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Objectives: The area detector 320‐row CT scanner, which can cover the whole heart in one rotation, can aid in reducing radiation exposure during electrocardiography (ECG)‐gated coronary CT angiography (CCTA). Recently, researchers have proposed dose‐modulated dynamic CCTA with a 320‐row scanner for the detection of functional myocardial ischemia. In the present study, we compared and validated the radiation dose of this method with that of the standard CCTA method and the latest diagnostic reference levels (DRLs). Materials and Methods: The study included a total of 164 consecutive patients with suspected or known coronary artery disease (CAD) who underwent CCTA with a 320‐row scanner. The patients were randomly divided into dynamic and standard CCTA groups, and the CT dose index (CTDIvol) and dose length product (DLP) calculated by the CT system were compared between the two protocols and with the latest DRL. Results: Standard and dynamic CCTA scans were performed in 77 and 87 patients, respectively. CTDIvol was significantly higher for standard CCTA than for dynamic CCTA (41 ± 35 mGy vs. 22 ± 7 mGy, p = 0.0014). DLP was also significantly higher for standard CCTA than for dynamic CCTA (864 ± 702 mGy × cm vs. 434 ± 106 mGy × cm, p <.0001). For standard scans, CTDIvol and DLP exceeded the 2020 DRL in Japan in 16% (12/77) and 17% (13/77) of cases, respectively. In contrast, rates for the dynamic scan were only 1% (1/87) for CTDIvol and 0% (0/87) for DLP. Conclusion: The dose of radiation exposure during dynamic CCTA with a 320‐row scanner does not exceed that of standard CCTA and is sufficient to meet the latest DRL. Thus, our results suggest that the method is safe from the perspective of radiation exposure. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate differences in volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values according to facility size in Japan. A questionnaire survey was sent to 3000 facilities throughout Japan. Data from each facility were collected including bed number, computed tomography (CT) scan parameters employed and the CTDIvol and/or DLP values displayed on the CT scanner during each examination. The CTDIvol and DLP for 11 adult and 6 paediatric CT examinations were surveyed. Comparison of CTDIvol and DLP values of each examination according to facility size revealed key differences in CT dose between small and large facilities. This study highlights the importance of lowering the dose of coronary artery examination with contrast agent in smaller facilities and of lowering the dose of adult and paediatric head CT without contrast agent in larger facilities. The results of this study are valid in Japan. [ABSTRACT FROM AUTHOR]

Background: Several studies have confirmed the advantages of delivering high doses of external beam radiotherapy to achieve optimal tumor-control outcomes in patients with localized prostate cancer. We evaluated the medium-term treatment outcome after high-dose, image-guided intensity-modulated radiotherapy (IMRT) using intra-prostate fiducial markers for clinically localized prostate cancer. Methods: In total, 141 patients with localized prostate cancer treated with image-guided IMRT (76 Gy in 13 patients and 80 Gy in 128 patients) between 2003 and 2008 were enrolled in this study. The patients were classified according to the National Comprehensive Cancer Network-defined risk groups. Thirty-six intermediate-risk patients and 105 high-risk patients were included. Androgen-deprivation therapy was performed in 124 patients (88%) for a median of 11 months (range: 2-88 months). Prostate-specific antigen (PSA) relapse was defined according to the Phoenix-definition (i.e., an absolute nadir plus 2 ng/ml dated at the call). The 5-year actuarial PSA relapse-free survival, the 5-year distant metastasis-free survival, the 5-year cause-specific survival (CSS), the 5-year overall survival (OS) outcomes and the acute and late toxicities were analyzed. The toxicity data were scored according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up was 60 months. Results: The 5-year PSA relapse-free survival rates were 100% for the intermediate-risk patients and 82.2% for the high-risk patients; the 5-year actuarial distant metastasis-free survival rates were 100% and 95% for the intermediate and high-risk patients, respectively; the 5-year CSS rates were 100% for both patient subsets; and the 5-year OS rates were 100% and 91.7% for the intermediate- and high-risk patients, respectively. The Gleason score (<8 vs. ≥8) was significant for the 5-year PSA relapse-free survival on multivariate analysis (p = 0.044). There was no grade 3 or 4 acute toxicity. The incidence of grade 2 acute gastrointestinal (GI) and genitourinary (GU) toxicities were 1.4% and 8.5%, respectively. The 5-year actuarial likelihood of late grade 2-3 GI and GU toxicities were 6% and 6.3%, respectively. No grade 4 GI or GU late toxicity was observed. Conclusions: These medium-term results demonstrate a good tolerance of high-dose image-guided IMRT. However, further follow-up is needed to confirm the long-term treatment outcomes. [ABSTRACT FROM AUTHOR]

Japanese people experienced the Hiroshima and Nagasaki atomic bombings, the Japan Nuclear Fuel Conversion Co. criticality accident, it was found that many human resources are needed to respond to residents' concerns about disaster exposure in the event of a radiation disaster. Medical radiologic technologists learn about radiation from the time of their training, and are engaged in routine radiographic work, examination explanations, medical exposure counseling, and radiation protection of staff. By learning about nuclear disasters and counseling, we believe they can address residents' concerns. In order to identify items needed for training, we examined the perceptions of medical radiologic technologists in the case of different specialties, modalities and radiation doses. In 2016, 5 years after the Fukushima Daiichi nuclear power plant accident, we conducted a survey of 57 medical radiologic technologists at two medical facilities with different specialties and work contents to investigate their attitudes toward radiation. 42 participants answered questions regarding sex, age group, presence of children, health effects of radiation exposure, radiation control, generation of X rays by diagnostic X ray equipment, and radiation related units. In a comparison of 38 items other than demographic data, 14 showed no significant differences and 24 showed significant differences. This study found that perceptions of radiation were different among radiology technologists at facilities with different specialties. The survey suggested the possibility of identifying needed training items and providing effective training.

The Great East Japan Earthquake and Tsunami that occurred in March 2011 not only resulted in the loss of many human lives due to earthquakes and tsunamis, but also led to the occurrence of nuclear accidents involving the widespread diffuse release of radioactive materials at the Fukushima Daiichi Nuclear Power Plant (FDNPP). The nuclear accident created great apprehension among residents of the Fukushima Prefecture, where the FDNPP is located, and residents of Northeastern Japan outside of Fukushima, such as the south region of the Miyagi Prefecture, which is adjacent to the northern part of Fukushima Prefecture. The Miyagi Prefecture is located approximately 50 to 120 km from the FDNPP. In Miyagi before the nuclear accident, nuclear disaster drills including respondent to residents' anxieties had been conducted at Onagawa Town, Ishinomaki City and prefectural office, and radiologic technologists had participated in the drills. In the face of the actual nuclear disaster, radiologic technologists carried out personalized consultation activities with the aim of eliminating anxiety among pregnant women and parents with infants at two local governments in the south region of Miyagi. After the activities, we conducted questionnaire survey on the activities, and were able to obtain evaluations and various opinions. This paper discusses regarding the efforts to personalized consultation and the results of questionnaire survey conducted by the radiologic technologists in the southern Miyagi following the FDNPP accident.

Purpose: It is very important to manage the radiation dose of cardiovascular interventional (CVI) procedures. Overseas, the diagnostic reference levels for cardiac interventional procedures were established with the air kerma at the patient entrance reference point (Ka,r) and the air kerma-area product (P KA ). Although the Japan DRLs 2015 was established by the Japan Network for Research and Information on Medical Exposure (J-RIME), the Japan DRL for CVIs were established by fluoroscopic dose rates of 20 mGy/min at the patient entrance reference point with 20 cm thickness polymethyl methacrylate (PMMA) phantom. In the present our study, we performed a questionnaire survey of indicated values of angiographic parameters in CVI procedures., Methods: A nationwide questionnaire was sent by post to 765 facilities. Question focused on angiographic technology, exposure parameters and radiation doses as the displayed dosimetric parameters on the angiographic machine., Results: The recovery rate was 22.8% at 175 out of 765 facilities. In total 1728 cases of the coronary angiography (CAG), 1703 cases of the percutaneous coronary intervention (PCI), 962 cases of the radiofrequency catheter ablation (RFCA) and 377 cases of pediatric CVI. The 75th percentile value of Ka,r, P KA , fluoroscopy time (FT) and number of cine images (CI) for CAG, PCI, RFCA and pediatric CVI were 702, 2042, 644, and 159 mGy, respectively, 59.3, 152, 81.3, and 14.9 Gy・cm 2 , respectively, 10.2, 35.6, 61.1, and 35.6 min, respectively and 1503, 2672, 722, and 2378 images, respectively. Our investigation showed that the angiographic parameters were different in several CVI procedures., Conclusions: The displayed dosimetric parameters on the angiographic machine in CVI procedures showed different values. We should classify the dosimetric parameters for each procedure.

To monitor radiocesium activity in skeletal muscle of live cattle, the animals were given radiocesium-contaminated feed continuously, then switched to contamination-free feed after radiocecium concentration in peripheral blood (PB) reached plateau. Radioactivity in skeletal muscles of neck and rump was measured by attaching the probe of a NaI survey meter closely on the body surface just above the muscle of the live cattle (external measurement). We validated the strong positive correlation between the value of the external measurement and radiocesium activity concentration of dissected muscle (r = 0.89, P < 0.001 for neck; r = 0.80, P < 0.001 for rump). Accumulation of radiocesium both in muscle and PB was proportional to the total amount of radiocesium cattle ingested. However, radioactivity concentration in PB was constant in the cattle that had continuously ingested radiocesium, lower than 2.0 × 10 5 Bq in total within 67 days from the beginning of radiocesium intake. In addition, the ratio of radiocesium activity in muscle to that in PB was lower during the time when radiocontaminated feed was ingested than that of contamination-free feed ingestion. Using the correlation of radioactivity between muscle and PB, we confirmed that a majority of the cattle in the ex-evacuation zone of the Fukushima Daiichi nuclear power plant accident, from 167 to 365 days after the accident occurred, were in the declining period of radiocesium intake.

Objective:: To propose a new set of Japanese diagnostic reference levels (DRLs) and achievable doses (ADs) for 2017 and to verify the usefulness of Japanese DRLs (DRLs 2015) for CT, by investigating changes in the volume CT dose index (CTDI vol ) from 2014 to 2017., Methods:: Detailed information on the CT scan parameters used throughout Japan were obtained by questionnaire survey. The CTDI vol and dose-length product for the 11 commonest adult and 6 commonest paediatric CT examinations were surveyed and compared with 2014 data and DRLs 2015., Results:: Evaluations of adult head (helical), and abdomen and pelvis without contrast agent, paediatric chest without contrast agent, and abdomen and pelvis without contrast agent showed a slightly lower mean CTDI vol in 2017 than in 2014 (t-test, p < 0.05). The interquartile range of CTDI vol for all 2017 examinations was lower than in 2014., Conclusions:: This study verified the lower mean, 75th percentile, and interquartile range by investigating changes in the CTDI vol from 2014 to 2017. The DRLs 2015 contributed to CT radiation dose reduction., Advances in Knowledge:: The widespread implementation of iterative reconstruction algorithms and low-tube voltage in CT scanners is likely to facilitate further reduction in the CT radiation dose used in Japan. Although radiological technologists may require further education on appropriate CTDI vol and DLP usage, the DRLs 2015 greatly contributed to the reduction of the CT radiation dose used in Japan.

Objective: Cardiac interventional radiology (IR) can cause radiation injury to the staff who administer it as well as to patients. Although education in the basic principles of radiation is required for nurses, their level of radiation safety knowledge is not known. The present study used a questionnaire protocol to assess the level of radiation safety knowledge among hospital nurses., Methods and Results: A questionnaire to assess the level of training and current understanding of radiation safety was administered to 305 nurses in 2008 and again to 359 nurses in 2010. Our study indicates that nurses had insufficient knowledge about radiation safety, and that a high percentage of nurses were concerned about the health hazards of radiation. Moreover, more than 80% of the nurses expressed an interest in attending periodic radiation safety seminars. Annual radiation protection training for hospital staff (including nurses) is important., Conclusions: Our results suggest that nurses do not have sufficient knowledge of radiation safety and should receive appropriate radiation safety training. Many had a minimal understanding of radiation and thus had significant concerns about the safety of working with radiation. Periodic radiation safety education/training for nurses is essential.

Objective: The aims of this study were to estimate the effective radiation doses from CT examinations of both adults and children in Japan and to study the impact of various scan parameters on the effective doses., Methods: A questionnaire, which contained detailed questions on the CT scan parameters employed, was distributed to 3000 facilities throughout Japan. For each scanner protocol, the effective doses for head (non-helical and helical), chest and upper abdomen acquisitions were estimated using ImPACT CT Patient Dosimetry Calculator software v. 1.0.4 (St George's Hospital, London, UK)., Results: The mean effective doses for chest and abdominal examinations using 80-110 kV were significantly lower than those using 120 kV. However, there was no statistically significant difference in the mean effective doses for head scans between facilities employing 80-110 kV and 120 kV. In chest and abdominal examinations, the mean effective doses using CT scanners from Western manufacturers [Siemens (Forchheim, Germany), Philips (Eindhoven, Netherlands) and GE Medical Systems (Milwaukee, WI)] were significantly lower than those of examinations using Japanese scanners [Hitachi (Kashiwa, Japan) and Toshiba (Otawara, Tochigi, Japan)], except for in paediatric chest examinations., Conclusion: The mean effective doses for adult head, chest and abdominal CT examinations were 2.9, 7.7 and 10.0 mSv, respectively, whereas the corresponding mean effective doses for paediatric examinations were 2.6, 7.1 and 7.7 mSv, respectively., Advances in Knowledge: Facilities using CT scanners by Western manufacturers commonly adopt low-tube-voltage techniques, and low-tube-voltage CT may be useful for reducing the radiation doses to the patients, particularly for the body region.

Objective: The Fukushima nuclear power plant accident resulted in the discharge of radioactive particulate material into the atmosphere. Consequently, several hospitals in Japan have observed black spots on x-ray computed radiography (CR) images caused by particulate radioactive fallout., Conclusion: These black spots have no effect on human health. To reduce the influence of black spots on CR images, we need to erase latent images on imaging plates (IPs) immediately before clinical use and read the IPs soon after the x-ray examination. Alternatively, the contaminated felt of a cassette can be cleaned or exchanged, if possible.

Although measurement and management of angiographic entrance skin dose (ESD) are deemed extremely important, accurate determination of maximum ESD and its location is generally difficult because of the dependence on therapeutic technique and position. Following our development of body-mounted gear bearing radiophotoluminescence glass dosimeter (RPLD) arrays for direct measurement of ESD in cranial and cardiovascular angiography and interventional radiology (IVR), our focus next turned to the limited number of facilities equipped to read RPLD outputs and the need for methods to effectively provide feedback to clinical facilities. As described here, we first constructed an RPLD reading facility capable of sending and receiving RPLDs by post, offering the potential to enable utilization of the developed gear at all hospitals in Japan that perform angiography and IVR. We next developed specialized web-based system to generate dose maps from RPLD dose data, thereby enabling any facility to perform trial system analysis, evaluation, and implementation; and investigated the results and related problems.

The Fukushima nuclear disaster occurred on March 11, 2011. For about six weeks, I worked as a counselor for phone consultations regarding radiation risk. I analyzed the number of consultations, consultations by telephone, and their changing patterns with elapse of time, to assist with consultations about risk in the future. There were a large number of questions regarding the effects of radiation, particularly with regard to children. We believe that counseling and risk communication are the key to effectively informing the public about radiation risks.

This paper describes the present status and countermeasures for patient dose and occupational exposure in Japan. The patient radiation dose resulting from a large number of diagnostic radiological procedures presents no substantial risk(deterministic and stochastic effects). Nevertheless, some procedures (e.g., interventional radiology: IVR) carry a risk of deterministic effects, such as skin injury. The regulatory dose limit of the occupational dose for most medical workers was not exceeded. Nevertheless, radiation injuries, such as cataracts, to physicians performing IVR have been reported recently, although not many cases. When radiation protection/optimization issues are addressed adequately, medical exposure will decrease without decreasing the diagnostic benefit to the patient. Consequently, decreasing the patient dose will also decrease occupational exposure.

Radiation safety education/training is essential and is associated with a reduction in the radiation dose to both patients and staff. We used a questionnaire to assess the level of radiation safety knowledge among nurses working at Tohoku Kosei-Nenkin Hospital. Some nurses were also interviewed. The results of our study indicate that the nurses had insufficient radiation safety knowledge and that a high percentage of nurses were concerned about the health hazards of radiation. Moreover, more than 80% of the nurses expressed an interest in attending periodic radiation safety seminars. Appropriate radiation safety training is required to reduce nurse radiation doses, and an understanding of radiation safety can help to optimize the patient dose.

Today, interventional radiology (IR) X-ray units are required for display of doses at an interventional reference point (IRP) for the operator (IR physician). The dose displayed at the IRP (the reference dose) of an X-ray unit has been reported to be helpful for characterizing patient exposure in real time. However, no detailed report has evaluated the accuracy of the reference doses displayed on X-ray equipment. Thus, in this study, we compared the displayed reference dose to the actual measured value in many IR X-ray systems. Although the displayed reference doses of many IR X-ray systems agreed with the measured actual values within approximately 15%, the doses of a few IR units were not close. Furthermore, some X-ray units made in Japan displayed reference doses quite different from the actual measured value, probably because the reference point of these units differs from the International Electrotechnical Commission standard. Thus, IR physicians should pay attention to the location of the IRP of the displayed reference dose in Japan. Furthermore, physicians should be aware of the accuracy of the displayed reference dose of the X-ray system that they use for IR. Thus, regular checks of the displayed reference dose of the X-ray system are important.

At present, interventional radiology (IVR) tends to involve long procedures (long radiation duration), and physicians are near to the source of scattered radiation. Hence, shielding is critical in protecting physicians from radiation. Protective aprons and additional lead-shielding devices, such as tableside lead drapes, are important means of protecting the physician from scattered radiation. The purpose of this study was to evaluate whether non-lead aprons are effective in protecting physicians from radiation during IVR procedures. In this study, the radiation protection effects of commercially available protective lead and non-lead aprons, when exposed to diagnostic X rays, are compared. The performance of these non-lead and lead aprons was similar for scattered X rays at tube voltages of 60-120 kV. Properly designed non-lead aprons are thus more suitable for physicians because they weigh approximately 20% less than the lead aprons, and are non-toxic.