Monte Carlo (MC) simulations are employed extensively in breast dosimetry studies. In the energy interval of interest in mammography energy deposition is predominantly caused by the photoelectric effect, and the corresponding cross sections used by the MC codes to model this interaction process have a direct influence on the simulation results. The present work compares two photoelectric cross section databases in order to estimate the systematic uncertainty, related to breast dosimetry, introduced by the choice of cross sections for photoabsorption. The databases with and without the so-called normalization screening correction are denoted as ‘renormalized’ or ‘un-normalized’, respectively. The simulations were performed with the PENELOPE/penEasy code system, for a geometry resembling a mammography examination. The mean glandular dose (MGD), incident air kerma (K _air), normalized glandular dose (DgN) and glandular depth-dose (GDD(z)) were scored, for homogeneous breast phantoms, using both databases. The AAPM Report TG-195 case 3 was replicated, and the results were included. Moreover, cases with heterogeneous and anthropomorphic breast phantoms were also addressed. The results simulated with the un-normalized cross sections are in better overall agreement with the TG-195 data than those from the renormalized cross sections; for MGD the largest discrepancies are 0.13(6)% and 0.74(5)%, respectively. The MGD, K _air and DgN values simulated with the two databases show differences that diminish from approximately 10%/3%/6.8% at 8.25 keV down to 1.5%/1.7%/0.4% at 48.75 keV, respectively. For polyenergetic spectra, deviations up to 2.5% were observed. The disagreement between the GDDs simulated with the analyzed databases increases with depth, ranging from −1% near the breast entrance to 4% near the bottom. Thus, the choice of photoelectric cross section database affects the MC simulation results of breast dosimetry and adds a non-negligible systematic uncertainty to the dosimetric quantities used in mammography.

蒙特卡罗 (MC) 模拟广泛用于乳房剂量学研究。在乳腺摄影中感兴趣的能量区间中，能量沉积主要是由光电效应引起的，MC 代码用来模拟这种相互作用过程的相应横截面对模拟结果有直接影响。目前的工作比较了两个光电横截面数据库，以估计与乳房剂量测定相关的系统不确定性，这是由光吸收横截面的选择引入的。有和没有所谓的归一化筛选校正的数据库分别表示为“重新归一化”或“未归一化”。模拟是使用 PENELOPE/penEasy 代码系统进行的，用于类似于乳房 X 光检查的几何形状。平均腺体剂量（MGD），K _air )、归一化腺体剂量 (DgN) 和腺体深度剂量 (GDD( z )) 均使用这两个数据库对均质乳房模型进行评分。AAPM 报告 TG-195 案例 3 被复制，结果被包括在内。此外，还讨论了具有异质性和拟人化乳房幻影的情况。与重归一化横截面相比，未归一化横截面模拟的结果与 TG-195 数据的总体一致性更好；对于 MGD，最大的差异分别为 0.13(6)% 和 0.74(5)%。MGD、K _空气和两个数据库模拟的 DgN 值显示的差异分别从 8.25 keV 的大约 10%/3%/6.8% 减少到 48.75 keV 的 1.5%/1.7%/0.4%。对于多能谱，观察到高达 2.5% 的偏差。与分析数据库模拟的 GDD 之间的差异随着深度的增加而增加，范围从靠近乳房入口的 -1% 到靠近底部的 4%。因此，光电截面数据库的选择会影响乳房剂量测定的 MC 模拟结果，并为乳房 X 线照相术中使用的剂量测定量增加了不可忽略的系统不确定性。