日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
75 巻 , 6 号
選択された号の論文の11件中1~11を表示しています
巻頭言
原著
  • 早川 岳英, 山田 巧, 坂井 裕則, 笹本 龍太
    2019 年 75 巻 6 号 p. 525-535
    発行日: 2019年
    公開日: 2019/06/20
    ジャーナル フリー

    In X-ray therapy, equivalent square field (side of equivalent square field) is important because it influences the accuracy of independent verification of monitor unit (MU) by calculation. To calculate the side of equivalent square field for rectangular fields, we often use a table of domestic standard measurement method (Day’s method), or A/P method calculated by area-perimeter ratio. The sides of equivalent square fields of these methods are assumed to be unchanged by depth and energy, but there are reports that it is not valid. Therefore, the depth dependency of side of equivalent square fields of Day’s method, A/P method, and area ratio correction (ARC) method was compared by measuring phantom scatter factors (Sp). From the analysis of Sp measured at different depths, the estimated value of Sp on the equivalent square side of the Day’s method and A/P method had a depth dependency that the difference from the measured value was large when the measurement depth was deep. The estimated value of Sp on the equivalent square side of the ARC method had a small difference from the measured value even when the measurement depth was deep, and the depth dependency was small compared with the Day’s method and the A/P method. Side of equivalent square field of ARC method had a smaller difference of depth dependency than in the case of Day’s method and A/P method. Therefore, in the independent verification of MU for rectangular field, using the equivalent square side of the ARC method is better.

ノート
  • 南 和芳, 松原 孝祐, 林 勇樹, 藤原 康人, 森元 勝浩, 小畠 敏典
    2019 年 75 巻 6 号 p. 536-545
    発行日: 2019年
    公開日: 2019/06/20
    ジャーナル フリー

    In electrocardiographic (ECG)-gated computed tomography (CT) for diagnosis of cardiac diseases, radiation dose and image quality are optimized by limiting field of view (FOV) and centering on the heart. However, it is necessary to set wide FOV with large bowtie filter depending on patient positioning or various diagnoses such as aortic diseases. The purpose of this study is to clarify influence of bowtie filter and patient positioning on in-plane dose distribution, organ-absorbed dose, image quality in ECG-gated CT. In-plane dose distribution and organ-absorbed dose were evaluated with radio photoluminescence glass dosimeters, and signal-to-noise ratio (SNR) were measured for evaluation of image quality. The bowtie filter was used small (S) and large (L). With automatic exposure control, volume computed tomography dose index was 55.3 mGy at S and 71.8 mGy at L. The phantom was positioned on the heart of phantom (Heart) and the center of phantom (Body). In Heart-L compared with Heart-S, organ-absorbed dose was 1.29 times at breasts. In Heart-S compared with Body-S, in-plane dose distribution was increased 25% at left anterior and decreased 20% at right posterior. In SNR, S and L were decreased from 50 mm off-center. To set appropriate bowtie filter and positioning was reduced radiation dose and improved image quality in ECG-gated CT.

資料
教育講座─放射線技術学を用いた先端生命科学研究─
教育講座─放射線治療装置を立ち上げよう─
教育講座─放射線技術学におけるImageJの活用─
教育講座─放射線技術学における研究の進め方:研究計画から論文発表まで─
基礎講座─定量とその不確かさ─
国際研究集会派遣報告
JIRAトピックス
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