日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
77 巻, 12 号
選択された号の論文の15件中1~15を表示しています
巻頭言
臨床技術
  • 辻 慶歩, 岡 あすか, 有原 成美, 大西 隆太郎, 澤谷 令香, 齋藤 茂芳
    2021 年 77 巻 12 号 p. 1393-1399
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    Purpose: This study aims to investigate inflammatory changes and osteophyte formation in a rat osteoarthritis (OA) model longitudinally by using 7 T-magnetic resonance imaging (MRI) and micro-computed tomography (CT). Method: This OA model is induced surgically by removing the medial collateral ligament and medial meniscus of the right knee joint. Using 7 T-MRI, we compared the relative signal value of the medial collateral site and the area (mm2) of the upper end of the tibia at the right knee joint to those of the left knee joint on T2WI. In addition, we compared statistically the coefficient of variance (CV) of signal intensity on the subchondral bone, the area (mm2), the major axis (mm) and the minor axis (mm) of the upper end of the tibia by the use of micro-CT images. Results: In MRI experiment, the relative signal value was significantly higher at 2, 6, and 10 weeks postoperatively in the medial part of right knee joint than that in the left one. In micro-CT experiment, CV was significantly higher from 6 weeks postoperatively in the subchondral bone of surgical side. Rough and irregular surface at the medial tibia was also observed by 3D images. Conclusion: Using 7 T-MRI and micro-CT, we’re able to observe the knee osteoarthritis model rat longitudinally.

  • 大吉 一, 橘 英伸, 染谷 貴士, 良知 寿哉, 武田 陽平, 有路 貴樹
    2021 年 77 巻 12 号 p. 1400-1410
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    In liver stereotactic body radiotherapy (SBRT) using fiducial markers, the accuracy of automatic image recognition of fiducial markers is important, and the imaging dose cannot be neglected in image-guided radiotherapy. Optimal imaging parameters of fiducial markers were investigated for automatic image recognition and imaging dose. We investigated automatic recognition with fiducial markers of different shapes and sizes. In addition, the optimum imaging conditions were examined based on the automatic recognition when the presence or absence of a filter, focal spot size, and phantom thickness were altered using the fiducial markers with a high automatic recognition. The results for different shapes and sizes of fiducial markers showed that larger markers were recognized more automatically, whereas shorter markers were recognized in the correct position. By using the filter, we were able to reduce the imaging dose by one third or one half compared to the case without the filter. The results for the focal spot size showed that using a larger size resulted in higher automatic recognition accuracy than using a smaller size. For the relationship between the automatically recognized imaging conditions and the air kerma when the phantom thickness was altered, it was necessary to keep the tube current–time product constant and increase the tube voltage in order to avoid poor recognition accuracy. The parameters we proposed are effective in shortening the treatment time and reducing the imaging dose because they allow us to acquire images with low doses and high accuracy of automatic recognition.

  • 片山 竜也, 渡邉 啓太, 成松 秀州, 掛田 伸吾, 興梠 征典
    2021 年 77 巻 12 号 p. 1411-1415
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    The voxel-based specific regional analysis system for Alzheimer’s disease (VSRAD), which targets volume loss in medial temporal lobe, was developed as a sensitive diagnostic tool to detect early stages of Alzheimer’s disease. However, conventional three-dimensional T1 -weighted image (3D-T1WI) for VSRAD analysis acquires relatively long acquisition time. Recently, it became possible to acquire Scout images (Scout) for positioning as a 3D image in a short time. The aim of this study was to determine whether Scout was reliable in VSRAD. We measured voxel-based analysis of gray matter volume using VBM and Z-score of medial temporal lobe atrophy using VSRAD advance 2 from conventional 3D-T1WI and Scout. It showed significantly different gray mass between conventional 3D-T1WI and Scout. However, there was no significant difference in Z-score (p=0.41). The Z-scores measured from Scout and conventional 3D-T1WI were significantly correlated (r=0.96, p<0.05). There is a possibility that Scout can be used to detect brain morphometry abnormalities instead of conventional 3D-T1WI in the VSRAD analysis.

  • 山室 修, 築島 正拓
    2021 年 77 巻 12 号 p. 1416-1423
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    In magnetic resonance imaging (MRI) examinations, a trade-off is noted among acquisition time, resolution, and signal-to-noise ratio (SNR). High-resolution images are expected to improve the detection of small lesions. However, to ensure a high SNR, the imaging time must be extended. If the number of additions is reduced to shorten the imaging time, a reduction in slice thickness and in-plane resolution is necessary to ensure an adequate SNR. A combination of acceleration and denoising using deep learning has been previously reported. However, although it may be useful as a noise reduction technique onboard device, it cannot be used for general purposes. We studied the effects of a recently developed general-purpose image-based noise reduction software on MRI by measuring SNR and other parameters such as contrast, resolution, and noise power spectrum (NPS). NPS was influenced by the difference in processing mode, whereas contrast remained uninfluenced. Regarding resolution, the edge information was retained and was found to be better in iNoir 3D than in iNoir 2D. However, owing to the increased intensity of noise-reduction processing, the slope of the edge in the low-contrast area was smoothed, presenting a visually blurred impression.

  • 藤原 誠, 汐月 剣志, 河野 実月, 納戸 大智, 奥川 幸洋, 古庄 剛, 西村 賢一, 財前 博文
    2021 年 77 巻 12 号 p. 1424-1431
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    Objective: We compared the contrast-enhancement effects of the coronary arterial phase and the aortic phase in coronary and aorta computed tomography angiography (CA-CTA) using the bolus-tracking technique-based single-peak contrast medium injection (BT-SPI) method and the bolus-tracking technique-based dual-peak contrast medium injection (BT-DPI) method. Method: CA-CTA images were acquired from 30 patients, using BT-SPI and BT-DPI. Regions of interest were selected in the right ventricle and ascending aorta during the coronary arterial phase, and in the aorta during the aortic phase to obtain mean CT values. The mean CT values were used to compare the contrast-enhancement effects of BT-SPI and BT-DPI. Results: The mean CT value of the right ventricle during the coronary arterial phase obtained using BT-SPI (320 Hounsfield unit [HU]) and BT-DPI (83 HU) was significantly different (p<0.05). Using BT-SPI and BT-DPI, the mean CT values of the ascending aorta during the coronary arterial phase were 361 HU and 379 HU, respectively, and those of the aorta during the aortic phase were 436 HU and 437 HU, respectively. The difference in the mean CT values for the aorta between BT-SPI and BT-DPI during the coronary arterial and aortic phases was insignificant. Conclusion: The retention of the contrast medium in the right ventricle during the coronary arterial phase using BT-DPI was lower than that using BT-SPI. BT-DPI showed substantial contrast-enhancement effects in both the coronary arterial and aortic phases.

  • 小山内 暢, 佐藤 華菜, 佐藤 秀紀, 工藤 幸清, 細川 翔太, 藤田 彰, 北島 麻衣子, 對馬 惠, 小宮 睦弘, 工藤 真也, 齋 ...
    2021 年 77 巻 12 号 p. 1432-1443
    発行日: 2021年
    公開日: 2021/12/20
    ジャーナル フリー

    Purpose: Radiation protection glasses is a useful tool for dose reduction of eye lens. However, the method to evaluate the dose of eye lens, which is covered with radiation protection glasses in actual radiation management situation, has not been established. We invented the easy-to-use procedure to estimate the dose of eye lens inside of radiation protection glasses for occupationally exposed person using an X-ray shielding material and an additional personal dosimeter for trunk of the body. The objective of this study was to evaluate the feasibility of the new method. Methods: The radiation field in interventional radiology (IR) was reconstructed. A personal dosimeter was set to the eye position and neck position of medical staff phantom. Each dosimeter was covered by radiation protection glasses or X-ray shielding material, and the 1 cm or 70 mm dose equivalent quantity in the neck position was compared to the 3 mm dose equivalent quantity in the eye position. Results: The dose equivalent quantity measured inside of X-ray shielding material in the neck position was similar to that of inside radiation protection glasses. Thus, the X-ray attenuation by radiation protection glasses was able to be simulated using the X-ray shielding material. Conclusion: It was suggested that the dose of eye lens inside of radiation protection glasses could be easily estimated by covering the conventional personal dosimeter for trunk of the body with the X-ray shielding material.

会員インタビュー~学会に貢献された人々~
教育講座─CTの基礎と応用技術─
教育講座─放射線技術学におけるファントムスタディ─
教育講座─MRIの基礎と応用技術─
教育講座─Radiomics/Precision Medicine研究の現状と将来─
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