Radiation dose estimation for pencil beam X-ray luminescence computed tomography imaging.
Radiation dose estimation for pencil beam X-ray luminescence computed tomography imaging.
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DOI：
10.3233/xst-210904
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发表时间：
2021-06
影响因子：
3
通讯作者：
Ignacio O. Romero;Changqing Li
中科院分区：
文献类型：
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作者：
Ignacio O. Romero;Changqing Li
双光束X射线发光计算机断层摄影（XLCT）成像提供了比其它成像几何形状（如片束和锥束几何形状）更优越的上级空间分辨率。然而，笔形射束几何形状的扫描时间较长，导致过量问题，这阻碍了笔形射束XLCT的使用。目的研究笔形束XLCT成像中的剂量沉积，以估算三种不同X射线源的一次成角投影扫描的剂量。研究了典型小动物XLCT成像中的沉积剂量。方法采用蒙特卡罗模拟平台GATE（Geant4 Application for Tomographic Emission），对3种不同X射线源对小鼠腿部模型进行单角度投影扫描，估算剂量。在GATE中对由肌肉、脊椎骨和肿瘤组成的小鼠躯干模型进行了三种不同X射线源能量的六角投影扫描的剂量估计。结果使用Sigray源，对于典型的XLCT成像，使用6个角投影，扫描步长为100 μ m，每次线性扫描106个X射线光子，小鼠腿骨髓的辐射剂量估计为44 mGy。采用Sigray X射线源和典型的XLCT扫描参数，对小鼠躯干的脊柱骨、肌肉组织和肿瘤结构的剂量分别为38.49 mGy、15.07 mGy和16.87 mGy。结论我们的结果表明，X射线台式源（如Sigray Inc.的X射线源）具有高亮度和准单色特性的激光器可以减少与笔形射束几何形状有关的剂量问题。这项工作的结果可以适用于其他成像方式，如X射线荧光计算机断层扫描，如果成像协议包括笔形束的几何形状。
BACKGROUND Pencil beam X-ray luminescence computed tomography (XLCT) imaging provides superior spatial resolution than other imaging geometries like sheet beam and cone beam geometries. However, the pencil beam geometry suffers from long scan times, resulting in concerns overdose which discourages the use of pencil beam XLCT. OBJECTIVE The dose deposited in pencil beam XLCT imaging was investigated to estimate the dose from one angular projection scan with three different X-ray sources. The dose deposited in a typical small animal XLCT imaging was investigated. METHODS A Monte Carlo simulation platform, GATE (Geant4 Application for Tomographic Emission) was used to estimate the dose from one angular projection scan of a mouse leg model with three different X-ray sources. Dose estimations from a six angular projection scan by three different X-ray source energies were performed in GATE on a mouse trunk model composed of muscle, spine bone, and a tumor. RESULTS With the Sigray source, the bone marrow of mouse leg was estimated to have a radiation dose of 44 mGy for a typical XLCT imaging with six angular projections, a scan step size of 100 micrometers, and 106 X-ray photons per linear scan. With the Sigray X-ray source and the typical XLCT scanning parameters, we estimated the dose of spine bone, muscle tissues, and tumor structures of the mouse trunk were 38.49 mGy, 15.07 mGy, and 16.87 mGy, respectively. CONCLUSION Our results indicate that an X-ray benchtop source (like the X-ray source from Sigray Inc.) with high brilliance and quasi-monochromatic properties can reduce dose concerns with the pencil beam geometry. Findings of this work can be applicable to other imaging modalities like X-ray fluorescence computed tomography if the imaging protocol consists of the pencil beam geometry.