Oda Nobuhiro, Uehara Shuzo, Nakano Tsutomu, Tabata Yoshito, Mizuta Masayoshi, Ideguchi Tadamitsu, Aoki Takatoshi
Department of Radiology, Fukuoka School of Health Sciences (Current address: Emeritus Professor, Kyoto College of Medical Science).
Emeritus Professor, Kyushu University.
Nihon Hoshasen Gijutsu Gakkai Zasshi. 2022;78(2):159-170. doi: 10.6009/jjrt.780206.
Contrast-to-noise ratio (CNR) of four X-ray beams (90 kV with 0.15-mm Cu filter, 90 kV with 0.2-mm Cu filter, 120 kV without filter and 120 kV with 0.2-mm Cu filter) in CsI-flat panel detector (FPD) radiography for lung cancer diagnosis was investigated using Monte Carlo simulation.
Two billion photons were injected to the chest phantom model (width: 300 mm, length: 300 mm, thickness: 200 mm) with imitated lung nodules (10 mm diameter, CT value: +30 Hounsfield unit (HU), -375 HU, and -620 HU). Individual primary and secondary photon's process (absorption, scattering and penetration) in the phantom and CsI-detector was recorded by Monte Carlo simulation. CNR was calculated using primary and secondary absorbed photon's number in the CsI-detector.
CNR of 90 kV X-ray beam with 0.15 mm and 0.2 mm Cu filters was higher to 120 kV X-ray beam because of higher primary object contrast and photon's contribution, and high photon's absorption to CsI.
By Monte Carlo calculation, it was verified that 90 kV X-ray beam with 0.15 mm and 0.2 mm Cu filters yielded higher CNR to 120 kV X-ray beam.
利用蒙特卡罗模拟研究在用于肺癌诊断的碘化铯平板探测器（FPD）X线摄影中，四种X线束（90 kV加0.15 mm铜滤过、90 kV加0.2 mm铜滤过、120 kV无滤过以及120 kV加0.2 mm铜滤过）的对比噪声比（CNR）。
向具有模拟肺结节（直径10 mm，CT值：+30亨氏单位（HU）、-375 HU和-620 HU）的胸部体模模型（宽：300 mm，长：300 mm，厚：200 mm）注入20亿个光子。通过蒙特卡罗模拟记录体模和碘化铯探测器中单个初级和次级光子的过程（吸收、散射和穿透）。使用碘化铯探测器中初级和次级吸收光子数计算CNR。
90 kV加0.15 mm和0.2 mm铜滤过的X线束的CNR高于120 kV X线束，原因是初级物体对比度和光子贡献更高，以及光子对碘化铯的吸收更高。
通过蒙特卡罗计算，证实90 kV加0.15 mm和0.2 mm铜滤过的X线束比120 kV X线束产生更高的CNR。
