Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
Current issue
Displaying 1-6 of 6 articles from this issue
Clinical Technology
  • Shinichi Takahashi, Hidenobu Tachibana, Riki Oshika, Rie Tachibana, Ma ...
    2025 Volume 81 Issue 3 Article ID: 25-1465
    Published: 2025
    Released on J-STAGE: February 07, 2025
    JOURNAL OPEN ACCESS

    Previous studies have not demonstrated the influence of various imaging acquisition and reconstruction conditions on three-dimensional star shot analysis using an X-ray-based gel dosimeter. Therefore, we investigated the effects of image acquisition and reconstruction conditions on the method in this study and evaluated the robustness of the method. Firstly, we set a reference condition (80 kVp, 1080 mAs, full fan, full trajectory, 1800 projection number, iterative reconstruction) and nine other comparison conditions (80–125 kVp, 540–2160 mAs, half or full fan, full or half trajectory, 420–5400 projection number and iterative reconstruction or filtered back projection). Cone-beam computed tomography scans were performed under each condition before and after irradiation of the single gel dosimeter, and the position of the radiation isocenter relative to the image isocenter, beam isocentricity, and contrast-to-noise ratio (CNR) was measured. The differences compared to the reference were as follows: for isocenter distance, 0.0±0.1 mm on the X-axis, 0.0±0.2 mm on the Y-axis, and 0.1±0.3 mm on the Z-axis. The beam isocentricity was 0.0±0.2 mm. The CNR ranged from a maximum of 5.8 to a minimum of 2.6 in median comparisons. In contrast, compared to the results under the reference condition, the results under other conditions matched within a range of ±0.25 mm. This investigation showed that analysis is feasible within an uncertainty of 0.25 mm under imaging conditions where CNR is 3 or higher.

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  • Tomofumi Misaka, Satoshi Takenaka, Takayuki Ishida
    2025 Volume 81 Issue 3 Pages 1-15
    Published: 2025
    Released on J-STAGE: February 05, 2025
    JOURNAL OPEN ACCESS

    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.

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  • Hirotoshi Murakami, Naoki Hosoda, Natsuki Oyama, Ryoya Hatsuoka, Itaru ...
    2025 Volume 81 Issue 3 Article ID: 25-1505
    Published: 2025
    Released on J-STAGE: February 08, 2025
    JOURNAL OPEN ACCESS

    In interventions for structural heart disease (SHD), an echocardiologist and an anesthesiologist are also present close to the side of the bed at the patient’s head. The purpose of this study was to investigate the effectiveness of X-ray protective devices in reducing exposure to scatter radiation for medical staff at the side of the head end of the angiography system bed during interventions for structural heart disease. The ambient radiation dosage was measured, with and without X-ray protective equipment, to determine the rate of reduction of scatter radiation. The dosage tended to be higher at the working angle compared to the PA direction. When protective equipment was not used, the dosage tended to be higher at the side of the head end of the bed than at the operator’s position. The dose was reduced by more than 90% compared to that without protective equipment by installing a protective device at the side of the head end of the bed. It is important to understand the spatial dose distribution at the working angle, and the installation of protective equipment at the side of the head end of the bed during SHD interventions can reduce the exposure of attending staff.

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  • Issei Matsuo, Masayuki Tachibana, Hirofumi Honda, Hiroki Namba
    2025 Volume 81 Issue 3 Article ID: 25-1475
    Published: 2025
    Released on J-STAGE: February 08, 2025
    JOURNAL OPEN ACCESS

    Purpose: The purpose of this study was to perform auto-segmentation on cases in the head and neck region and to elucidate the characteristics of the extraction performance. Methods: Auto-segmentation was performed on 100 cases in the head and neck region in Japan. The Auto-segmentation contours were compared with the clinical contours. The evaluation structures were the brain, brainstem, spinal cord, mandible, parotid gland, larynx, and eyeballs. DSC and HD were used for similarity evaluation. Results: Overall, there was a high similarity in the eyeball and spinal cord. However, the lower the contrast with neighboring objects and the greater the variation in shape, the lower the similarity. In addition, metal artifacts lowered the similarity in some areas. Conclusion: When auto-segmentation extraction was performed, differences were observed in the degree of similarity between organs. Depending on the case and morphology, the accuracy of auto-segmentation extraction varied from site to site, even for the same organ. The characteristics of the extractability found in this study make it useful for the manual modification of contouring.

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Data
  • Ikumi Kataoka, Mitsuyo Itoh, Mari Itoh, Tokiko Nakamura, Chieko Itaki, ...
    2025 Volume 81 Issue 3 Article ID: 25-1495
    Published: 2025
    Released on J-STAGE: January 24, 2025
    JOURNAL OPEN ACCESS

    Purpose: Hereditary breast and ovarian cancers (HBOC) carry a high risk of breast cancer, and detailed screening with contrast-enhanced breast MRI (breast MRI surveillance) is recommended. With the increase in the number of individuals diagnosed with HBOC, the demand for breast MRI surveillance is also rising. However, the current system is inadequate, with factors such as lack of knowledge and indifference among healthcare professionals, and insufficient understanding of breast MRI surveillance being cited. This study aims to investigate the knowledge of HBOC and the awareness of breast MRI surveillance among radiological technologists, and to analyze the factors that promote these practices. Methods: A web-based survey was conducted among radiological technologists at 1278 facilities with MRI installations. Results: Responses were obtained from 433 individuals. The knowledge of HBOC was insufficient, with 49.6% unaware that breast MRI surveillance is recommended. Factors promoting awareness included the amount of knowledge about HBOC, age, and the presence of MRI specialists and mammography screening specialists. Conclusion: By enhancing the acquisition of knowledge about HBOC and raising awareness of breast MRI surveillance, it is expected that discussions towards building a robust system will deepen.

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  • Kazuki Maekawa, Masakazu Sato, Toshihiro Hayashi, Ryota Hasegawa, Kazu ...
    2025 Volume 81 Issue 3 Article ID: 25-1525
    Published: 2025
    Released on J-STAGE: February 05, 2025
    JOURNAL OPEN ACCESS

    Purpose: In DRLs 2020, in addition to the fluoroscopic dose rate, air kerma at the patient entrance reference point (Ka,r) and air kerma-area product (PKA) by types of medical treatment and diseases were set as DRL quantity. We surveyed the current equipment setting dose at each facility and the exposure dose in clinical practice. We considered the optimal DRL classification of Ka,r and PKA for the next DRLs update. Methods: We conducted a questionnaire survey of 428 facilities in Japan with angiography devices and analyzed the obtained angiography dose data. Results: Fluoroscopic dose rate, Ka,r, and PKA were lower values compared to past studies and DRLs 2020 data, and significant differences were observed in Ka,r and PKA by procedure. Conclusion: Equipment setting doses have been optimized at each facility, and it is expected that radiological protection will be optimized by setting DRL values that reflect the current situation.

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