Abstract：
BACKGROUND: Although the benefits of breast screening and early diagnosis are known for reducing breast cancer mortality rates, the effects and risks of low radiation doses to the cells in the breast are still ongoing topics of study.
OBJECTIVE: To study specific energy distributions ( f ( z , D g ) $f(z,D_{g})$ ) in cytoplasm and nuclei of cells corresponding to glandular tissue for different x-ray breast imaging modalities.
METHODS: A cubic lattice (500 μm length side) containing 4064 spherical cells was irradiated with photons loaded from phase space files with varying glandular voxel doses ( D g $D_{g}$ ). Specific energy distributions were scored for nucleus and cytoplasm compartments using the PENELOPE (v. 2018) + penEasy (v. 2020) Monte Carlo (MC) code. The phase space files, generated in part I of this work, were obtained from MC simulations in a voxelized anthropomorphic phantom corresponding to glandular voxels for different breast imaging modalities, including digital mammography (DM), digital breast tomosynthesis (DBT), contrast enhanced digital mammography (CEDM) and breast CT (BCT).
RESULTS: In general, the average specific energy in nuclei is higher than the respective glandular dose scored in the same region, by up to 10%. The specific energy distributions for nucleus and cytoplasm are directly related to the magnitude of the glandular dose in the voxel ( D g $D_{g}$ ), with little dependence on the spatial location. For similar D g $D_{g}$ values, f ( z , D g ) $f(z,D_{g})$ for nuclei is different between DM/DBT and CEDM/BCT, indicating that distinct x-ray spectra play significant roles in f ( z , D g ) $f(z,D_{g})$ . In addition, this behavior is also present when the specific energy distribution ( F g ( z ) $F_{g}(z)$ ) is considered taking into account the GDD in the breast.
CONCLUSIONS: Microdosimetry studies are complementary to the traditional macroscopic breast dosimetry based on the mean glandular dose (MGD). For the same MGD, the specific energy distribution in glandular tissue varies between breast imaging modalities, indicating that this effect could be considered for studying the risks of exposing the breast to ionizing radiation.
OBJECTIVE: To study specific energy distributions ( f ( z , D g ) $f(z,D_{g})$ ) in cytoplasm and nuclei of cells corresponding to glandular tissue for different x-ray breast imaging modalities.
METHODS: A cubic lattice (500 μm length side) containing 4064 spherical cells was irradiated with photons loaded from phase space files with varying glandular voxel doses ( D g $D_{g}$ ). Specific energy distributions were scored for nucleus and cytoplasm compartments using the PENELOPE (v. 2018) + penEasy (v. 2020) Monte Carlo (MC) code. The phase space files, generated in part I of this work, were obtained from MC simulations in a voxelized anthropomorphic phantom corresponding to glandular voxels for different breast imaging modalities, including digital mammography (DM), digital breast tomosynthesis (DBT), contrast enhanced digital mammography (CEDM) and breast CT (BCT).
RESULTS: In general, the average specific energy in nuclei is higher than the respective glandular dose scored in the same region, by up to 10%. The specific energy distributions for nucleus and cytoplasm are directly related to the magnitude of the glandular dose in the voxel ( D g $D_{g}$ ), with little dependence on the spatial location. For similar D g $D_{g}$ values, f ( z , D g ) $f(z,D_{g})$ for nuclei is different between DM/DBT and CEDM/BCT, indicating that distinct x-ray spectra play significant roles in f ( z , D g ) $f(z,D_{g})$ . In addition, this behavior is also present when the specific energy distribution ( F g ( z ) $F_{g}(z)$ ) is considered taking into account the GDD in the breast.
CONCLUSIONS: Microdosimetry studies are complementary to the traditional macroscopic breast dosimetry based on the mean glandular dose (MGD). For the same MGD, the specific energy distribution in glandular tissue varies between breast imaging modalities, indicating that this effect could be considered for studying the risks of exposing the breast to ionizing radiation.
摘要：
背景：尽管众所周知，乳腺癌筛查和早期诊断的好处是降低乳腺癌死亡率，低辐射剂量对乳腺细胞的影响和风险仍是研究的主题。
目的：研究特定的能量分布（f（z，Dg)$f(z,D_{g}）$）对于不同的X射线乳腺成像方式，对应于腺体组织的细胞的细胞质和细胞核。
方法：用从相空间文件加载的光子以不同的腺体体素剂量（Dg$D_{g}$）照射包含4064个球形细胞的立方晶格（500μm长）。使用PENELOPE（v。2018)+penEasy(v.2020）蒙特卡洛（MC）代码。相空间文件，在这项工作的第一部分中产生的，是从MC模拟中获得的，在对应于不同乳房成像方式的腺体体素的体素化拟人化体模中，包括数字乳房X线照相术(DM)，数字乳房断层合成（DBT），对比增强数字乳腺X线摄影（CEDM）和乳腺CT（BCT）。
结果：一般来说，核中的平均比能高于同一区域中相应的腺体剂量，高达10%。细胞核和细胞质的比能量分布与体素中腺体剂量的大小直接相关（Dg$D_{g}$），对空间位置的依赖性很小。对于类似的Dg$D_{g}$值，f(z,Dg)$f(z,DM/DBT和CEDM/BCT的核D_{g})$不同,表明不同的X射线光谱在f(z，Dg)$f(z,D_{g})$。此外,当考虑到乳房中的GDD时，也存在这种行为。
结论：微剂量学研究是基于平均腺体剂量（MGD）的传统宏观乳房剂量学的补充。对于相同的MGD，腺体组织中的特定能量分布因乳腺成像模式而异，这表明这种影响可以被考虑用于研究乳房暴露于电离辐射的风险。
目的：研究特定的能量分布（f（z，Dg)$f(z,D_{g}）$）对于不同的X射线乳腺成像方式，对应于腺体组织的细胞的细胞质和细胞核。
方法：用从相空间文件加载的光子以不同的腺体体素剂量（Dg$D_{g}$）照射包含4064个球形细胞的立方晶格（500μm长）。使用PENELOPE（v。2018)+penEasy(v.2020）蒙特卡洛（MC）代码。相空间文件，在这项工作的第一部分中产生的，是从MC模拟中获得的，在对应于不同乳房成像方式的腺体体素的体素化拟人化体模中，包括数字乳房X线照相术(DM)，数字乳房断层合成（DBT），对比增强数字乳腺X线摄影（CEDM）和乳腺CT（BCT）。
结果：一般来说，核中的平均比能高于同一区域中相应的腺体剂量，高达10%。细胞核和细胞质的比能量分布与体素中腺体剂量的大小直接相关（Dg$D_{g}$），对空间位置的依赖性很小。对于类似的Dg$D_{g}$值，f(z,Dg)$f(z,DM/DBT和CEDM/BCT的核D_{g})$不同,表明不同的X射线光谱在f(z，Dg)$f(z,D_{g})$。此外,当考虑到乳房中的GDD时，也存在这种行为。
结论：微剂量学研究是基于平均腺体剂量（MGD）的传统宏观乳房剂量学的补充。对于相同的MGD，腺体组织中的特定能量分布因乳腺成像模式而异，这表明这种影响可以被考虑用于研究乳房暴露于电离辐射的风险。
