Purpose: The measurement of slice sensitivity profile (SSP) in non-helical CT is conventionally performed by repeated scans with moving a micro-coin phantom little by little in the longitudinal direction at a small interval, which is reliable but laborious and time-consuming. The purpose of this study was to propose a simple method for measuring the SSP in non-helical CT based on a previous method that measured the slice thickness using a tilted metal wire. Methods: In the proposed method, a CT image was obtained by scanning a wire tilted at an angle θ=30° to the scan plane. By deconvolving the image with the point spread function (PSF) measured at the scanner, we obtained an image that was not affected by the PSF blurring. The CT value profile along the wire was acquired on the obtained image. The SSP was determined by multiplying the profile by tan θ. In addition, the SSP was measured by the conventional method using a micro-coin phantom and compared with the SSP obtained by the proposed method. Results: The SSP measured by the proposed method agreed well with that measured by the conventional method. The full-width at half-maximum values of these SSPs were the same. Conclusion: The proposed method was demonstrated to easily and accurately measure the SSP in non-helical CT.

Purpose: In this study, we aimed to develop an application that computes dose values resembling diagnostic reference level (DRL) conditions when disparity prevents direct dose comparisons between the national diagnostic reference levels in Japan 2020 (Japan DRLs_2020) and facility-specific computed tomography (CT) protocols. Methods: We developed an application using the R programming language and RStudio software that computes dose values and median values based on Japan DRLs_2020 imaging conditions following extraction of necessary information for dose calculations from the Radiation Dose Structured Report (RDSR) and Digital Imaging and Communications in Medicine (DICOM) tags. To ensure a user-friendly experience, we used the Shiny package to develop a graphical user interface that enables the application to operate seamlessly in web browsers. Results: The developed application successfully facilitated the calculation of dose and median values that aligned with the Japan DRLs_2020 for protocols whose imaging range and acquisition timing differed from those of the Japan DRLs_2020. Conclusion: By calculating dose values that align with DRL conditions, our application contributes to the implementation and optimization of dose management in CT for facilities that use diverse imaging protocols.

Purpose: Patients who were administered radiopharmaceuticals can be a source of radiation exposure to sonographers. This study aimed to identify factors associated with radiation exposure to breast sonographers from patients administered radiopharmaceuticals for bone scanning. Methods: The exposure dose of six sonographers was measured during breast sonography in 59 patients administered ^99mTc-HMDP. We predicted the following factors to be related to exposure dose: time interval between administration and sonography, sonography examination time, estimated radioactivity at sonography, sonographer's years of experience, and patients’ clinical data (age, renal function and surgical procedure). Spearman's rank correlation coefficient was used to examine the relationship between radiation dose and the aforementioned factors. Results: The mean±standard deviation of the exposure dose for the sonographers was 9.3±3.8 µSv. The time interval between administering the radiopharmaceutical agent and sonography, the sonography examination time and estimated radioactivity at sonography were found to be factors related to the exposure of the sonographer. The exposure dose increased as a function of the shorter time interval, longer examination time and higher estimated radioactivity at sonography. Conclusion: The time interval between drug administration and sonography, sonography examination time and estimated radioactivity at sonography contributed to the increased dose to breast sonographers. Although we considered that the exposure dose of sonographers would not possibly exceed the dose limit in the present study, we suggested that radiological technologists need to educate the physicians requesting sonography, and the sonographers about the radiation exposure in nuclear medicine.

Purpose: The purpose of this study was to evaluate the protective performance of several new radiation-protective clothing and to clarify issues of quality control. Methods: The composition of the shielding elements was analyzed using X-ray fluorescence analysis, and the energy spectrum of transmitted X-rays was measured. Furthermore, the lead equivalent and uniformity were measured from the transmitted X-ray doses according to Japanese industrial standards (JIS). Uniformity was evaluated by transmitting X-ray images of each radiation protective clothing in addition to the conventional method. Results: The energy spectrum showed K-absorption edges of lead, bismuth, tin, etc., which were detected in the composition analysis. The multi-layered protective material maintained higher shielding ability at high tube voltages. In addition, X-ray images of the radiation-protective clothing showed uneven density and dots, and the differences in uniformity measurement methods and points that didn’t meet the required shielding capacity were seen. Conclusion: The current JIS does not allow accurate evaluation of the lead equivalent and uniformity, so visual evaluation of X-ray images is important. It is necessary to establish standardized standards for quality control performed by each facility.