Among all the institutions, Harvard University was regarded as a leader for research collaboration. We analyzed the keywords and identified seven COVID-19 vaccine research hotspot clusters. COVID-19 vaccine research hotspots focus on clinical trials on vaccine safety and efficacy, research on vaccine immunology and immunoinformatics, and vaccine hesitancy. Our analysis results demonstrated that cooperation between countries, institutions, and authors were insufficient. The results suggested that clinical trials on vaccine safety, efficacy, immunology, immunoinformatics, production and delivery are research hotspots. Furthermore, we can predict that there will be a lot of research focusing on vaccine adverse reactions.
  A volume scan can cover a range of 160 mm with a single gantry rotation. It can be performed sequentially (a wide volume [WV] scan) to cover more than 160 mm, and volume Xact+ (Xact+) can be used when volume scan is done to extend the reconstruction area. The purpose of this study was to investigate the dose distribution and organ doses for a WV scan during chest CT.
 
  We arranged radiophotoluminescence glass dosimeters (RPLDs) linearly on the surface and inside of the phantom to evaluate the dose distribution along the z-axis. We also placed RPLDs at the lens, thyroid, and breast positions to evaluate organ doses. We performed WV and helical scans and WV scan using Xact+.
 
  The absorbed doses increased at the borders of the volume scans, and dose peaks were observed there. The organ doses for the WV scan outside the acquisition range were lower than those for the helical scan. The organ doses inside the acquisition range changed by the locations of borders.
 
  The WV scan increases the absorbed doses at the overlapping scanned regions, which can be reduced by using Xact+.
 The WV scan increases the absorbed doses at the overlapping scanned regions, which can be reduced by using Xact+.
  In cerebral angiography, the patient's exposure dose varies greatly depending on the target site, purpose, and difficulty of the procedure. Therefore, it is necessary to manage the dose based on not only the disease but also the procedure.
 
  In this study, diagnostic cerebral angiography (diagnosis group) was classified into 13 procedures and neuro-interventional radiology (treatment group) was classified into 10 procedures, and the total dose, fluoroscopy dose, radiographic dose, fluoroscopy time, and number of radiographic frames were compared.
 
  For each item, the treatment group was significantly higher than the diagnosis group, but for some, the diagnosis group exceeded the median of treatment group. For the diagnosis group, the total irradiation time and fluoroscopy time were significant, and for the treatment group, all the items showed significant differences due to differences in procedures, and there were also cases where the same disease had differences due to procedures.
 
  To manage patient exposure in cerebral angiography, it is necessary to manage the usage rate and dose of fluoroscopy and radiography. In addition, it is important to evaluate, manage, and optimize the total dose, fluoroscopic dose, and radiographic dose for each procedure in not only the treatment group but also the diagnosis group.
 To manage patient exposure in cerebral angiography, it is necessary to manage the usage rate and dose of fluoroscopy and radiography. In addition, it is important to evaluate, manage, and optimize the total dose, fluoroscopic dose, and radiographic dose for each procedure in not only the treatment group but also the diagnosis group.
  Magnetic resonance elastography (MRE) of the liver was performed to examine the appropriate external driver amplitude according to the physique of the subject and the index useful for determining the physique.
 
  For 60 subjects who underwent MRE examination, we measured the unmeasurable elastic modulus area in the liver based on the stiffness map obtained from MRE. The external driver amplitude with the smallest unmeasurable elastic modulus area was taken as the appropriate external driver amplitude for the subject. The receiver operating characteristic (ROC) analysis was performed on the indicators of physical constitution (abdominal depth, waist circumference, body weight and body mass index (BMI) ) and external driver amplitude of 30%, 50% and 70%. BMI was the most appropriate tool for the comparison of indicators of physical constitution.
 
  The appropriate external driver amplitude was 30% when the cutoff value of BMI was less than 25.3 kg/m², 70% when it was 31.0 kg/m² or more, and 50% when it was between them.
 
  It is considered that an accurate elastic modulus can be obtained by setting an appropriate indicator of physical constitution and external driver amplitude according to physique in MRE.
 It is considered that an accurate elastic modulus can be obtained by setting an appropriate indicator of physical constitution and external driver amplitude according to physique in MRE.
  To evaluate image quality for chest radiography at different radiation qualities, using phantoms with scatter fractions similar to those of lungs.
 
  Two base phantoms with 10 and 4 cm thicknesses, respectively, made of a soft tissue-equivalent material, were used to mimic the X-ray attenuation of the human lung.  https://www.selleckchem.com/products/ins018-055-ism001-055.html  Two plates with soft tissue- and bone-equivalent materials, respectively, were placed on the base phantom as contrast objects. The image data were obtained with the same entrance surface dose in each radiation quality. Six radiation qualities generated using 120 and 90 kV, and additional copper filters with thicknesses 0, 0.1, and 0.2 mm were selected. The signal-difference-to-noise ratio (SdNR) and a contrast ratio of the soft tissue to the bone were measured for the six radiation qualities.
 
  The thicker the additional filter, the better the SdNR at both tube voltages. The SdNR values were not significantly different between 120 and 90 kV for the same filter thickness. The contrast ratio was higher at 120 than at 90 kV by approximately 8%.
 
  Because of the advantage of the contrast ratio and the highest SdNR, the radiation quality with 120 kV and 0.2-mm copper filtration was the best. It was indicated that the conventional tube voltage of 120 kV remains to be better than the lower tube voltage of 90 kV.
 Because of the advantage of the contrast ratio and the highest SdNR, the radiation quality with 120 kV and 0.2-mm copper filtration was the best. It was indicated that the conventional tube voltage of 120 kV remains to be better than the lower tube voltage of 90 kV.