2022
Journal of— E n g l is h e d i t io n —2220

The Japan Association of Radiological Technologists

Journal of2220—English editio 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)

6

original articles

Arts and Sciences

Radiological assessment of joint space width using different weight-bearing
radiographic methods for knee osteoarthritis
YAMAGUCHI Masanori, KOSEKI Hironobu, ENGUCHI Kousei, IWANAGA Hitoshi, KYUMA Shunta, SHINDO Hiroyuki

13

original articles

New simple imaging method for short-axis view in cardiac MRI inferredfrom chest X-ray
FUJII Tomoki, USUI Hiromi, SATO Hisaya, KATO Kyoichi

25

original articles

Calculation of optimal TI associated with temperature changes of the waterusing Synthetic MRI assuming postmortem brain FLAIR imaging
OKAWA Ryuya, YASUI Go, KANAI Yoshihiro, MIHARA Ban, HAYASHI Norio

33

original articles

Trial of dose reduction of Digital Breast Tomosynthesis
HAYAKAWA Saki, SHINOHARA Norimitsu

40

original articles

Modification methods of radiographic conditions alternative to tube voltage
coefficient chart
HATAKEYAMA Norihito

47material

New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–
MOCHIGI Kazuya, SHINAGAWA Kazuki

58

material

Portable chest X-ray examination procedures for COVID-19-positive patients:
performance time necessary for radiological technologists
KOBAYASHI Tomoya, ISHIBASHI Tomomichi, SOMEYA Satoka, TASHIRO Kazuya, ITO Yoshiyuki, MIYAMOTO Katsumi,
YOKOKAWA Hiroshi, SHIIGAI Masanari, SHIOTANI Seiji

66

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

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 2022

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

Foreword ◆ 3

History

The Japan Association ofof Radiological Technologists ( JART)

1947
1951

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

1983

1985

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

1954

1956

1962

1968

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

1969

1975

1979

1987

1989

1991

1993

1994

1995

1996

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

1998

Completion of the Education Center for
JART

1999

4 ◆ Journal of JART English edition 2022

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

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

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

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

2000

2001

2003
2004

2005

2006

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

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

2014

Relocation of offices to the World Trade
Center Building in Tokyo

Launch of the radiation exposure advisor
certification system

2015

Revision of the Medical Exposure Guidelines

2008

2009

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

2010

2011

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

2012

2019

2020

2021

Renaming as public interest incorporated association JART

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

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

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

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

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

Holding the 23th AACRT with 37th JCRT in
Tokyo

2022

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

History of JART ◆ 5

Arts and Sciences
original articles

Radiological assessment of joint space width using different weight-bearing radiographic methods for knee osteoarthritis
YAMAGUCHI Masanori1）, KOSEKI Hironobu2）, ENGUCHI Kousei1）, IWANAGA Hitoshi3）,
KYUMA Shunta1）, SHINDO Hiroyuki3）1）Department of Radiology, Wajinkai Hospital2）Department of Health Sciences, Nagasaki University Graduate School of Biomedical Sciences3）Department of Orthopedic Surgery, Wajinkai Hospital

Note: This paper is secondary publication, the first paper was published in the JART, vol. 65 no. 783: 22-26, 2018.
Key words: Osteoarthritis, Knee, Joint space width, Radiograph【Abstract】

Background. Although joint space width on weight-bearing radiographs of the knee is critical for early diagnosis andgrading knee osteoarthritis, the optimal method with which to accurately measure this value remains controversial.
Materials and Methods. We compared plateau gaps and joint space widths on bilateral weight-bearing plainradiographs acquired using three different methods in 17 medial knee osteoarthritis patients (32 knee joints): standing
with the knee extended (standard imaging method); SynaFlexer method; and modified Rosenberg method. Measured
values were compared statistically, with values of P < 0.05 considered significant.
Results. Maximum plateau gap in the medial compartment was significantly lower with the SynaFlexer method (3.9
± 1.3 mm) and modified Rosenberg method (2.9 ± 1.5 mm) than with standard imaging method (5.8 ± 2.0 mm; P< 0.05 each). Minimum width of the medial joint space was also significantly lower with the SynaFlexer method (3.6
± 1.3 mm) and modified Rosenberg method (3.1 ± 2.1 mm) than with standard imaging method (4.6 ± 1.6 mm; P <0.05 each).
Conclusion. With the SynaFlexer method and the modified Rosenberg method, the X-ray beam can pass parallel to themedial tibial plateau, and the area with the most thinning of femoral condylar cartilage can be observed. Therefore,
we believe that the SynaFlexer and modified Rosenberg methods are useful for diagnosing early osteoarthritis and forthe assessment of disease severity.

1. Background
Knee osteoarthritis (OA) is one of the mostcommon musculoskeletal disorders, particularly among elderly persons. This is of major
concern because the proportion of people inthis age range is rapidly increasing, and a medical means to stop progression of knee OA is
currently unavailable. The estimated prevalence of symptomatic and asymptomatic knee
OA in Japan is about 8 and 25 million respectively 1). In order to diagnose and evaluate theseverity of knee OA, the precise measurementof articular cartilage thickness is essential 2).
Magnetic resonance imaging (MRI) can directly visualize joint cartilage and provide an
accurate measure of cartilage volume, thick-6 ◆ Journal of JART English edition 2022

ness, and surface areas 3). However, investigations of articular cartilage using MRI have generally been limited to quantifying total cartilage
plates or femoral sub-regions because the progression of cartilage loss occurs heterogeneously 4). Moreover, MRI requires a large accommodation space and specially dedicatedtechnicians, and may causes distress for claustrophobic patients. Measuring joint space width(JSW) in weight-bearing radiographs can indirectly reflect articular cartilage thickness and it
is currently accepted as the primary structural
outcome measure for clinical studies of knee
OA. X-ray equipment spreads widely in many
institutions, and relatively inexpensive. Although standard weight-bearing radiographic
assessment of JSW is generally accepted as theoriginal articles
Radiological assessment of joint space width using different weight-bearing radiographic methods for knee osteoarthritis

most relevant 5), it is associated with someproblems. Multi-center trials have verified that
JSW reproducibility on knee radiographs acquired in the traditional weight-bearing position with full knee extension is inadequate 6, 7).
Furthermore, visualizing both the anterior andposterior margins of the tibial plateau is often
inadequate because most knee OA occurs in
the medial compartment, the optimal alignment of which is usually inclined posteriorly 8).
Moreover, the most obviously thinned regionof articular cartilage is in the 30 ~ 60 posterior
aspect of the femoral condyle, which cannot
be reflected 8, 9). Therefore, a critical need for
accurate and precise radiographic quantitation
has emerged.
The present study aimed to define differences in measured values derived from plain
weight-bearing radiographs of the knee acquired using three different methods and toinvestigate the optimal usage to evaluate knee
OA. This study was approved by the Ethical
Review Board of Wajinkai hospital and the objectives of which were explained in detail inwriting and verbally to all participants. Informed consent was obtained from each patient prior to enrollment.

2. Patients and Methods
Patients

17 patients (32 knee joints) with medial knee
OA were qualified for inclusion based on clinical and radiographic evidence of chronic knee
pain with Osteoarthritis Research Society International (OARSI) grades 1 or 2 10). Exclusion criteria included evidence of other types of arthritis, such as previous trauma, surgical intervention, or treatment with corticosteroids. Participants included 12 female patients (22 knee
joints) and 5 male patients (10 knee joints), andthe average age of was 64.7 years (range: 55 84 years) (Table 1). All patients were seronegative for rheumatoid factor and had erythrocyte
sedimentation rates within the normal range.

Table 1 Physical characteristics of the study participantsAge

64.7（55～84）

Hight (cm)159.5（148～176）

Body weight (kg)65.0（55～100.4）

BMI(Body Mass Index)(kg/m2)

25.5（19.7-32.4）

Experimental design

Bilateral femorotibial radiographs were taken using a high-voltage device (KXO-80G,
Toshiba, Tokyo, Japan) and a beam-limiting
device (TF-6TL-6, Toshiba) under conditions of
50 kV, 100 mA, 0.1 sec. and an image distanceof 100 cm. All imaging was performed by one
radiology technician under uniform conditions.
Three different radiographic methods wereadapted for imaging (Figures 1a-1c: standardized radiographic method (standard imaging
group) and two semi-flexed techniques including SynaFlexer method (SynaFlexer group) andmodified Rosenberg method (Rosenberg
group). The standard imaging was proceededwith patients standing upright with their knees
extended and their feet parallel position. The
X-ray beam was focused directly over the midpoint of the femorotibial joint antero-posteriorly (Figure 1a). In the SynaFlexer group, semiflexion posteroanterior (PA) radiographs weretaken with the SynaFlexerTM (Synarc, Inc., San
Francisco, CA, USA), which is a commerciallyavailable Plexiglass frame to standardize knee
flexion and foot positioning 11, 12). The frame allows convenient, reproducible positioning of
the knee for serial examinations without aneed for creation and storage of foot maps.
The feet were externally rotated 10 , and thethighs touched the vertical platform anteriorly,
resulting in a fixed knee flexion of approximately 20 . The X-ray beam was angled at 10
caudally (Figure 1b). In the Rosenberg group,
PA radiographs were taken according to theoriginal Rosenberg method basically 8). We
Arts and Sciences ◆ 7

a

b

c

Figure 1 Acquisition of radiographs
Standing with knees extended (standard imaging method; a), SynaFlexer method (b) and modified
Rosenberg method (c).
X-ray beam (arrow) was directed anteroposteriorly in standard imaging method, and posteroanteri orly in SynaFlexer and modified Rosenberg methods.

Figure 2 Methods of measuring plateau gap
and joint space width.a
Maximum value of plateau gap (A)Minimum value of joint space width (B)Both values were measured parallel to tibial axis.

finely adjusted X-ray beam angles with reference to the angle between the axis of fibulaand medial tibial plateau in lateral view of theknee (Figure 1c). The acquired images wereassessed after conversion to DICOM format(L1750, HP Inc.) (17-inchesʼ resolution, 1,280*
1,024 pixels) and then, the plateau gap and
JSW were measured through the image analyzing software (POP-Net Essential ver. 4.2C, imageONE Co., Ltd., Tokyo, Japan).
After the contours of the medial and lateralcompartments of femur and tibial plateaus

8 ◆ Journal of JART English edition 2022

were delineated, the maximum distance of plateau gap (between the anterior and posterioredges of tibial plateau) and the minimum JSW
between opposing weight-bearing subchondral cortical surfaces was measured (Figure 2).
Three observers evaluated radiographs fromeach patient twice at a minimal interval of two
weeks. Intra-observer reliability was assessed
based on evaluations by the first author, andinter-observer reliability was assessed basedon evaluations between the first and second
authors. The readers were blinded to the initial
measurements, and mean values were taken as
the measured values.
Statistical analysis

The reproducibility and intra-observer reliability of the measurement was assessed using
kappa statistics. Parameters (plateau gap andJSW) were compared among the three methods using a one-way analysis of variance(ANOVA) and Tukey-Kramer and Bonferroni/
Dunn post hoc multiple comparison tests. Significance was defined at P < 0.05.

3. Results
Test-retest reproducibility and intra-observer
reliability did not significantly differ (kappa

original articles
Radiological assessment of joint space width using different weight-bearing radiographic methods for knee osteoarthritis

values, 0.76 and 0.86, respectively). Table 2
shows the mean values and standard deviations of the plateau gap and JSW in each assessment method. The mean values of the plateau gap of medial compartment were significantly smaller for the SynaFlexer and Rosenberg group, than the standard imaging group(3.9 ± 1.3 and 2.9 ± 1.5 vs. 5.8 ± 2.0, P < 0.05;
Figure 3). The average JSW value of medialcompartment was also significantly smaller for
the SynaFlexer and Rosenberg group, than thestandard imaging group (3.6 ± 1.3 and 3.1 ±1.5 vs. 4.6 ± 1.6, P < 0.05). On the other hand,no statistically difference of plateau gap and
JSW were seen in lateral compartment of knee
joint among the three groups (P > 0.05).

4. Discussion
For diagnosis of early knee OA or assessment of disease severity, accurate and precise
articular cartilage thickness, which is reflectedby optimal tibiofemoral JSW values derived
from weight-bearing knee radiograph, is critical. A number of studies, however, verified thatthe reproducibility of JSW determined from traditional weight-bearing radiographs with fullknee extension is inadequate 7, 13), because of
the insufficiency of anterior and posterior margins of the medial tibial plateau 11). Moreover, apathological study by Messieh et al. 14) indicated that most OA cartilage destruction occurs ina posterior site of the femoral condyle. Therefore, the JSW in patients with knee OA might
be much smaller on radiographs acquired withthe knee at various degrees of flexion 14, 15).
However, the accuracy of these views for JSW
assessment has rarely been scientifically evaluated quantitatively.
The present study assessed femorotibial JSW
in patients with knee OA and investigated discrepancies among three radiographic methods.
The plateau gap and JSW were significantly
smaller in the same patients with medial knee
OA assessed using the SynaFlexer and Rosenberg methods, than the standard imaging

Table 2 Comparisons of plateau gap and joint space
width among the three methods(mm)Standard imaging

SynaFlexer

Rosenberg

medial5.8±2.0

3.9±1.3*

2.9±1.5*

lateral3.0±2.0

2.0±1.4

1.8±1.2

medial4.6±1.6

3.6±1.3*

3.1±1.5*

lateral5.6±1.8

5.1±1.4

5.6±2.1

Plateau gap

Joint spacewidth＊ : P<0.05 compared to the standard imaging group

A

B

C

Figure 3 Representative X-rays of 62-year-old female patient acquired using three methods.
Standing with knee extension (standard imaging method; A): medial plateau gap and joint space width, 6.4 and 5.7 mm,
respectively. SynaFlexer method (B): medial plateau gap and joint space width, 3.6 and 3.0 mm, respectively. Modiﬁed
Rosenberg method (C): medial plateau gap and joint space width, 2.0 and 2.6 mm, respectively.

Arts and Sciences ◆ 9method. An increased plateau gap blurs theanterior and posterior margin of the tibial plateau, which leads to inaccurate JSW measurements 6). Therefore, consort of these two margins (small plateau gap) is indispensable for
precise JSW measurements. Decrease of JSW in
the knee flexion methods is consistent with arthroscopic findings, showing that OA cartilage
destruction occurs at a posterior site of thefemorotibial joint 8, 9). Matsuda et al. reported
that the medial tibial plateau in the Japanese
population posteriorly inclines approximately
10 16). In the present study, the value of plateau gap and JSW of medial compartment in
Rosenberg group were statistically small compared to the standard imaging group. Piperno
et al. 7) suggested that the schuss view, which isa variant of the Rosenberg method, can alsovisualize evidence of osteophytosis, which is
helpful to diagnose early OA. From these reasons, images of a flexed knee such as in Rosenberg method, are currently considered moresensitive for screening knee OA compared to
traditional weight-bearing radiographs 7, 17). We
devised fine adjustment way of X-ray beam
angle with reference to the knee lateral view tominimize radiation exposure. However, there
remains several problems. For example, somepatients suffering from knee OA cannot flex
their knees at 45 and if they can, pain often
prevents them from maintaining the position
long enough to take images 18). The plexiglass
SynaFlexer frame, on the other hand, standardizes knee flexion and foot positioning. Charles
and Kothari et al reported that SynaFlexer
frame allows convenient, reproducible positioning of the knee and engagement of themost damaged femoral articular cartilage to
produce images that are of similar quality to
Rosenberg view 11, 12). Patients only have toplace their feet in the foot support and touch
their thighs to the vertical platform anteriorly,
which allows examinations of even elderly patients with joint contracture and pain. The plateau gap and JSW on SynaFlexer images in the

10 ◆ Journal of JART English edition 2022

present study were statistically smaller thanthose on standard images that were not inferior
to Rosenberg images. A small plateau gap
means that the direction of the X-ray beam isalmost parallel to the tibial plateau. The present findings indicate that the Rosenberg method is beneficial to diagnose early knee OA in
relatively young and active patients, whereas
the SynaFlexer method is more appropriate forassessing disease severity or progression in patients with painful intermediate to severe knee
OA.
The present study has several limitations. A
significant positive difference in the plateau
gap and JSW of the lateral femorotibial joint
was not identified. It is assumed that all patients included in this study had confirmed medial knee OA and that they had no evidence of
cartilage damage or destructive changes in thelateral compartment of the knee. In addition,
multiple regression analysis could not be performed for small number of patients. Large
sample cohort study including lateral knee OA
patients should be assessed in a future. Nonetheless, the present findings provide valuable
information about measuring JSW using different imaging methods, which should impact
clinical diagnoses and assessments of knee osteoarthritis severity.

5. Conclusions
We compared the plateau gap and joint
space width of 32 knees with osteoarthritis onradiographs acquired using three different
methods of bilateral weight-bearing radiographs (standard imaging, SynaFlexer, andmodified Rosenberg method). The maximum
value of the plateau gap and the minimum value of the joint space width of the medial compartment in images acquired were significantly
higher using the standard imaging method,
than the SynaFlexer and modified Rosenberg
methods (P < 0.05). The SynaFlexer and modified Rosenberg methods might be useful fororiginal articles
Radiological assessment of joint space width using different weight-bearing radiographic methods for knee osteoarthritis

diagnosing early osteoarthritis and for assessing disease severity in various populations, including elderly people.

6. Declarations
Funding

This work was supported by the Grants-inAid for Scientific Research of Japan Society for
the Promotion of Science, Grant Number
232024000.

with the ethical standards of the institutional
and/or national research committee and in linewith the 1964 Declaration of Helsinki and its
later amendments or comparable ethical standards. This study was approved by the ethics
review board of the authorsʼ affiliated institutions (approval code 2017-2301). The nature of
the study was thoroughly explained to eachpatient, and all patients provided written, informed consent prior to participation.
Consent for publication

Conflict of interest / Competing interests

Masanori Yamaguchi, Hironobu Koseki,
Kousei Enguchi, Hitoshi Iwanaga, Shunta Kyuma, Hiroyuki Shindo declare that they have noconflicts of interest nor competing interests. All
authors have not and will not receive benefits
or funding from any commercial party directly
or indirectly related to the subject of this article.
Availability of data and material

The authors do not wish to share the data
because the dataset is part of ongoing study
protocols.
Code availability

Not applicable
Authorsʼ contributions

All authors substantially contributed to thisarticle. MY and HK conceived and designed
the study. MY, HK, KE, HI, and SK participatedin the experiments and gathered data. MY, HK,
and HI analyzed and interpreted the data. MY
initially drafted the manuscript, and MY and
HS statistically analyzed and ensured the accuracy of the data. All authors have read andapproved the final version of the manuscript
and affirm that the work has not been submitted or published elsewhere in whole or in part.
Ethics approval

All procedures in studies involving humanparticipants were performed in accordance

Not applicable.

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18）Inoue S, et al.: Anteroposterior weight-bearing radiography of the knee with both knees in semiﬂexion, using new equipment. J Orthop Sci, 6, 475-480, 2001.

Arts and Sciences
original articles

Received March 26, 2019; accepted March 27, 2020

New simple imaging method for short-axis viewin cardiac MRI inferred from chest X-ray
FUJII Tomoki1）, USUI Hiromi2）, SATO Hisaya1），3）, KATO Kyoichi3），4）
1）Showa University Hospital, Department of Radiological Technology2）Showa University Northern Yokohama Hospital, Department of Radiological Technology3）Showa University Graduate School of Health Sciences4）Showa University Radiological Technology

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 819: 20-29, 2021.
Key words: Cardiac Magnetic Resonance Imaging, Short Axis, Chest X-rays, Coronary Computed Tomography Angi-

ography, New simple imaging method, Reliable imaging method【Abstract】

Cardiac Magnetic Resonance Imaging (CMRI) is often performed under respiratory standstill. Vertical Long Axis
imaging (VLA) and Horizontal Long Axis imaging (HLA) are used to acquire short-axis imaging (SA) although it
requires patients to hold their breath for a long time. Therefore, in some patients, the image quality in SA may beaffected by repeated breath-holds. This study aims to devise a new method to acquire SA without VLA and HLA.
Initially, 116 patients who underwent Coronary Computed Tomography Angiography (CCTA) and front and lateralchest X-rays were investigated to assess the relationship between the SA angle in the CCTA images and the angle ofthe cardiac shadow in the X-rays for application in the new method. Then, 20 subjects were randomly selected forassessment of inter- and intra-reproducibility studies. Finally, 10 participants underwent CMRI using the new and theconventional methods for visual and objective evaluations.
A strong relation was found between the SA angle and the cardiac shadow. The measurements of the SA angle
and the cardiac shadow were excellently reproducible. Compared with the conventional method, the new method
proposed in this study has improved the time of respiratory standstills. It is suggested that this new method has thepotential to provide a high-quality image as obtained with the conventional method.

1. Introduction
Cardiac Magnetic Resonance Imaging(MRI) is an indispensable examination thatcan diagnose cardiac function and display
morphological information. Cardiac MRI is
also useful in evaluating the prognosis ofpatients with coronary artery disease 1), 2).
Cardiac delayed contrast MRI has been used
for myocardial viability diagnosis of myocardial
infarction and is reported to be effective in thedetection of right ventricular infarction andasymptomatic infarction 3), 4). In addition, stresstested myocardial perfusion MRI has higher
spatial resolution than single-photon emission
computed tomography (SPECT), and it has
been reported to enable the visualization ofsubendocardial ischemia clearly 5).
Cardiac cine MRI can acquire a moving
image in an arbitrary direction without

artifacts due to bone or air compared withultrasonography. Currently, cardiac cine MRI is
the gold standard of cardiac function diagnosis
method because it can acquire left ventricularfunction accurately and quantitatively in most
myocardial deformities and abnormalities 6).
Furthermore, quantitative analysis of the left
ventricular function using cardiac cine MRI is
highly reproducible 7), 8).
Cardiac cine MRI is performed underpaused breathing. To obtain a short-axis crosssectional image of the heart, the imaging
section is commonly set by using the verticallong-axis section image (VLA) and horizontal
long-axis section image (HLA). However, VLA
and HLA imaging require the patient to stop
respiration for several seconds. Therefore,
the diagnosis of cardiac function analysis isaffected in patients with difficulty in stopping
respiration due to poor short-axis crossArts and Sciences ◆ 13

sectional images. In such patients, images canbe acquired for cardiac MRI using synchronous
respiration imaging along with synchronouselectrocardiogram imaging. However, thismethod is tedious for the operator andpatients, as it takes longer examination time
for imaging. Moreover, the short-axis crosssectional image is acquired by the operator
subjectively based on a short axis definedas the perpendicular cross-sectional images
connecting the apex and the base of the heart.
This subjective position setting might differ
from operator to operator, thereby causing an
uncertainty in the position.
This study aims to suggest a new examination method for acquiring short-axis cross-sectional images without HLA and VLA by using
the cardiac shadow of the chest X-ray.

2. Methods
2.1 Materials

SOMATOM Definition AS+ (SIEMENS Co.,
Ltd.) was used for the CT examination, BENEO(FUJIFILM Co.) for the X-ray examination, andMAGNETOM AVANTO 1.5T (SIEMENS Co.,
Ltd.) for the cardiac MRI. ZIO Station2 (AminCo.) was used as a medical image processing
workstation for measuring the short-axis angleof the cardiac CT image. Synapse (FUJIFILM
Co.) was used for the measurement of theshort-axis angle in the X-ray image. Statisticalanalysis was performed using JMP 13.0 (SASInstitute Inc.).
2.2 Measurement of short axis in cardiac
X-ray and CT
2.2.1 Participants

The subjects in the study were 116 patients
who had underwent coronary computed
tomography angiography (CCTA) and front
and lateral chest X-ray examinations fromJanuary 2012 to August 2013. No criteria wereset for the time interval between the chest
X-ray examination and the CCTA examination.
Characteristic of the 116 participants wasshown in Table 1 . CCTA examination havebeen performed in various ways, and mostpatients who underwent CCTA were suspectedof stable work angina. Two of the 116
patients underwent CCTA for morphologicalassessment of dilated cardiomyopathy or
cardiac tumor. Also, 14 of the 116 patients(12%) have history of Cardiac hypertrophy.
As a result of CCTA, 51 participants wereconfirmed at least 50% stenosis at coronary
artery (15 in one-branch, 11 in two-branch,and 25 in three-branch, respectively). Also,

Table 1 Characteristic of the 116 participants who underwent CCTA
Table 1 Characteristic of the 116 participants who underwent CCTA
Parameters

Studied Group (N=116)

Sex

Parameters

Studied Group (N=116)

Purpose of CCT A examination

Parameters

Studied Group (N=116)

Diagnosis for CCT A*

Male

75 (64.7%)

Stable work angina

36

Female41 (35.3%)

OMI

16

Single vessel disease

15

Chest pain

11

Double vessel disease11

E xertion angina

9

T riple vessel disease25

Age (years)

Coronary Disease51

Mean ± SD

66. 4 ± 13. 7

palpitation

6

Intact vessels

65

Range

24

Heart Failure

5

Kawasaki disease

1

Back pain

4

Dilated cardiomyopathy

1

Paroxysmal artrial fibrillation

4

Car diac tumor

1

syncope4- 89

Height (cm)Mean ± SD

161.8 ± 8.9

Vasospastic angina

4

Range

140.0 - 180.0

Chronic artrial fibrillation

3

PVC

3

AMI

2
2

Weight (kg)
Mean ± SD

61. 6 ± 14. 7

Heart murmur

Range

28.0 - 162.0

Scleening for operation2

Chest compression

2

Body Mass Index ( kg/m2)

Kawasaki disease1

Mean ± SD

23.4 ± 4.43

Dilated cardiomyopathy

1

Range
Value are mean ± SD.

10. 0 - 50. 0

Cardiac tumor

1

14 ◆ Journal of JART English edition 2022

History of Cardiac Hypertrophy

14* Multiple selections were possible in these parametersoriginal articles
New simple imaging method for short-axis view in cardiac MRI inferred from chest X-ray

Fig.1

Extraction and measurement of cardiac short-axis angle in CT imaging

a: HLA and VLA images were displayed using Multi-Planar Reconstruction (MPR) from the volume CT data. A line connecting
the center of the mitral valve and the apex of the heart was deﬁned as the “short axis”, which was drawn using a 3D measurement tool.
b: The coronal and sagittal section was displayed using the CT volume data. The angle “A” between the body axis and theshort axis of the heart and the angle “B” between the sternum and the short axis of the heart were measured as the shortaxis angle.

few patients diagnosed with Kawasaki
disease, dilated cardiomyopathy, and heart
tumors were also included. This research
was approved by the Ethics Committee at theShowa University School of Medicine.
2.2.2 Visualization of the cardiac short axis in CT

HLA and VLA images were displayed using
Multi-Planar Reconstruction (MPR) from thevolume CT data. A line connecting the centerof the mitral valve and the apex of the heart
was defined as the “short axis”, which was
drawn using a 3D measurement tool (Fig.1a).
2.2.3 Measurement of cardiac short-axis angle

spinous processes of the thoracic vertebrae,
and when the deformity of the thoracic
vertebra is significant, it is based on the axis of
the sternum.
Next, the sagittal section was displayedusing the same volume data. Following this,the angle “B” between the sternum and theshort axis of the heart was measured. Lateralchest X-ray examination was performed in astanding position, and the body axis depictedon the image changes according to theexamined position. To evaluate the anatomical
angle, we measured the angle between
the sternum and the short axis of the heart(Fig.1b).

in CT imaging

The coronal section was displayed using
the CT volume data. The angle “A” between
the body axis and the short axis of the heart
was measured. The body axis is based on the

2.2.4 Measurement of cardiac shadow in chest
X-ray image

Using the cardinal shadow of the XP frontal
image, a cardiac lateral edge corresponding to
Arts and Sciences ◆ 15

Fig.2 Measurement of cardiac shadow in chest X-ray image
a: A cardiac lateral edge corresponding to the third and fourth bows were connected as the line for measurement of theangle α formed by this line and the median in the XP frontal image.
b: The point of the cardiac shadow located at the farthest end and the apex of the heart were connected by a line using the
XP lateral image. The angle β between this line and the sternum axis was measured.

the third and fourth bows representing the left
atrium and the left ventricle were connected
as the line for measurement of the angle α(expected short axis from the XP frontal image)formed by this line and the median (Fig.2a).
The median is based on the spinous processesof the thoracic vertebrae; when the deformityof the thoracic vertebra is intense, it is basedon the sternum axis.
Next, an XP lateral image was displayed on
Synapse. From the anatomical structure, we
noticed that the left atrium is the most dorsalside of the heart. Therefore, the point of the
cardiac shadow located at the farthest end
and the apex of the heart were connected bya line using the XP lateral image. The angle
β between this line and the sternum axis (theexpected short axis from the XP lateral image)was measured (Fig.2b).
2.2.5 Comparison of cardiac short axis in chest
X-ray and CT

The relationship between the chest X-ray
image described above and the minor axis
angle of the CT was examined. We analyzed

16 ◆ Journal of JART English edition 2022

the relevancies of the angle α of the cardiac
shadow in the XP frontal view and the shortaxis cardiac angle A in the coronal section as
well as the angle β of the cardiac shadow in
the XP lateral image and the cardiac shortaxis angle B in the sagittal section using the
cardiac CT. The analysis was performed using
Pearsonʼs correlation of the regression line. A
linear approximation formula of the regression
line of angle α and angle A, and that of angle
β and angle B were calculated for angle
consistency.
2.2.6 Ve r i f i c a t i o n o f r e p r o d u c i b i l i t y o fmeasurement method
Inter-observer and intra-observer
reproducibility analyses were performedby two experienced observers in 20 cases
randomly extracted from the cases selected
for the study. As parameters of the reliability
analysis, the intraclass correlation coefficient(ICC) and the dif fer ence between themeasurements of both groups as the meandifference and standard deviation of the meandifference were measured. We evaluated theoriginal articles
New simple imaging method for short-axis view in cardiac MRI inferred from chest X-ray

Fig.3 New imaging procedure of short axis imaging

ICC higher than 0.8 as “Excellent” and from 0.6
to 0.8 as “Moderate”. The interval in each intrareliability analysis was more than two weeks.
The inter-reliability analysis was performed
using the above-described measurement
method by a radiologic technologist with 5
or more years of experience in projectional
radiography and CT examination. Each
result was evaluated by comparing with theunderlying analysis data.
2.3 Comparison between the new method
and the conventional method

Cardiac cine magnetic resonance imaging
was performed on a subject by using the result
obtained from the relation between the cardiac
shadow and the true short-axis angle.
2.3.1 Participants

The 10 participants were volunteers
who agreed to perform cardiac cine MRI
examination and agreed with the purpose ofthis study. The participants were randomly
divided into two groups to compare theconventional and new methods.

2.3.2 Examination of cardiac cine MRI withshort-axis angle obtained from cardiac
shadow

A localized image was taken containing three
directions corresponding to the transverse,
coronal, and sagittal sections so that theposition and morphology of the heart could
be recognized. The localized image of thecoronal section was taken from a cross sectionin which the margin of the heart was depicted.
Similarly, the localized image of the sagittal
section was imaged so that the apex of theheart and its dorsal side were visualized.
Next, using the localized images of thecoronal and sagittal sections, the imaging angle
was adjusted to the short-axis angle based on
the relation between the cardiac shadow andthe true short-axis angle, and cine imaging was
performed in the range that included the entire
left ventricle (Fig.3).
2.3.3 Reduction in imaging time of short-axis
image by new method

Five radiologic technologists examined theshort-axis image using the new method tofind the time required to obtain the short-axis
Arts and Sciences ◆ 17

Table 2 Rating criterion for the visual evaluation
Score
5
4
3
2
1

Rating criterion
No difference compared with the conventional method.
Acceptable on diagnosis although an angle may be difference compared with the conventional method.
Possibility to affect diagnosis due to a difference short axis angle compared with the conventional method.
Unacceptable on diagnosis
Not a short axis image

angle and determine whether the respiratory
pause time of the subject could be shortened.
The time to be considered is the time fromthe start of imaging of the localized image tothe acquisition of the first short-axis image(the examination time) and the time for which
breathing is withheld during the examination(the breath-hold time). The examination time
was calculated from Synapse described on
the DICOM image, and the breath-hold time
was measured using a stopwatch during theexamination. Wilcoxon ʼ s signed-rank sum
test was performed to assess the significant
difference.

test was performed using a chi-square test.

2.3.4 Comparison of short-axis images

3.1.2 Relationship between the short-axis angle

We compared the short-axis image obtainedby the conventional method and that capturedby the new method. A visual evaluation was
performed for comparison using confidence
rating by the double blind method.
Two radiologic technologists with experienceof 5 to 15 years and two cardiovascularphysicians compared the short-axis images of
the conventional and the new methods by the
double blind method. Using confidence rating
as a visual evaluation method, the conventionaland new methods were scored based on therating criterion shown in Table 2. A score was
assigned in all cases, and significant difference

3. Result
3.1 Measurement of cardiac short axis inchest X-ray and CT image
3.1.1 Measurement of short-axis angle of heart

In the measurement of the short-axis angleof the heart, the short-axis angle A for all cases
was 46.0 ± 11.1 . In addition, the short-axis
supposed angle α for all cases was 42.6 ± 10.1
on average. The short-axis angle B for all cases, and the short-axis supposed
was 47.6 ± 7.2 °angle β for all cases was 46.8 ± 6.5°(Table 3).

of the CT and the short-axis assumed
angle of the chest X-ray
The relationship between the short-axis
angle A and the short-axis supposed angle α
is shown in Fig.4. The primary approximation
formula was derived as Y = 0.94 X + 6.13 (Y:cardiac short-axis angle A in the coronal
section in the CT image, X: short-axis
supposed angle α in the XP front image) andPearsonʼs correlation coefficient r was 0.85,
suggesting a statistically strong correlation. The
relationship between the short-axis angle B
and the short-axis supposed angle β is shownin Fig.5. The primary approximation formula

Table 3 Measurement of cardiac short axis in chest X-ray and CT image
Measurement angle
The short-axis angle A
The short-axis supposed angle α
The short-axis angle B
The short-axis supposed angle β

Mean (SD)
46.0 (11.1)
42.6 (10.1)
47.6 (7.2)
46.8 (6.5)

18 ◆ Journal of JART English edition 2022

Median [IQR]
46.4 [38.6 – 52.4]
42.0 [36.0 – 49.8]
48.3 [44.0 – 51.8]
47.0 [42.5 – 51.0]

Range
21.4 – 72.4
18.0 – 69.0
27.1 – 73.6
27.0 – 65.0

original articles
New simple imaging method for short-axis view in cardiac MRI inferred from chest X-ray

α

Fig.4 The relationship between the short-axis angle
A and the short-axis supposed angle α

Fig.5 The relationship between the short-axis angle
B and the short-axis supposed angle β

The primary approximation formula was derived as Y = 0.94
X + 6.13 (Y: cardiac short-axis angle A in the coronal section in the CT image, X: short-axis supposed angle α in
the XP front image) and Pearsonʼs correlation coefﬁcient r
was 0.85, suggesting a statistically strong correlation.

The primary approximation formula was derived as Y = 0.97
X +1.96 (Y: cardiac short-axis angle B in the sagittal section in the CT image, X: short-axis supposed angle β in
the XP lateral image) and Pearsonʼs correlation coefﬁcient r
was 0.87, suggesting a statistically strong correlation.

Table 4 The assessment of reproducibility for the measurement of the short axis angle
Intra-observer reliability
Parameters

Analysis 1

Analysis 2

Mean Difference

ICC

The assumed short-axis angle α43.4 ± 8.66

41.3 ± 9.41

-2.15 ± 2.63

0.91*

The assumed short-axis angle β46.8 ± 6.58

45.9 ± 6.61

-0.90 ± 2.61

0.91*

The short-axis angle A

44.0 ± 9.71

43.7 ± 9.06

-0.32 ± 2.89

0.93*

The short-axis angle B

46.1 ± 7.11

45.0 ± 8.27

-1.03 ± 2.90

0.91*

Parameters

Observer 1

Observer 2

Mean Difference

ICC

The assumed short-axis angle α43.4 ± 8.66

41.7 ± 8.27

-1.75 ± 3.85

0.82*

The assumed short-axis angle β46.8 ± 6.58

47.0 ± 4.60

0.15 ± 2.97

0.83*

The short-axis angle A

44.0 ± 9.71

43.9 ± 9.35

-0.16 ± 4.54

0.87*

The short-axis angle B

46.1 ± 7.11

44.5 ± 6.05

-1.58 ± 2.92

0.87*

Inter-observer reliability

Value are Mean ± SD, SD: standard deviation, ICC: intraclass correlation coefficient. * = p < 0.05.

was derived as Y = 0.97 X + 1.96 (Y: cardiac
short-axis angle B in the sagittal section in the
CT image, X: short-axis supposed angle β in
the XP lateral image) and Pearsonʼs correlation
coefficient r was 0.87, suggesting a statisticallystrong correlation.
3.1.3 Ve r i f i c a t i o n o f r e p r o d u c i b i l i t y o fmeasurement method

The results of the intra- and inter-r e p r o d u c i b i l i t y a r e s h o w n i n Ta b l e 4 .
Regarding the intra-observer reliability of
the chest X-ray, the mean difference at theassumed short-axis angle α was −2.15 ± 2.63,
and the ICC was 0.91. In addition, the meandifference at the assumed short-axis angle β
was −0.90 ± 2.61 with ICC = 0.91. Regarding
the intra-observer reliability of the CT image,the mean difference at the short-axis angle A
was −0.32 ± 2.89, and the ICC was 0.93. The
Arts and Sciences ◆ 19

−1.58 ± 2.92 with ICC = 0.87.

mean difference at the short-axis angle B was−1.03 ± 2.90 with ICC = 0.91.
In the inter-observer reliability test of
the chest X-ray, the mean difference at theassumed short-axis angle α was −1.75 ± 3.85,
and the ICC was 0.82. In addition, the meandifference at the assumed short-axis angle β
was 0.15 ± 2.97 with ICC = 0.87. In the interobserver reliability test of the CT, the meandifference at the short-axis angle A was −0.16± 4.54, and the ICC was 0.87. In addition, themean difference at the short-axis angle B was

image
Comparison of the examination time ineach method is shown in Fig.6 and thecomparison of the breath-holding time isshown in Fig.7. The examination time in theconventional method was 619.4 ± 215.6 s andthe breath-holding time was 122.0 ± 15.4 s. In

Fig.6 Comparison of the examination time in eachmethodFig.7 Comparison of the breath-holding time ineach method

The Boxes show the mean value, with whiskers indicate
standard deviation. * = p < 0.05.
The examination time in the new method was 76.4 ± 9.6 s
although the conventional method was 619.4 ± 215.6 s( p < 0.05).

The Boxes show the mean value, with whiskers indicate
standard deviation. * = p < 0.05.
The examination time in the new method was 18.6 ± 0.9 s
although the conventional method was 122.0 ± 15.4 s( p < 0.05).

Fig.8

3.2 Comparison of new and conventional
methods
3.2.1 Comparison of imaging time of short-axis

Examples of short-axis images with the conventional and the new methods

20 ◆ Journal of JART English edition 2022

original articles
New simple imaging method for short-axis view in cardiac MRI inferred from chest X-ray

4. Discussion

Fig.9 The results of the visual evaluations of theshort-axis image by the conventional andthe new methods
The average of the confidence rating method scores
was 4.8±0.4 points in the conventional method and 4.7±0.4 points in the new method. No signiﬁcant difference
was observed between the conventional method and the
new method in the chi-square test for visual evaluation(p = 0.4652).

comparison, the examination time in the new
method was 76.4 ± 9.6 s (p<0.05 in comparison
with the conventional method) and the breathholding time was 18.6 ± 0.9 s (p<0.05 incomparison with the conventional method).
3.2.2 Comparison of short-axis images

Examples of short-axis images with theconventional and the new methods are shownin Fig.8. Furthermore, the results of the visualevaluations of the short-axis image by theconventional and the new methods are shownin Fig.9. In the visual evaluation, the averageof the confidence rating method scores was
4.8 ± 0.4 points in the conventional method
and 4.7 ± 0.4 points in the new method. In the
new method, one observer assigned 5 points
to all cases, and the lowest score assignedby all observers was 4 points. In the result of
the chi-square test for visual evaluation, no
significant difference was observed between
the conventional method and the new method(p = 0.47).

In this study, it was suggested that it ispossible to estimate the cardiac short axis
from the cardiac shadow by clarifying therelationship between the cardiac shadow of
the chest X-ray image and the short axis of theheart. Presently, a standardization protocol for
cardiac MRI examination has been publishedby the Society of Cardiovascular Magnetic
Resonance (SCMR) 9) . According to thisprotocol, the scout images of the body axis of
the axial, coronal, and lateral views are firstexamined to assess the position of the heart.
Thereafter, the image sections of the HLA andVLA are set by acquiring a cross-sectional
image across the body axis covering the entire
chest. This protocol consumes considerable
examination and br eath-hold time f or
obtaining the short-axis image, which can bepainful for the patient. In this study, the anglesof the outermost edges of the third and fourthbows of the cardiac shadow in the XP frontal
view were used as the determining index of
the angle of the left ventricle. The third bow of
the cardiac shadow shows the left atrium fromthe anatomical positional relationship and thefourth bow of the cardiac shadow shows theleft ventricle10). Therefore, we could estimate
the possibility of predicting the short axis of theheart from the cardiac shadow by estimatingthat the extracardiac lateral side is the angle
formed by the left atrium and the left ventricle.
Several outliers are seen in the relation
between the short-axis supposed angle
α and the cardiac short-axis angle A.
These cases corresponded to patients withdilated cardiomyopathy, cardiac tumor, andpericardial effusion, and they are believed tobe due to the change in the cardiac shadow in
the X-ray frontal image.
Furthermore, in the XP lateral image, thepoint at the back of the cardiac shadow is usedas the indicator, which can be determinedon the position of the left atrium and on theArts and Sciences ◆ 21

image. This index can be measured without
being affected by the cardiac shadow even in
the above-mentioned case; therefore, it can beconcluded that a very strong correlation was
obtained.
We also evaluated the intra- and interreproducibility to assess the reliability of theseanalyses. We could confirm high measurement
reliability in each analysis. The inter-observer
reproducibility in the short-axis supposed
angle α of the XP frontal image was less thanthe maximum reproducibility. This may be due
to a slight mismatch between analysis of thestarting point and ending point positions of the
cardiac shadow in the third and fourth bows,which are the measurement indexes. However,
the analysis method is considered very reliablebecause the mean difference between eachobserver was −1.75 ± 3.85 degrees and the
ICC was 0.82 from the statistical evaluation.
This is despite the fact that the definitionsof the starting points of the third bow andthe fourth bow were ambiguous, as themeasurement part uses a clearly identifiable
index as the outer side edge.
With the proposed method, it is possible
to obtain a short-axis image without HLAand VLA imaging. Therefore, it is understoodthat it is possible to drastically reduce theexamination time and number of breathholds until the acquisition of the short-axis
image. In the conventional method, theexamination time until the acquisition of theshort-axis image varied widely (Fig.6). Thismay be because of the necessity to examine
the localizer multiple times and because of
the variation in the operator settings. On theother hand, the operator-induced variationin the examination time in the new method
remarkably decreased. Moreover, the durationfrom the imaging of the localizer until theimaging of the short-axis image is minimized,
and the setting time for the short-axis image
is reduced. Because the angle of the imaging
section in the new method is derived by the

22 ◆ Journal of JART English edition 2022

shape of the heart of the subject, almost nochange in the imaging cross section occurs dueto the difference in the operator. Therefore,
even if a follow-up examination is required,
it is possible to provide images with highrepeatability of past short-axis cross sectionsof the heart. As an additional study, thedifferences in the imaging angle in the coronaland sagittal sections in cardiac MRI images
with respect to the body axis when imaging
with the new method and the conventional
method were compared. The difference inthe angle in the coronal section was 90.8 ±3.5 °, and that in the sagittal section was 91.0
± 3.7 °
, which indicates that approximately thesame angle was obtained in each method. The
results of the visual evaluation suggested that
there was no influence of this angle difference.
In addition, the new method has the ability
to image the VLA and HLA after obtaining theshort-axis image. In the conventional method,
the short-axis image is obtained after imaging
the VLA and HLA. However, in this new
method, it is possible to freely determine theimaging section after operating the localizer.
Several comparable research reports havereported techniques for detecting the shortaxis of the heart. Nitta, et al. 11) published an
application technology to detect the cardiac
reference cross section using the body-axis
transverse plane covering the entire heart.
Clare E. Jackson, et al. 12) estimated the angleof the cardiac short axis using the threshold of
the signal value of the image. However, theseprior studies used special application softwareor algorithms, and have the disadvantage that
it is difficult to easily adopt these techniques.
Also, in recent years, compressed sensing
technology has been noted as a high-speed
MRI imaging technology 13).
Compressed sensing refers to a group of
methods for accelerated MR data acquisition
based on semi-random, incomplete samplingof k-space. A final image is created throughan iterative optimization process using non-original articles
New simple imaging method for short-axis view in cardiac MRI inferred from chest X-ray

Fourier transformation and thresholding ofintermediately reconstructed images. Recently,
some MRI devices can use compressed sensing
technology and it has ability to reduce theimaging time significantly. However, it is stillin the development stage and there are a
lot of MRI devices without this technology.
In this research, we established a method toestimate the short-axis cross section without
special application software or complicatedalgorithms. This will encourage its adoption in
more facilities.
We need to state the limitations of thisresearch. First, because this is a cross-sectional
study and does not have the concept ofelapsed time, it does not consider the change
in the medical condition over time. Therefore,
the proposed method may be unusable if there
is a sudden change in the medical condition
during the period between cardiac MRI andchest X-ray imaging.
Next, a difference in the examination
positions arises, as the chest X-ray is takenin the standing position whereas the cardiac
CT is taken in the supine position. Although
the relationships between these images
were statistically strongly correlated in thisstudy, it is necessary to pay attention to thedifference in the examination positions, as
it has been reported that a change in theexamination position affects the visualizationof the cardiac shadow in the chest X-ray
image 14). Nevertheless, the new method ofimaging proposed in this study makes it
possible to set a short-axis cross section byusing the outermost edges of the heart at
the time of cardiac MRI. Therefore, it would
be unnecessary to consider the examination
position.
At last, there is a difference of the type ofparticipants between CCTA and MRI in thisstudy. While CT scans often predominantly
complained of coronary artery disease,
MRI scans often targeted patients withcardiomyopathy or arrhythmias. Unfortunately,

all participants who underwent MRI in thisstudy were normal volunteers. This must
be considered as a limitation of this study.
However, we believe that this can be useable
for more cases in this new method because
the present study indicate that the indices of
the cardiac short axis and cardiac shadow arealmost same unless affected by a cardiac tumor
or the like.

5. Conclusion
In this study, we devised a method to image
the cardiac short axis without VLA and HLA.
It was demonstrated that the new method
could shorten the examination and breath-holdtime of the patient. In addition, it provides
highly reproducible images irrespective of theoperator-induced variation.

Acknowledgments
The authors are grateful to all staff of the
Department of Radiological Technology,
Showa University Hospital, for theircooperation in this study. This manuscript
was partly supported by Akiyoshi Ohtsuka
Fellowship of the Japanese Society ofRadiological Technology for improvement inEnglish expression of a draft version of themanuscript. We would like to thank Editage(www.editage.jp) for English language editing.
Funding: No funding was received for thisstudyCompliance with Ethical Standards: Allprocedures performed in the study thatinvolved human participants were inaccordance with the ethical standards of the
Ethics Committee at the Showa University
School of Medicine and with the 1964 Helsinki
declaration and its later amendments orcomparable ethical standards. As an animal
rights disclosure statement, this article does notcontain any studies with animals performed byArts and Sciences ◆ 23

any of the authors.
Informed Consent: Informed consent was
obtained from all individual participants
included in the study.
Conflicts of Interest: The authors declare thatthey have no conflict of interest.

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be associated with atherosclerosis. Radiology, 245:103-10, 2007.
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perfusion-cardiac magnetic resonance with single-

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photon emission computed tomography for thedetection of coronary artery disease in a multicentre,
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X-ray examination. Medicina, 54: 626-9, 2017. (inJapanese)Arts and Sciences
original articles

Received May 7, 2020; accepted August 28, 2020

Calculation of optimal TI associated with temperature changes of the water using Synthetic MRI
assuming postmortem brain FLAIR imaging
OKAWA Ryuya1），2）, YASUI Go1）, KANAI Yoshihiro1）, MIHARA Ban3）, HAYASHI Norio4）1）Department of diagnostic imaging, Radiological Technologist, Mihara Memorial Hospital2）Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences3）Department of Neurology, Doctor, Mihara Memorial Hospital4）Department of Radiological Technology, Associate Professor, Gunma Prefectural College of Health Sciences

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 820: 33-39, 2021.
Key words: magnetic resonance imaging (MRI), Synthetic MRI，Autopsy imaging (Ai),fluid attenuated inversion recovery (FLAIR), Inversion Time (TI)
【Abstract】

In postmortem brain fluid-attenuated inversion recovery (FLAIR) imaging, we sometimes encounter failure of
cerebrospinal fluid (CSF) signal suppression. The reason for this is because the T1 value of CSF begins to fluctuatealong with the decreases in the body temperature after death, which prevents one from setting the appropriate
TI setting. Therefore, it is necessary to measure the T1 value corresponding to the temperature change of CSF andcalculate the optimal inversion time (TI). In this study, we conducted a phantom experiment to investigate theusefulness of synthetic magnetic resonance imaging (MRI) for calculating the optimal TI corresponding to CSF
temperature change. Using the optimal TI setting enabled us to obtain FLAIR images with sufficient water signal
suppression. We considered that synthetic MRI is a useful method for measuring T1 values and calculating the optimal
TI corresponding to change in water temperature.

Introduction
The brain fluid attenuated inversion recovery(FLAIR) imaging method suppresses cerebrospinal fluid (CSF) signals using the inversion
recovery (IR) pulse and adjusts the inversion
time (TI) parameter 1). In a spin-echo (SE)based sequence, if a 180-degree inverted pulse
is irradiated first before irradiating a 90-degree
pulse, and a long TI is set, then CSF signals willcontinue to pass through their null point eventhough T1 of signals from the brain and othernormal tissues have adequately recovered;
therefore, if signals are collected at this point,
images can be taken using suppressed CSF signals 2, 3). Hence, the brain FLAIR imaging method has high sensitivity to signal changes in awide variety of lesions, such as around theventricle in demyelinating and inflammatory
diseases, and it is an indispensable imaging sequence for MRI examination of the brain 4-6).

However, during clinical imaging ̶ especially“Autopsy imaging (Ai)”̶ the brain FLAIR imag-

ing method may fail to suppress CSF signals.
This is because the temperature of CSF falls
owing to the changes that occur in the bodyafter death, causing the T1 value to fluctuateand preventing the appropriate TI from being
set 7-11).
On the other hand, a new relaxation timemeasurement method has emerged in recent
years called synthetic MRI. In it, a pulse sequence called “quantification of relaxation
times and proton density by multi-echo acquisition of saturation recovery using turbo spinecho readout” (QRAPMASTER) is used. Using
multi-delay, multi-echo data collection, eighttypes of data are collected from each slice,
comprising four types of saturation delay andtwo types of echo time (TE). The T1 relaxation
curve is then estimated from the image of thefour kinds of saturation delay, and the T1 value
Arts and Sciences ◆ 25

and proton density (PD) are calculated foreach pixel. Similarly, the T2 value is calculated
for each pixel from the image of the two kinds
of TE, and multiple contrast images are createdunder arbitrary conditions from the obtained
quantitative value 12-15). Furthermore, by using a
dedicated application and setting the region ofinterest (ROI) at any part of the selected slice
section, it is possible to gauge the quantitativevalue of relaxation time. This has drawn attention as an effective technology for TI calculation, because the T1 value can be easily obtained 16, 17).
In this study, we focused on the capabilitiesof the synthetic MRI, which can measure relaxation time quickly and easily at any location.
Using these capabilities, we explored the efficacy of the synthetic MRI in suppressing CSF
signals for postmortem brain FLAIR imaging by
calculating the optimal TI for the temperaturechange and comparing the FLAIR images̶
captured using the clinical TI̶ to images captured using the optimal TI.

1. Methods

Fig.1

Placement of prepared sample on MRI phantom.

Fig.1 Placement of prepared sample on MRI
phantom.

for medical image display (Exa Vision PLUS,
Zio Soft Corporation, Tokyo, Japan); the statistical analysis software we used was Easy R(EZR).
Six samples simulating CSF were preparedby changing the temperature of pure water
Fig.2 Console screen with application of Synthetic MRI expanded.
℃ to
35℃ in 5℃ increments, and enfrom(A) 10
Preparedsample(B) PVA gel built into the Phantom
closing
it in a plastic bottle for MRI measure(C) Quantitative value of relaxation for prepared sample(D) R and R maps for prepared sample
ment. The temperature of pure water was measured with a digital thermometer (A&D Corporation, Japan) and adjusted so that it was thetarget temperature. In addition, for each imaging session, one of the prepared samples wasplaced in the upper left pocket of the MRI
phantom (Fig.1).
1

2

1-1 Equipment used and fabrication of thephantom

The MR device we used was the Discovery
MR750W 3.0 Tesla scanner (General Electric
Healthcare Medical Systems Corporation, Milwaukee, Wisconsin, USA); the receiver coil
was an Anterior Array coil; and the synthetic
MRI software application was Magnetic Resonance Image Compilation (MAGiC), whichcame with the equipment. The image analysis
software we used was ImageJ (National Institutes of Health, Bethesda, MD, USA, http://rsb.
info.nih.gov/ij/). To fabricate the phantom, weused an MRI imaging container (MRI phantom
90-401 type, Nikko Fines Industry Corporation,
Japan), a plastic bottle for MRI measurement(inner diameter 19 mm), and pure water (Super Desaliner, Organo Corporation, Japan). For
visual evaluation, we used a display monitor

26 ◆ Journal of JART English edition 2022

1-2 Obtaining FLAIR images
1-2-1 T1 value measurement by Synthetic MRI

Synthetic MRI imaging was carried out foreach prepared sample, and the T1 value wasgauged using the dedicated software application. The synthetic MRI imaging conditions
were as follows: repetition time (TR)=4,430 ms,
echo time (TE)=21.4/106.8 ms, band width(BW)=22.73 kHz, matrix=320×224, slice thickness=5 mm, number of signals averaged(NSA)=1, field of view (FOV)=230 mm, RFOV=
100%, echo train length (ETL)=16, asset factor=2, number of slices=23, TI=12.26 ms (onlythe shortest value is displayed due to device
function limitations), scan time=4 m 34 s. To
account for the influence of temperaturechanges due to the time elapsed during imaging and the heat absorption rate (specific ab-original articles
Calculation of optimal TI associated with temperature changes of the water using Synthetic MRI assuming postmortem brain FLAIR imagingof the sample and the temperature measured
after synthetic MRI imaging.

TI ＝ T1 Value × 0.693 ……………………… (1)
1-2-3 FLAIR imaging

Fig.2 Console screen with application of Synthetic
MRI expanded.
(A) Prepared sample(B) PVA gel built into the Phantom(C) Quantitative value of relaxation for prepared sample(D) R1 and R2 maps for prepared sample

In order to confirm whether the T1 value ofeach sample ̶ measured using a synthetic MRI
function ̶ was a quantitative value corresponding to temperature change, two types of phantom images were taken: a FLAIR image withclinical TI (2,700 ms) and a FLAIR image with
optimal TI. The imaging conditions for the
FLAIR images were as follows: TR=12,000 ms,
TE=140 ms, BW=35.71 kHz, matrix=320×224,
slice thickness=5 mm, NSA=1, FOV=230 mm,
RFOV=100%, flip angle=160 , ETL=21, asset
factor=2, number of slices=20, TI=1,600, 1,710,
1,800, 1,990, 2,160 ms (scan time=3 m 49 s),
2,400, 2,700 ms (scan time=2 m 36 s).
1-3 Evaluation of the FLAIR images
1-3-1 Visual evaluation

Fig.3 This figure is an enlarged view of parts (C)and (D) in the Figure 2．

sorption rate=SAR), the temperature of each
prepared sample was measured after synthetic
MRI imaging. Fig.2 shows the imaged MRI
phantom image expanded on a console screen
using the synthetic MRI application. By settinga rectangular ROI of any size in the center ofthe sample, quantitative values of relaxation
time (T1, T2) and R1 and R2 maps were obtainedin real time corresponding to the position
where the ROI was set (Fig.3).
1-2-2 Calculating the optimal TI

The T1 value of each prepared sample, measured using a synthetic MRI function, was substituted into a simple formula (1), and the appropriate TI was calculated. The optimal TI
computed for each prepared sample is a value
within the change between the set temperature

Visual evaluation was carried out to compare
the degree of signal suppression in the FLAIR
images of the sample portions between thoseimaged with the TI set to the clinical value andthose imaged with the TI set to the optimalvalue. The observers were eight radiological
technologists with between 3 and 40 years ofclinical experience working with MRI testing(male to female ratio=6:2, mean age=36.6
years). We obtained written informed consent
to publish the results obtained through visualevaluation. The evaluation method involved
randomly displaying on the monitor the 12
FLAIR images of the samples one at a time,with the imaging parameters hidden, and theobservers giving each image a score on the following 5-point scale:
5: the signal has been suppressed
4: the signal has been almost suppressed
3: neither / unable to discern
2: the signal has hardly been suppressed
1: the signal is not suppressed
Arts and Sciences ◆ 27

Reference images were presented to the observers in advance, and the scoring method of
evaluation was sufficiently explained and practiced. The average and standard deviation (SD)of the 12 FLAIR images were calculated fromthe scores assigned by 8 observers. To compare whether there was a difference between
the average score values of the two types of
FLAIR images, those with clinical TI and thosewith optimal TI, statistical analysis was carriedout at a significance level of 5% using Wilcoxonʼs signed rank sum test to compare the twocorresponding groups 18).
1-3-2 Physical evaluation

Signal intensity (SI) and SD were measured
for each FLAIR image captured with the TI set
to the clinical value and the TI set to the optimal value. The measurement points were set tothe sample and a 14 mm diameter ROI at thecenter of the nearest adjacent the polyvinyl alcohol (PVA) gel built into the MRI phantom(Fig.4). Based on the measured SI and SD, thesignal-to-noise ratio (SNR) of each preparedsample, and the contrast-to-noise ratio (CNR)
between the prepared sample and the PVA gel,were calculated with equations (2) and (3). It
has previously been reported that when calculating SNR, the difference method is the mostcorrelated with the theoretical value 19). How-ever, in this study, due to the temperature control of the specimens, it was not possible totake two consecutive images under completely
identical environmental conditions. Therefore,
we used the same region of interest method
instead of the difference method 19-21). For the
CNR calculation, we employed the EU proposed method 22). Here, SIa and SIb are the avTI ＝ T1 Value × 0.693 .............................. （1）eragevaluesin ..............................
the circular ROIs （1）set in
TI ＝ signal
T1 Value× 0.693
the prepared sample and PVA gel, and SDa andSDb are standard deviations in ROI, set thesame way as SIa and SIb.
𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = 𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼/𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼 ........................................ （2）𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = 𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼/𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼 ........................................
（2）………………………………
(2)
1... （3）
𝐶𝐶𝐶𝐶𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = |(𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼 − 𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝑆𝑆𝑆𝑆)|/(𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼/ + 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆/ )2 ……
(3)
1
/
/ 2
𝐶𝐶𝐶𝐶𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = |(𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝐼𝐼𝐼𝐼 − 𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼𝑆𝑆𝑆𝑆)|/(𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝐼𝐼𝐼𝐼 + 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 ) ... （3）2. Results
2-1 T1 value and the optimal TI of each sample
Table 1, Fig.5, and Fig.6 show the T1 value

and calculated optimal TI of each sample, as
well as the relationship to temperature, determined using synthetic MRI. The T1 value andcalculated optimal TI of each sample is a value
within the change between the set temperatureof the sample and the temperature measured
after synthetic MRI imaging. The T1 value ofeach sample measured via synthetic MRI declined as the temperature falls below 35 C,
which is close to body temperature. Like the T1
value, the calculated optimal TI also showedsmaller values as the temperature dropped.
2-2 Visual evaluation of the FLAIR images
Fig.7 depicts the FLAIR images of each sam-Fig.4 Placement of ROI in physical evaluation.
(a) Prepared sample(b) PVA gel (water content rate: 80%, gadolinium
concentration: 0.3 mmol)

28 ◆ Journal of JART English edition 2022

ple, captured with the IT set to the clinical value and to the optimal value. For all images,
window width (WW) and window level (WL)
are constant. In the FLAIR images with the TI
set to the clinical value, the water signals were
suppressed at temperatures close to the temperature of a living body, but the lower thetemperature, the more defects in suppression

original articles
Calculation of optimal TI associated with temperature changes of the water using Synthetic MRI assuming postmortem brain FLAIR imaging

occurred. On the other hand, in the FLAIR images with the TI set to the optimal value, water
signals were suppressed in all samples. Table 2
portrays the means and SD of the visual evaluation scores, the differences in the mean scores,
and the test results. The average score for
FLAIR images with the TI set to the clinicalvalue was 2 or less at all temperatures, whereas the average score for FLAIR images with the
TI set to the optimal value was 4 or higher. The
difference between the average scores for thetwo TI values was 3 or higher at all temperatures, and a significant difference was observed

4000
3500

T1 Value [ms]

3000
2500
2000
1500
1000
500
0

10

15

20

25

30

35

Temperature [℃]
Fig.5

Relationship between T1 value that measured using the function of Synthetic

Fig.5MRI and
RelationshipT1 value that meatemperature of eachbetween
prepared sample.
thehasfunction
Synthetic
MRI
The Tsured
value forusing
each sample
smaller valuesof
in cases
where temperatures
were andlower, temperatureand higher values inof
theeachcase ofpreparedhigher temperatures.
sample.
1

The T1 value for each sample has smaller values in cases
where temperatures were lower, and higher values in thecase of higher temperatures.

4000
3500

Optimal TI [ms]

3000
2500
2000
1500
1000
500
0

10

15

20

25

30

35

Temperature [℃]
Fig.6

Fig.7 The two types of FLAIR image for each prepared sample.

Relationship between optimal TI that calculated from measured T1 value andFig.6temperature
Relationshipbetween
optimal TI that calcuof each preparedsample.
The optimalfor eachmeasured
sample has smaller
in casestemperatures
latedTIfrom
T1values
value
andwheretemperawere ture
lower, ofand eachhigher values
in the caseof higher temperatures.
preparedsample.

In the upper half, the FLAIR images obtained with theclinical TI setting demonstrate failure of water signal
suppression. In the bottom half, the FLAIR images
obtained with the optimal TI setting show decreased
signal intensity for all samples, and there is sufficientwater signal suppression.

The optimal TI for each sample has smaller values incases where temperatures were lower, and higher values
in the case of higher temperatures.

Table 1 Relationship between the temperature of each prepared sample after imaging andthe measured T1 value and the calculated optimal TI
Preset temperature［℃］

10

15

20

25

30

35

Temperature after imaging［℃］

12.6

16.2

20.7

24.7

28.6

33.2

T1 value［ms］

2,309

2,468

2,597

2,872

3,117

3,463

Optimal TI［ms］

1,600

1,710

1,800

1,990

2,160

2,400

Table 2 Average score and standard deviation of visual evaluation results of clinical TI and optimal
TI with the average score differences
Temperature［℃］

10

15

20

25

30

35

Clinical TI

1.00 ± 0.00

1.13 ± 0.33

1.13 ± 0.33

1.00 ± 0.00

1.00 ± 0.00

1.38 ± 0.48

Optimal TI

4.13 ± 0.33

5.00 ± 0.00

5.00 ± 0.00

4.63 ± 0.48

4.88 ± 0.33

4.38 ± 0.48

Differences

3.13

3.87

3.87

3.63

3.88

3.00

Wilcoxon rank sum test

＊

＊

＊

＊

＊

＊

＊：p<0.05

Arts and Sciences ◆ 29

due to statistical analysis (p < 0.05).
2-3 Physical evaluation of the FLAIR images
Table 3 and Fig.8 display the SNR calculation

calculation between the sample and the PVA
gel at each temperature. The CNR of each sample in the FLAIR images with optimal TI revealed a large value, regardless of the change
in temperature. Moreover, compared with the
CNR of each sample in the FLAIR images withclinical TI, setting the optimal TI demonstrated
a higher value at all temperatures.

outcomes of the FLAIR images of each sample,
captured with the TI set to the clinical value
and to the optimal value. In the FLAIR images
with the TI set to the clinical value, the SNR ofeach sample exhibits higher values when thetemperature is lower, whereas in the optimal
TI FLAIR images, the SNR of each sample indicates constant values regardless of temperaturechange. Also, comparing the SNR values ofboth denotes that for all samples, setting the TI
to the optimal value produces lower values,
and the difference increases as the temperature
falls.
Table 4 and Fig.9 present the findings of CNR

Previous studies indicate that fluid T1 and T2
values are temperature dependent, the idea
being that the magnetic relaxation phenomenon is a transition in which the dipole-dipole
interaction is shaken by molecular motion 7, 23).
Therefore, the postmortem FLAIR imaging occurs the failure of CSF signal suppression be-

Table 3 The results of SNR calculations for thetwo types of FLAIR images

Table 4 The results of CNR calculations for thetwo types of FLAIR images

3. Discussion

SNR
Temperature［℃］

Clinical TI

CNR
Optimal TI

Temperature［℃］

Clinical TI

Optimal TI

10

48.5

8.15

10

4.38

27.6

15

38.3

5.47

15

1.30

28.2

20

33.2

4.81

20

2.76

30.8

25

25.6

4.61

25

7.92

27.4

30

16.2

5.01

30

13.1

31.0

35

11.8

4.90

35

16.7

28.6

50

35.00
30.00

40

25.00
20.00

Clinical TI

20

Optimal TI

CNR

SNR

30

Clinical TI

15.00

Optimal TI

10.00

10

0

5.00
0.00

10

15

20

25

30

35

Temperature [℃]

10

15

20

25

30

Temperature [℃]35

Fig.8 The results of SNR calculations for the two
The SNR values were smaller for the FLAIR images obtained with optimal TI setting
types of FLAIR images.

Fig.9 The results of CNR calculations for the two types of FLAIR images.
Fig.9
The results of CNR calculations for the two
The CNR values were higher for the FLAIR images obtained with optimal TI setting
types of FLAIR images.
than for those obtained with the clinical TI setting, for all temperatures.

The SNR values were smaller for the FLAIR images
obtained with optimal TI setting than for those obtainedwith the clinical TI setting, for all temperatures.

The CNR values were higher for the FLAIR images
obtained with optimal TI setting than for those obtainedwith the clinical TI setting, for all temperatures.

Fig.8 The results of SNR calculations for the two types of FLAIR images.

than for those obtained with the clinical TI setting, for all temperatures.

30 ◆ Journal of JART English edition 2022

original articles
Calculation of optimal TI associated with temperature changes of the water using Synthetic MRI assuming postmortem brain FLAIR imaging

cause the temperature of the CSF decreases as
the body temperature decreases after death,and the T1 of the CSF shortens. Tofs et al. referto these images as cold FLAIR and highlight theimportance of setting an optimal TI for postmortem FLAIR imaging of the brain 11). The
present study has also confirmed similar information to previous findings regarding the temperature dependence of fluid T1 values. Results
2-1 denote that the T1 value of water at 35 C,
near biological body temperature, is about
3,500 ms, and because this falls by about 500
ms for every 10 degrees drop in temperature,
the T1 value of water is greatly affected by temperature changes. In addition, since the T1 value of water is lower at lower temperatures, T1
levels in CSF can be predicted to decline in thebrain of a cadaver as well due to a decrease inbody temperature after death. Furthermore,
the difference between the optimal TI, when
the temperature of water is 35 C, and the optimal TI at 10 C, is 800ms, and since the TI set
during postmortem FLAIR imaging of the brain
will decrease with the decline in T1 value, it is
crucial to calculate the optimal TI for temperature changes in CSF.
In visual evaluation, the average score for
FLAIR imaging with the TI set to the optimalvalue was 4 or higher, and the difference in the
average score for FLAIR images with the TI set
to the clinical value compared to those with
the TI set to the optimal value was 3 or higher
at all temperatures. The SNR in FLAIR images
with the TI set to the optimal value was also
lower in all samples compared to FLAIR images with the TI set to the clinical value; the CNRvalues were also high, suggesting that the water signals were suppressed properly by setting
the appropriate TI and that clear FLAIR images
were obtained. In other words, using the synthetic MRI function makes it possible to quantify fluctuations in the T1 value due to the temperature change of water and to calculate theoptimal TI, and is an effective technique for
improving defects in the suppression of CSF

signals arising in postmortem FLAIR imaging of
the brain. Conventionally and in recent years,
the IR method has often been used to measure
T1 values. However, measuring the T1 value ofwater by the IR method requires a very longTR setting, which leads to the problems of inaccurate quantification due to the temperaturechange of CSF during imaging and a significant
extension of the imaging time 24). Therefore,
the IR method was unrealistic when quantifying substances with long T1 values such as CSF.
The above suggests that synthetic MRI is effective at measuring T1 values corresponding tochanges in the temperature of CSF and calculating optimal TI.
In this study, we focused on synthetic MRI
functions that can measure relaxation timequickly and easily at any location, and throughphantom experiments, we examined the efficacy of synthetic MRI in calculating the optimal
TI with the temperature change of water. The
results confirmed that it is possible to use synthetic MRI to measure T1 values easily and appropriately and to calculate optimal TI. Previous studies indicate that the measurement value of relaxation time in CSF varies dependingon imaging conditions 25). Hence, it is necessary
to examine whether synthetic MRI imaging
conditions affect T1 value measurements carried out for TI calculation, and to research the
optimal imaging protocol. In the future, it will
be necessary to perform postmortem brain MRI
imaging on cadavers using the Synthetic MRI
to obtain results similar to those obtained inthis study and to investigate whether it is possible to optimize the FLAIR imaging method
under the influence of postmortem temperature decrease.

4. Conclusion
In this study, we have clarified the efficacy ofsynthetic MRI in the measurement of T1 values
with changes to temperature of water and in
the calculation of optimal TI. Moreover, weArts and Sciences ◆ 31

suggest that this may improve defects in the
suppression of CSF signals that occur in postmortem brain FLAIR imaging.

Acknowledgments
I would like to express my heartfelt gratitude
for the guidance and cooperation of many
people in this research. A part of this paper
was presented at the 34th Japan Conference ofJapanese Radiological Technologists in Shimonoseki, Japan, in 2018.

References
1） Joseph V. Hajnal, David J. Bryant, et al.: Use of
Fluid-Attenuated Inversion Recovery (FLAIR) Pulse
Sequences in MRI of the Brain. Journal of Computer
Assisted Tomography, 16(6), 841-844, 1992.
2） Aoki S, et al.: A Key to Brain MRI Interpretation. 1721, Gakken Medical Shujunsha Co.,Ltd, 1998.
3） Kasai T, et al.: Imaging Technology for Magnetic Resonance. 136-137, Ohmsha Co.,Ltd, 2001.
4） Beatrice De Coene, Joseph V. Hajnal, et al.: MR of
the Brain Using Fluid-Attenuated Inversion Recovery(FLAIR) Pulse Sequences. American Journal of Neuroradiology, 13(6), 1555-1564, 1992.
5） Susan J. white, Joseph V. Hajnal, et al.: Use of FluidAttenuated Inversion Recovery Pulse Sequences for
Imaging the Spinal Cord. Magn Reson Med, 28, 153162, 1992.
6） Valerie L. Stevenson, et al.: Imaging of the spinal cordand brain in multiple sclerosis: a comparative study
between fast ﬂair and fast spin echo. Journal of Neurorlogy, 224, 119-124, 1997.
7） Kobayashi T, Isobe T, et al.: Special Edition on MRI
No.2 Understanding Ai - Signal Changes in MRI.
Journal of JART, 58, 40-47, 2011.
8） Kobayashi T. : Optimization of inversion time for postmortem short-tau inversion recovery (STIR) MR imaging. Ph.D. Dissertation, Ibaraki Prefectural University
of Health Sciences, 8-10, 51-54, 2014.
9） Kobayashi T, Shiotani S, et al.: Characteristic signal
intensity changes on postmortem magnetic reso nance imaging of the brain. Jpn J Radiol, 28, 8-14,
2010.

32 ◆ Journal of JART English edition 2022

10）Kobayashi T, Isobe T, et al.: Postmortem magnetic
resonance imaging dealing with low temperature objects. Magn Reson Med, 9, 101-108, 2010.
11）Tofts PS, Jackson JS, et al.: Imaging cadavers: cold
FLAIR and noninvasive brain thermometry using CSF
diffusion. Magn Reson Med, 59, 190-195, 2008.
12）Warntjes JB, Leinhard OD, et al.: Rapid magnetic
resonance quantification on the brain: optimization
for clinical usage, Magn Reson Med, 60(2), 320-329,
2008.
13）Hagiwara A, Hori M, et al.: Clinical Applications andFuture Prospects of Synthetic MRI. INNERVISION,
31(9), 13-15, 2016.
14）Blystad I, Warntjes JB, et al.: Synthetic MRI of thebrain in a clinical setting. Acta Radiol, 53(10), 11581163, 2012.
15）Asano K.: MAGiC technology and its potential. A
Monthly Journal of Medical Imaging and Information,
47(14), 142-147, 2015.
16）Krauss W, Gunnarsson M, et al.: Accuracy and reproducibility of a quantitative magnetic resonance imaging method for concurrent measurements of tissue
relaxation times and proton density. Magn Reason
Imaging, 33(5), 584-591, 2015.
17）Horita M, Hagiwara A, et al.: Quantitative of Synthetic
MRI. INNERVISION, 32(9), 5-7, 2017.
18）Kanda Y,: Investigation of the freely available easy-touse software ʻEZRʼ for medical statistics. Bone Marrow Transplantation, 48, 452-458, 2013.
19）Ogura A, Miyai A, et al.: Accuracy of Signal−to−noise
Ratio Measurement Method for Magnetic Resonance
Images. Journal of JSRT, 59(4), 508-513, 2003.
20）Ogura A, Miyati T, et al.: Method of SNR Determination Using Clinical Images. Journal of JSRT, 63(9),1099-1104, 2007.
21）Wada Y.: Examination about the relationship between
image scan sequence and SNR measuring method.
Journal of JART, 64, 24-29, 2017.
22）Wada Y, Hara T, et al.: Basic Assessment of the CNR
Measurement Method of MRI System in Phantom －Suggestion for Improvement in the CNR Evaluation
Method － . Journal of JSRT, 64(2), 268-276, 2008.
23）Bloembergen N, et al.: Relaxation effects in nuclear
magnetic resonance absorption. Phys Rev, 73, 679712, 1948.
24）Hayashi N, Ujita K, et al.: Development of an Opti mizing Program of Scanning Parameters for Double
Inversion Recovery MRI. Journal of JSRT, 71(6), 512519, 2015.
25）Konta N, Shibukawa S, et al.: The Effect of Scan
Parameters on the Synthetic MRI. Journal of JSRT,
74(2), 117-123, 2018.

Arts and Sciences
original articles

Received October 21, 2019; accepted July 29, 2020

Trial of dose reduction of Digital Breast Tomosynthesis
HAYAKAWA Saki1），2）, SHINOHARA Norimitsu1），2）
1）Department of Radiological Technology, Faculty of Health Sciences, Gifu University of Medical Science2）Master Course of Health and Medicine, Graduate School of Health and Medicine, Gifu University of Medical Science

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 821: 17-22, 2021.
Key words: Digital Breast Tomosynthesis, Imaging Dose Reduction, Breast Cancer, Quality Control【Abstract】

In recent years, mammography devices with digital breast tomosynthesis (DBT) technology have become
widespread. In this study, which focuses on the overall image quality characteristics of DBT, we examined thepossibility of dose reduction in slice images of reconstructed data (proc data). Low-contrast resolution and signal
difference-to-noise ratio (SDNR) were measured based on EUREF (European Reference Organisation for Quality
Assured Breast Screening and Diagnostic Services). The mAs value was based on 90 mAs close to the AEC auto mode.
The SDNR limiting value was calculated by reducing the mAs value. The projection data did not achieve the required
SDNR due to lower mAs value. Therefore, the auto mode setting was confirmed as ʻgoodʼ. The proc data achieved
the standard at 80 mAs, and it was considered possible to reduce the dose. It is necessary to confirm that the analysis
software supports proc data.

1. Introduction
In recent years, mammography devices withdigital breast tomosynthesis (DBT) technology
have become widespread. DBT continuously
or pulses X-rays to the breast from different
angles in a single photograph, and multiple
cross-sections can be obtained by reconstructing the image after shooting 1).
In breast cancer screening in Japan, mammography examinations in which the breasts
are pressed and pushed out are recommended.
Mammography tests can depict ﬁne lesions
such as calciﬁcation with high resolution; however, there is a risk that the lesions will be hidden in the mammary glands 2). DBT has theadvantage of reducing the inﬂuence of mammary gland overlap because multiple crosssections can be obtained, and it is expected to
be a useful technique for diagnosis 3). However, DBT is currently photographed in addition
to mammography, with no insurance listing or
establishment of essential scenes 4).
According to the classiﬁcation of the Interna-

tional Commission on Radiological Protection(ICRP), the tissue weighting coefﬁcient of the
mammary gland is highest at 0.12, and it is anorgan with high radiosensitivity 5). Normally,
the diagnostic reference level (DRL) of mammography is as little as 2.4 mGy or less per
direction photograph 6), and there is no need toworry about the deﬁnite effect if it is a normal
dose or inspection frequency 7). However, DBT
does not have a reference value for dose, andsince it is left to the judgment of manufacturers
and facilities 4), the establishment of performance evaluation standards and quality control procedures is urgently needed 8). In thisstudy, we focus on the overall image quality
characteristics of DBT, and examine the possibility of dose reduction in slice images of reconstructed data (proc data).

2. Method
In this study, Pe ru ruTM La Plus, manufactured by Canon Medical Systems Co., Ltd., wasused as the DBT device. Table 1 lists the speciArts and Sciences ◆ 33

Table 1 Specifications and reconfiguration of DBT
equipment
item
Conversion method・FPD

Table 2 Shooting conditions on each slice surface
Target /Filter

Tube voltage (kV)mAs

specification

W/Ag

29

63

Direct conversion
a-Se/TFT

W/Ag

29

71

W/Ag, Al, Rh

W/Ag

29

80

W/Ag

29

90

Output pixel size (DBT)

85 μm

Tomosynthesis oscillation angle± 7.5°

Tomosynthesis Shooting Time―

Reconstruction method

Sequential
approximation

X-Ray Tube Motion

Continuous

Tomosynthesis Number of Shots

17 shotsﬁcations and reconﬁguration methods for DBT
equipment. Basic parts of the experiment, suchas phantom placement and measurement position, were carried out based on the Protocol
for the Quality Control of the Physical andTechnical Aspects of Digital Breast Tomosynthesis Systems ver 1.03 9) (Protocol DBT) method published by EUREF (European Reference
Organisation for Quality Assured Breast Screening and Diagnostic Services). The data used foranalysis is measured using projection data (prjdata) in Protocol DBT. However, in order tomeasure overall characteristics, the data ismeasured by sliced images (proc data) in thisstudy. Moreover, prj data was also measured at
the same time in order to verify the accuracy ofthe measurement.
This study consisted of two experiments. In
Experiment 1, the signal difference to noise ratio (SDNR) was measured by the difference insliced surfaces, as in a previous experiment.
This reveals the effect of protocol DBT andaluminum arrangement on measured values.
In Experiment 2, we attempted to reduce thedose using CDMAM phantom and SDNR.
2.1 Pre-experiment effect of slice plane differences on SDNRFirst, the shooting conditions were determined. A 50 mm thick polymethylmethacrylate(PMMA) was placed on the breast support table, and the position of the compression pad-34 ◆ Journal of JART English edition 2022

Fig.1 Aluminum sheet placement and measurement ROI for SDNR measurement

dle was set to 60 mm. Using the most commonly used auto-mode in clinical practice, the
AEC was activated, and X-rays were irradiated.
The shooting conditions obtained at that time
were target W (tungsten), ﬁlter Ag (silver), tube
voltage 29 kV, and mAs value of 87.7 mAs. The
irradiation mode was set to manual, and thetarget ﬁlter and tube voltage were set in thesame manner as in auto mode. The mAs value
was 90 mAs, which is the closest mAs value
exceeding the condition of auto mode. In thisstudy, the mAs values were set to 63 mAs, 71
mAs, and 80 mAs based on the shooting conditions of the auto mode (Table 2), to try andreduce the dose.
SDNR aluminum sheet placement is shownin Fig.1. Aluminum sheets of 10 mm × 10 mm
were placed on PMMA at a position 60 mm
from the chest wall side in the left and rightcenters. The PMMA thickness was constant at
50 mm, and the height (slice surface) of thealuminum sheet was changed from the breast
support table in six stages: 5, 10, 15, 25, 35,
and 45 mm. The pressure plate was placed at a
position of 60 mm and photographed on eachoriginal articles
Trial of dose reduction of Digital Breast Tomosynthesis

slice surface under the conditions listed in Table 2.
The photographed image was measured using ImageJ_1.52a by setting an ROI of 5 mm ×
5 mm. The pixel value (PV) and standard deviation (SD) were obtained from Equation 1,
and the SDNR was calculated. PV (signal) is
the average pixel value in the aluminum sheet,
and PV (background) and SD (background)are the average values of the background pixels and standard deviation in the two ROIs.
… Equation 1

SDNR =SD (background) =PV (background) =∑∑The images to be analyzed used prj data andproc data, and SDNR was calculated from each
image.
2.2.1 Experiment Low contrast resolution
measurement

CDMAM 3.4 phantoms were used to measure
low-contrast resolution. It was attached to agrid-like square similar to a burger phantom.
The signal is a gold disk whose diameter andthickness change logarithmically, and one isarranged in the center and four corners of thesquarely separated area (Fig.2). The CDMAM
phantom was placed at the center of the PMMA
(thickness of 40 mm) according to Protocol
DBT (Fig.3), and the pressure plate was placed
at a position of 60 mm. Table 2 was used as theshooting conditions, and 16 measurements
were taken each time.
After shooting, CDMAM 3.4 Analyser 2.3.3(Artinis) was used to calculate the values fromeach image before and after image processing.
The IQFinv (inverse image quality ﬁgure) of
each mAs value was obtained from Equation 2.
Since IQFinv increases with the improvement ofimage quality, it can be said that the higher thevalue of IQFinv, the better the low-contrast res-olution 10).
IQF inv =∑… Equation 2

C i : gold disc thickness (μm)
Di, min : the smallest diameter perceived in thecolumn corresponding to a gold thickness Ci (mm)n : Number of columns in the contrast ﬁeld thatcan be identiﬁed
2.2.2 Experiment Measuring SDNR

As in the experiment in 2.1, SDNR was used
to place a 10 mm × 10 mm aluminum sheet on
PMMA at a position 60 mm from the chest wallside in the left and right centers. Protocol DBT
places aluminum sheets at a height of 10 mmfrom the breast support table. However, in thisstudy, aluminum sheets were placed at a heightof 25 mm, which is the same position as the
CDMAM phantom. The pressure plate wasplaced at 60 mm. Table 2 was used as theshooting condition, and the average of themeasured values was taken three times each as

Fig.2 Overview of CDMAM 3.4 Phantom

PMMA 20 mm
CDMAM phantom
PMMA 20 mm
Fig.3 Geometric arrangement of CDMAM phantom (cross-sectional view)
Arts and Sciences ◆ 35

3. Results
3.1 Pre-experiment effect of slice plane differences on SDNR
Table 3 lists the measurement results of SDNR

on each slice surface of the prj data. The farther away the slice surface is from the breast
support stand, the lower the SDNR, and a dropof up to 5.9% was observed. However, there
was no signiﬁcant change in the SD or contrast.
Table 4 shows the measurement results of
SDNR on each slice surface of proc data. At 5,
10, and 15 mm, the SDNR decreased slightly as
it separated from the breast support table, andat 25, 35, and 45 mm, there was no signiﬁcantchange in SDNR due to the slice surface. SD
increased as it was separated from the breast
support table. The contrast decreased as it separated from the breast support table at 5, 10,
and 15 mm, and there was no signiﬁcant differ-

Table 3 SDNR (90 mAs) on each slice surface of
prj data
Height(mm)

SD (bg)contrast

SDNR

Difference
(%)

5

13.6

28.8

2.12

100.5

10

13.2

27.9

2.12

100.0

15

13.6

27.9

2.05

96.7

25

13.2

27.3

2.06

97.5

35

13.5

27.1

2.01

94.8

45

13.6

27.0

1.99

94.1

Table 4 SDNR (90 mAs) on each slice surface ofproc data
Height(mm)

SD (bg)contrast

SDNR

Difference
(%)

5

189.3

653.5

3.45

108.9

10

193.1

608.6

3.17

100.0

15

197.0

568.9

2.89

91.1

25

200.3

498.8

2.49

78.5

35

200.3

514.9

2.57

81.1

45

200.9

532.7

2.65

83.6

36 ◆ Journal of JART English edition 2022

Threshold gold thickness（μm）

SDNR. The analysis was carried out on prj andproc data images.

63mAs

1

71mAs
80mAs
90mAs

0.1

Acceptable
Achievable

0.01
0

0.5
Detail Diameter（mm）

1

Fig.4 Relationship between mAs value and low
contrast resolution in prj data
Table 5

IQFinv for prj datamAs

IQFinv

IQFinv 0.16

63

106.8

173.7

71

110.9

180.5

80

114.1

181.2

90

127.2

211.2

ence in contrast at 25, 35, and 45 mm.
3.2.1 Experiment low-contrast resolution
Fig.4 shows the result of low-contrast resolu-

tion of the prj data. EUREF publishes guidelines for a quality system for breast cancer
screening, and the fourth edition (MMG guidelines) is used as an accuracy management manual for digital mammography 11). In the MMG
guidelines, acceptable and achievable levels
are shown as thresholds to be achieved when
digital mammography is used clinically. However, Protocol DBT does not show a thresholdin DBT. Therefore, the acceptable and achievable levels of Fig.4 are thresholds in digital
mammography. The prj data had a lower dose
per sheet than that of digital mammography,
but all mAs values satisﬁed the acceptable level. At 90 mAs, the same low-contrast resolution
was obtained as the achievable level.
The IQFinv at each mAs value is shown in Table 5. Since the pixel size of the detector of the
DBT device used this time is 85 μm, IQFinv0.16
up to 0.16 mm, which is the disk diameter closest to 0.17 mm per period, was also calculated.

original articles
Trial of dose reduction of Digital Breast Tomosynthesis

Threshold gold thickness（μm）

Table 7 SDNR at each mAs value
mAs
1

63mAs
71mAs
80mAs

SDNR
prj data

proc data

63

1.68

2.14

71

1.78

2.20

80

1.89

2.29

90

2.06

2.49

90mAs

0.1
0

0.2

0.4

0.6

0.8

1

Detail Diameter（mm）

Fig.5 Relationship between mAs value and low
contrast resolution in proc data
Table 6

IQFinv for proc datamAs

IQFinv

IQFinv 0.16

63

74.33

85.40

71

75.60

86.71

80

77.42

88.04

90

79.81

91.20

In the prj data, the IQFinv increased in conjunction with the mAs value.
Fig.5 shows the result of low contrast resolution of proc data. The low-contrast resolutionof the proc data satisﬁes the achievable level at
all mAs values.
IQFinv at each mAs value is shown in Table 6.
As with prj data, the higher the mAs value, thebetter the IQFinv.
IQFinv and IQFinv0.16 showed similar trends.
Therefore, IQFinv0.16 is used for the analysis of
the following CDMAM considering the pixel
size of the detector of the DBT device.
3.2.2 Experiment SDNR

The results of SDNR are shown in Table 7. In
the prj and proc data, the SDNR improved as
the mAs value was increased.

4. Considerations
4.1 Pre-experiment effect of slice plane differences on SDNR

In the prj data, the SDNR decreased as the

slice surface separated from the breast support
stand, but there was no signiﬁcant change in
the SD or contrast. Therefore, the effect of theslice surface on SDNR was small in the prj data.
In the proc data, the change inf SDNR due tothe difference in the slice surface was not signiﬁcant. Therefore, there was a change of
SDNR by the slice surface in proc data compared with prj data.
4.2.1 Experiment low-contrast resolution

In the prj data, the low-contrast resolution
improved because IQFinv increased in conjunction with the mAs value.
In proc data, IQFinv improved as the mAs
value was increased, similar to the prj data.
4.2.2 Experiment SDNR

In prj and proc data, the SDNR improved inconjunction with the mAs value.
4.3 Overall judgment

In the MMG guidelines, threshold contrast(Threshold contrast limiting value) by CDMAM isshown. To use digital mammography clinically,
the measured SDNR (SDNR measured) needs to exceed the SDNR limiting value calculated using Equation 3.
SDNR limiting value = (Threshold contrast measured ／Threshold contrast limiting value) × SDNR measured…Equation 3
However, since the threshold contrast limiting
value in DBT is not presented, it canʼt be evaluated by dose reduction. In this study, we calculated the SDNR limiting value at each mAs value
Arts and Sciences ◆ 37

Table 8 Calculation result of prj data
mAs

CDMAM0.16

SDNRmeasured SDNRlimiting value

63

0.61

1.68

1.93

71

0.60

1.78

1.99

80

0.56

1.89

2.00

90

0.53

2.05

Table 9 Calculation result of proc data
mAs

CDMAM0.16

SDNRmeasured SDNRlimiting value

63

0.83

2.14

2.37

71

0.81

2.20

2.38

80

0.74

2.29

2.26

90

0.75

2.49

from Equation 4 based on 90 mAs.
SDNR limiting value = (Threshold contrast measured／
Threshold contrast 90mAs) × SDNR measured…Equation 4
SDNR measured：SDNR measurements at PMMA 50
mm
Threshold contrast measured：Detectable disc thickness at 0.16 mm diameter
Threshold contrast 90mAs：Limit of disk thicknessof 0.16 mm in disc diameter at 90 mAs
The calculation results of the prj data areshown in Table 8. In the prj data, SDNR measured
was 1.68 at 63 mAs, 1.78 at 71 mAs, and 1.89 at
80 mAs, and the SDNR limiting value could not be
met. Therefore, the auto-mode setting is currently the best option.
Next, the calculation results for proc data areshown in Table 9. The SDNR measured was 2.14 at
63 mAs, 2.20 at 71 mAs, and 2.29 at 80 mAs,
and the SDNR limiting value could not be met at 60
mAs and 71 mAs. However, at 80 mAs, it was
equivalent to the SDNR limiting value. Therefore, themAs value could be reduced to 80 mAs. Since
the shooting dose was 1.83 mGy at 90 mAs and1.65 mGy at 80 mAs, if the mAs value is reduced from 90 mAs to 80 mAs, the shooting
dose can be reduced by 0.18 mGy.

38 ◆ Journal of JART English edition 2022

5. The limits of this study and future issues
The analysis software used in this study
needs to use prj data for IQFinv, and veriﬁcationis necessary for the accuracy of the analysis
results of proc data. In addition, it is necessary
to examine not only physical evaluation but
also use visual evaluation to check consistency.
In addition, the detector, target/ﬁlter, vibration angle, reconstruction method, number ofphotographs, etc., differ depending on the device, but this study has the results for a uniquedevice. Therefore, it is necessary to examine
dose reduction by this method in each type ofequipment while ensuring image quality.

6. Conclusion
In this study, overall image quality characteristics were examined using CDMAM phantom
and SDNR. In the image of proc data, the possibility of dose reduction was indicated.

References
1） T Shiomi: The Principle and Clinical Application of
Tomosynthesis. Medical Imaging and Information Sciences, 24 (2), 22-27, 2007.
）
2 Japan Association of Breast Cancer Screening, et al.:Recommendations for dealing with the dense breast
problem in Organisation screening for breast cancer.
2017.
3） N Uchiyama, et al.: Diagnostic Performance of combined Full Field Digital Mammography (FFDM) andDigital Breast Tomosynthesis (DBT) in Comparison
with Full Field Digital Mammography (FFDM). RSNA,
2010.
4） T Uematsu: Expectations and Challenges for Mammography Screening Using Breast Tomosynthesis.
Journal of Japan Association of Breast Cancer
Screening, 23 (2), 270-278, 2014.
5） The 2007 Recommendations of the International
Commission on Radiological Protection. Annals of the
ICRP. ICRP Publication 103, 37 (2-4), 182, 2007.
6） Japan Network for Research and Information on Medical Exposure, et al.: Diagnostic reference levels based

original articles
Trial of dose reduction of Digital Breast Tomosynthesison latest surveys in Japan –Japan DRLs 2015–．20,
2015．
7） I Isomoto: The Harm Due to Radiation Exposurein Screening Mammography. Japanese Journal ofBreast Cancer, 30 (1), 29-35, 2015．
8） N Shinohara: Trial of the Quality Control in Digital
Breast Tomosynthesis System. Bulletin of Gifu University of Medical Science, 12, 1-4, 2018．
9） European Reference Organisation for Quality Assured
Breast Screening and Diagnostic Services: Protocol

for the Quality Control of the Physical and TechnicalAspects of Digital Breast Tomosynthesis Systems version 1.03.
10）T Okabe, et al.: Shin-iyouhousyasenkagakukouza iyougazoujouhoukougaku. 208. ISHIYAKU Publishers,Inc., 2018.
11）European Reference Organisation for Quality Assured
Breast Screening and Diagnostic Services: European
Guidelines for Quality Assurance in Breast Cancer
Screening and Diagnosis 4th edition.

Arts and Sciences ◆ 39

Arts and Sciences
original articles

Received April 21, 2020; accepted August 28, 2020

Modification methods of radiographic conditions
alternative to tube voltage coefficient chart
HATAKEYAMA Norihito
Osaka Roudoueisei Center Daiichi Hospital, Radiology Department, Radiological Technologist

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 821: 23-28, 2021.
Key words: Radiographic condition, exposure index, tube voltage coefficient, computer simulation, inverse square law【Abstract】

This study aimed to improve the conventional method of imaging, using the tube voltage coefficient chart.
Accordingly, the MAS coefficient was introduced as the new, alternative coefficient to the tube voltage coefficient, andits chart was prepared. Using the approximate function obtained by measuring the exposure index (EI), we calculated
the radiographic conditions for correction. The difference between the measured EI and target EI was below ± 0.1.
Hence, our corrections eliminated some error factors associated with the conventional method.

1. Introduction
Uchida et al. 1-2) proposed a conventional imaging method using a tube voltage coefficient
chart for correcting the radiographic conditions
designed for a standard body type, while Asahi
et al. 3-4) and Morikawa et al. 5) proposed an
imaging method using a correction coefficient.
The conventional method was theoreticallysimplified for use in clinical radiological examinations; however, its precision was compromised. The conventional method has several
issues that include elements associated withradiography, the decrease in the elements thatexhibit differences in the radiation quality, andthe power n that constitutes the exponentialfunction of a tube voltage which expresses theradiation quality, does not have clear criteria
for calculation. The standard for approximation in the calculation of n was unclear. In thisinstance, the term “unclear” signifies the generation of the tube voltage coefficient by a radiological technologist for a hospital on thebasis of the considered tolerable error range
generated by the clinical radiological examinations and set arbitrarily.
Our proposed method resolved some of theissues associated with the conventional meth-

40 ◆ Journal of JART English edition 2022

od. Specifically, our proposed method used a
computer to correct the radiographic conditions to avoid any reading errors associatedwith the tube voltage coefficient chart.

2. Materials and methods
For the conventional and proposed methods,
the standard radiographic conditions (standard
condition) with modifications were consideredas the primary modified radiographic conditions (primary condition), and the primaryconditions with modifications were consideredas the secondary modified radiographic conditions (secondary condition). The issues associated with the conventional method for which
improvements were made in the proposed
method are indicated by “( )” with the letter A
and a number from 1 to 7.
2.1 Experimental devices

The following devices were used for the experiments.
X-ray tube: 0.6/1.2 P323 DK-85 SHIMADZU
Corporation (Kyoto, Japan)
X-ray apparatus for general radiography: RAD
speed Pro SHIMADZU Corporation (Kyoto,
Japan)

original articles
Modification methods of radiographic conditions alternative to tube voltage coefficient chart

High voltage generator: UD150L-40 SHIMADZU Corporation (Kyoto, Japan)
X-ray detector: SKR3000 (AeroDR3 1417HD)
KONICA MINOLTA (Tokyo, Japan)
Phantom: a few 1 cm polymethyl methacrylateboards (PMMA)

between a focal spot and an image (Source–
Image Distance [SID], cm), B is a Bucky factor(exposure magnifying factor), and G is the factor with respect to the area of an irradiation
field (cm2).
Applying the logarithm operator to Equation(1) yields Equation (2).

2.2 Modification of the standard conditions
and setting of the primary conditionsln�� � � �� � �……… (2) - ( 2 )Each X-ray system of each clinical radiologiこ こ で 、 q は mAsec 値 で 管 電 流 i (mA) と 撮 影 時 間 t
Whereq is the mAs, a current time product,cal examination room programs the standard(sec) を 乗 じ た 管 電 流 時 間 積 、 μ は １ 次 方 程 式 の 傾 き 、obtained by multiplying i (mA) and t (s), μ is
condition into the memory of the X-ray system
L は任意に決定する値を含む定数を纏めたもので、切6)
the slope of a linear equation, and L is a comby using the paired comparisons and/or the片となる。
ranking method 7) or considering the width ofpiled
set of intercepts and constants, includingつまり 、1arbitrarily
次方程式の傾きと切片を実験的に求めれば、
the dynamic range of the digital system andthe values
determined.
In
otherwords,
slopeandintercept
energy characteristics of the detector 8). If aあるファン
ト ム 厚if dthe
の適
正な写
真を
得 る た めofに必要なsubject possesses phantom thickness, object
a linearequationcanbeobtained
empirically,mAsec 値 が 求 め ら れ る 。
motion and the magnification ratio based on
the mAs necessary for a phantom image with a
この連立方程式は、2 つの異なるファントム厚を用いthe広 geometrical
さ を 考 慮 し 、positional
検 出 器 の エrelationship
ネ ル ギ ー 特 性forの 観an
点 か ら 8 ）thickness of d can be obtained.
て、スタンダード条件にある管電圧で同等な写真効果
These equations can be simultaneously
object in a standard body shape (a subject),
決定されたスタンダード条件が、X 線システムのメモ
の画像
取得す
るこ
とによっ
て解くこ
とができる
solvedbyをusing
two
different
phantom
thickappropriate images can be obtained by using
リにプログラムされていることだろう。被写体が、ス（ A1：
線 質theの 明tube記 ）。voltage under standard
nessesandthe standard condition. When the thickness
タンダード条件で想定されているファントム厚とオブ
conditions,by厚 みtakinganに 換 算 さand fleshiness of the subject differ from the
た だ し 、 被and
写体のと 肉 質imagesが フ ァ ンwith
トム厚
ジ
ェ
ク
ト
の
動
き
量
を
有
す
る
な
ら
ば
、
そ
の
条
件
で
撮
影
す
equivalent photographic effect (A1: specificastandard body shape, the conventional method
れる必要がある。
is れapplied.
Equation
isさanれempirical
ば 、適 正な 画 像 が(1)取得
る 。 被 写 formula
体 の 厚 み や 肉 質 tion of radiation quality). Therefore, the mAs iscalculated to obtain an image of a subject with
used
by the Japanese radiological technoloが 標 準 体 と 異 な る と き に 、従 来 法 が 実 行 さ れ る 。式 ( 1 )1 次条件を補正して 2 次条件を作製
gists as it includes the elements necessary forthe2 . 3same
photographic effect as the standard
は、日本の診療放射線技師に知られた実験式である。
し か し な が ら 、 私 達 は 、 mAsec 値 を 変 更 せ ず に 、 管 電radiography.
condition.
X 線画像を形成するのに必要な各要素が含まれている。
However,andfleshiness
the条 件 と 同
圧 を 変 更 しthe
た いthickness
場合がある。式( 3 ) は 、of
1 次
subject
must be converted to the phantom� � ����� ���
等 な Exposure Index 値 （ EI 値 ） を 有 す る 2 次 条 件 に 補……… (1) - ( 1 )
��� �
�
� ��
thickness.
正 す る と き 、 (1) を 用 い て 作 ら れ る 。

ここで、E はフィルムに与えられた写真効果（ここでWhere E denotes a finite radiographic effect
2.3 Setting the secondary conditions by modは 写 真 濃 度 ）、 K は そ の 写 真 効 果 を 調 節 す る た め の 定
on the film (photographic density), K is
ifying the primary conditions
数 、 V は 管 電 圧 (kVp)、 n は 線 質 の 特 徴 を 表 す 指 数 、 i
However, sometimes radiological technoloa constant used for adjusting the photograph管 電 流V (representsm A ) 、t は 撮 a影 tube
時 間 voltage( s e c ) 、s は増 感n
紙 の 増 感 gists prefer to change the tube voltage without
ic はeffect,
(kV),
p. 7
率（係数）
、f は
フィル
感度
、Z は X 線管
焦 点 の 構 成 changing the mAs. Equation (3) is derived usthe
power
ofムan
exponential
funcrepresents
tion
that
describes
a characteristics
物質の原子 番 号 、μdは 被 写 体 の 線 減of弱radiation
係 数 と 厚 さ 、r は ing Equation (1) when the primary condition isquality,i is a tube current (mA), t is imaging
modified to the secondary condition with the
焦 点 と 画 像 間 距 離 (Source-Image Distance, cm SID)、 B
time (second: s), s is the magnifying power of
equivalent exposure index (EI) to the primary
はグリッドの露出倍数、G は照射野の大きさに関する
an intensifying screen, f represents film sensicondition.
因子である。
tivity, Z represents the atomic number of a fo( 1 ) substance,
は、対数を取て 纏dめrepresent
る と (2) とる。
μっandtheな atcal式spot௏ଵ೙భ ௜ଵ௧ଵிଵ௓ଵ ିఓଵௗ௏ଶ೙మ ௜ଶ௧ଶிଶ௓ଶ ିఓଶௗ
‫ܭ‬
݁
ൌ‫ܭ‬
݁
- (3)
మ
ሺ௥ଵሻ ஻ଵீ
ሺ௥ଶሻమ ஻ଶீtenuation factor and thickness (cm) of an examineeʼs body, respectively, r is the distance
こ こ で 、 1 が 付 さ れ た 要 素 は 1 次 条 件 を………
表 し 、 2(3)が付
p. 6

された要素は 2 次条件を表す。

41◆れ て いSciences
し か し な が ら 、( 1 ) に あ る sArtsと f andは 、Fに代えらる 。F は フ ラ ッ ト パ ネ ル デ ィ テ ク タ ー ( F P D ) の 感 度 で

こ と に よ っ て 取 得 さ れ る 係 数 で あ る （ A2 ： 式 (4) を(こ
5 ) とにに単よ純っ化て
し取
な得
いさ
）
（
3：
値Aの
算式
出 を( 4避れAる係私数達ではあ、n
る（
2：
) け
を
る
さ単
ら純
に化
、私し達なはい、）
マ
係数
関数
( 5）
) 。に
（ス
A 3：
私の
達近
は似
、n
値を
の作
算製
出し
をた
避。
け
る
）。さ
らమに 、私 達 は 、マ ス 係 数 の 近 似 関 数 を 作 製 し た 。
௜ଶ௧ଶ
ሺ௥ଵሻ
ൌܳ
- (6)
మ

ሺ௥ଶሻ ௜ଵ௧ଵమ
௜ଶ௧ଶ ሺ௥ଵሻ

ൌ theܳ MAS coefficient, V2 is the - ( 6 )The variables listed with the index of one
Where
Q is
మ
ሺ௥ଶሻ
ሺܸʹሻ
ܳ
ൌ ܻ௜ଵ௧ଵ
- (7)indicate the primary condition, whereas themodified tube voltage (kVp) which is also a೙భ೙మ௏ଵ ௜ଵ௧ଵிଵ௓ଵ ିఓଵௗ௏ଶ ௜ଶ௧ଶிଶ௓ଶ ିఓଶௗこ
Q はሻ マ ス 係 数 、 V 2 は 補 正 さ れ た 管 電 圧 - ((k7Vܳこൌでܻ、ሺܸʹ) p)‫ܭ‬݁ the ൌ‫ ܭ‬of two݁- ( 3 ) variable, Y - (V2) is an approximate function
variables
listed withindex
indicateሺ௥ଵሻమ ஻ଵீሺ௥ଶሻమ ஻ଶீ
で
数
あ V2
るス
、is係
Y(数
V the
2 ) Vは
横補
軸正
にさ
変れ
数
2and
、
こ変
こvariable
でで
、も
Q は
マ
、
2horizontal
は
たV管
電縦
圧軸(に
k Vマ
p)
the secondary condition.
when
on
axis
೙భ
೙మ
ここ
で
、
1
が
付
さ
れ
た
要
素
は
1
次
条
件
を
表
し
、
2
が
付
௏ଵ ௜ଵ௧ଵிଵ௓ଵ
௏ଶ (1)
௜ଶ௧ଶிଶ௓ଶ
係
近は似横関軸数にで変あ
でMAS
変数
数を
で設
も定
あし
るた
、と
Y(on
Vの
2 )the
数る 。
V2、 縦 軸 に マିఓଶௗHowever,s and݁ ିఓଵௗf in Equation
were ݁subtheス
coefficientisきvertical
axis.
‫ܭ‬
ൌ‫ܭ‬
- (3)
మ ஻ଵீ
మ ஻ଶீ
ሺ௥ଵሻ
ሺ௥ଶሻ
さ れ たby要素
条 件sensitivity
を 表 す 。 of flat panel
stituted
F.はF 2is次theス係数を設定したときの近似関数である。
こ
こ
で
、
1
が
付
さ
れ
た
要
素
は
1
次
条
件
を
表
し
、
2
が
付
E
is
considered
detector(FPD).
Furthermore,
2.4
Preparation of the approximate function
し か し な が ら 、( 1 ) に あ る s と f は 、F に 代 え ら れ て い
2.4 近 似 関 数 の 作 製
as さEI.。Fたは要フ素ラはッ2ト次パ条ネ件ルをデ表ィすテ。ク タ ー ( F P D ) の 感 度 で When V2 ≤ V1 or Q ≥1, for example, we use
るれ私< =のV作
1 ま
2.達
4 は
近 、V
似 関2 数製 た は 、Q = > 1 の と き 、例 え ば 、 YEquation (3) can be converted to Equation
Equation (8) with Y - (V2).
し
るとs し
とてf み
はな
、Fさに
あか
るし
。な
さが
らら
に 、(
、 E1 )はにEあ
I 値
れ代
るえ
。ら れ て い
(私
V 2達
) は
と、V
して
。 = > 1 の と き 、例 え ば 、 Y2、< =( 8V)1 を
ま用
たい
はる
、Q
(4).
る
フ、
ラ(ッ
式 。F
( 3 )はは4 ) トにパ変ネ形ルでデきィるテ。ク タ ー ( F P D ) の 感 度 である、 E は E I 値 と しమて み な さ れ る 。
೙భ 。 さ ら にషഋభ೏௏ଵிଵ௓ଵ஻ଶ௘

ൌ௜ଶ௧ଶ ሺ௥ଵሻ

௏ଶ
ሺ௥ଶሻ
式 ೙మ
( 3ிଶ௓ଶ஻ଵ௘
) は 、 ( 4షഋమ೏) に変形でమき௜ଵ௧ଵ
る。

……… (4) - ( 4 )(V2) と し て、 (8) を 用 い る 。
௘ ሺೖమሻ

ܻሺܸʹሻ ൌೖభሺ௏ଶሻ௘ ሺೖమሻ

……… (8) - ( 8 )ܻሺܸʹሻ ൌ- (8)ೖభV 2 > V 1 ま ሺ௏ଶሻた は 、 Q < 1 の と き 、 私 達 は 、 Y- ( V 2 ) と し೙భ ிଵ௓ଵ஻ଶ௘
従
法 に お けషഋభ೏る (4) は、線
質మの 影 響 を 軽 微 と し て ( 5 ) When V2 > V1 or Q <1, for example, we
௏ଵ来
௜ଶ௧ଶ
ሺ௥ଵሻ
て
9 ) 、をQ用< いV 2、>例Vえ
1 ば
ま、
た(は
1る
の。
と き 、 私 達 は 、 Y- ( V 2 ) と しൌ೙మ ிଶ௓ଶ஻ଵ௘మ ௜ଵ௧ଵ
Equation(4)షഋమ೏
in the ሺ௥ଶሻconventional
method is - ( 4 ) used Equation (9) with
Y
(V2).
௏ଶ
ೖయ
に単純化される。
ሺିሺ௏ଶሻ
( 9 ) を ା௞ସሻ用いる
ܻてሺ、
ܸʹ例ሻ えൌば݁、
൅。݇ͷ
- (9)
simplified to Equation (5) by assuming a minor
従来
法
に
お
け
る
(
4
)
は
、
線
質
の
影
響
を
軽
微
と
し
て
(
5
)
ೖయ ା௞ସሻ
೙భమሺିሺ௏ଶሻ
௏ଵ௜ଶ௧ଶ ሺ௥ଵሻ
こ
で ሻ、k
し ݇ͷ
て 、k 5 ………
はその近(9)似 -関( 9数) に
radiation
impact.
ܻሺこܸʹ
ൌ1 、k݁ 2 、k 3 、k 4 そ൅ൌ quality
- (5)
೙మ 純
మ る
௏ଶ単
௜ଵ௧ଵ
に
化ሺ௥ଶሻ
され
。
含
値1 で
る。
それ
らし
はて
、 、k
ファ
こま
これ
でる
、k
、kあ2 、k
3 、k
4 そ
5 ン
はト
そム
の厚
近ご
似と
関に
数設
に

మ 管 電 圧 係 数 で あ り 、右 辺 は 実 験 に よ式
左 辺ሺ௥ଵሻ
は、
Where
k1,
k4,
and
k5、arevalues௏ଵ೙భ( 5 ) の௜ଶ௧ଶ
定
。
含さ
まれ
れる
る
値 k2,
で あk3,る。
それらは
ファ
ン ト ムthat厚ごとに設ൌ……… (5) - ( 5 )
೙మ
మ
௏ଶ
௜ଵ௧ଵ
ሺ௥ଶሻ
constitutetheapproximate
function.
These
are
っ て 取 得 で き る 。さ ら に 、管 電 圧 係 数 は 、近 似 的 に n1定される。

set for each phantom thickness.
式) の= n 2( 5 と
し左
て辺
演は
算、
さ管
れ電
る圧
。係 数 で あ り 、 右 辺 は 実 験 に よThe left side of Equation (5) is the tube voltGiven that we followed the conventional
っ
近る
似。
的
提て
案取
法得
でで
はき
、( 4る) 。
のさ右ら辺にを、マ管ス電係圧数係と数名は付、けマにス n係1
p. 9 in setting the primary condition, we
age coefficient, and the right can be obtained
method
= nと
2は
と、
し
数
あて
る演
中算
心さ
かれ
らる
放。
射された X線の生成において、experimentally. The tube voltage coefficient isomittedp. 9 the demonstration experiment to mod提
案
法
で
は
、
(
4
)
の
右
辺
を
マ
ス
係
数
と
名
付
け
る
。
マ
ス
係
2
次
条
件
の
単
位
表
面
積
当
た
り
の
m
A
s
e
c
値
を
、
1
次
条
件
ify the standard condition, and assumed theapproximately calculated as n1 = n2.
数
と
は
、
あ
る
中
心
か
ら
放
射
さ
れ
た
X
線
の
生
成
に
お
い
て
、
The
right
side
of
Equation
(4)
is
named
as
の 単 位 表 面 積 当 た り の m A s e c 値 を 基 に し て 正 規 化 す る following as the primary condition: tube volt“theMASin当theproposed2 次
条 件coefficientの 単 位 表 面” 積たりの m A s e c method
値 を 、 1 次 条 件 age of 50 kVp, tube current of 200 mA, imagbyのus.
The MAS coefficient is defined as a coefing time of 18 ms, irradiation field of 20×20
単 位 表 面 積 当 た り の mAsec 値 を 基 に し て 正 規 化 す る
cm on the FPD, an SID of 120 cm and phantom
ficient that is obtained by normalizing a newp.
8
thickness of 8 cm PMMA. The imaging protomAs per unit surface area that is used when
col used was “TEST QC S value” of KONICAMIgenerating X-rays are emitted from a given
NOLTA CS-7. The conditions associated withcenterp. 8 in the secondary condition, on basis of
this protocol produced an EI of approximately
a mAs per unit surface area that is used when
250. Several secondary conditions were pregenerating X-rays are emitted from a given
pared in an experiment with an SID 120 cm tocenter in the primarily condition (A2: Equationachieve the EI before and after 250, as linear(4) is not simplified to Equation (5), A3: We
interpolation was performed between them.
avoided
calculation of n).
こ と に よ っ て 取 得 さ れ る 係 数 で あ る （ A2 ： 式 (4) をこ と に よ っ て 取we
得され
る係数であ
る （ A 2 ： 式 ( 4 ) を Table 1 lists the linear interpolation outcomes
Furthermore,
prepared
approximate(5) に 単 純 化 し な い ）（ A 3： 私 達 は 、n 値 の 算 出 を 避 け
functionforcoefficient.
(5) に 単純 the
化 しMASない）（ A 3： 私 達 は 、n 値 の 算 出 を 避 け of the radiographic conditions that were reる ）。さ ら に 、私 達 は 、マ ス 係 数 の 近 似 関 数 を 作 製 し た 。
quired to achieve an EI of 250 and the calcuる ）。さ ら に 、私 達 は 、マ ス 係 数 の 近 似 関 数 を 作 製 し た 。
మlated MAS coefficient Q.
௜ଶ௧ଶ ሺ௥ଵሻ
……… (6) - ( 6 )మ ൌ ܳ௜ଶ௧ଶమ ሺ௥ଵሻ
௜ଵ௧ଵ
ሺ௥ଶሻ
Figure 1 shows Q from Table 1 plotted on theൌܳ- (6)ሺ௥ଶሻమ ௜ଵ௧ଵvertical axis as a function of V2 on the horizonܳ ൌ ܻሺܸʹሻ
- (7)
ሺ
ሻ
ܳ ൌ ܻ ܸʹ……… (7) - ( 7 ) tal axis. Figure 2 shows the approximate funcこ こ で 、Q は マ ス 係 数 、V 2 は 補 正 さ れ た 管 電 圧 ( kVp)
こ こ で 、 Q は マ ス 係 数 、 V 2 は 補 正 さ れ た 管 電 圧 ( k V p )tion of the MAS coefficient chart expressed by
で 変 数 で も あ る 、 Y- ( V 2 ) は 横 軸 に 変 数 V 2 、 縦 軸 に マ
で 変 数 で も あ る 、 Y- ( V 2 ) は 横 軸 に 変 数 V 2 、 縦 軸 に マス係数を設定したときの近似関数である。
of JART English edition 2022
42ス◆係Journal数を設定したときの近似関数である。

original articles
Modification methods of radiographic conditions alternative to tube voltage coefficient chart

MAS coefficient Q

Equations (8) and (9), with Q on the verticalaxis and V2 on the horizontal axis. This approximate function was prepared based on k1,
k2, k3, k4, and k5, which were calculated tohave the following values: 5.74091, 22.47204,
0.55992, 8.87683, and 0.07114, respectively,
with a pass-point limit Q = 1.0 using Excel (Microsoft Office 2013, Microsoft Corp., Redmond,
WA, USA). Q = 1.0 was used as a calculation
constraint to resolve the problem of the tube
voltage coefficient not always passing the value of 1.0 in the chart, although it should during

the modified condition calculation withoutchanging the tube voltage (A4: resolving thepassing point issue).
2.5 Demonstration experiment

We left imaging time as blank and set thesecondary condition using the approximate
function. Then, the secondary condition taps
(tic marks of the X-ray system) were set by applying the radiographic condition taps by setting their values so that they fell within thepractical range of our hospital, and the values

2

1.5
Table 1 Interpolated radiographic conditions and
1 the MAS coefficient Q with an EI of 250
0.5
kVp

mAs

coefficient Q

046
4845

29.45

1.61

65
85
23.14
1.27
secondary condition kVp

Condition No.

kVp

mA

cm SIDms

8 cm, No.1

45

160

115

38.87

45

200

115

31.09

18.24

1.00

8 cm, No.2

56

10.52

0.58

8 cm, No.3

56

250

125

9.41

63

6.11

0.34

8 cm, No.4

73

80

75

3.30

72

3.56

0.20

8 cm, No.5

51

200

75

6.57

0.14

8 cm, No.6

73

100

115

6.20

8 cm, No.7

62

80

85

8.48

8 cm, No.8

68

100

75

3.51

8 cm, No.9

45

80

125

91.84

8 cm, No.10

68

320

105

2.15

50

78

2.60

Fig. 1 Plot of Q as a function of V2
MAS coefficient Q

Table 2 Secondary conditions generated by theapproximate functions when imaging time
was assumed as blanks

2
1.5
1
0.5
0

45

65
secondary condition kVp

85

Fig.1 Plot of Q as a function of V2

Table 3 Secondary conditions recalculated by theapproximate functions when we assumed
a tube voltage of blank by setting of 5 ms
or more, the measured EI by the secondary conditions, and the relative errors between the measured EI and the target EI
kVp

mA

cm
SID

ms

measured relative
EI
error

8 cm, No.1

45

160

115

40.0

264.140.057

8 cm, No.2

45

200

115

32.0

262.960.052

8 cm, No.3

56

250

125

9.0

245.80-0.0171

8 cm, No.4

62

80

75

6.3

246.36-0.0150.5

8 cm, No.5

51

200

75

6.3

232.89-0.0680

8 cm, No.6

73

100

115

6.3

257.11

0.028

8 cm, No.7

62

80

85

8.0

245.25-0.0198 cm, No.8

62

100

75

5.0

237.12-0.052

8 cm, No.9

45

80

125

90.0

260.020.040

8 cm, No.10

56

320

105

5.0

245.25-0.019MAS coefficient Q

Condition
No.

2

Fig. 1 Plot of 1.5
Q as a function of V2

45

65
secondary condition kVp

85

Fig.2 Q chart of the MAS coefficient using Equations (8) and (9) (45–85 kVp)

Fig. 2 Q chart of the MAS coefficient using (8) and (9) (45-85 kVp)

Arts and Sciences ◆ 43

were determined randomly by rolling dicethrice. The three rolls of the dice yielded thefollowing values: 45, 51, 56, 62, 68, and 73 fortube voltage (kVp), 80, 100, 160, 200, 250, and
320 for tube current (mA), and 75, 85, 95, 105,
115, and 125 for SID (cm).
Table 2 shows the secondary condition calculated by using the approximate function
with imaging time as blank. However, at our
hospital, considering the reliability of the linearity of the timer, we did not use imaging
times <5 ms. Thus, when the imaging time wasless than 5 ms, we set it to ≥5 ms, left the tube
voltage as blank, and recalculated the secondary condition using the approximate function.
Table 3 lists the secondary condition recalculated with the approximate function (A5: we
did not read the values from the chart). However, all the secondary conditions were prepared with taps that can be set for the X-ray
system. In other words, we selected the nearest taps for the set imaging time and the tube
voltage calculated by the approximation function. Table 3 shows the relative difference between the measured EI and target EI of 250 for
the secondary condition.

3. Results

4. Discussion
The developmental objective of the conventional method was to maintain a relative errorof ±0.25 with the target photographic density.
The aim was to avoid reacquiring an analog
image even if there were shades. The proposed
method aimed to maintain the relative error
with the target EI within ±0.1 (A6: specification of the developmental objective).
In the initial experiment, there was an error
in the solution of the simultaneous equations
at Equation (2), which did not achieve the developmental objective. Specifically, to set the
primary condition, we assumed that the phantom thicknesses ranged from 1 to 15 cm for thedemonstration experiment and grid-less imaging of four limb, and measured the mAs with
the PMMA phantom as 1, 4, 7, 10, 13, and 15
cm to achieve an EI of 250. We then performeda regression analysis (Figure 3). However, withthis regression line, we were unable to express
the actual value that yielded a slight convex
downward, thus leading to residual difference.
Coupled with the error of the secondary condition, we were unable to achieve the developmental objective. Thus, we performed another
regression analysis by dividing the entire range

3
2.5
2
ln(mAs)In the demonstration experiment that used 8
cm PMMA, the measured EI under the secondary condition prepared with the approximate
function of the MAS coefficient Q was within
the relative error of ±0.1 of the target EI. In
addition, we changed PMMA to 1, 5, 11, and 15
cm and performed the same demonstration ex-

periment. The results that did not fall within
the relative error of ±0.1 are listed in Table 4.

1.5
1Table 4 Demonstration experimental outcomeswith relative errors >±0.1

0.5

ms

measured relative
EI
error

-0.5

Condition
No.

kVp

mA

cm
SID

1 cm, No.9

45

80

125

22

276.290.11

15 cm, No.6

73

100

115

18

221.15-0.12

15 cm, No.7

62

80

85

32

281.94

0.13

0

0

5

10

Phantom thickness (cm)Fig.3 Plot of Equation (2). The solid line denotes
the data. The dotted line is the regression line2−0.2794:
cm:(2).
y =The0.1996x0.9996).
Fig. 3 Plot of (1–15
Equationsolid line
denotes R
the=data.
The dotted line denotes t(1 - 15 cm: y = 0.1996x – 0.2794: R2 = 0.9996).

44 ◆ Journal of JART English edition 202215

original articles
Modification methods of radiographic conditions alternative to tube voltage coefficient chart

3ln(mAs)into 1–72.5
cm and 7–15 cm segments, and used
ing time with the approximate function with2
a regression line with a coefficient of determithe closest taps as follows: 21.11 ms being ei1.5
2nation R = 0.9999 to perform a demonstration
ther equal to 20 or 22 ms, 18.97 ms being ei1
experiment for a phantom thickness of 8 cm
ther equal to 18 or 20 ms, and 30.06 ms being
0.5(Figure 4). In this manner, we achieved the deeither equal to 28 or 32 ms.
0velopmental0 objective.
Figure 5 shows the approximate function of
5
10
15
-0.5
Similarly,
we performed
moredemonstrationtheMAS coefficient used for calculation with
Phantom thickness (cm)experiments by changing the phantom thickthe phantom thicknesses of 1, 8, and 15 cm.
ness to 1, 5, 11, and 15 cm. Some results that
For example, if we want the MAS coefficient Q
did not meet the developmental objectives arefor a radiographic condition of 50 kVp to be
Fig. 3 Plot of Equation (2). The solid line denotes the data. The dotted line denotes the regression line
listed in Table 4. However, these results were0.5, even in the same system, modifications(1 - 15 cm: y = 0.1996x – 0.2794: R2 = 0.9996).
attributed to the calculation result of the imagmust be implemented with a difference of 59.3
kVp for the thickness of 1 cm, 57.8 kVp for 8
cm, and 56.9 kVp for 15 cm.
3
2.5

5. Conclusions2

MAS coefficient Q

ln(mAs)

We eliminated several causes of errors associated with the conventional method and intro1
duced a method to modify radiographic condi0.5
tions with fast calculations. However, the data0base of the approximate function of the MAS
0
5
10
15
-0.5
coefficient Q for each structure of an X-ray
Phantom thickness (cm)system, imaged part, and the phantom thickFig.4 Plot of Equation (2). The solid line denotes
ness must be prepared ahead of time (A7:the data. The dotted line is the regression
2
specification of notes). The proposed methodline (1–7 cm: y = 0.1899x−0.2448: R =2
0.9999, 7–15 cm: y = 0.2053x−0.3481: R =required setting radiographic conditions that
0.9999).
were modified for each subject. Specifically,
Fig. 4 Plot of Equation (2). The solid line denotes the data. The dotted line denotes the regression line
there
was
an EI that was equivalent to the EI(1 - 7 cm: y = 0.1899x - 0.2448: R2 = 0.9999, 7 - 15 cm: y = 0.2053x - 0.3481:
R2 =0.9999)obtained in the standard condition. X-ray sys5
4.5
tem vendors should release X-ray systems that4
allow for more fine-tuned settings of imaging
3.5
time for setting of appropriate radiographic
3
conditions.
2.5
In actual X-ray examination, radiological2
technologists
often acquire images using an
1.5
1
automatic exposure control, as it is not easy to
0.5
convert the subject to phantom thickness.
0
However, as the foundation of radiological
40
50
60
70
secondary condition kVp
techniques, we must identify ways to modify
the radiographic conditions. When discussing
Fig.5 Q chart of the mAs coefficient (40–75 kVp)
a method to select one radiographic condition
for the demonstration experiment. The solidline is the approximate function for 8 cm
from multiple ones with the same EI, it will
brokenthe forapproximate
Fig. 5 Q chart of PMMA.
the MAS The
coefficient(40line– 75iskVp)
the demonstration experiment: The solid line
become clear why radiological technologists
function for 1 cm PMMA. The dotted line isdenotes the approximate function for 8 cm PMMA. The broken line denotes the approximate function
must have a priori knowledge of the modulathe approximate function for 15 cm PMMA.
1.5

for 1 cm PMMA. The dotted line denotes the approximate function for 15 cm PMMA.

Arts and Sciences ◆ 45

tion transfer function and the noise power
spectrum. This is because the automatic exposure control does not see the actual subject. In
other words, it determines the radiographic
condition regardless of the movement andgeometric position of the object in a subject.
Thus, the image is not necessarily an appropriate diagnostic image. The automatic exposure
control and automatic gradation conversion
processing are complementary technologies
for radiological techniques.

Acknowledgements
The author would like to extend the sincerest appreciation to late Prof. Masaru Uchida forrequesting the redevelopment of the imaging
method, late Prof. Kazuya Yamashita for teaching me the weaknesses of the conventional
method, and Prof. Hiroshi Inatsu who permitted the use of the copyright for the conventional method. The author also would like tothank Ulatus in manuscript translation.

Funding
No funding was received for the pursuit andcompletion of this study.

Conﬂicts of interest
The author has no conflict of interest to declare.
However, we secured a patent in Japan andthe United States to ensure the novelty of theprocess of correcting the primary conditionand creating the secondary condition.

46 ◆ Journal of JART English edition 2022

Ethics statement
No humans or animals were involved in thisstudy.

References
1） UCHIDA Masaru, et al.: HOUSHASEN GIJUTSUSHANO TAMENO GAZOU KOGAKU (Imaging technology
for radiologists). Tokyo: Tsusho sangyo kenkyu sha,co. 1978, in Japanese.
2） KOZUKA Takahiro, et al.: Textbook of clinico-radiological technology. Version 14. First volume. Tokyo:
Nankodo Co., Ltd., P.13-72, 2019, in Japanese.
3） ASAHI Toshiharu: The ﬁrst report on the study of correction coefﬁcient for radiographic condition for eachtype of X-ray device. Correction coefficient: Photographic effect from ﬁlm blackening. Japanese Journalof Radiological Technology, Vol.23, No.1, p 94, 1967,
in Japanese.
4） ASAHI Toshiharu: Attempts with correction coefﬁcient
for radiographic conditions (with dosimeter method).
Japanese Journal of Radiological Technology, Vol.24,
No.1, p 95, 1968, in Japanese.
5） MORIKAWA Kaneo, et al.: Correction table for radiographic condition. Japanese Journal of RadiologicalTechnology, Vol.37, No.3, p 385-386, 1981, in Japanese.
6） OHGA Yasufumi, et al.: Method of subjective evaluation on radiograph - Scaled experiment by Thurstoneʼs
method of paired comparisons. Japanese Journal ofRadiological Technology, Vol.45, No.7, p 831-839,
1989, in Japanese.
7） NAKAMAE Mitsuhiro: Study of the reliability of visualevaluation by the ranking method - analysis of ordinalscale and psychological scaling using the normalizedrank approach. Japanese Journal of RadiologicalTechnology, Vol.56, No.5, p 725-730, 2000, in Japanese.
8） ODA Nobuhiro, et al.: Evaluation of 90 kV beam with
0.15 mm Cu filter in chest radiography using CsIﬂat panel detector. Japanese Journal of RadiologicalTechnology, Vol.76, No. 5, p 463-473, 2020, in Japanese.

Arts and Sciencesmaterial

Received June 15, 2020; accepted September 25, 2020

New challenges for SARS-CoV-2–Infection control in Mobile X-ray–
MOCHIGI Kazuya1）, SHINAGAWA Kazuki2）1）National Center for Global Health and Medicine, Radiology department, Chief2）National Center for Global Health and Medicine, Radiology department, Radiological Technologist

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 821: 29-37, 2021.
Key words: COVID-19, Infection control, Mobile chest X-ray, Nosocomial infection【Abstract】

PurposeThe purpose of this study is to examine the procedures in use related to portable chest radiography in COVID-19
patients and to prevent nosocomial infections as well as infections among Radiology Department staff.
MethodA dedicated mobile X-ray machine for COVID-19 patients was utilized, and the procedures related to the disinfectionof the device, as well as attachment/detachment of infection protection equipment, was examined.
ResultFrom January 21, 2020 to April 28, 2020, the number of mobile X-ray cases for COVID-19 at this hospital was 1,439.
As of May 15, 2020, COVID-19 positivity according to PCR testing was 0% among 50 medical radiologists. The
information was shared via Microsoft Teams, with immediate distribution, and it was designed to enable browsing
and access on mobile devices at any time.
Conclusion
By incorporating the portable X-ray imaging method into COVID-19 diagnosis and treatment, it was both effective
and ensured the safety of the radiologic technologists and also prevented nosocomial infections.

Introduction
During the COVID-19 pandemic this hospital
accepted numerous returnees from Wuhan,
China, arriving both on charter ﬂights and fromocean-going cruise ships.
Additionally, to evaluate inﬁltrating shadowsin the lung ﬁelds for both suspected and conﬁrmed COVID-19 cases, mobile chest X-ray examinations have been performed, including
febrile outpatients and within the hospitalemergency medicine department.
In portable chest radiography, a cassette (CR:
Computed Radiography, or FPD: Flat Panel
Detector) must be positioned on the patientʼsback and adjusted. As a result, many situations
exist where direct physical contact between
the radiologist or radiology technician, and thepatient is required. Therefore, maintaining a
speciﬁed minimum distance from the patient is
impossible.

In recent years, a variety of devices havebeen introduced into portable X-ray systems.
As a result, imaging is performed while touching various devices in addition to the portable
X-ray system. Inevitably, the number of contaminated areas increases, resulting in an examination which demonstates a heightenedrisk of infection for both patients and medical
personnel.
A manual for the prevention of nosocomial
infections was prepared by the hospitalʼs Infection Control Team (ICT) with speciﬁc measures
such as hand disinfection methods, proceduresfor donning and dofﬁng personal protective
equipment (PPE), and separation of linens andinfectious waste. It is believed that if all staff
members work together according to this manual, preventing nosocomial infections will bepossible. However, speciﬁc infection-control
methods for portable radiography have yet to
be deﬁned.
Arts and Sciences ◆ 47

Radiologists must take the lead and examine
what countermeasures must be taken in eachsituation while performing actual portable radiography and what measures must be taken
according to the principles of infection control.
The purpose of this study is to review theprocedures of portable chest radiography in
the COVID-19 environment, evaluate the clinical diagnostic options, to ensure the safety ofradiologists and radiology technicians and toprevent nosocomial infection.

1. Methods
1-1 Confirmation of the route of infection in
COVID-19
The current evidence suggests that SARSCoV-2, the pathogen which causes COVID-19,
is isolated from airway secretions and fecesand enters the body when it comes into contact with the mucous membranes of the eyes,
nose, and mouth.
Based on this understanding, standard precautions, including respiratory hygiene andcough etiquette, as well as contact and droplet
infection-control measures, should be taken
for suspected and positive COVID-19 cases.
Additionally, because procedures such as suctioning patientsʼ airways, endotracheal intubation, and the collection of lower respiratory
tract specimens may generate aerosols, N95
masks should be worn to reduce the possibilityof airborne infection 1). However, for safety reasons, all personnel conducting mobile chest Xrays at this hospital use N95 masks.

made known to the staff of the radiology department (Fig.1).
1-3 Infection-Control Measures for Equipment
Used
1-3-1 Equipment used

The portable X-ray system utilized was a HITACHI Sirius 130H inverter-type cordless mobile X-ray system. Additionally, a KONICA
wireless FPD Aero DR System was used as thecassette so that body movements and breathing, which can cause blurring and require reimaging, can be checked in the contaminatedarea while wearing PPE.
In addition to the FPD, the Aero DR System
includes the CS-7 (notebook PC) as a console,
the Aero DR rounding unit (UF unit), and abarcode reader for patient authentication.
1-3-2 Equipment contact location

Since COVID-19 is a contact and droplet infection, researchers decided that points of contact are required to be limited in advance toprevent the spread of contamination. Therefore, red circular stickers were placed on the

1-2 Confirmation of COVID-19 compliant wards

In addition to checking infection routes, understanding the location of infection-control
items in COVID-19 outpatient clinics and in inpatient wards dedicated to COVID-19 is very
important. The locations of PPE and designated clean and contaminated areas were conﬁrmed, and the locations of infectious waste
containers were identiﬁed in advance and48 ◆ Journal of JART English edition 2022a) Map of hospital wardsa）病棟全体図① 病室b) Enlarged
view of ab）病室拡大図
hospital room

Fig.1
Layout of COVID-19 compliant wards (e.g.,②
個人防護具の物品置場
ICUX wards)③ ポータブル
線置場④ 汚染エリア① Hospital room

⑤ 清潔エリア② Personal Protective Equipment article storage
感染ゴミ箱locations③ Storage location for portable X-ray equipment

Fig.1④ Contamination
area 病棟を例に）
COVID-19
対応病棟の配置図（ICU⑤ Clean area

Trash can for infection

material
New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–

①

②

③

④

⑤

Fig.3 Temporary clean area for equipment
Fig.3

装置の一時的クリーンエリア

Fig.3 Fig.3
装置の一時的クリーンエリア
装置の一時的クリーンエリア
①

②

③

④

⑤

Fig.2 Equipment contact location① Equipment actuating lever② Both side handles of aperture handle, irradiation ﬁeld

aperture, irradiation ﬁeld lamp, and shooting condition
setting switch③ Front/rear and left/right locking parts (2 locations)④ Handle switch⑤ exposure switch

Fig.4 FPD contamination prevention measures

FPD の汚染防止対策
Fig.4 Fig.4
FPD の汚染防止対策

Fig.4

FPD の汚染防止対策

minimum necessary areas to visually identify
the points of contact (Fig.2).
Infection Prevention Measures for CS-7
CS-7の汚染防止対策
Fig.5 Fig.5
CS-7Fig.5の汚染防止対策

1-3-3 Secure temporary clean areas for equipment

Since all imaging locations were within thecontaminated area, a temporary clean area was
required to keep the FPD clean. As a result, a
temporary clean area was set up in the cassette
folder of the portable device, and the FPD, CS7, UF unit, physical grid, barcode reader, anddisinfection items were placed there based on
the assumption that this area would not be
contaminated (Fig.3).
1-3-4 FPDTo prevent contamination, the FPD was covered prior to use with a 45 L plastic bag. Whenusing the FPD, procedures (1) through (5)were followed (Fig.4).

Fig.5

CS-7 の汚染防止対策

1-3-5 CS-7

The CS-7 is a touch-panel type console.
Therefore, it was covered with a standard plastic bag No. 15 (300 mm x 450 mm) when inuse, to prevent contamination (Fig.5).
1-3-6 Items to be disinfected

SARS-CoV-2 exhibits an envelope protein,
making alcohol disinfection effective 1).
Therefore, researchers decided to prepare alcohol or sodium hypochlorite in advance (Fig.6).
1-3-7 Infection protection devices

The infection related items required for COVID-19 are shown in Figure 7. In portable radiArts and Sciences ◆ 49

③ N95 マスク④ Ns アルファキャップ⑤ アウター手袋⑥ アルコール消毒⑦ インナー手袋
Fig.7 感染防護具

Fig.6 Preparation of disinfection supplies
N95 mask fit test
Fig.8 Fig.8
N95 マスクのフィットテスト

Fig.6 消毒用物品の準備

①

③

②

⑤

④

⑥
① FPD
② CS-7③ Items to be disinfected④ UF ユニット⑤ bar code reader⑦① アイソレーションガウン

② ユニシールド アイプロテクションマスクあるいは、ゴーグル① Fig.9
FPD Storage in temporary clean area
③ N95 マスク②

④ Ns アルファキャップ③ 消毒物品⑤ アウター手袋
Fig.7
Infection protection devices⑥ アルコール消毒① Isolation gown
⑦ インナー手袋② Uni-Shieldeye protection mask or goggles③ N95 Mask
Fig.7
感染防護具
④ NS
Alpha
Cap
⑤ Outer glove⑥ Alcohol disinfection⑦ Inner glove④

CS-7
UF ユニット

fore, for safety reasons, the radiology techni⑤ バーコードリーダー
cian chose to wear an N95 mask beforehand.
TheFig.9
N95一時的クリーンエリアへの収納
mask was ﬁtted while looking in a
mirror, and a ﬁt test was conducted beforehand to ensure that no air leaks were found(Fig.8).
1-4-2 Preparation for Imaging

ography, the wrist may be exposed when thecassette is placed on the patientʼs back. To prevent exposure, an inner glove that can cover
the wrist tightly is used. Conﬁrming the appropriate glove size in advance is important (Fig.7).
Fig.8 N95 マスクのフィットテスト

1-4 Preparation before inspection
1-4-1 Wear of an N95 mask

The duration of SARS-CoV-2 in the environment is unknown at this time, and to respondto this situation, surgical masks may be used if
aerosols are not generated 1). However, howmuch virus is airborne as a result of the prolonged stays of hospitalized patients in their
hospital rooms is not readily apparent. There-

50 ◆ Journal of JART English edition 2022

The FPD, CS-7, and disinfection supplies
needed for imaging were covered with plasticbags and temporarily stored in the clean area.
Since the barcode reader for patient authentication was used in advance in the clean area,
researchers decided not to cover it with a plastic bag to simplify its operation. Additionally,
a）後面
b）側面
reader was stored in the tempotheFig.10
barcodeガウンの装着方法
rary clean area (Fig.9).
1-5 PPE Wear Procedures
1-5-1 Wear of PPE

When PPE was worn, the hands were ﬁrst
disinfected, and then, gowns were donned. In
portable radiography, the FPD is attached to

①

①
FPD

FPD

②

②
CS-7

CS-7

a）悪い例 a）悪い例③ 消毒物品③ 消毒物品④

Fig.11

UF ユニット
UF④ユニットｂ）良い例 ｂ）良い例

material

Fig.11 キャップ装着時のチェックポイント
キャップ装着時のチェックポイント

New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–⑤ バーコードリーダー⑤ バーコードリーダー
Fig.9 一時的クリーンエリアへの収納
Fig.9 一時的クリーンエリアへの収納

a）悪い例

ｂ）良い例

Fig.11 キャップ装着時のチェックポイント

a）悪い例

ｂ）良い例

Fig.11 キャップ装着時のチェックポイント
Fig.12 インナー、アウター手袋装着手順
Fig.12 インナー、アウター手袋装着手順

Procedure for fitting inner and outer gloves
Fig.12 Fig.12
インナー、アウター手袋装着手順a）シールド部分の折り曲げ方a）シールド部分の折り曲げ方
Fig.12 インナー、アウター手袋装着手順a) Backa）後面a）後面b)b）側面
Sideb）側面

ガウンの装着方法
Fig.10 Fig.10
ガウンの装着方法
Fig.10How to wear the gowna）シールド部分の折り曲げ方c）ゴーグル装着時a）シールド部分の折り曲げ方b）アイプロテクションマスク装着時c）ゴーグル装着時a) How
to bendb）アイプロテクションマスク装着時b) When wearingc) WhenwearingFig.13 アイプロテクションマスクおよびゴーグルの装着
theFig.13
shield アイプロテクションマスクおよびゴーグルの装着
eye protection
gogglessectionmask

Fig.13 Wearing an eye protection mask andgogglesb）アイプロテクションマスク装着時c）ゴーグル装着時

Fig.13 アイプロテクションマスクおよびゴーグルの装着
b）アイプロテクションマスク装着時a) Poor examplea）悪い例 a）悪い例

b) Good exampleｂ）良い例ｂ）良い例

c）ゴーグル装着時

Fig.13 アイプロテクションマスクおよびゴーグルの装着

Fig.11 Checkpoints when installing caps

Fig.11 キャップ装着時のチェックポイント
Fig.11 キャップ装着時のチェックポイント

the patientʼs back. This requires bending overin cramped hospital rooms, raising both hands
to adjust the position, and slipping between
the cables of the equipment. The use of openbacked plastic aprons was avoided in favor ofisolation gowns that provide good back proFig.12 インナー、アウター手袋装着手順
Fig.12 インナー、アウター手袋装着手順
tection. Care was taken to ensure that the backof the gown was ﬁrmly aligned, and a mirror
was used to conﬁrm that the back was not exposed after the gown was put on. Althoughsome literature suggests tying the gown stringsat the back, we chose to tie the strings at thesides of the body because if the back side ofa）シールド部分の折り曲げ方a）the
シールド部分の折り曲げ方
gown is exposed, it potentially could directly touch the clean area without being noticed when removing the gown (Fig.10).

1-5-3 Wearing gloves (inner and outer)

Gloves were worn over the sleeves of thegown, and subjects wore inner gloves of a typewhich allowed the grip of the sleeves with
their ﬁngers and covered the wrists tightly overthe sleeves. For the outer gloves, different colors were selected, so that they could be distinguished from the inner gloves when the patients were undressing (Fig.12).
1-5-4 Eye Protection

An eye protection mask was worn to protect
the eyes. Since it has become more difﬁcult tosecure supplies, arrangements were made sothat personal goggles could be used in place ofeye protection masks. The eye protection mask
was utilized by bending both sides of the shieldportion, and an eye protection mask was wornon top of the N95 mask (Fig.13).
1-6 Mobile X-ray Procedure

1-5-2 Cap Mounting

When putting on the cap, researchers decided to use a mirror to ensure that hair was notthatsticking out of the cap. Also,
we ensuredb）アイプロテクションマスク装着時b）アイプロテクションマスク装着時c）ゴーグル装着時c）ゴーグル装着時
the ears
were covered by the cap (Fig.11).
Fig.13 アイプロテクションマスクおよびゴーグルの装着
Fig.13
アイプロテクションマスクおよびゴーグルの装着

1-6-1 Patient Authentication

As part of the patient authentication procedure, Modality Worklist Management using
barcode readers was performed in the clean
area and deployed in the CS-7. To prevent contamination, the barcode readers were stored inArts and Sciences ◆ 51

Fig.15 曝射スイッチのコードリール抑制
曝射スイッチのコードリール抑制
Fig.15

Fig.14
患者認証用バーコードリーダー
Fig.14
患者認証用バーコードリーダー
Barcode reader for patient authentication
Fig.14

Fig.14

患者認証用バーコードリーダー

a)
FPD
a）
a）FPD
FPD

b)
CS-7
b）
b）CS-7
CS-7

Fig.16 How to store FPD and CS-7

Fig.16
FPD,CS-7の収納手法の収納手法
Fig.16 FPD,CS-7

Fig.17 How to remove outer gloves

Fig.17 アウター手袋の外し方
Fig.15
Fig.15 曝射スイッチのコードリール抑制
曝射スイッチのコードリール抑制

Fig.15 Fig.15
Curl 曝射スイッチのコードリール抑制
cord suppression of exposureswitches

plastic bags were disposed of in an infectious
waste container located in the contaminatedarea (Fig.16).
1-7-2 Outer gloves

the clean area immediately after use (Fig.14).
a）FPD
a）FPD

b）CS-7b）CS-71-6-2 Procedures from positioning to imaging

Fig.16 FPD,CS-7 の収納手法
Fig.16 FPD,CS-7 の収納手法

The portable device was moved to the contaminated area, and the plastic bag covered
FPD was placed under the patientʼs back. Thea）FPD
portable device was only allowed to contact
the pre-designatedarea,
its position was adの収納手法
Fig.16 FPD,CS-7
justed, and the imaging conditions were set appropriately (Fig.2). The hand switch cord was
not extended, and it remained secured to thedevice to prevent contamination of the cord
(Fig.15).
1-7 Procedures for removing PPE following

Fig.18 汚染エリア内での装置消毒手法

Due to their contamination, outer gloves
were discarded in the infectious waste container located in the contaminated area immediately after the FPD and CS-7 were stored. The
outer gloves were removed with the inside of
the gloves facing out so as not to contaminateb）CS-7the inner gloves, and the hand wearing theoutergloves was used to grip the removed
Fig.19アイソレーションガウン、インナー手袋脱衣手順
gloves. To prevent contamination of the innerglove of the hand that removed the outer
glove, the ﬁngers were placed inside the outer
glove on the opposite side and removed sothat the inner side of the outer glove was facing out, as if covering the outer glove that was
being held (Fig.17).

imaging (in contaminated areas)
1-7-1 Storage of FPD and CS-7

1-7-3 Equipment disinfection

After the imaging was completed, a 45 L
plastic bag was removed from the outside of
the FPD and temporarily stored in a clean area.
In doing so, great care was taken, to ensurethat the FPD was not contaminated.
Similarly, the standard bag No. 15 was removed from the outside of the CS-7, and only
the CS-7 was stored in clean areas. The used

After removing the outer gloves, the innergloves were disinfected with alcohol, and then,the device was disinfected. The disinfection of
the device was based on the disinfection of theentire device, with a focus on the previously
determined points of contact (Fig.18). The
gowns were donned and doffed before thetemporary clean area was disinfected.

52 ◆ Journal of JART English edition 2022

material
New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–

Fig.17
アウター手袋の外し方
Fig.17
アウター手袋の外し方

a）アイプロテクションマスク使用時a) When using eye protection maska）アイプロテクションマスク使用時a）アイプロテクションマスク使用時

Fig.18 Equipment disinfection methods in
Fig.18 汚染エリア内での装置消毒手法
Fig.18 汚染エリア内での装置消毒手法
contaminated areasb) When using gogglesb）ゴーグル使用時b）ゴーグル使用時b）ゴーグル使用時
Fig.20 How to remove eye protection mask andFig.20 アイプロテクションマスク、ゴーグルの外し方
gogglesFig.20 アイプロテクションマスク、ゴーグルの外し方
Fig.20 アイプロテクションマスク、ゴーグルの外し方
Fig.19 アイソレーションガウン、インナー手袋脱衣手順
Fig.19 Isolation gown and inner glove removal
Fig.19 アイソレーションガウン、インナー手袋脱衣手順

procedure

1-7-4 Dofﬁng gowns and inner gloves

After disinfection of the equipment, the innergloves were disinfected. The isolation gown
was untied, and the gown was peeled off bypulling the surface, so that the contaminatedpart of the surface was on the inside. The gown
was removed slowly together with the innergloves. The surfaces of the gowns and gloves
were rolled up into a small ball so as not totouch them, and they were discarded in an infectious waste container in the contaminatedarea (Fig.19).

a）ゴーグルの消毒b）ゴーグル置き場へ保管
a）ゴーグルの消毒b）ゴーグル置き場へ保管
a) Goggleb) Stored ina）ゴーグルの消毒b）ゴーグル置き場へ保管
Fig.21 Disinfection
ゴーグル使用後の消毒手法goggle storage
Fig.21 ゴーグル使用後の消毒手法
Fig.21 ゴーグル使用後の消毒手法areac）防護衝立の消毒c)c）防護衝立の消毒
Disinfectingc）防護衝立の消毒
impulsestorage areas

Fig.21 Disinfection technique after goggle use

1-7-6 Goggles Disinfection

When goggles were used, an additional procedure for disinfecting the goggles had to be
added. After putting on gloves, the goggles
were disinfected and placed in the goggle storage area. During this process, the radiation-protection impulse was also contaminated, so researchers decided to disinfect it again (Fig.21).

1-7-5 Removing eye protection mask and goggles

Hand sanitization was performed before removing the eye protection mask to protect theeyes. The mask was removed by holding therubber part of the mask so as not to touch its
surface, and then, it was discarded directly into
the infectious waste container in the contaminated area. In case of shortage of supplies,
personal goggles were used. The goggles were
removed by holding the rubber part of thegoggles, so as not to touch the surface of thegoggles, and placed on the radiation-protection barrier of the equipment (Fig.20).

1-7-7 Glove and cap removal

After disinfecting the gloves, they were removed. The removal was done so that the inside of the glove was on the outside, and theremoved glove was held with the gloved hand.
With the other hand, the glove was removed
so that the inside of the glove was on the outside, and the glove being held was covered(the removed gloves were disposed of in an
infectious waste container located in the contaminated area, and the procedure was thesame as when the outer gloves were removed)(Fig.22).
Arts and Sciences ◆ 53

Fig.22 手袋の外し方
Fig.22 手袋の外し方
Fig.22

Fig.22 手袋の外し方

How to remove gloves

マスク

Fig.23 キャップの外し方
Fig.23

How to remove the cap
Fig.23 キャップの外し方
Fig.23 キャップの外し方
Fig.25 Procedure notation

Fig.24 N95 マスクの外し方

Fig.24 How to remove the N95 mask

Fig.24 N95 マスクの外し方
Fig.24 N95 マスクの外し方

Hand disinfection was performed before removal of the cap. Fingers were placed inside
the cap so that the outside of the cap did nottouch the hair or face, and the cap was removed
and disposed of in an infectious waste container located in the contaminated area (Fig.23).

LCD screen can be disinfected by attaching acommercially available protective sheet to thescreen, but due to the unavailability of thissheet, researchers decided not to spray alcohol
directly onto the LCD surface. Instead, the surface was disinfected by spraying alcohol ontoa soft gauze cleaning pad, using the pad toclean the LCD surface. In this case, sodium hypochlorite was not acceptable.
1-9 Removal of the N95 mask

1-8 Disinfection of equipment (Responding
within clean area)

After hand disinfection, the equipment was
moved to a clean area. The equipment was
moved to a location where space could be secured in advance, and disinfection was performed again. Although the basic policy was
not to contaminate the temporary clean area,
the area was disinfected again. Wearing gloves,
the FPD, physical grid, CS-7, UF unit, and barcode reader were disinfected, and the exteriorof the equipment was also disinfected again.
Since the CS-7 exhibits a touch panel, researchers decided to disinfect the LCD surface withalcohol after shutting down the system. The

54 ◆ Journal of JART English edition 2022

Researchers decided not to remove the N95
mask in the dedicated COVID-19 ward. Whenremoving the N95 mask, the rubber band underthe mask was to be removed without touching
the surface of the N95 mask, and then, the upper rubber band was to be removed without
touching the surface and disposed of in the infection waste container (Fig.24).
1-10 Installation of simplified manuals

Simpliﬁed procedural documentation was
posted on the mobile radiography equipment.
By posting the simpliﬁed procedures, the radiology technician can perform the procedureswith certainty and without hesitation (Fig.25).

material
New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–

1-11 Creation of a mobile radiography manual

care unit, a new infectious disease ward, an
emergency room, and operating rooms.
Under these circumstances, the procedures
were able to be conﬁrmed, including the ﬂow
lines on each ﬂoor, as well as timely updates tothe response manuals.
In mobile radiography, not only the donningand dofﬁng of PPE, but also equipment operation and disinfection procedures can be complicated due to the large number of items used.
Therefore, by posting simple procedures on
the equipment, each on-site staff member
could follow the COVID-19 infection-control
procedures.
Among 50 radiology technologists within theradiology department as of May 15, 2020, thePCR test results showed a COVID-19 positivity
rate of 0%.
In an environment where people cannot
communicate with each other, Microsoft Teamsdelivery was immediate and could be viewed
and checked at any time on portable devices,even in situations where procedures were required to be revised frequently.

for COVID-19

The manual was revised three times to accommodate ever-changing circumstances anddevelopments. A detailed manual was developed to disseminate procedures within the radiology department. The manual was distributed throughout the department using Microsoft Teams to avoid congestion and to preventthe spread of infection.

2. Results
The number of mobile X-ray imaging procedures for COVID-19 performed at the hospitalfrom 21 January 2020 to 28 April 2020 are shownin Fig.26. There were 618 suspected COVID-19
cases with negative results, 67 suspected COVID-19 cases with positive results, and 739 positive conﬁrmed COVID-19 cases (Table).
The hospital system was constantly changing, including an outpatient unit for patientswith suspected COVID-19, a dedicated ward
for COVID-19 patients, a COVID-19 intensive

Table

COVID-19 Number of responded to cases

COVID-19 Suspicion(negative)

COVID-19 Suspicion(Positive)

COVID-19(Positive)

COVID-19 Suspicion(Polymerase chain reaction:
Waiting for results)

total

618

67

739

15

1439

Fig.26 Number of mobile X-ray taken with COVID-19 at our hospital (from January 21, 2020 to April 28, 2020)
Arts and Sciences ◆ 55

3. Consideration
The hospital involved in this study is a designated medical institution for speciﬁc infectious
diseases and is well equipped to deal with new
and unknown infectious diseases. In 2015, thehospital experienced a suspected case of Ebola
hemorrhagic fever, so each staff member waswell prepared for mobile radiography. However, the rapid increase in the number of patients made assigning the expected two radiologists per patient difﬁcult. Additionally, theteam was required to go through a trial-anderror process to address challenges, including
the deployment of multiple mobile X-ray systems dedicated to COVID-19, systematic staffing issues, and coordination with each corresponding ﬂoor, such as when imaging outside
the new infectious disease ward and when
conducting emergency imaging to respond to
rapid and severe cases of infection. As mentioned in the introduction, mobile radiography
must be performed while operating not only
the equipment but also various additional devices. Therefore, covering all devices withplastic bags (or similar) was necessary in orderto sufﬁciently clear contact and droplet infection routes.
However, if plastic bags were installed tocover entire devices, the time required to set
up the plastic bags and the increased risk ofcontact infection due to the bulkiness of theplastic bags had to be considered.
The examination time per patient in the COVID-19 environment was approximately 15 to
20 minutes, which is about three times longer
than usual. Despite this additional challenge,
we believed that the ability to identify contact
infection sites and avoid the bulkiness of plastic bags, etc. as much as possible, rather than
preparing to cover the equipment with plastic,
etc., reduced the risk of infection.
Conversely, one problem with the protective
clothing used in this study was that the neckarea remained exposed. While the full PPE

56 ◆ Journal of JART English edition 2022

used during the Ebola response protected theneck area, the PPE used during the current
COVID-19 pandemic focused on preventing
the pathogen SARS-CoV-2 from entering the
body through contact with the mucous membranes of the eyes, nose, and mouth.
This resulted in potential limitations to theeffectiveness of the procedures utilized. Whenbeds were set relatively high, as in critical carewards, maintaining a sufﬁcient distance fromthe patient was not possible when the FPD
was placed on the patientʼs back. Therefore,
the possibility of contamination of the unprotected neck cannot be ruled out.
Considering the possibility of a second or
third wave occurring in the future, we believe
considering measures to improve the protection of the neck area is necessary.
In order to reduce the complexity of the procedure for unknown contact and droplet infections, this hospital utilized a single device (Tiara-F) that integrated the console and device.
However, the need to deploy several mobile
devices dedicated to COVID-19 forced the useof a device composed of various components.
Because of the complexity of the procedure, asufﬁcient risk of procedural violations existed,even if the procedures were written in the formof a manual. Therefore, posting simple procedures directly on the devices so that the procedures could be checked on the spot was considered more effective in preventing procedural errors and as a measure to prevent the
spread of infection by each staff member.
However, if a dedicated general radiographysystem that takes into account the patientʼs lineof ﬂow could be introduced in the future, notonly would image quality be improved, but thesafe distance between the technician and thepatient could be maintained, allowing the technician to image the patient more safely. Also,
the risk of infection could be greatly reduced.
This hospital conducts PPE donning anddofﬁng training under the guidance of the ICT
and other infectious disease specialists, and al-material
New challenges for SARS-CoV-2 –Infection control in Mobile X-ray–

Fig.26
XX
線撮影の件数
Fig.26 COVID-19
COVID-19におけるポータブル
におけるポータブル
線撮影の件数
（2020
日から
2020
年年
4月
2828
日まで）
（2020年年1 1月月2121
日から
2020
4月
日まで）

Fig.27 PPE Training for donning and doffing

Fig.27 PPE 着脱訓練
Fig.27 PPE 着脱訓練

though some procedures were different fromwhat was expected due to COVID-19, the PPE
donning and dofﬁng went relatively smoothly
thanks to the conducted training (Figure 27).
Unfortunately, the training of how to share themobile radiography procedures for COVID-19
could not be conducted as a group due to current national and local government outbreakprevention (cluster) requirements.
Under these circumstances, sharing procedures that corresponded to the ever-changing
conditions in the department was necessary.
Due to the limitations of using actual equipment, creating a procedure manual that was asdetailed and easy to understand as possible forthose parts that could not be explained using
actual equipment was necessary. Microsoft
Teams has been used since last year to sharevarious information within the department,
and the sharing of these procedure manuals
through Teams has been very effective. Therefore, the expectation exists that Teams distribution will also be effective in sharing updates
and new information, such as future improvements to the procedure manual.

4. Conclusion
The safety of healthcare workers must be
guaranteed in order for the entire world towork together to bring COVID-19 to an end.
Mobile radiography requires various procedures from equipment handling to disinfection, in addition to donning and dofﬁng of
PPE. Mistakes in procedures not only increase
the risk of infection among radiographers, butthey can also lead to the spread of nosocomial
infections.
The radiology department is a special medical service which cannot expect support fromother medical professions. Therefore, the riskof infection to a single staff member in the radiology department is immeasurable, and thismay lead to the illness of not only the individual radiographer, but also the shutdown of theentire radiology department, and may evenmake maintaining overall hospital functions
difﬁcult.
In this study, infection-control proceduresfor portable radiography, which were expected to exhibit a relatively high risk of infection
among radiographic examinations, were examined. The results were shared in a manual
within the department, which was consideredeffective in reducing individual infection risks
and preventing nosocomial infections.

References
1） The Japanese Society of Environmental Infectious
Diseases: A Guide for Responding to New Coronavirus Infections in Medical Institutions, 3rd Edition, May
7, 2020.

Arts and Sciences ◆ 57

Arts and Sciencesmaterial

Received August 31, 2020; accepted March 24, 2021

Portable chest X-ray examination procedures for
COVID-19-positive patients: performance timenecessary for radiological technologists
KOBAYASHI Tomoya, RT 1）, ISHIBASHI Tomomichi, RT 2）, SOMEYA Satoka, RT 2）,
TASHIRO Kazuya, RT 2）, ITO Yoshiyuki, RT 2）, MIYAMOTO Katsumi, RT 2）,
YOKOKAWA Hiroshi, NS3）, SHIIGAI Masanari, MD4）, SHIOTANI Seiji, MD5）
1）Department of Radiological Sciences, Ibaraki Prefectural University of Health Science2）Department of Radiological Technology, Tsukuba Medical Center Hospital3）Department of Infection Control, Tsukuba Medical Center Hospital4）Department of Radiology, Tsukuba Medical Center Hospital5）Department of Radiology, Seirei Fuji Hospital

Note: This paper is secondary publication, the first paper was published in the JART, vol. 68 no. 824: 21-28, 2021.
Key words: corona virus disease 2019 (COVID-19), portable chest X-ray (CXR), examination time, infection prevention,

personal protective equipment【Abstract】

Purpose: To measure time needed to conduct portable chest X-ray (CXR) examinations for in-patients with thecoronavirus disease 2019 (COVID-19) and to compare that for non-COVID-19 patients.
Material and Methods: Portable CXR examinations were conducted on three COVID-19-positive in-patients fromMarch 1, 2020 to May 14, 2020 for follow-up evaluation of pneumonia by four radiological technologists with work
experience of 2 to14 years. As controls, data of five in-patients who had follow-up examinations of pneumonia in thesame ward (from October 22, 2017 to February 29, 2020) but without COVID-19 infection were investigated. Times
taken before and after portable CXR examination, as well as for the entire examination, were recorded in each case,and the mean times were calculated.
Results: Five portable CXR examinations of COVID-19-positive in-patients were done, consisting of two times eachfor two patients and once for one patient. Mean preparation time before portable CXR examination was 15.8 minutes,
mean time spent after portable CXR examination was 28.3 minutes, and mean total examination time was 44.1
minutes. Whereas, in contrast, in the five portable CXR examinations for non-COVID-19 patients, mean preparation
time was 2.5 minutes, mean time after portable CXR examinations was 9.4 minutes, and mean total examination timewas 11.9 minutes.
Conclusion: Time spent for portable CXR examinations of COVID-19-positive patients was 3.7-fold greater than thatof non-COVID-19 patients, due to infection prevention measures particularly after portable CXR examinations.

1. Introduction
A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),
was identified as the etiology for a cluster ofpneumonia cases in Wuhan, a city in the Hubei
Province of China 1). It globally spread rapidly,
and imaging features of patients with pneumonia induced by the coronavirus disease 2019
(COVID-19) were published 2, 3).
Fang et al. reported that sensitivity of unenhanced computed tomography (CT) for
detection of COVID-19 is higher than that of

58 ◆ Journal of JART English edition 2022

real-time polymerase chain reaction (RT-PCR)
test particularly when results of RT-PCR tests
are negative 4). Also, radiography screening
images can be used as an alternative to PCR
examination, as they exhibit a higher sensitivity in some cases; even portable chest X-ray(CXR) examinations are effective in detecting
the presence of pneumonia as well as for use
in follow-up examinations after treatment forpneumonia 4, 5). Portable CXR examinations
may be more useful and practical than CT for
patients who are difficult to move from bed
or room, especially in epidemic disease casesmaterial
Portable chest X-ray examination procedures for COVID-19-positive patients: performance time necessary for radiological technologists

such as COVID-19, due to a lower risk of
spreading infection during an emergency referral, reducing the downtime for CT needed forother patients, and substantially reducing required numbers of personal protective equipment (PPE) per examination 6 - 9).
When conducting portable CXR examinations especially in patients with COVID-19,
radiological technologists (RTs) must undertake adequate infectious prevention measures,
including PPE, to avoid spreading infection
within the hospital and a potential collapse of
the medical care system 10, 11); therefore, infectious prevention measures for portable CXR
examination are much more labor-intensive
than for ordinary portable CXR situations. Zhao
et al. reported their order of PPE fitting process
as “putting on the 1st surgical cap, the respirator, the 2nd surgical cap, isolation gowns,
the 1st surgical gloves, the 1st shoe covers, theprotective glasses, the disposable gowns, the
2nd surgical gloves, the 2nd shoe covers, thesurgical mask, and then checking for tightnessof the outfit”; they also reported the entire
PPE fitting time to be about 30 minutes for an
RT 12). To our knowledge, there have been noreports quantitatively examining time taken
for the entire process of portable CXR examination of COVID-19-positive patients fromregistration of the examination to completionof the examination. Herein we report our
procedures for portable CXR examination of

in-patients at our institution, comparing those
for COVID-19-positive and non-COVID-19 patients, to clarify the examination process andtime necessitated for RTs.

2. Materials and Methods
2.1 Subjects:

Our subjects were three male in-patientswith COVID-19-positive pneumonia (meanage: 64.3 years) who underwent follow-up
examination using a portable CXR device fromMarch 1, 2020 to May 14, 2020. Their symptoms ranged from mild to severe (Table 1).
Portable CXR examination of the severe-symptom patient was done twice in supine position,and the other two patients were imaged twiceand once, respectively, in a sitting-up position,
for a total of 5 examinations. Control subjects
were five in-patients with pneumonia without
COVID-19 infection who underwent follow-up
examinations using the same portable CXR
unit in the same ward from August 1, 2019
to February 29, 2020 (Table 2). We excluded
cases in which multiple sites were imaged forthe same patient, or when multiple patientswere imaged successively by the same RT. Ourevaluation for the COVID-positive subjects andcontrol subjects included portable CXR examinations by 9 RTs with working experienceof from 2 to 17 years (mean 8.1 years) (Table3). We measured time for each RT from their

Table 1 Clinical information of COVID-19-positive pneumonia patients
Case
I.D.

Age
(years)

Sex

Positioning at CXRSeverity ofsymptoms*

Number of CXR
examinations duringhospitalization

A

52

M

Supine position

Severe

2

B

80

M

Sitting-up position

Moderate

2

C

61

M

Sitting-up position

Mild

1

*Note : Definition of COVID-19 severity was as follows :Severe : Necessitated extracorporeal membrane oxygenation (ECMO) and mechanical ventilation (ECMO was used only atthe beginning, then removed)
Moderate : Having SpO2 ≦ 93%
Mild : Having only fever

Arts and Sciences ◆ 59

2.3 Scan parameters and protocols:leaving the radiology department to returning
to the department after completing a portable
CXR examination.
This study was approved by the ethics committee of our institution (Approval No. 2020009).

Portable CXR examinations (Portable X-ray
unit: MobileArt Evolution, Shimadzu, Tokyo,
Japan; FPD unit: CALNEO smart, Fujifilm Corp.,
Tokyo, Japan) were performed in the anteroposterior projection, and all were obtainedby one RT using standard clinical acquisition
parameters according to our institutionʼs protocols. The layout map of the ward for infectious
diseases is shown in Fig.1. Zoning was done in
the ward for each COVID-19-positive patient,while the sites for wearing and removing the
PPE and placement of the portable X-ray unit
are fixed.
Examination procedures for COVID-19-positive patients are as follows:① The RT registers reception of the patient using the Radiology Information Systems (RIS).

2.2 Specification of PPE and Disinfection ofequipment:

The PPE in our institution includes 1) eye
protection (face shield), 2) a filtering facepiece
respirator (N95), 3) a surgical cap, 4) gloves,and 5) a fluid-resistant gown. Surface wiping
disinfection was not necessary for the flat panel
detector (FPD), portable X-ray unit, and its
peripheral equipment, as those were dedicatedsolely for infected patientsʼ use in the ward.

Table 2 Clinical information of non-COVID-19 patients
Case
I.D.

Age
(years)

Sex

Positioning at CXR

Reasons for
hospitalization

D

91

M

SupinePneumonia

E

84

F

Sitting-up

Radius fracture

F

50

M

Sitting-up

Pelvic fracture

G

84

M

Sitting-up

Cervical fracture

H

91

M

Sitting-up

Pneumonia

Abbreviations : M = male, F = female

Table 3 Radiological technologists conducted portable CXR examination
I.D. number of Radiological
technologist

Sex

Experience as atechnologist (years)

Ⅰ

M

14

Ⅱ

F

2

Ⅲ

M

4

Ⅳ

F

3

Ⅴ

M

8

Ⅵ

F

3

Ⅶ

M

14

Ⅷ

F

8

Ⅸ

F

17

60 ◆ Journal of JART English edition 2022

material
Portable chest X-ray examination procedures for COVID-19-positive patients: performance time necessary for radiological technologists② The RT confirms the patientʼs body type

and previous X-ray images on RIS or onelectronic medical records.
③ The RT moves from the radiology department to the infectious disease ward on the
3rd floor.
④ The RT must put on specialized PPE at the
specified location on the 3rd floor (“on” in
Fig.1b) (Fig.2).
⑤ The RT goes to the room where the portable X-ray unit is located (“Po” in Fig.1b).
⑥ The RT goes to the ward with the portable
X-ray unit where the patient is staying.
⑦ The RT performs portable CXR examination.
⑧ The RT transfers the image data to DICOM.
⑨ The RT returns the portable X-ray unit to
its usual location (“Po” in Fig.1b).
⑩ The RT removes specialized PPE, andshoes must be disinfected at the specified
location (“off ” in Fig.1b) (Fig.3).
⑪ The RT returns to the radiology department.
⑫ The RT records the examination data on RIS.

RTs conducting imaging examinations for
COVID-19-positive patients are required torecord their own body temperature and healthcondition for two weeks after conducting a
portable CXR examination of a suspected or
COVID-19-positive patient. The possible routeof an intra-hospital-acquired COVID-19 infection is quickly checked and evaluated for our
hospital staff.
2.4 Time calculation:
Figure 4 shows portable CXR examination

procedures from reception to completion of
portable CXR examinations. Among them, timeat reception ( ① ), time at transfer the image
data ( ⑧ ), and time at recording the data to RIS( ⑫ ) could be confirmed from the Digital Imaging and Communications in Medicine (DICOM)
data. Accordingly, time spent for each procedure was calculated by the following formula(Fig.4):
Time spent from the preparation to onset of

1-aStairs3F
1-bFig. 1. Locations of the specialized ward for infectious disease
1-a: Floor mapFig.1of the third
floor.
Locationsof the specialized ward for infectious disease
Radiological technologists move from the radiology department on the first floor to the infectious disease-specialized ward
1-a on: Floor
map
of
the
third
ﬂoor.
the third floor (outlined in red) going up the stairs for CXR examination of COVID-19-positive patients.
1-b: Enlarged
view of the infectious
disease-specialized
ward on thethird floor (outlined
in redin Fig.
1a).to the infectious
Radiological
technologists
movefrom the radiology
department
on thefirst
floor
Zoning is done for theward
infectious
ward as shownin yellow(border
portion),orange(ward examination
floor hall),disease-specialized
on disease-specialized
the third ﬂoor (outlined
in red)going
up thestairsfor CXRofand pale orange (eachpatients.
ward room, outlined in red). Places are specified for the portable radiography unit (Po), putting PPE
COVID-19-positive(on), and removing the PPE (off).

1-b: Enlarged view of the infectious disease-specialized ward on the third ﬂoor (outlined in red in Fig.1a).
Zoning is done for the infectious disease-specialized ward as shown in yellow (border portion), orange(ward ﬂoor hall), and pale orange (each ward room, outlined in red). Places are speciﬁed for the portable radiography unit (Po), putting PPE (on), and removing the PPE (off).

Arts and Sciences ◆ 61

3

2

1

4

Fluid- resistant gown

Inner gloves

7

8

6

Outer gloves

Ready for
X-ray examination

Filtering face piece
respirator (N95)

5Face shield

Surgical cap

Use sterilizing hand spray

Fig. 2. Process for wearing personal protective equipment (PPE)
Fig.2 Process for wearing personal protective equipment (PPE)PPE is put on starting with inner gloves, a fluid-resistant gown, a filtering facepiece respirator
PPE is put on starting with inner gloves, a ﬂuid-resistant gown, a ﬁltering facepiece respirator (N95), a surgical cap, a face(N95),
a surgicalface shield, and outer gloves, in that order.
shield,and outergloves, cap,in thata order.

1

2

4

3

Outer gloves

10

Face shield

9

Finished

Inner gloves

5

Surgical cap

Fluid- resistant gown87Filtering face-piece
respirator (N95)

Disinfecting shoes

Use sterilizing hand spray

Fig. 3. Process of removing
personal protective equipment (PPE)
Fig.3 Process of removing personal protective equipment (PPE)PPE is taken off starting with the outer gloves, the face shield, surgical cap, fluid-resistant gown; then,

PPE is taken off starting with the outer gloves, the face shield, surgical cap, ﬂuid-resistant gown; then, disinfecting of shoes,
disinfecting of shoes, followed by removal of the filtering facepiece respirator (N95) and outer gloves, in that
followed by removal of the filtering facepiece respirator (N95) and outer gloves, in that order. Radiological technologists
order.
technologists
use sterilizing
shoulduseRadiologicalsterilizing handspray beforeshouldeach procedure
step. hand spray before each procedure step.

62 ◆ Journal of JART English edition 2022

material
Portable chest X-ray examination procedures for COVID-19-positive patients: performance time necessary for radiological technologists

portable CXR examination (Preparation time) =⑧−① .
Time spent after completion of portable CXR
examination (Time after portable CXR) = ⑫−⑧ .
Entire time from the reception to completion of
portable CXR examination (Total examinationtime) = ⑫−① .
2.5

Statistical analysis:

Preparation time, time after portable CXR,
and total examination time were measured foreach portable CXR examination, and all data
were shown as mean.

3. Results
COVID-19-positive patients had a total of
five portable CXR examinations, including twotimes for two patients and one time for one
patient by RT ID No. I, II, II, and IV (Table3). Mean preparation time was 15.8 minutes,
mean time after portable CXR examination was
28.3 minutes, and mean total examination timewas 44.1 minutes (Table 4).
By comparison, the five portable CXR examinations for five patients without COVID-19
infection were conducted by RT ID No. V to
IV (Table 3). Mean preparation time was 2.5
minutes, mean time after portable CXR exami-① Reception (DICOM data)② Viewing the patient’s information③ Go to the specialized ward
Preparation time

④ Wear PPE (Fig. 2)⑤ Go to the portable X-ray unit’s place⑥ Go to the patient’s room
⑦ Perform CXR examination

Total examination
time for an RT⑧ Transfer the image data (DICOM data)⑨ Return to the portable X-ray unit’s place
Time after
portable CXR⑩ Take off PPE (Fig. 3)⑪ Return to radiology department⑫ Record the data on RIS (DICOM data)

Fig. 4. Portable CXRFig.4
examination
procedures
Portable
CXR examination proceduresNote: ①，⑧，and ⑫ were automatically recorded as DICOM data. Therefore, we could deﬁne ⑧ − ①
Note: ①，⑧，and ⑫ were automatically recorded as DICOM data. Therefore, we could define= Preparation time, ⑫ − ⑧ = Time after CXR, and ⑫ − ① = Total examination time.
⑧ - ① = Preparation time, ⑫ - ⑧ = Time after CXR, and ⑫ - ① = Total examination time

Table 4 Time spent regarding portable chest X-ray (CXR) examination in COVID-19-positive patients
Examination
order number

Case
ID

ID of Radiological
technologist

Preparation time(minutes)

Time after
CXR (minutes)

Total examination
time (minutes)

1

A

Ⅰ

11.0

32.1

43.1

2

A

Ⅱ

18.2

25.3

43.5

3

B

Ⅲ

17.8

27.0

44.8

4

C

Ⅲ

13.0

31.7

44.7

5

B

Ⅳ

18.8

25.6

44.4

15.8

28.3

44.1

Mean

Arts and Sciences ◆ 63

Table 5 Time spent regarding portable chest X-ray (CXR) examination in non-COVID-19 patients
Examination
order number

Case
ID

ID of Radiological
technologist

Preparation time(minutes)

Time after
CXR (minutes)

Total examination
time (minutes)

6

D

Ⅴ

4.0

8.7

12.7

7

E

Ⅵ

1.6

8.6

10.2

8

F

Ⅶ

3.5

9.5

13.0

9

G

Ⅷ

1.2

8.8

10.0

10

H

Ⅸ

2.3

11.4

13.7

2.5

9.4

11.9

Mean

nation was 9.4 minutes, and mean total examination time was 11.9 minutes (Table 5).
As of May 31, 2020, the five RTs had no
COVID-19 symptoms, had been tested as
COVID-19-negative, and there had been no
hospital-acquired COVID-19 infection cases in
our institution.

4. Discussion
In this study, mean total examination time
for non-COVID-19 patients was 11.9 minutes
and that for COVID-19-positive patients was
44.1 minutes, a 3.7-fold greater time for the
COVID-19-positive cases. This is mainly attributable to time spent for prevention of infection (namely, putting on and taking off thespecialized PPE). In COVID-19-positive cases,
the mean time after portable CXR examination(28.3 minutes) was much longer than the mean
preparation time (15.8 minutes) due to theneed for carefully disinfecting the hands after
removing each PPE item. Zhao et al. reported
fitting time of PPE was about 30 minutes, probably due to a greater number of procedural
steps than ours and their higher stage of infection prevention level 12).
SARS-CoV-2 remains detectable in aerosols
for up to 3 hours, up to 24 hours on cardboard,and up to 2-3 days on plastic and stainlesssteel 13). RTs are among the first-line health care
workers who might be exposed to COVID-19;
thus, sufficient preventive measures should
be taken to avoid infection. There have been

64 ◆ Journal of JART English edition 2022

no COVID-19-infected RTs or other staff at
our institution, indicating that the measures
for COVID-19 prevention have been effective.
Since the portable CXR unit used in our institution is dedicated solely for use in the infectious
disease ward and zoning is done for patients
within that ward, time spent disinfecting theportable CXR unit is substantially less, contributing to a shorter overall examination time
while preventing hospital-acquired infection.
Our study has several limitations. The firstlimitation is the small number of our study
subjects, insufficient for statistical verificationof possible effects of the environmental factors.
The second limitation is that performing time（⑥−⑦）was including in the preparation timein our study, because time to perform portable
CXR examination was not recorded as DICOM
data. The X-ray examination time differs depending on the pathological condition of eachpatient. Portable CXR examination time for patients with very severe COVID-19 symptoms is
considered to be longer than that for our study
subjects. Therefore, further study including
very severe symptom cases is necessary. The
third limitation is the lack of inclusion of cases
in which one RT conducted several portable
CXR examinations sequentially, although one
RT did perform two examinations in our study.
An greater number of portable CXR examinations by each RT may subsequently reduce theentire examination time, due to more experience, skill, and improved technique at putting
on and removing PPE. The fourth limitation ismaterial
Portable chest X-ray examination procedures for COVID-19-positive patients: performance time necessary for radiological technologiststhat the RTs were different for COVID-19-positive and non-COVID-19 patients; therefore,
the time spent to conduct a portable CXR
examination could not be easily compared
for inter-operator variation. Further time measurement studies with the same RT members
on COVID-19-positive and non-COVID-19 patients are necessary to eliminate such a bias.

5. Conclusion
From our findings on the entire procedureand time spent for each portable CXR examination for COVID-19-positive patients in our
institution, a 3.7-fold increase in time wasneeded compared with that for non-COVID-19
patients due to infection prevention measures,
particularly after a portable CXR examination,requiring a mean total of 44.1 minutes per case.
Acknowledgement: The authors thank Ms. Yu-

miko Moriyama for her help with manuscript
preparation.

Compliance with ethical standards
Conflict of interest: The authors declare thatthey have no conflict of interest regarding thepresent study.
Ethical approval: The present study was ap-

proved by the ethics committee of our institution (Approval No. 2020-009).
Informed consent: Informed consent was obtained from all RTs included in the study.

References
1） Wang D, et al.: Clinical characteristics of 138
hospitalized patients with 2019 novel coronavirus,
infected pneumonia in Wuhan, China. JAMA, 323（11）1061-1069, 2020.
2） Pan Y, et al.: Initial CT ﬁndings and temporal changes
in patients with the novel corona-virus pneumonia（ 2019-nCoV ）: a study of 63 patients in Wuhan,
China. Eur Radiol, 1-4, 2020.
3） Pan F, et al.: Time course of lung changes on chest
CT during recovery from 2019 novel coronavirus（COVID-19）pneumonia. Radiology, 295, 715-721,
2020.
4） Fang Y, et al.: Sensitivity of chest CT for COVID-19:, E115-E117,
comparison to RT-PCR. Radiology, 296（2）2020.
5） Wong HYF, et al.: Frequency and distribution of chest
radiographic findings in COVID-19 positive patients.
Radiology, 296（2）, E72-E78, 2020.
6） Ai T, et al.: Correlation of Chest CT and RT-PCR Testingin Coronavirus Disease 2019（COVID-19）in China: A, E32-E40,
Report of 1014 Cases. Radiology, 296（2）2020.
7） Rubin GD, et al.: The Role of Chest Imaging in PatientManagement during the COVID-19 Pandemic:
A Multinational Consensus Statement from the
Fleischner Society. Radiology, 296（1）, 172-180, 2020.
8） American College of Radiology: ACR Recommendations
for the use of Chest Radiography and Computed
Tomography（CT）for Suspected COVID-19 Infection.
Accessed 1st Apr 2020. https://www.acr.org/
Advocacy-and-Economics/ACR-Position-Statements/
Recommendations-for-Chest-Radiography-and-CTfor-Suspected-COVID19-Infection9） Kooraki S, et al.: Coronavirus (COVID-19) outbreak:
What the Department of Radiology should know. J.
Am. Coll. Radio, 17, 447-451, 2020.
10）Wang J, et al.: Exploring the reasons for healthcare
workers infected with novel coronavirus disease 2019
（COVID-19）in China. J Hosp Infect, 105（1）, 100101, 2020.
11）Cavallo JJ, et al.: Hospital capacity and operations in
the coronavirus disease 2019（COVID-19）pandemic:planning for the Nth patient. JAMA Health Forum, 1（3）: e200345, 2020.
12）Zhao Y, et al.: Radiology department strategies toprotect Radiologic Technologists against COVID19:
experience from Wuhan. Eur J Radiol, 108996, 2020.
13）Van Doremalen N, et al.: Aerosol and surface stabilityof SARS-CoV-2 as compared with SARS-CoV-1. N
Engl J Med, 382（16）, 1564-1567, 2020.

Arts and Sciences ◆ 65

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.

66 ◆ Journal of JART English edition 2022

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.
Regulations and Requirements for Submissions ◆ 67

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

68 ◆ Journal of JART English edition 2022

Journal of JART–English edition 2022–

June 1, 2022
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Ⓒ2022, Printed in Japan.

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