunderstanding of technical term for each modality before and after clinical training. Before
clinical training, the level of understanding oftechnical term for each modality were 42.4%
for GR, 43.4% for CT, 34.3% for MR, 38.4% for
NM, 23.2% for radiotherapy, and 4.0% for angiography. After clinical training, the level of understanding of technical term for each modality
improved to 83.5% for GR, 85.6% for CT, 83.5%
for MR, 47.4% for NM, 61.9% for radiotherapy,
and 49.5% for angiography. There was a significant difference in the recognition level before and after clinical training of GR, CT, MR,
radiotherapy, and angiography ( p < 0.001).
3-4. Free description of reasons for first choiceof modality

For the top three modalities of interest, weinvestigated the free descriptions of why studentsʼ ranked these as their first choice. Before
clinical training the free descriptions of students who chose GR included comments suchas “I am interested in mammography” and “thebasics of radiological technologist work is GR.”74 ◆ Journal of JART English edition 2021

GR

CT

MR

NM

radiotherapy angiography

Each modality

FIGUREof levelunderstandingof technicalof
terms
Figure 3.
3 Comparison
Comparison
of of
level
of understandingfor each modality before and after clinical training

technical terms for each modality before
and after clinical training

The Pearson chi-square test was used for the significance test.
***: p < 0.001

The Pearson chi-square test was used for the significance test.
***: p < 0.001
45

For CT, the comments included “main work ofradiation work” and “CT is a convenient andimportant examination.” Comments relating
to MR included “I actually experienced MR
through on-campus training and deepened mydesire to be involved in MR in the future.” Afterclinical training the descriptions of students
who chose GR included comments such as “I
felt that GR was a basic modality in the workof radiological technologist and that it shouldbe learned first through clinical training.” For
CT, the comments included “there was enthusiasm taught by the person in charge of CT inclinical practice” and “I was able to operate CT
during clinical training.” For MR, the comments
included “I felt the fun of MR by listening to MR
imaging technicians about the imaging principle.”

4. Discussion
In this study, we investigated changes instudentsʼ modalities of interest by clinical training education and the relationship between
interest and the degree of learning for thatmodality. GR, CT, and MR were the modalities
of most interest to students who had acquired
all specialized subjects both before and after
their clinical training. First, before clinical train-

5

original articles
Survey of the relationship between radiological technology students’ modalities of interest and their level of understanding of technical terms–Questionnaire survey of RT students–

ing, participants mentioned that these threemodalities offered many opportunities to comeinto contact with the devices used in thesemodalities during the third-year of on-campus
training. In this way, students could get asense of actual clinical work by handling therelevant devices. In addition, it was thoughtthat the students may have deepened theirknowledge and become interested by studying
the devices. GR was also popular with female
students interested in mammography. However, our university does not have the devices
used for the three modalities with the least
interest (NM, radiotherapy, and angiography).
Therefore, it is possible that students were notinterested in these modalities because they had
not handled the devices associated with thesemodalities. In addition, few lectures are given
on angiography during on-campus education,and there is no on-campus practical training.
As a result, angiography was not interesting
to students, and was scored the lowest of thesix modalities. Participatory training leads tomore improvement in learning motivation andstudy compared with visit-type training, andhas been reported to be effective 2）. In addition, there are reports that participatory training also improves communication skills 3-7）. We
think that some kind of participatory training
should be offered, even for modalities forwhich universities do not have the necessary
equipment. The modalities of most interest to
students after clinical training were those inwhich they had many opportunities to handle
the devices during clinical training and be involved in performing these modalities. Numerous clinical practice hospitals are able to perform imaging position or device operation inthese modalities, meaning that these modalities
were of most interest to students. In addition,
it is thought that the enthusiasm of the radiological technologist instructor at the hospital
who was in charge of students during theirclinical training was also an influential factor. The enthusiasm of the instructor may also

increase satisfaction with clinical practice 8）.
Some students were interested in modalities
about which their instructors were enthusiastic.
In contrast, clinical training in modalities ofless interest to students tended to be those forwhich visit-type training was offered. Theselower-level modalities were also taught withenthusiasm from instructors in clinical practice,
but it is thought that students were more interested in participatory practice than in visit-type
practice. At present, clinical training is limited
to visit-type clinical training in some hospitals
in Japan 9）. However, participatory training isbeing promoted in current clinical training 10）.
There are many participatory clinical training
sessions in clinical training for other medical
occupations 11）. The instructorʼs leadership is
indispensable for participatory training. The
clinical training instructor needs to be able tounderstand studentsʼ acquisition of specialized
knowledge and examine the content of the
training 12）. Participatory practical training has
been promoted in all training modalities for radiological technologists. For all modalities, instructors are expected to improve their teaching skills and introduce participatory training,
mainly in communication skills education,in both on-campus and clinical training. It isthought that studentsʼ motivation will increase
through such high-quality clinical training.
Next, we considered studentsʼ learning levelfor each modality. Before clinical practice, therecognition of the technical term “Seldinger”
used in angiography was 51.5%, which was
the lowest value. Seldinger is a common termin the clinical setting; however, because of thesmall number of lectures on angiography in
our university, this term was less familiar for
students. However, studentsʼ learned about
Seldinger through clinical practice, and thelevel of recognition of this term increased to90.7% after clinical practice. Through clinicaltraining, the recognition level of this term has
increased significantly. Moreover, the recognition of the “Jacoby line”, which is a GR term,
Academic Research Grant Report ◆ 75

also increased after clinical training ( p < 0.05).
However, the recognition level of the Jacoby
line before clinical training was 91.9%, and it
is considered that the students who did notrecognize it increased after learning the Jacoby line during clinical training. The technical term for other modalities had recognitionlevels of 90% or more before and after clinicaltraining, which indicated that technical termswith almost the same difficulty were selected.
However, studentsʼ level of understanding oftechnical term for all modalities was lower
than the recognition level. The level of understanding for technical terms increased throughclinical training, and there was a significant
increase in GR, CT, MR, radiography, and angiography ( p < 0.001). In particular, the understanding level for angiography before clinicaltraining was 4%, but improved to 49.5% after
clinical training. The level of understandingof angiography-related technical term before
clinical training was extremely low, which may
also be attributable to the few angiography
lectures at our university. Therefore, we should
increase the number of lectures on angiography and offer more opportunities for students
to study angiography. In addition, the knowledge gained from pre-clinical training lacks
relevance to clinical training 13）. It is necessary
to educate the students so that the knowledge
gained from pre-clinical training can be related
to clinical training. The level of understandingof autoradiography (ARG), which was used
as a terminology for NM examinations, was
38.4% before clinical training and 47.4% after
clinical training (n.s.). This percentage increasein understanding level was the lowest compared with other modalities. The ARG method
is a quantitative test used for brain perfusion
single photon emission computed tomography(SPECT). Many hospitals in Japan do not use
the ARG method of brain perfusion SPECTin clinical training, meaning there would be
no opportunity to study the ARG method,which may explain the low rate of increase76 ◆ Journal of JART English edition 2021

in understanding. In addition, the level of understanding after clinical training for the mostinteresting modalities was 83.5% for GR, 85.6%
for CT, and 83.5% for MR. The percentage ofunderstanding level for these modalities washigher than the understanding level of modalities with less student interest. This suggeststhat studentsʼ were learned more about theirmodalities of interest. Participatory training
may therefore contribute to more improvementin learning motivation and studying comparedwith visit-based training.
In addition, the terminology of each modality
used this time was examined and selected by
the teachers. However, it should be noted that
there is a possibility that the difficulty level ofthe technical term of each modality is not unified. In this research, we set the degree of difficulty of each modality terminology to “easy”,“normal”, and “difficult”, and adopted the term
corresponding to “ normal” . In the next research, we would like to consider a method of
selecting words that are more consistent than
this time.
In this questionnaire, we excluded ultrasonography. Currently in Japan, radiological
technologists and clinical laboratory technologists are technicians involved in ultrasound.
Ultrasound was excluded from the present
study because few hospitals in Japan haveradiological technologists performing ultrasound. However, ultrasound is one of the tasksof radiological technologists. In the questionnaire survey planned for next year, we intend
to include ultrasound as an option. In addition,
there were modalities for which good results
could not be obtained by extracting technicalterms. We aim to carefully examine the extraction of technical terms for the questionnaire
survey planned for next year.
Our study showed that the most interesting modalities for students were GR, CT, and
MR. These modalities also had high levels oflearning. In hospitals in Japan, young radiological technologists can play an active roleoriginal articles
Survey of the relationship between radiological technology students’ modalities of interest and their level of understanding of technical terms–Questionnaire survey of RT students–

in any modality, and there is a need for multiutility radiological technologists that can respond immediately, even if new equipment isintroduced. The current work of radiological
technologist continues to increase and become
more complex 14）. In addition, with the advancement of medical care, the technology expected of health care worker such as radiological technologist is increasing15-16）. Therefore,
we want students to be interested in all modalities and study all modalities without bias.
This means on-campus training and clinicaltraining should include participatory training
for all modalities. It is hoped that studentsʼ interest and willingness to learn will be increased
by such changes. We want to contribute to
the development of high-quality radiological
technologists required by hospitals. Therefore,
we plan to use this data to inform educational
improvements.
As a future research topic, this study does
not compare the results of the questionnairewith the studentʼs basic academic ability. In the
future, we would like to evaluate the relationship between the results of this questionnaireand basic academic ability. The results of thisstudy are limited to students of Suzuka University of Medical Science. Since different schools
have different teaching methods, the same
research may produce different results at otherschools. In the future, we would like to conduct research on student education that goesbeyond the boundaries of schools throughjoint research with other schools.

5. Conclusion
The purpose of this study was to investigate
the relationship between studentsʼ modalities

of interest in clinical training and their levelof learning for those modalities. Modalities ofmost interest to students were GR, CT, andMR, and the level of learning for these modalities was particularly high. We will improve
our education program based on the results ofthe present questionnaire to contribute to thetraining of high-quality radiological technologists.

Data Availability
The data used to support the findings of thisarticle are available from the corresponding
author upon reasonable request.

Conflicts of Interest
The authors declare that they have no conflicts of interest.

Funding Statement
This study received a research grant in
FY2019 from The Japan Association of Radiological Technologists.

Acknowledgments
We also deeply appreciate the support we
received from Ryo Higashide and Koichi Shibata from the Department of RadiologicalTechnology, Suzuka University of Health Sciences for their cooperation and radiological
technologists from the facility in charge of clinical training. We also thank Audrey Holmes,
MA, from Edanz Group (www.edanzediting.
com/ac) for editing a draft of this manuscript.

Academic Research Grant Report ◆ 77

References
1） H. Muto: Relationship between satisfaction andself-proficiency of clinical training for radiological
technologist; questionnaire survey of students
in radiological technology. The Japan Society of
Education for Radiological Technologists, 9; 3-9,2017.
2） H. Suzuki, et al.: Clinical Clerkship and Extra neural
Clinical Training in Medical Education. Journal of
Clinical and Experimental Medicine (IGAKU NOAYUMI), 256; 919-923, 2016.
3） JN. Itri, et al.: Teaching Communication Skills toRadiology Residents. Curr Probl Diagn Ragiol, 46;
377-381, 2017.
4） A. Takamura, et al.: Community and Interns ʼ Pers
pectives on Community-Participatory Medical
Education: From Passive to Active Participation. FamMed, 49; 507-513, 2017.
5） K. Svensberg, et al.: Nordic Pharmacy Schoolsʼ Ex
perience in Communication Skills Training. Am J
Pharm Educ, 81; doi: 10.5688/ajpe6005, 2017.
6） J. Koponen, et al.: Comparing three experiential
learning methods and their effect on medical studentsʼ
attitudes to learning communication skills. Med Teach,
34; 198-207, 2012.
7） DM. Kaufman, et al.: Communication skills in medical
school: exposure, confidence, and performance. Acad
Med, 75; 90-92, 2000.
8） H. Muto, et al.: Current status and issues of clinicaltraining for radiological technologist; questionnaire
survey of students in radiological technology.
The japan Society of Education for RadiologicalTechnologists, 5; 7-14, 2013.
9） H. Muto: Current status and issues of clinical training
for radiological technologist; survey questionnaires

78 ◆ Journal of JART English edition 2021of studentʼs satisfaction with clinical training facilities.
The japan Society of Education for RadiologicalTechnologists, 8; 9-15, 2016.
10）H. Muto: Educational contents for introducing clinicalparticipatory training -What should be taught at theuniversity before clinical training begins in order to shift
to clinical participatory practices? -. The japan Societyof Education for Radiological Technologists, 10; 1216, 2018.
11）T. Nishizawa, et al.: A study of the ideal way for clinicaltraining of radiological student Improving the qualityof start education and the introduction of participatory
clinical practice. The japan Society of Education forRadiological Technologists, 6; 13-20, 2014.
12）T. Nishizawa, et al.: Suggestion to Clinical Training
in Radiology Technician Education; Problems in
Introduction of Participatory Clinical Training and
its Solutions. The japan Society of Education forRadiological Technologists, 11; 9-18, 2019.
13）M. Okubo, et al.: In Practical Training, a Questionnaire
Survey and Analysis to Pharmacy Students of the
Utilization Situation of the Course Contents ofPharmacy School. Yakugaku Zasshi, 137; 745-755,
2017.
14）B. Reiner, et al.: SCAR Radiologic Technologist Survey:
analysis of technologist workforce and staffing. J Digit
Imaging, 15; 121-131, 2002.
15）T. Terashita, et al.: Problem-based learning forradiological technologists: a comparison of student
attitudes toward plain radiography. BMC Med Educ,
16; Article number 236, 2016.
16）T. Ishida, et al.: Evolving radiological technologists(discussion). Nihon Hoshasen Gijutsu Gakkai Zasshi,
68; 1-13, 2012.

Arts and Sciences
original articles

Received July 5, 2019 ; accepted February 27, 2020

Effects and Limitations of Visceral Fat Area Evaluation and Written Instruction by X-ray Computed
Tomography
MIZUI Masato1）, KASAI Chika2）, SENDA Yutaka3）, TASHIRO Takao4）
1）Suzuka Kaisei Hospital Department of Radiology2）Suzuka Kaisei Hospital Health Examination Center3）Yokkaichi Health Examination Clinic4）Graduate School of Open University of Japan

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 817: 14-19, 2020.
Key words: Visceral Fat Accumulation, CT Scan, Metabolic Syndrome, Obesity【Abstract】

This study aimed to evaluate the effects of visceral fat area, abdominal circumference, and body mass index (BMI)
on X-ray computed tomography (CT) and the effect of comments on results.
In this study, subjects were recruited for 94 months, and 232 subjects were assessed for visceral fat area, BMI, andabdominal circumference, and images and guidance comments were distributed as reports to the subjects.
As a result, 57.6% of the subjects had visceral fat accumulation. These subjects were instructed to improve theirlifestyle after 6 months and reexamined. However, only 9.7% of the subjects followed it. Those who followed thereexamination instructions did not reduce BMI or abdominal circumference but tended to reduce visceral fat area.
We conclude that the motivating effect of this study is limited. However, it was estimated that visceral fat area was
likely to be reduced, even if the reexamination did not reduce weight and abdominal circumference.

Introduction
People in modern society consume more nutrients while consuming less total calories.
As a result, the problems caused by malnutrition have decreased, but the increase in thenumber of obese individuals have led to anincrease in the incidence of various diseases.
Obesity is a problem not only in Japan but alsoworldwide. The countries with the highest percentage of overweight with a BMI ≥ 25 are theUnited States, Mexico, Australia, the United
Kingdom, and China. More than 60% of the
population in these countries is overweight.
The 2002 World Health Report by the World
Health Organization pointed out the importance of measures against cardiovascular diseases, which are rapidly increasing in developed countries and China and Asian countries,
as global health measures 1). The percentage ofoverweight in Japan is 22.4%, which is lower

compared to that of other countries. However,the number of obese individuals is increasing
due to the rapid westernization of eating habitsthat has changed in the last 50 years. Against
this background, even mildly obese individuals
with a relatively low BMI develop lifestyle-related diseases. Thus, Japanese individuals have
low tolerance to obesity and are at greater riskof obese individuals for lifestyle-related diseases than individuals of Western countries.
In 1996, the Ministry of Health, Labour andWelfare focused on individual lifestyle involvement in the factors responsible for obesity, type2 diabetes, dyslipidemia, hypertension, and cardiovascular disease. Moreover, the basic policyof disease management was formulated 2). Subsequently, in 2000, focusing on multiple risk
factor syndrome, a secondary health checkup
benefit system was implemented with workersʼ
accident compensation insurance 3). LDL cholesterol is the greatest risk factor for atheroscleArts and Sciences ◆ 79

rosis, but the accumulation of other risk factors
has been shown to worsen the onset and prognosis of heart disease. When risk factors areaccumulated, it is called metabolic syndrome.
Particularly, visceral fat-accumulating obesity is
considered one of the pathological causes ofmetabolic syndrome.
The initiation of the process of establishingmetabolic syndrome is based on fat accumulation around the abdominal organs, such as thegastroepiploic artery and mesentery. Moreover,when risk factors, such as insulin resistanceand impaired glucose tolerance, arteriosclerosis-inducing lipoprotein abnormality, and hypertension, are accumulated, heart disease islikely to develop. Metabolic syndrome is established through such a process.
The diagnostic criteria for metabolic syndrome were established in April 2005 by theInternational Diabetes Federation and eight related academic societies in Japan 4). The diagnostic criteria in Japan were abdominal circumference of ≥ 85 cm in men and ≥ 90 cm in women and visceral fat area around the navel of >100 cm2 defined as visceral fat obesity. Moreover, among those with visceral fat-fat obesity,
those with at least two of hypertension, hyperglycemia, and cholesterol abnormalities were
defined as metabolic syndrome. In addition,
X-ray computed tomography (CT) is recommended to evaluate the visceral fat area 5), 6). It
is presumed that the reason that the standard
value of abdominal circumference is higher inwomen is that subcutaneous fat is generally
higher in women. Our study found that more
women have normal abdominal circumference
measurements, even though their visceral fat
area is > 100 cm2. The ratio was 2.4 times higher in women than in men 7). Subcutaneous fat
is not a direct cause of arteriosclerosis like visceral fat, and it is difficult to reduce comparedwith visceral fat. If a subject with subcutaneous
fat obesity uses the abdominal circumference
measurement method to determine visceral fat
loss effect due to exercise or the like, it be-

80 ◆ Journal of JART English edition 2021

comes difficult to determine the effect of visceral fat loss. As a result, when the abdominal
circumference measurement method is used todetermine the visceral fat loss effect, there is aconcern that the motivation of the subject who
attempts to reduce visceral fat may be reduced.
If the visceral fat area is evaluated using X-ray
CT, problems like abdominal circumference
measurement method do not occur.
Moreover, an example of the X-ray CT examination method and image display method
used in the visceral fat area evaluation is presented in the obesity clinical practice guidelines 8). However, they are not based on clear
grounds, and it is presumed that they copied
the exposed conditions of abdominal CT usedclinically. In a previous study, we instructedsubjects with visceral fat accumulation assessedby X-ray CT to obtain written guidance andreexamination after 6 months. Subsequent reexaminations investigated the body weight andabdominal circumference of subjects whose
visceral fat area decreased by ≥ 10%. As a result, there was no significant difference in themean weight and abdominal circumference ofthe subjects whose visceral fat area decreased.
In some cases, the body weight and abdominal
circumference increased even though the visceral fat area decreased 9).
This study aimed to examine how the visceral fat area evaluation and written guidance
using X-ray CT affect the subjects.

MethodFrom July 2010 to December 2017 (94 months),
we recruited subjects for bulletin boards, pamphlets, and optional examination of complete
medical examination (Ningen dock). There
were 232 (male/female ratio 107: 125) subjects
in the study. We performed CT of the umbilicalregion of these subjects and analyzed the visceral fat region, BMI, and abdominal circumference using visceral fat region analysis software. Subjects were categorized based on ab-original articles
Eﬀects and Limitations of Visceral Fat Area Evaluation and Written Instruction by X-ray Computed Tomography

Table 1 Classification of subjects by diagnosis and comments of medical doctors
Vicseral
CATEGORY Fat Area
(VFA)
Threshold100cm2or more＋BMI

Abdominal
Circumference
Comments and Instructions

male:
85cm or more
25 or
more Female:
90cm or more＋＋

You are obese and your abdominal circumference is above normal, and you
have a buildup of visceral fat. You need to improve your lifestyle and exercise
habits.
You should improve your lifestyle and reexamination 6 months later.

＋

＋

−

Your abdominal circumference is normal. but you have obesity and visceral fat
accumulation.
You should improve your lifestyle, mainly exercise therapy, and reexamination
after 6 months.

＋

−

＋

You are not obese, but you abdominal circumference is above normal and you
have accumulated visceral fat.
You should improve your lifestyle, mainly exercise therapy, and reexamination
after 6 months.

＋

−

−

You have a normal range of obesity and abdominal circumference, but you haveaccumulated visceral fat. You should improve your lifestyle and reexamination
6 months later.

−

＋

＋

You have excess abdominal circumference and obesity. However, there is novisceral fat accumulation. You should try to control your weight.

−

＋

−

You have a normal abdominal circumference and no buildup of visceral fat.
But you are obese. You should try to control your weight.

−

−

＋

You have no obesity and no visceral fat accumulation. You are only above thenormal range of abdominal circumference. You should develop an exercise
habit.

−−−You have normal abdominal circumference, no obesity, and no buildup ofvisceral fat. You should maintain your current lifestyle.

Your abdominal CT image

HeightVisceral fat

167.7 cm

Body weight81.4 kg

Subcutaneous Fat

274.7 cm2

Visceral Fat

103.8 cm2

BMI

28.9

Ideal weight61.9 kg

Abdominal
circumference

98.1 cm

Subcutaneous fat

Instructions
You are obese and your abdominal circumference is above normal, and you have a buildup
of visceral fat. You need to improve your lifestyle and exercise habits.
You should improve your lifestyle and reexamination 6 months later.

Fig.1 Report example issued to the subject

Arts and Sciences ◆ 81

dominal circumference of 85 cm in men and 90
cm in women, BMI of 25, and visceral fat areain 100 cm2. The guidance comments shown in
Table 1 and the captured images were attachedto the report and results mailed to the subjects.
(Fig.1 shows an example of a report to thesubjects.) Moreover, 134 (male/female ratio,
91: 43) subjects had visceral fat area > 100 cm2.
We instructed them to undergo reexamination
after 6 months.
Then, we investigated changes in visceral fat
area, abdominal circumference, and BMI before and after the initial examination and reexamination of subjects. If the subject underwent
reexamination > 4 months after the initial examination or within 14 months, the result wasdetermined to be valid. Subjects who underwent reexamination earlier or later were excluded from the analysis. Concurrently, we
also observed the compliance rate for reexamination. The deadline for accepting new examination was May 2017, and for subsequent
tests, only those who were reexamined werecounted. The subject paid a cost of 3,000 yen(JPY) (+ 8% tax) for each examination. The
equipment used was Aquilion64 manufactured
by Canon Medical Systems Corporation, andthe visceral fat analysis software used was Slim
Vision manufactured by Cybernet. The imaging conditions were tube voltage of 120 kVp,
tube current of 300 mA, rotation time of 0.5 s,slice thickness of 6 mm, reconstruction filter
function for abdomen (FC10), and slice-andscan imaging method. This study was approved
after undergoing an ethical review at the medical institution that collected the data.

Results
Table 2 shows the subjects who underwent

reexamination and the subjects who were instructed to undergo reexamination but did not
respond (ignored).
Of 134 subjects who were instructed to undergo reexamination, 121 subjects did not respond (male/female ratio, 77: 44), and 13 subjects responded to the reexamination instructions. Subjects reexamination compliance rate
was 9.7%. Table 3 shows the initial examination and reexamination of 13 subjects who responded to the instruction.
The subjects had a male-female ratio of 7: 6,
an average age of 56.6 ± 11.0 years, an average visceral fat area of 130.2 ± 29.4 cm2 at theTable 2 The average value of the gender ratio, age, BMI, abdominal
circumference and visceral fat area of the group that had
been reexamined and were not reexamined（ignored）
Re-Ex

IgnoreMale: Female

7: 6

77: 44Age (yo)56.6 ± 11.0

60.3 ± 11.5

2

VFA (cm )130.2 ± 29.4

137.9 ± 31.5

BMI

26.6 ± 1.9

26.7 ± 3.3

Abdominal Circumference (cm)

89.7 ± 5.7

93.2 ± 7.5

Table 3 Comparison of initial and reexamination of subjects who
have undergone reexaminationn = 13 (Male: 7, Female: 6)

BeforeRe-Ex

VFA (cm )130.2 ± 29.4

119.3 ± 31.4

BMI

26.6 ± 1.9

26.5 ± 2.1

Abdominal Circumference (cm)

89.7 ± 5.7

89.9 ± 5.52

82 ◆ Journal of JART English edition 2021

original articles
Eﬀects and Limitations of Visceral Fat Area Evaluation and Written Instruction by X-ray Computed Tomography

first examination, and an average visceral fat
area of 119.3 ± 31.4 cm2 at the reexamination.
Moreover, the subjects had an average BMI of
26.6 ± 1.9 at the first examination, average BMIof 26.5 ± 2.1 at the reexamination, average
abdominal circumference of 89.7 ± 5.7 cm at
the first examination, and average abdominal
circumference of 89.9 ± 5.5 cm at the reexamination. Nine subjects (male/female ratio, 6:3) exceeded the standard values in all items ofvisceral fat area, BMI, and body weight. In thethree subjects (male/female ratio 1: 2), the visceral fat area and BMI exceeded the standard
values and the abdominal circumference waswithin the standard values. In one subject(male/female ratio, 0: 1), the visceral fat area
exceeded the standard value, and the BMI andabdominal circumference were within the standard value. In the paired t-test, the P-value ofvisceral fat area was 0.06, the P-value of BMI
was 0.39, and the P-value of abdominal circumference was 0.84. Comparing the meanvalues between the initial examination and reexamination of the subjects, there was no significant difference at 5% level. However, thevisceral fat area of four subjects was < 100 cm2
at the time of reexamination, and the visceralfat accumulation disease was resolved (elimination rate of visceral fat accumulation disease,30.8%) (Fig.2).
The average observation period until thesubject underwent reexamination was 351.1 ±86.2 days. The average age of 121 subjects
who did not undergo reexamination was 60.3
± 11.5 years, the average visceral fat area atthe first examination was 137.9 ± 31.5 cm2, theaverage BMI at the first examination was 26.7
± 3.3, and the average abdominal circumference at the first examination was 93.2 ± 7.5
cm. Comparing the subjects who did not respond to the reexamination and the subjects
who responded to the reexamination instructions using the Mann-Whitney U test, visceralfat area showed P = 0.33, BMI showed P =0.89, abdominal circumference showed P =0.14, and age showed P = 0.52 (Fig.3). The
percentage of subjects who could confirm thatthe visceral fat accumulation disease had disappeared was 3.0% (4/134).

Discussion
In this study, we performed abdominal CT

cm2

P = 0.33

P = 0.14
cm2

P = 0.89

P = 0.52

cm

Fig.2 Changes in indicators according to instructions for reinspection

Fig.3 Comparison of people who responded to
instructions for reinspection and those who
did not respond
Arts and Sciences ◆ 83

examinations on 232 subjects who were concerned about visceral fat accumulation and desired to undergo evaluation of the visceral fat
area. As a result, 57.6% (134 subjects) of thesubjects had visceral fat accumulation disease.
These subjects were instructed by mail to undergo reexamination after 6 months by improving their lifestyle, such as exercise anddiet. However, only 9.7% (13 subjects) of thesubjects complied with the reexamination instructions, and 90.3% (121 subjects) did not undergo reexamination.
We believed that the reasons that the subjects did not undergo reexamination were as
follows:“The subject forgot that he was instructed toundergo reexamination.”“The subject was interested in own visceralfat area and wanted to undergo examination
only once.”“The subject died or had difficulty in moving
freely.”“Subjects were not retested because they
were not convinced that they had succeeded in
reducing visceral fat.”Fig.2 shows the group that complied withthe reexamination instructions.
From this figure, the average visceral fat area
tends to decrease even though BMI and abdominal circumference do not decrease. The
results of this study indicate that the effect of
reducing visceral fat area cannot be indirectly
inferred from BMI and abdominal circumference. We are presumed that the subjects who
received the instruction for reexamination used
BMI (or body weight) and abdominal circumference as indicators of progress. However,since many subjects could not confirm theweight reduction effect of BMI (or body weight)
and abdominal circumference, it is consideredthat the motivation of the subjects to continue
the weight reduction effort was reduced. As aresult, we can infer that many subjects did notundergo reexamination. The fact that the decrease in BMI and abdominal circumference

84 ◆ Journal of JART English edition 2021

cannot be confirmed despite the decrease invisceral fat area is consistent with the results ofour previous studies 8). The low reexamination
compliance rate of the subjects is a direct factor that only 3.0% can confirm the resolution ofvisceral fat accumulation disease.
Subjects who desired to measure the visceralfat area themselves are a group that is concerned about their own visceral fat accumulation and wants to know the fact. Thus, it canbe said that this group of subjects has a highinterest in health. Comparing the subjects who
responded to the reexamination and those
who did not respond to the reexamination,
there was no significant difference in all items(visceral fat area, abdominal circumference,
BMI, and age). There is no significant difference between the retested group and non-retested group. Therefore, it can be inferred thatthe subjects with decreased visceral fat area
were not small in the group that did not undergo reexamination. The average visceral fat
area of 13 subjects who adhered to the reexamination instructions tended to decrease
overall from 130.2 ± 29.4 cm2 to 119.3 ± 31.4
cm2, but the P-value was 0.06 in the paired ttest. It has not reached 5% significance level.
This is due to the statistical examination that
included subjects with significantly increased
visceral fat area. The limitation of this study isthat the sample size is small. However, among
the subjects who underwent reexamination,
the elimination rate of visceral fat accumulation disease was 30.8% (4 of 13).
In addition, 53.8% (7 of 13) of the subjects
who underwent reexamination had a visceralfat area decreased by ≥ 10%. It can be inferredthat these test subjects adhered to the written
instruction of the physician. Written instructions by a physician provide some motivation.
However, 90.3% of the subjects did not respond to the reexamination instruction.
Moreover, the subjects who responded to thereexamination instruction were often significantly delayed even though they were instruct-original articles
Effects and Limitations of Visceral Fat Area Evaluation and Written Instruction by X-ray Computed Tomography

ed after 6 months.
Thus, the written instruction of a physicianalone has a limited motivational effect.
Takenaka et al. point out that it can be explained that “health checkups are difficult tosell” 10). The problems are that the subjects must
pay for the reexamination and that he has tovisit the medical institution again for reexamination. We can expect an improvement in thesubjectʼs reexamination rate by improving theservice to the subject. Eventually, we believethat the number of subjects who can confirm
the elimination of visceral fat accumulation disease will increase.

Conclusion
If the subjects were evaluated for visceral fat
area by abdominal CT and the subjects who
pointed out visceral fat accumulation were instructed to undergo reexamination in writing
after 6 months, ≥ 90% of the subjects would not
respond to the reexamination instruction. The
reason is that it is difficult to determine thedecrease in visceral fat area by body weightmeasurement (BMI calculation) or abdominal

References
1） WORLD HEALTH ORGANIZATION: The world healthreport 2002: reducing risks, promoting healthy life.
World Health Organization, 2002.
2） Ministry of Health, Labor and Welfare Public HealthCouncil: About the basic direction of disease control
focusing on lifestyle. December 17, 1996. (Japan)
3） Quoted from Homepage of Osaka Labor Bureau, Ministry of Health, Labor and Welfare. https://jsite.mhlw.
go.jp/osaka-roudoukyoku/hourei_seido_tetsuzuki/anzen_eisei/hourei_seido/kyufu.html (2018 May access).
4） K. Shimamoto: Concept and clinical significance of
metabolic syndrome (metaborikkushindoromunokangaekatatorinshouigi). The Journal of the Japan Medical Association, 136(S29-31), 2007. (Japanese)5） Y. Matsuzawa, et al.: New Obesity Judgment andObesity Diagnostic Criteria (atarashiihimannohanteitohimanshounosindankijun). Journal of Japan Society
for the Study of Obesity, 6(1), 18-28, 2000. (Japanese)
6） New criteria for ʻobesity diseaseʼ in Japan: Examina-

circumference measurement.
It is presumed that the subjectsʼ motivation
decreased because the only methods for confirming the progress until the reexamination
were body weight measurement (BMI calculation) and abdominal circumference measurement. Although the number of samples was
small, the visceral fat area of the subjects who
responded to the reexamination tended to decrease, and 30.8% of the subjects had resolution of visceral fat accumulation disease. Only
3.0% of subjects with visceral fat accumulation
were finally confirmed to have resolved visceral fat accumulation. The main reason is thatmany subjects do not respond to our reexamination instructions.
We conclude that the motivational effect of
abdominal CT on visceral fat accumulation disease in subjects is limited. However, we speculated that the visceral fat area of the subjects
was likely to be reduced even if the bodyweight (BMI) and abdominal circumference
were not reduced.
*There is no conflict of interest in this study.

tion Committee of Criteria for ʻObesity Diseaseʼ in Japan. Japan Society for Study of Obesity, 66(11), 987992, 2002. (Japanese)
7） M. Mizui, et al.: The comparison of man and woman
in the result of the metabolic syndrome CT examination in our hospital. The Journal of the Japanese Society of CT Screening, 19(2), 94-101, 2012. (Japanese)
8） Guidelines for the management of obesity disease.
(Japanese)9） M. Mizui, et al.: Comparison between intra-abdominal
fat area and abdominal circumference amd bodyweight in subjects who successful in reduction of theirvisceral fat accumulation. The Journal of the Japanese Society of CT Screening, 23(3), 32-37, 2016.
(Japanense)
10）K. Takenaka, et al.: What are the efforts to increase
the implementation rate of medical examinations?
-Consider an effective population approach (kenshinnjissiritsuwotakamerudoryokutoha? -koukatekinaa purochiwokangaeru). The Japanese journal for publichealth nurse, 64(12), 1096-1101, 2008. (Japanese)

Arts and Sciences ◆ 85

Arts and Sciences
original articles

Received August 21, 2020 ; accepted November 25, 2020

Basic Evaluations of JIS Certified Radiation Protection Eyewear for Eye Lenses Using Different
Evaluation Methods
KATO Kyoichi1）, KITTAKA Daisuke1）, YASUDA Mitsuyoshi1）, NAKAMURA Tokiko2）,
SATO Hisaya1）, SUZUKI Shoichi3）1）Showa University Graduate school of Health Sciences2）Department of Radiology, Juntendo University Shizuoka Hospital3）School of Health Sciences, Fujita Health University

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 823: 23-30, 2021.
Key words: the lens of the eye radiation exposure, dose reduction, radiation protection【Abstract】

In 2011 the International Commission on Radiological Protection recommended that “the threshold dose for cataracts
and the lens equivalent dose limit should be significantly reduced”, and the Ministry of Health, Labour and Welfare
has notified medical institutions to strengthen measures to protect eye lenses from radiation exposure. This shows thenecessity to protect medical professionals by using equipment with increased levels of protection.
This study developed new radiation protective eyewear in accordance with Japanese Industrial Standards (JIS) foreye lens exposure, and conducted basic evaluations of the protection efficiency in angiography, general radiography,
fluoroscopy, and C-arm applications. The results showed that these newly developed radiation protective eyewear
provide a high level of radiation protection.

Introduction
In recent years, medical devices using radiation have advanced remarkably, and they arewidely used clinically, from diagnosis to treatment. However, patient exposure to radiation
has become an issue. In 1977, the International
Commission on Radiological Protection (ICRP)
has recommended three basic principles in radiation protection: legitimacy, protection optimization, and dose limits. In clinical settings,
there are numerous situations where both
medical professionals and patients are exposed
to radiation. In particular, the eye lens is ahighly radiosensitive organ, and if the dose ofradiation exposure exceeds threshold limits, it
may cause radiation damage such as cataracts.
For this reason, in 2011 the ICRP has conducted epidemiological studies and announced
that the threshold doses recommended in 1990
and 2007 for prevention of lens opacity (5 Gy)
and impaired sight (8 Gy) were underestimat-

86 ◆ Journal of JART English edition 2021

ed, and has amended the values to 0.5 mSv.
Along with this, the ICRP suggested that thelens equivalent dose limit should not exceed
20 mSv / year on average for 5 years and 50
mSv in any one year 1-2). Under the current regulations, with the exposure dose evaluated indirectly by attaching a personal dosimeter,
which measures the 1 cm dose equivalent or
70 μm dose equivalent, to the chest and abdomen or the head and neck, it is difficult to evaluate eye lens exposure accurately. This evaluation method is based on the assumption that
if the dose limits are ensured for a 1 cm dose
equivalent of effective dosage and the 70 μm
dose equivalent for the skin equivalent dose,the dose limit for the eye lens is also assured.
However, as the shielding effects of protection
eyewear have not been considered, a previous
study by Kato et al. (2020) 3) reported the development of protection eyewear that comply
with Japanese Industrial Standards (JIS) (JIS T
61331-3) 4) to achieve further reductions in theoriginal articles
Basic Evaluations of JIS Certiﬁed Radiation Protection Eyewear for Eye Lenses Using Diﬀerent Evaluation Methods

exposure in order to protect eye lenses in clinical settings. In the present study, we conducted basic evaluations of the eye lens protection
efficiencies of protection eyewear used in cardiovascular examinations, chest radiography,
fluoroscopy, and intraoperative examinations,and examined the effectiveness.

Methods
1. Dosimetry

After attaching JIS certified protection eyewear, Dr. B-Go® (manufactured by Dr. Japan
Co., Ltd.), to a phantom, and assuming a clinical standing position, the scattered dose wasmeasured with an optically stimulated luminescence (OSL) dosimeter. We used a small OSL
dosimeter, nano Dot (manufactured by Nagase
Landauer Co., Ltd.) for the dosimeter, PMMA(W D H) 20 cm as the scatterer phantom,
and THRA-1 (manufactured by Kyoto ScientificCo., Ltd.) as the human body equivalent phantom. The measurement conditions were thesame as they would be in actual clinical use in
all tests. Doses were calculated by correcting
the used energy of the OSL dosimeter and thecalibration value for each element involved.

Front

The OSL dosimeters were placed inside andoutside of the front surface of the protection
eyewear, inside and outside the frame for thelateral direction, and above both eyes. Without
protection eyewear, the doses were measured
only directly above both eyes (Fig.1). We used
the following devices: Allura Xper FD10/10(manufactured by Phillips Japan Co., Ltd.) as
the angiography device; CUREVISTA (manufactured by Hitachi, Ltd.) as the X-ray fluoroscope; CALINEO (manufactured by Fujifilm
Medical Co., Ltd.) as the X-ray device; andOEC9900 (manufactured by GE Healthcare Japan Co., Ltd.) as a C arm. We also used Marbic,
lead equivalent 0.5 mmPb (manufactured byGetinge Group Japan Co., Ltd.) for the X-ray
protection plate of the heart catheter (protection
plate); and a scattered ray protection cloth NP(protection cloth), lead equivalent 2.5 mmPb
(manufactured by Hoshina Seisakusho Co.,
Ltd.) for the fluoroscope. The measured values
were the average of three measurements.
1-1

The measurement angle for the cardiovascular radiography was LAO 60 degrees + Caud 30
degrees, the maximum dose in the previousSide

Fig.1 Placement of radiation protective eyewear and dosimeters① eyewear lens surface ② On the top of the eye③ Inside eyewear ④ Outside of eyewear

Arts and Sciences ◆ 87

Fig.2 Measurement geometry and measurement conditions in Angiography

study. The X-ray field was 12 12 inches (30.5
30.5 cm), and the source flat panel detector
distance (SFD) was 110 cm, with the height of
the treatment bed 85 cm from the floor. Assuming a standing position of a technologist, theposition of the phantom was set 40 cm in frontof and 80 cm away from the middle (centerline)of the bed at the surface of the eye, and 150 cm
from the floor to the eye lenses. The tube voltage and current were set as Full Auto for PMMA
20 cm. For filters we used 0.1 mm Cu + 1.0 mm
Al in the radiography, and 0.4 mm Cu + 1.0 mm
Al for the fluoroscopy. The irradiation durations were 1 minute for imaging and 10 minutes for the fluoroscopy. The fluoroscopy was
operated at 15 frames / sec (Fig.2).
1-2

For the chest radiography, assuming a technologist assisting a patient, the phantom wasplaced 50 cm from the middle (centerline) of
the patient phantom. The SFD was 130 cm,
and the height of the centerline of the detector
was 122 cm from the floor. The human phan-

88 ◆ Journal of JART English edition 2021

tom was at 150 cm from the floor, at 50 cm tothe surface of the eye lenses, and 150 cm fromthe floor to the eye lenses. The irradiation angle, fluoroscopy / imaging conditions, and position of the dosimeter were tube voltage / current 90 kV / 20 mAs for the PMMA of 20 cm.
The irradiation field was 17 17 inches (43.2
43.2 cm), and the filter was 0.1 mm Cu at thetime of the radiography ; with 10 times of imaging (Fig.3).
1-3

In the fluoroscopy, a scattered radiation protection cloth NP was attached to the device,
and assuming a standing position of the technologist, the position of the surface of the eyelenses of the phantom was 60 cm in front ofand 80 cm away from the middle of the bed,
and the distance from the floor to the eye lenses was 150 cm. In the fluoroscopy, the tube
voltage and current were set as Full Auto for
PMMA 20 cm, 92 kV, 0.7 mA, 21 21 inches(53.3 53.3 cm), and a 120 cm source-image
distance (SID), at 6.3 Pulse / sec for 10 min-

original articles
Basic Evaluations of JIS Certiﬁed Radiation Protection Eyewear for Eye Lenses Using Diﬀerent Evaluation Methods

Fig.3 Measurement geometry and measurement conditions in General radiography

Fig.4 Measurement geometry and measurement conditions in Fluoroscopy

utes. In the radiography, the tube voltage andcurrent were 82 kV, 200 mA; 21 21 inches(53.3 53.3 cm); 120 cm SID; with 20 times ofimaging (Fig.4).

from the middle of the bed to the surface ofthe eye lenses, and 150 cm from the floor to
the eye lenses. Other conditions were 85 kV,
3.5 mA, SID 120 cm, 4 Pulse/sec, and a 5 minduration (Fig.5).

1-4

In the fluoroscopy for an intraoperative Carm, assuming a standing position of the technologist, the human body phantom was set ata distance of 50 cm in front of and 50 cm away

Results
1-1

Table 1 shows the results of the measureArts and Sciences ◆ 89

Fig.5 Measurement geometry and measurement conditions in C-armwear), 0.124 mGy and 0.038 mGy (front-external side of the right eyewear), 0.036 mGy and0.014 mGy (front-internal side of the right eyewear), 0.088 mGy and 0.016 mGy (lateral-external side of the right eyewear), and 0.026
mGy and 0.001 mGy (lateral-internal side of
the right eyewear). Immediately above the left
and right eyes without protection eyewear andprotection plate: 0.091 mGy and 0.078 mGy;theleft and right eyes with protection eyewear andments with the angiography settings. The values with protection eyewear and without protection plate and with protection eyewear andprotection plate at each position were as follows: 0.339 mGy and 0.095 mGy (lateral-external side of the left eyewear), 0.179 mGy and0.052 mGy (lateral-internal side of the left eyewear), 0.263 mGy and 0.080 mGy (front-external side of the left eyewear), 0.050 mGy and0.018 mGy (front-internal side of the left eye-

Table 1 Radiation protection dose by radiation protection eyewear and protective plate in Angiography：protective plate（−）
eyewear（＋）：protective plate（＋）
eyewear（＋）

Left side: Outside of eyewear

0.339

0.095

Left side: Inside eyewear

0.179

0.052

Left front: Outside of eyewear

0.263

0.080

Left front: Inside eyewear

0.050

0.018

Right front: Outside of eyewear

0.124

0.038

Right front: Inside eyewear

0.036

0.014

Right side: Outside of eyewear

0.088

0.016

Right side: Inside eyewear

0.026

0.001

On the top of the left eye

0.091

0.078

On the top of the right eye

0.114

0.030

：protective plate（−）
eyewear（−）：protective plate（＋）
eyewear（−）

On the top of the left eye

0.300

0.090

On the top of the right eye

0.130

0.036

Angiography（mGy）

90 ◆ Journal of JART English edition 2021

original articles
Basic Evaluations of JIS Certified Radiation Protection Eyewear for Eye Lenses Using Different Evaluation Methods

Table 2 Radiation protection dose by radiation protection eyewear in General radiography
eyewear（＋）

eyewear（−）

Left side: Outside of eyewear

0.098

−

Left side: Inside eyewear

0.083

−

Left front: Outside of eyewear

0.139

−

Left front: Inside eyewear

0.012

−

Right front: Outside of eyewear

0.009

−

Right front: Inside eyewear

0.007

−

Right side: Outside of eyewear

0.087

−

Right side: Inside eyewear

0.028

−

On the top of the left eye

0.022

0.150

On the top of the right eye

0.099

0.131

General radiography（mGy）

Table 3 Radiation protection dose by radiation protection eyewear and protective cross in Fluoroscopy：protective cross（−）
eyewear（＋）：protective cross（＋）
eyewear（＋）

Left side: Outside of eyewear

0.166

0.006

Left side: Inside eyewear

0.045

0.006

Left front: Outside of eyewear

0.163

0.002

Left front: Inside eyewear

0.016

0.003

Right front: Outside of eyewear

0.125

0.015

Right front: Inside eyewear

0.009

0.002

Right side: Outside of eyewear

0.021

0.001

Right side: Inside eyewear

0.036

0.001

On the top of the left eye

0.030

0.002

On the top of the right eye

0.031

0.002

Fluoroscopy：protective cross（−）
eyewear（−）：protective cross（＋）
eyewear（−）

On the top of the left eye

0.156

0.006

On the top of the right eye

0.087

0.003
（mGy）

protection plate: 0.114 mGy and 0.030 mGy.
Immediately above the left and right eyes
without protection eyewear and protection
plate vs. without protection eyewear and withprotection plate were 0.300 mGy and 0.090
mGy (left), 0.130 mGy and 0.036 mGy (right).
1-2

Table 2 shows the measurement results withthe general radiography. Values with protection eyewear at each position were as follows:
0.098 mGy (lateral-external side of the left eyewear), 0.083 mGy (lateral-internal side of theleft eyewear), 0.139 mGy (front-external sideof the left eyewear), 0.012 mGy (front-internalside of the left eyewear), 0.009 mGy (front-ex-

ternal side of the right eyewear), 0.007 mGy(front-internal side of the right eyewear), 0.087
mGy (lateral-external side of the right eyewear), 0.028 mGy (lateral-internal side of theright eyewear). Values immediately above theleft eye with protection eyewear vs. without
protection eyewear were 0.022 mGy and 0.150
mGy; those of the right eye were 0.099 mGy
and 0.131 mGy.
1-3

Table 3 shows the measurement results withthe fluoroscopy. Values with protection eyewear and without protection cloth and withprotection eyewear and protection cloth ateach position were as follows: 0.166 mGy andArts and Sciences ◆ 91

0.006 mGy (lateral-external side of the left eyewear), 0.045 mGy and 0.006 mGy (lateral-internal side of the left eyewear), 0.163 mGy and0.002 mGy (front-external side of the left eyewear), 0.016 mGy and 0.003 mGy (front-internal side of the left eyewear), 0.125 mGy and0.015 mGy (front-external side of the right eyewear), 0.009 mGy and 0.002 mGy (front-internal side of the right eyewear), 0.021 mGy and0.001 mGy (lateral-external side of the righteyewear), 0.036 mGy and 0.001 mGy (lateralinternal side of the right eyewear). Immediately
above the left and right eyes without protection eyewear and protection cloth vs. with protection eyewear and protection cloth were0.030 mGy and 0.002 mGy (left), 0.031 mGy
and 0.002 mGy (right).
Values immediately above the left eye without protection eyewear and without protection
cloth vs. without protection eyewear andwith protection cloth were 0.156 mGy and0.006 mGy; those of the right eye were 0.087
mGy and 0.003 mGy.

(front-external side of the left eyewear), 0.002
mGy (front-internal side of the left eyewear),0.015 mGy (front-external side of right eyewear), 0.001 mGy (front-internal side of theright eyewear), 0.001 mGy (lateral-externalside of the right eyewear), 0.012 mGy (lateralinternal side of the right eyewear).
Values immediately above the eyes were0.006 mGy (left) and 0.006 mGy (right). Without protection eyewear, values immediately
above eyes were 0.011 mGy (left) and 0.010
mGy (right).

Discussion
The developed protection eyewear use eyewear lenses containing high-density lead, alead equivalent of 0.88 mmPb. In addition,
since the frame is also lead-coated, the frame
provides protection also for the direct radiation.
Further, for the scattered radiation from the vertical and lateral directions there is also a protective effect as the frame is designed to reduce
the gap between the frame and the surface ofthe skin. In the basic measurements in previous
studies using only protection eyewear, a 98% or
better protection against exposure to direct
frontal radiation over the full range from 80 kV
to 140 kV. There was also protection against
direct lateral radiation: the maximum was 80%
or better, and the minimum was 66% or better.

1-4

Table 4 shows the measurement results withthe fluoroscopy for an intraoperative C-arm.
Values with protection eyewear at each place
were as follows: 0.017 mGy (lateral-externalside of the left eyewear), 0.007 mGy (lateralinternal side of the left eyewear), 0.018 mGy

Table 4 Radiation protection dose by radiation protection eyewear in C-arm
eyewear（＋）

eyewear（−）

Left side: Outside of eyewear

0.017

−

Left side: Inside eyewear

0.007

−

Left front: Outside of eyewear

0.018

−

Left front: Inside eyewear

0.002

−

Right front: Outside of eyewear

0.015

−

Right front: Inside eyewear

0.001

−

Right side: Outside of eyewear

0.001

−

Right side: Inside eyewear

0.012

−

On the top of the left eye

0.006

0.011

On the top of the right eye

0.006

0.010

C−arm

（mGy）

92 ◆ Journal of JART English edition 2021

original articles
Basic Evaluations of JIS Certified Radiation Protection Eyewear for Eye Lenses Using Different Evaluation Methods

When a protection plate was introduced together with the protection eyewear, the scattered dose reduced to about 1/7 on average,
suggesting that the combined use of eyewear
with a protection plate has a very considerable
effect on lens radiation protection 3).
In the measurements for the present study,
the maximum dose that a technologist is exposed to in one procedure in cardiovascularangiography would be 0.300 mGy on the lateral-external side of the left eyewear without protection eyewear and without a protection plate,with an average of 20 mGy over 5 years. Therefore, the threshold value of the eye lens will be
exceeded after performing 66 procedures. The
result immediately above the right eye is 0.13
mGy, and with this exposure the thresholddose will be exceeded after performing 153
procedures, and even with protection eyewear
without a protection plate there is the possibility of exceeding the upper limit of the threshold dose for the eye lens.
Considering a maximum of 50 mGy per year,
166 cases can be handled.
However, physicians who handle many cases
or perform treatment that last longer periods
may exceed the threshold dose. With protection eyewear and protection plate, the maximum exposure per procedure dose is 0.095
mGy at the lateral-external side of the left eyewear. Assuming a threshold value of 20 mGy,
210 cases could be acceptable, and if thethreshold is considered as 50 mGy, 526 cases
would become acceptable. Overall, these numbers suggest that it is preferable to use a radiation protection plate together with the protection eyewear.
It is estimated that the maximum dose of
scattered radiation that a radiologic technologist who assists patients in general radiography
receives in one month is 0.15 mGy immediately above the left eye without protection eyewear and protection plate, averaging 20 mGyover 5 years. Based on this estimate, a radiologic technologist can perform assistance 133

times. The dose immediately above the righteye is 0.131 mGy, giving an estimated numberof possible procedures of 153. However, if theannual number of working days is 200, there isa strong possibility that this upper limit will be
exceeded. With a maximum dose of 50 mGy
per year, this would allow 333 times of exposure. In this case, 1.6 times of assistance per
day for 200 days could exceed the thresholdvalue. With protection eyewear, the dose immediately above the left eye is 0.022 mGy, andthat at the right eye 0.099. Compared to thesituation without protection eyewear, the exposure doses with protection eyewear were
1/6.80 for the left eye and 1/1.30 for the righteye. These results show the necessity to use
protection eyewear when assisting patientsduring general radiography, resulting in good
agreement with the results reported by Takei 5).
Results of the measurements assuming fluoroscopy showed that the exposure doses withboth protection eyewear and protection cloth
decreased to 1/78 on the left eye and 1/43.5 on
the right eye compared to the case without
such devices. The doses with only protection
cloth became 1/26 on the left, and 1/29 on theright eye. Considering the threshold value of
20 mGy, 128 tests could be performed without
using protection eyewear and protection cloth,and 645 with only protection eyewear. Using
both, it will be possible to handle 10,000 tests
annually. This suggests the advantage of using
protection eyewear at the very least.
When using the C-arm, the maximum dose
without protection eyewear is 0.011 mGy immediately above the left eye, averaging 20
mGy for 5 years, and suggesting 1,818 tests are
possible. Further, wearing only protection eyewear is effective because the exposure dose isreduced by half.
This present study did not measure the doses
at CT tests, but it is considered that wearing
protection eyewear is an effective means forprotecting the eye lens of technologists who
assist patients during CT examination or perArts and Sciences ◆ 93

form biopsies with CT.
Akahane reported that “The shielding effectof protection eyewear is affected by the positional relationship between the head, the eyewear, and the radiation source. If the positionof a technologist is not directly facing the radiation source, the shielding effect of the protection eyewear is reduced. If the gap between
the eyewear and the face is large, the shielding
effect of the protection eyewear may easily beattenuated. When a dosimeter is attached tothe inside of the protection eyewear, it is difficult to detect the attenuation of the shielding
effect of the protection eyewear, and there is arisk of underestimation when using these values as a standard for the eye lens equivalentdose” 6). As described above, because the distribution of the scattered radiation is complicated, it is possible that the results in the present
study will differ from the results of other basic
experiments on lenses and materials, and there
may be influences of wraparound radiation(radiation from unexpected angles) and thesecondary scattering as errors due to the influence of the incident direction.
The measurement results are notated as Gy
as physical quantities. Further, we think it isacceptable to consider the absorbed dose in
Gy of the eye lens and the equivalent dose in
Sv as equal because this study targets the eyelens, and the radiation weighting factor is 1.0
for X-rays.

References
1） ICRP, 1991. 1990 Recommendations of the International Commission on Radiological Protection. Publication 60. Ann. ICRP, 21(1-3), 1991.
2） ICRP, 2012 ICRP Statement on Tissue Reactions /Early and Late Effects of Radiation in Normal Tissues
and Organs – Threshold Doses for Tissue Reactions in
a Radiation Protection Context. ICRP Publication 118.
Ann. ICRP, 41(1/2), 2012.
3） Kato Kyoichi, et al.: Development of radiation protective eyewear for the lens of the eye. The Showa University Journal of Medical Sciences, 80(4); 2020.

94 ◆ Journal of JART English edition 2021

Limitations of the study

The measurements in the present study
showed a high protective effect, but in actual
clinical practice, some cases take more time forthe treatment, and in that case, the fluoroscopy
time, the number of radiographies, and thelarge angle of the load would increase, affecting the values of the protective effect.

Conclusions
We conducted a basic evaluation of the JIScompliant protection eyewear developed inthis study. As the results show highly protective effects for various clinical settings, it wasestablished that the protection eyewear are effective as a device for eye lens protection.
Acknowledgments

We wish to express our sincere gratitude to
Ikuo Kobayashi (Nagase Landauer, Ltd.) for
helpful and supportive cooperation in thisstudy.
Conflict of interest

This study was conducted with researchfunding under a contract for joint research anddevelopment between the Dr. Japan Co., Ltd.
and Showa University.

4） JIS. Protective devices against diagnostic medical Xradiation- Part 3: Protective clothing, eyewear and protective patient shields, JIS T61331-3: 2016.
5） Takei Yasutaka: The Non-uniform Exposure of Medical
Staffs in General Radiography. Journal of radiation protection research, 16(2),10-13, 2017.
6） Akahane Masaaki: Shielding effects of protection eyewear, Levels and factors of variation. 3rd Radiation
Council, Radiation Protection Study Group for Eye
Lens, Document 4.
www.nsr.go.jp/data/000205423.pdf (Accessed on2020 Jan. 29)

Contribution

Global Extension of Medical Technologies: What
can Radiologic Technologists do for Global Health?
KONO Yuzuru
Affiliation: Department of Radiology,
Department of Global Network and Partnership,
National Center for Global Health and Medicine, Japan

Note: This paper is secondary publication, the first paper was published in the JART, vol. 67 no. 814: 41-44, 2020.

Suppose that you are asked a questions fromone of your colleagues like, “What can we dofor global health?” How would you answer thequestion? Most of our colleagues would probably say “Sorry, pal. That should not be for radiologic technologists but for medical doctors
and nurses.”
I would do likewise, unless I had participated in the project of global extension of medical
technologies.
Most of the readers however, may not be familiar with this.
The projects are defined as follows;
The projects of global extension of medical
technologies dispatch Japanese experts in thefield of health policy, social security, healthcare and health industry to developing countries and accept health staff from various countries. Through these activities, Japan intends
to share experiences of medical institutions
such as the public health insurance schemeand promote excellent medical technologies,
drugs and equipment. Thus, the projects aim
to improve public health and medicine in developing countries while facilitating growth ofJapanese health industry. Such activities are
expected to increase trust in Japan in the international society and derive win-win relation
between Japan and developing countries 1）.
As you can image, there are many applicants

and lots of projects are carried out in developing countries. Among them, one that I joined
in and broadened my horizon is “Enhancing
computed tomography (CT) and cardio angiography in Republic of Zambia”.
For those who are not well informed of, letme introduce Zambia.
Zambia, unlike most of its neighbors, hasmanaged to avoid the war and upheaval thathas marked much of Africaʼs post-colonial history, earning itself a reputation for political stability. The landlocked country has experienced
rapid economic growth over the last decade as
Africaʼs second largest copper producer after
the DR Congo. But its over-reliance on copper
has made it vulnerable to falling commodity
prices. Zambia also has one of the worldʼs fastest growing populations with the UN projectingthat its population will triple by 2050. But economic growth and massive Chinese investment
have failed to improve the lives of most Zambians, with two-thirds still living in poverty 2）.
Zambia used to be British territory and theofficial language is English (less language barrier to us comparing to French-speaking area).
Victoria Falls, one of three largest waterfalls
in the world, attract lots of people from all of
the world. The distance between Tokyo andLusaka, the capital of Zambia, is approximately
12,917 km, and the flight time (Emirates flights)
from Narita international airport to Lusaka
Contribution ◆ 95

Fig.1

Fig.3

Fig.2

airport is 22 hours and 25 minutes via Dubai(Fig.1, 2, 3) ! No direct flight service is available. You cannot survive without movies orvideo games!

before the project (Fig.4).

The summary of the “Enhancing CT imaging
and cardio angiography in Rep. of Zambia”
project is as follows; University Teaching Hospital (UTH) in Lusaka procured two Canonʼsradiology systems in 2015: CT and cardio angiography. However, owing to the lack of skills
and knowledge of the staff, and sometimes
infrastructure gap (blackouts happen quite
often), the systems were not used effectively

Here is our story.
CT (2017)
Four radiologic technologists from the UTH
were invited and received education in Japan.
Contents of education include imaging protocol management, CT radiation dose control,
quality assurance/quality control (QA/QC) of
medical imaging devices, patient treatment,
etc. Through the intense hard training, trainees
in this project succeeded cardiac CT angiography (cardiac CTA). Eventually, Zambia became
the second country (after Rep. of South Africa)

Fig.4

Fig.5

96 ◆ Journal of JART English edition 2021

Contribution
Global Extension of Medical Technologies: What can Radiologic Technologists do for Global Health?

to perform cardiac CTA in Southern Africancountries. The fact was reported through themedia (TV and newspaper) across the country
and drew lots of attention.
Improved diagnostic CT imaging gathers
more clinical requests and resulted in increasing the number of CT cases from 40 a day (before the project) to 60 (after the project) : a 50%
jump rise! (Fig.5). The impact of the project
has progressively grown and finally extended
to Ministry of Health and Welfare. CT scannerʼsmaintenance and user support contract wereconcluded in 2019.
Please note that it is very unusual for a developing country to conclude an equipment
maintenance contract.
After the conclusion, the CT scanner has
been running 24/7 and providing useful clinical imaging.
UTH even procured a new Japanese 3D
work station in 2019, preparing for explosive
increase in Cardiac CTA. They decided to strikeout on their own.
Cardio angiography (2018 and 2019)
Added to four radiologic technologists, one
cardiologist and three nurses from UTH wereinvited and received education in Japan for thisproject.
The purpose of this project is to provide
world-standard cardio angiography and percutaneous coronary intervention (PCI) in UTH.
Unless otherwise, they would have to go to

Fig.6

South Africa for the medical treatment. Education contents for radiologic technologists include imaging protocol management, radiationdose control, quality assurance/quality control(QA/QC) of medical imaging devices, patient
treatment, etc. They received training in thecath lab of National Center for Global Healthand Medicine (NCGM) and Terumo Medical
Planex (Terumo Co. Tokyo, Japan).
After the hard training of two years, the UTH
cath lab team succeeded the first PCI case in
November 2019: the second country (after
Republic of South Africa) in Southern Africancountries (Fig.6).
Like the CT project, the fact was reported in
the local media (TV and newspaper) throughout the country (Fig.7). The cardiologist became famous overnight and was invited to see“Vice President of Zambia”. The meeting was
so quite an event to her that he keep appearing
on her cell phone wall paper since then.
On the last day of our visit to UTH in November 2019, an unforgettable event happened. A South African patient of acute
myocardial infarction was transferred froma modern private hospital for his treatment.
Although it was an early morning emergency
case, PCI was successful. The patient was thendischarged in a couple of days later and returned to Rep. of South Africa safely.
The UTH director was so delighted to hear
the news and it is not surprising to see that he

Fig.7
Contribution ◆ 97

Fig.8Fig.9

called the cardiologist “My daughter” since.
Please keep in mind that it is very unusual totransfer patients from a private hospital (often
foreign-affiliated and modernized) to a public
one (often older and not well-equipped).

So after the event, if a friend of mine ask me“Hey, whatʼs in it flying over such a long distance to see your colleagues?”
I would answer the silly question “For global
health promotion and it is definitely worthwhile.”
The project made me believe this.

The UTH staff were kind enough to invite
us Japanese staff to join a weekend safari park
tour. We had a big party over there (Fig.8, 9).
UTH team and NCGM still keep in contact
with each other; which serves great assets to
us. The project also had impact on academic
performance and achievement. Several of the
UTH staff were motivated to enroll in a college
and a postgraduate course.

98 ◆ Journal of JART English edition 2021

References
1） National Center for Global Health and Medicine,Japan, Bureau of International Health Cooperation,
http://kyokuhp.ncgm.go.jp/etc/gpmap/index.html
2） Zambia country profile-BBC News, https://www.bbc.
com/news/world-africa-14112449

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
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. Only members of the Association may submit to the Journal, etc., unless the author is not aradiographer, in which case this condition does not apply.
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 andimportant 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.
Regulations and Requirements for Submissions ◆ 99

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.

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.

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

The formatting requirements for manuscripts specified in Article 7 of the submission regulations of the
Journal of the Japan Association of Radiological Technologists are as follows:
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.
①Enter the authorʼs name, facility name, affiliation, occupation, and contact information, and selectthe specialized field.
②Select the type of post.
③Enter the title and co-author information in Japanese and English. Co-authors are limited to membersof the Society. However, this does not apply if the co-author is not a radiological technologist.
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
For the text and figures/tables, create and post both a separate file and a file containing figures andtables within the text.
①The manuscript should be written in Japanese or English.
Create the manuscript using Word with a paper size set to the A4 size. The type and size of the
fonts should be 12 points for both Japanese and English fonts, Mincho font, and Times. The line
spacing should be 18 points. Leave a margin of 2 cm or more on the top, bottom, left, and right.
②The specified number of pages and excess page costs of the manuscript are as shown in thefollowing table.

100 ◆ Journal of JART English edition 2021

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).
⑤Indicate the insertion position of the figure/table in red in the text created as a separate file fromthe figure/table.

⑥The figures and tables created as separate files from the main text are of higher resolution and canbe subjected to secondary processing in production.

⑦For academic treatises, write the title and characters in the table in English.
⑧When reprinting figures/tables, specify the source and obtain permission.
⑨Attach the explanation of the figures and tables in Japanese in a separate file.

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 Ⓡ.
2. Submission of copyright transfer agreement(1) The first author and co-authors must agree with the contents of the copyright transfer agreement
stipulated in the copyright management regulations.
(2) The copyright transfer agreement shall be stipulated by the rules regarding copyright management,
and the format specified on the Societyʼs website should 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 composition of the text is as follows (1) to (9).
(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

Regulations and Requirements for Submissions ◆ 101

Journal of JART–English edition 2021–

June 1, 2021
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
http://www.jart.jp
・Published by The Japan Association of Radiological TechnologistsⒸ2021, Printed in Japan.

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