Purpose: The purpose of this study was to optimize radiopharmaceutical dosage in single-photon emission computed tomography (SPECT) nuclear medicine. Therefore, we examined a variable dose (VD) method using body weight as an index in resting myocardial scintigraphy using a ^99mTechnetium (^99mTc) preparation. Methods: In this study, we compared the VD method with the fixed dose (FD) method without a variable by body weight. There were 50 patients using the VD method and 50 patients using the FD method. For the VD method, we set the target average count (counts/pixel) per SPECT view. Using the myocardial average count of the FD method, and the estimated intracorporeal radioactivity at the start of the examination, the dose of the VD method, which varies appropriately depending on the body weight, was calculated. Results: The VD method had less variation in myocardial counting and was closer to the target count than the FD method, and the median dosage decreased. Conclusion: The VD method suggested the possibility of obtaining a count independent of physique and stable image quality, reducing medical and occupational radiation exposure in resting myocardial blood flow scintigraphy.

Purpose: The purpose of this study was to evaluate the changes in membranous septum (MS) length during the cardiac cycle and by measurement methods using the preoperative computed tomography (CT) images for transcatheter aortic valve replacement (TAVR). Method: Among 34 consecutive patients who underwent preoperative contrast-enhanced CT for TAVR, we measured MS lengths by three measurement methods (coronal, stretched, and reformatted coronal view method) at 10% intervals in the cardiac cycle. Result: MS lengths differed between the three measurement methods in all cardiac phases. Moderate correlations were observed between the MS lengths measured by the coronal view method and the other two methods. In contrast, strong correlations were observed between the MS lengths measured by the stretched view method and the reformatted coronal view method. The frequencies of the minimum and maximum MS lengths during the cardiac cycle tended to be highest at R–R 90% and R–R 30%, respectively. The median MS lengths at R–R 90% were smaller than those at R–R 30% in all measurement methods. Conclusion: The MS length in patients undergoing contrast-enhanced CT for TAVR varies notably depending on the cardiac cycle and measurement methods. When evaluating MS length, it is crucial to consider the measurement method and to perform measurements during diastole in order to evaluate the minimum value during the cardiac cycle.

Purpose: Resilience engineering is the ability of a system to adjust its own functions and maintain the required behavior in the face of changes and disturbances, and resilience potential is a necessary requirement. We aimed to clarify the relationship between resilience potential and error prevention cases. Method: Based on the error cases reported in our department, we aggregated the relationship with resilience potential for each radiation treatment process. Result: As a result of tabulating the relationship, we were able to recognize and prevent errors by taking preventive measures from past cases. On the other hand, in cases that slipped through the check mechanism, errors were discovered because of a sense of discomfort in unusual situations, and some error cases could be prevented by increasing the resilience potential. Conclusion: This study found that preparation, observation, coping, and utilization of past experiences are related to resilience potential in preventive cases.

The Japanese Ministry of Health, Labour and Welfare announced about the expansion of duties by the radiological technologists in team medical care in April, 2010, and the importance of image interpretation assistance by the radiological technologists became higher. In that respect, for improvement in ability of image interpretation assistance by the radiological technologists in emergency medicine, we developed a support package for learning of image interpretation assistance (support package) and evaluated the usefulness for learning of image interpretation assistance by questionnaires. The support package included digital imaging and communications in medicine (DICOM) data of case, explainer video of urgent imaging findings, and DICOM viewer. In 100% of evaluators, the support package was useful for urgent imaging findings in emergency medicine. Moreover, 68.9% of the evaluators had an experience helped by learning to use the support package in the clinical site. In conclusion, we confirmed that the support package was useful for learning of image interpretation assistance by the radiological technologists.

The three-dimensional time-of-flight (3D-TOF), which is currently the most common acquisition technique of intracranial magnetic resonance angiography (MRA), may result in poor branch visualization due to reduced blood flow velocity. Proton density-weighted volume isotropic turbo spin-echo acquisition (PDVISTA) is less susceptible to these factors and has been reported to be useful in assessing cerebral vasospasm after subarachnoid hemorrhage. In this study, we investigated the effect of refocus flip angle (RFA) for PDVISTA on the contrast between blood vessels and background brain tissue using flow velocity phantom and clinical images, assuming the usefulness of PDVISTA in daily clinical practice. The phantom experiments showed that the contrast ratio significantly improved with decreasing RFA; however, considering the signal-to-noise ratio, RFA 80° was determined as optimal for clinical use. Visual assessment was performed on PDVISTA (RFA 80°) and conventional 3D-TOF MRA clinical images, which suggested the superiority of PDVISTA over 3D-TOF in the delineation of peripheral branches of cerebral vessels. The results suggest that PDVISTA is useful not only for subarachnoid hemorrhage patients but also in daily clinical practice.

Purpose: National diagnostic reference levels in Japan 2020 (DRLs 2020) have been published. In the field of angiography, in addition to the fluoroscopic dose rate, incident air kerma at the patient entrance reference point displayed on the equipment (K_a,r: mGy) and air kerma-area product displayed on the equipment (P_KA: Gycm²) were set. A questionnaire survey was conducted at each facility in the Tokai region to confirm the status of medical radiation dose control in the region. Method: A questionnaire survey was conducted at each facility in the Tokai region. The items were fluoroscopic dose rate in each area (head and neck, cardiac, chest and abdomen, and limbs), DA and DSA dose rates, and dose area product meter (K_a,r, P_KA) for the main procedures in each area. Result: The median values in this study were lower than those in the DRLs 2020, indicating that appropriate dose control is being implemented in the Tokai region. The trends of fluoroscopic and radiographic dose rates were different in each area, and there was some variation among the facilities. Conclusion: We believe that the incorporation of fluoroscopic and radiographic dose rates by area into the DRLs will facilitate more appropriate dose control at each facility in the future.