An EGS4-ready tomographic computational model of a 14-year-old female torso for calculating organ doses from CT examinations
An EGS4-ready tomographic computational model of a 14-year-old female torso for calculating organ doses from CT examinations
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DOI：
10.1088/0031-9155/44/9/309
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发表时间：
1999-09-01
影响因子：
3.5
通讯作者：
Pattison, J
中科院分区：
文献类型：
--
作者：
Caon, M;Bibbo, G;Pattison, J
使用 54 次连续 CT 扫描构建了 14 岁女性躯干的断层扫描计算模型，适合通过 CT 确定器官剂量。该模型称为 ADELAIDE，采用输入文件的形式，与基于 XYZDOS.MOR 的用户代码兼容，该用户代码来自现成的 EGS4 蒙特卡洛辐射传输代码。阿德莱德的尺寸接近澳大利亚同龄人的平均尺寸，因此该模特代表了 14 岁女孩。该模型中的真实解剖结构与 Cristy 15 年前的数学计算模型有很大不同，因为它具有真实形状的器官，并且适当地位于真实的外部轮廓内。在 ADELAIDE 中，使用通用电气高速优势 CT 扫描仪特有的几何形状内的 EGS4 以及使用扫描仪 X 射线管数据计算出的 X 射线光谱，计算了阿德莱德胸部和腹部模拟 CT 检查中器官的平均吸收剂量。模拟包括扫描仪的光束整形滤波器和患者检查台。建议与从具有数学解剖学和可能与扫描仪的光谱不匹配的 MIRD 样式模型计算的剂量系数得出的器官剂量相比，所得值具有更少的可能的不确定性来源。使用扫描仪的自由空气测量的 CTDI 和 CTDI 测量的 EGS4 模拟对器官剂量进行标准化。 26 层胸部和 24 层腹部检查（120 kV、200 mAs、7 毫米切片）对躯干的有效剂量分别为 4.6 +/- 0.1 mSv 和 4.3 +/- 0.1 mSv。
Fifty-four consecutive CT scans have been used to construct a tomographic computational model of a 14-year-old female torso suitable for the determination of organ doses from CT. The model, known as ADELAIDE, is in the form of an input file compatible with user codes based on XYZDOS.MOR from the readily available EGS4 Monte Carlo radiation transport code. ADELAIDE's dimensions are close to the Australian averages for her age so the model is representative of a 14-year-old girl. The realistic anatomy in the model differs considerably from that in Cristy's 15-year-old mathematical computational model by having realistically shaped organs that are appropriately located within a real external contour.Average absorbed dose to organs from simulated CT examinations of the chest and abdomen have been calculated for ADELAIDE using EGS4 within a geometry specific to the General Electric Hi-Speed Advantage CT scanner and using an x-ray spectrum calculated using data from the scanner's x-ray tube. The simulations include the scanner's beam shaping filter and patient table. It is suggested that the resulting values have fewer possible sources of uncertainty than organ doses derived from dose coefficients calculated for a MIRD style model with mathematical anatomy and a spectrum that may not match that of the scanner. The organ doses were normalized using the scanner's CTDI measured free-in-air and an EGS4 simulation of the CTDI measurement. Effective dose to the torso from 26-slice chest and 24-slice abdomen examinations (at 120 kV, 200 mAs, 7 mm slices) is 4.6 +/- 0.1 mSv and 4.3 +/- 0.1 mSv respectively.