Nihon Hoshasen Gijutsu Gakkai zasshi最新文献

Purpose: To investigate the accuracy of proton density fat fraction (PDFF) measurement using chemical shift-encoded MRI (CSE-MRI) with fast imaging techniques in a phantom.

Methods: A 1.5T imaging system (Prodiva; Philips Healthcare) and PDFF phantom (Fat Fraction Phantom Model 300; Calimetrix) were used in this study. The acquisitions without fast imaging techniques (conventional acquisition), with parallel imaging in phase-encode direction (SENSE acquisition), with compressed sensing (CS-SENSE acquisition), and with parallel imaging in both phase-encode and slice-encode direction (Dual-SENSE acquisition) were performed. The following acceleration factors in SENSE and CS-SENSE acquisition were used: 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, and 8.0. For Dual-SENSE acquisition, the same acceleration factors (1.5, 2.0, 3.0, 4.0, 5.0) were set in each of the two directions. The relationships between reference PDFF values and PDFF measurements obtained using each acquisition were assessed using linear regression analysis and Bland-Altman analysis.

Results: According to the linear regression analysis, the slopes and intercepts of regression lines were from 0.87 to 1.02 and from 0.06% to 3.55%, respectively. According to Bland-Altman analysis, there were fixed bias between reference PDFF values and PDFF measurements obtained using SENSE acquisition with reduction factor 8.0 and Dual-SENSE acquisition with reduction factor 5.0. For CS-SENSE acquisition with reduction factor from 7.0 to 8.0, SENSE acquisition with reduction factor from 3.0 to 8.0, and Dual-SENSE acquisition with reduction factor from 2.0 to 5.0, some vials had ±1.5% or more errors between the reference PDFF values and PDFF measurements in the range of 0% to 50% PDFF.

Conclusion: In CS-SENSE acquisition, the accuracy of PDFF measurement was maintained within 1.5% up to a reduction factor 6.0. The accuracy of PDFF measurement was maintained within 1.5% up to a reduction factor 2.0 in SENSE acquisition and a reduction factor 1.5 in Dual-SENSE acquisition.

Purpose: The purpose of this study was to evaluate the accuracy of dose information obtained from the digital imaging and communications in medicine (DICOM) using the study description for dose management in nuclear medicine (nuclear medicine SD), and to investigate the feasibility of nuclear medicine SD.

Methods: Single-photon emission nuclear medicine examinations and radionuclide therapy from June 1 to June 30 in 2021 (our hospital master period) and 2023 (nuclear medicine SD period) were included. The dose information in the radioisotope administration record was taken as the true value, and the agreement rate of the examination type, radiopharmaceutical, and dose in the dose management system and the error rate of the dose in the nuclear medicine SD period were calculated.

Results: The agreement rate of examination type and radiopharmaceutical was improved from 37.5% to 97.0% by using nuclear medicine SD, and the agreement rate of dose was 54.0%.

Conclusion: The use of nuclear medicine SD has remarkably improved the integrity of dose information. Dose consistency can be improved by unifying the checking system and the input method of dose information. The feasibility of nuclear medicine SD seems to be high in many facilities, and it may contribute to information collaboration among multi-center facilities and enable centralization of dose management systems.

Purpose: The purpose of this study is to evaluate the detection accuracy of a high-definition optical surface imaging (OSI) system for non-coplanar radiotherapy (by rotating a phantom instead of a couch rotation).

Methods: The constancy, reproducibility, and accuracy of the positioning of the OSI system, Catalyst HD (CHD), for non-coplanar treatment were examined by rotating the head phantom around the isocenter. For all the tests, the phantom was rotated by ±30°, ±45°, ±60°, ±90° after correction of the phantom position within 0.0 mm±0.2 mm, and 0.0°±0.1° using Cone Beam CT (CBCT); the CBCT images were acquired again after rotation. We compared the phantom position derived from CHD, translational displacements of the isocenter (Dev.), and rotational displacements (Rot.) to the position derived from CBCT. The constancy of monitoring was evaluated by observing the variation in the isocenter position for 30 min. For evaluating reproducibility, the positions derived from CHD were compared with those from the planning data. The accuracy of positioning was evaluated by comparing CHD and CBCT findings after the couch rotation of ±0.5°.

Results: The constancy test revealed a maximum Rot. of 0.02±0.01° and Dev. of 0.20±0.08 mm, and the reproducibility test showed a maximum Rot. of 0.26±0.15° and Dev. of 0.93±0.26 mm. In the accuracy tests, when the phantom was further rotated by +0.5°, the maximum values were Rot. of 0.73±0.05° and Dev. of 0.35±0.15 mm; at -0.5°, the values were Rot. of -0.37±0.34° and Dev. of 0.43±0.24 mm.

Conclusion: A high-resolution OSI system is useful for position detection during treatment, even in non-coplanar irradiation.

Purpose: This study was to investigate the cases of ferromagnetic objects brought into the MRI room by using incident reports.

Methods: We included incident reports on ferromagnetic objects brought into the MRI room over the past 10 years from January 2012 to December 2021. We investigated the incidence rate of the ferromagnetic objects into the MRI room, the cause for bringing ferromagnetic objects, the number of years of MRI experience, the time of occurrence, and the names of ferromagnetic objects.

Results: There were 248 incident reports, including 26 cases related to the ferromagnetic objects. The frequency of occurrence shows that the highest number of cases occurred within the first year of experience, accounting for approximately half of the case related to MRI staff. For newcomers, there are more incidents in the second quarter than in other quarters.

Conclusion: The number of cases of bringing in ferromagnetic objects was higher in the second quarter as there was less experience with MRI.