The Japan Society of Medical Physics (JSMP) held its 121st semiannual scientific meeting from April 15 to April 18, 2021 in Yokohama, jointly with two other radiological academic societies and radiological industry to constitute Japan Radiology Congress. The congress also included a web-based virtual venue from April 28 to June 3 to provide on-demand services of the same contents. Individual participants, once registered online, were given daily options to participate in either venue. The main theme of the congress was “Milestones and Beyond”, which was accidentally ideal for JSMP to commemorate 60th anniversary since its establishment in 1961. Of 121 research presentations collected, 8 were proffered by 7 guest speakers from allied medical physics organizations of India, Bangladesh, Hong Kong, Nepal, and Philippines. The meeting also featured many symposia and lectures on medical physics and interdisciplinary topics. Among them were a special lecture on the history of JSMP with current and past JSMP presidents and an international symposium with distinguished panelists invited from Bangladesh, China, Thailand, Vietnam, and Japan. Of total 919 registrants, 297 participated in the real meeting in Yokohama under the COVID-19 pandemic. Nevertheless, the meeting was perfectly implemented as planned because unvisited speakers had submitted their self-recorded video presentations in advance for onsite viewing in their sessions and many of them remotely participated in real-time discussion over the network. The individual presentations from the speakers, the recorded onsite sessions, and their associated bulletin boards for discussion constituted main contents of the virtual meeting. I would like to express my sincere appreciation to all participants and organizers of this successful meeting. This report supplements the official meeting record including extended abstracts of all presentations, which has been published as the Proceedings of the 121st Scientific Meeting of JSMP (Japanese Journal of Medical Physics Volume 41 Supplement 1, JSMP, Tokyo, April 1, 2021).

The intra- and inter-observer variability in diagnosis of thoracic CT images may affect the diagnosis of COVID-19. Therefore, several studies have been reported to develop artificial intelligence (AI) approaches using deep learning (DL) and radiomics technologies. The difference between them is automatic feature extraction (DL) and hand-crafted one (radiomics). The advantages of the AI-based imaging approaches for the COVID-19 are fast throughput, non-invasion, quantification, and integration of PCR results, CT findings, and clinical information. To the best of my knowledge, three types of the AI approaches have been studied: detection, severity differentiation, and prognosis prediction of COVID-19. AI technologies on assessment of severity/prediction of prognosis for COVID-19 may be more crucial than detection of COVID-19 pneumonia after COVID-19 becomes one of common diseases.

In Japan, mammography was introduced in 2000 for the early detection of breast cancer. In quality control of mammography, dosimetry is one of the most important items. For accurate dosimetry, calibration of dosimeters is necessary because radiation quality (target-filter combination) of mammography x-ray is different from that of general radiography. Therefore, development of dosimetry standard based on radiation quality of mammography x-ray was required. AIST/NMIJ developed an air-kerma standard for mammography x-rays and started its dissemination in 2009. Since then, the air-kerma standard has been extended to various radiation qualities that have come to be used in digital mammography. In this paper, an overview of the air-kerma standard for mammography x-ray together with a future plan is briefly presented.

IVR-CT was developed at Aichi Cancer Center (Japan) in 1992 and is now in use worldwide. It was developed initially for the purpose of performing CT more easily during arteriography, but also during non-vascular IR procedures such as biopsy and drainage. Four-detector-row IVR-MDCT was introduced to Shizuoka Cancer center in 2002, which was upgraded to 320-Row IVR-ADCT (320-IVR-CT) by 2013. Although we performed an initial investigation into the efficacy of 320 IVR-CT for vascular intervention, the direct MPR method using volume scanning is predominant in the field of non-vascular intervention. In this review, we describe the history of IVR-CT, report the efficacy of 320-IVR-CT for vascular and non-vascular intervention, and report our experiences.

In 1982, the Osaka General Medical Center made a modernization plan and started construction of a new hospital. The new radiology department was studied from the layout of the rooms to the newly introduced equipment and data storage system. Just around that time (1983), Fuji Computed Radiography (FCR) was developed.

Using this FCR, we took on the challenge of the world’s first full digitalization of a general radiography system.

At that time, we took the following policies to improve the system.

(1) To digitize all general radiography.

(2) To review the radiography process, improve the equipment, and build a system to link the equipment together.

(3) Change the selection of radiography equipment to one that is compatible with the digital system (small focus: magnified radiography).

(4) Convert all ideas, including image processing, to digital systems.

These attempts were successful and became the basis for the current field of general radiography.

Fuji Photo Film (then), a chemical manufacturer that manufactures film, succeeded in digitizing X-ray photographs for the first time in the world, and commercialized Computed Radiography (CR) in 1983. In addition to eliminating darkroom work from X-ray work and improving the efficiency of X-ray work and diagnosis, this CR also played a role in paving the way for networking of image information in hospitals and for computer-added diagnostic support. Nowadays, the mechanism of digital X-rays has been established and is known to many people, but there was no precedent in the latter half of the 1970s when the development of CR was started. In this paper, we will look back on the development process of such CR first, then we will outline the evolution of digital X-ray detectors and image processing technology, and introduce the technology we have challenged to estimate scattered X-rays in the human body.

Clinical studies of boron neutron capture therapy (BNCT) have been conducted using thermal and epithermal neutron beams generated from research reactors. Considering the spread and development of BNCT, it has been desired to realize BNCT using an accelerator-based neutron source that can be installed in medical institutions. To date, the accelerator-based BNCT has been developed by combining various accelerators such as a cyclotron and a linear accelerator with neutron generation targets. In Japan, the world’s first treatment system using a combination of a cyclotron and a beryllium target has received manufacturing and marketing approval as a medical device. In June 2020, BNCT insurance medical treatment was started at medical institutions. Currently, BNCT is being performed for cases of locally unresectable recurrent or unresectable advanced head and neck cancer. In this paper, it is shown that the history of reactor-based BNCT and the current development status and future prospects of the accelerator-based BNCT, which has been carried out in advance in Japan.

A charged particle therapy was proposed by Robert R. Wilson in 1946 and a clinical study of proton radiotherapy had been started at Lawrence Berkeley National Laboratory in 1954. Clinical studies have been promoted mainly in the United States and Europe. However, in Japan as well, the University of Tsukuba (KEK Campus) and the National Institute of Radiological Sciences (NIRS) started proton radiotherapy around 1980, and NIRS started carbon-ion radiotherapy in 1994. Following pioneering clinical studies, now in Japan, many proton and carbon-ion radiotherapy facilities are in operation, and some vendors are supplying equipment. Among them, charged particle therapy technologies originating in Japan have been developed, such as a respiratory-gated irradiation technology, a spot scanning irradiation technology, and a clinical dose design for ion radiotherapy. I look back on them and discuss the future direction of research and development of the charged particle therapy.

Since the Fukushima Daiichi Nuclear Power Station accident (hereinafter referred to as the “Fukushima Daiichi accident”) occurred in March 2011, many experts around the world have conducted the assessments on radiation doses and health effects attributed to the Fukushima Daiichi accident. During the months soon after the accident while the state of the nuclear reactor was not accurately grasped, the radiation exposure of the residents was estimated based on the predicted environmental behavior of various radionuclides. However, there were significant differences in the estimated doses and effects presented by different researchers and research institutes. As investigations on the causes and progress of the Fukushima Daiichi accident have progressed in last 10 years, now we know better the situation and consequence of the accident. In this article, the contents of relevant papers and reports published during the three years (–2014) after the Fukushima Daiichi accident are briefly reviewed and then compared with the relatively new scientific information obtained in 2015 or later. Through these analyses, the author tries to look back on how correct or incorrect the initial estimates were.

A calibration service using a medical accelerator has been launched to calibrate a radiotherapy dosimeter in terms of an absorbed dose to water. The radiotherapy dosimeter calibrated by the calibration service can measure the absorbed dose to water without a beam quality conversion factor. In this paper, an overview of the calibration service for a high-energy photon beam and a high-energy electron beam was described, as well as methods of absorbed dose measurement and cross-calibration using the calibrated radiotherapy dosimeter. And the development status of a dose standard for a particle beam was reported.

Exposure to ionizing radiation (IR) increases the risk of cancers, as epidemiology studies of atomic bomb survivors and patients who have received radiotherapy show. The carcinogenic effects of IR are well-documented, although the effects of radiation carcinogenesis change in each organ. The mammary gland is known to be highly susceptible to radiation-induced cancer. We have previously reported that (i) differential DNA methylation patterns in rat mammary carcinomas induced by pre-and post-pubertal IR; (ii) the effect of parity on rat mammary carcinogenesis varies between pre-and post-pubertal IR. In this review, we summarize our radiation researches as well as related with other radiation researches in rodent models.

This is a review on biological fingerprint for radiologic technology and forensic pathology by JSRT and JSMP (https://www.jsmp.org/en)

This is a review article on photon counting detector for radiation measurement by JSRT and JSMP (https://www.jsmp.org/en)