A new technique to characterize CT scanner bow-tie filter attenuation and applications in human cadaver dosimetry simulations.
A new technique to characterize CT scanner bow-tie filter attenuation and applications in human cadaver dosimetry simulations.
复制标题
一种表征 CT 扫描仪领结滤波器衰减的新技术及其在人体尸体剂量测定模拟中的应用。
DOI：
10.1118/1.4932364
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发表时间：
2015
期刊：
影响因子：
3.8
通讯作者：
Liu,Bob
中科院分区：
文献类型：
--
作者：
Li,Xinhua;Shi,JimQ;Zhang,Da;Singh,Sarabjeet;Padole,Atul;Otrakji,Alexi;Kalra,MannudeepK;Xu,XGeorge;Liu,Bob
目的提出一种使用线性阵列 X 射线探测器直接测量 CT 领结滤波器衰减的无创技术。方法使用基于闪烁体的 384 像素、307 毫米有效长度和快速数据采集的 X 射线探测器（型号 X-Scan 0.8c4-307，检测技术，FI-91100 Ii，芬兰）来同时检测整个扫描视场的辐射水平。采样时间短至0.24 ms。为了在 GE Lightspeed Pro 16 CT 扫描仪上测量身体领结衰减，X 射线管停在 12 点钟位置，探测器位于扫描场中心的等中心高度。在光束路径中有领结和没有领结的情况下进行了两次辐射暴露。每个读出信号都针对探测器背景偏移和信号电平相关的非线性增益进行了校正，两次曝光的比率给出了领结衰减。结果用于基于geant4的点剂量模拟，使用放置在人体尸体中的六个顶针室进行测量，腹部/骨盆CT扫描为100或120 kV，螺距为1.375，管电流恒定或可变，以及不同的X射线管起始角度。结果在80-140 kV下扫描人体领结时测量了绝对衰减。对于在尸体六个器官中测量的 24 个剂量，模拟结果与 CT 扫描仪测量结果之间的中值或最大差异分别为 8.9% 或 25.9%。 结论所描述的方法可以快速、准确地表征领结滤波器。
PurposeTo present a noninvasive technique for directly measuring the CT bow‐tie filter attenuation with a linear array x‐ray detector.MethodsA scintillator based x‐ray detector of 384 pixels, 307 mm active length, and fast data acquisition (model X‐Scan 0.8c4‐307, Detection Technology, FI‐91100 Ii, Finland) was used to simultaneously detect radiation levels across a scan field‐of‐view. The sampling time was as short as 0.24 ms. To measure the body bow‐tie attenuation on a GE Lightspeed Pro 16 CT scanner, the x‐ray tube was parked at the 12 o'clock position, and the detector was centered in the scan field at the isocenter height. Two radiation exposures were made with and without the bow‐tie in the beam path. Each readout signal was corrected for the detector background offset and signal‐level related nonlinear gain, and the ratio of the two exposures gave the bow‐tie attenuation. The results were used in thegeant4based simulations of the point doses measured using six thimble chambers placed in a human cadaver with abdomen/pelvis CT scans at 100 or 120 kV, helical pitch at 1.375, constant or variable tube current, and distinct x‐ray tube starting angles.ResultsAbsolute attenuation was measured with the body bow‐tie scanned at 80–140 kV. For 24 doses measured in six organs of the cadaver, the median or maximum difference between the simulation results and the measurements on the CT scanner was 8.9% or 25.9%, respectively.ConclusionsThe described method allows fast and accurate bow‐tie filter characterization.