ERSN Laboratory, Physics Department, Faculty of Sciences, University Abdelmalek Essaadi, Tetouan, Morocco.
Nuclear Medicine Department, Military Hospital Mohammed V, Rabat, Morocco.
Radiol Phys Technol. 2023 Jun;16(2):212-226. doi: 10.1007/s12194-023-00709-2. Epub 2023 Mar 14.
Internal radiation exposure using radiopharmaceuticals, as in nuclear medicine procedures, necessitates the estimation of the S-value to determine and improve the estimates of absorbed doses in at-risk organs and tissues. The S value is defined as the absorbed dose in the target organ per unit of nuclear transformation in the source organ. It is calculated using the specific absorbed fraction, which is an important quantity that connects the deposited energy in the target and emitting source organs. In this study, we applied DoseCalcs, a new Geant4-based tool, to estimate the S values of [Formula: see text]F using nuclear data from ICRP Publication 107. Geometrical data from ICRP Publications 110 and 143 were used to select four models representing male and female phantoms for adults and 15 years old to study the variability in the S-values arising from variations in anatomy and initial energy validations, because we used the [Formula: see text] mean energy instead of the full beta spectrum. The [Formula: see text]F-released photons and [Formula: see text] from 26 source organs were tracked using the Geant4 Livermore package. Accordingly, the S-values were calculated for 141 target organs. The results for the adult male and female phantoms were compared with the OpenDose reference data. These results agreed well with OpenDose, the average ratio for self-absorption S-values was 1.015, and the average ratios for the cross-irradiation were 1.2 and 1.22 for the AM and AF, respectively. This indicates the accuracy of DoseCalcs for subsequent use in estimating [Formula: see text]F S-values using voxelized geometries.
使用放射性药物进行体内放射照射，如核医学程序，需要估计 S 值，以确定和改进危险器官和组织吸收剂量的估计。S 值定义为源器官中每单位核转化的靶器官吸收剂量。它是使用特定吸收分数计算的，特定吸收分数是将靶器官和发射源器官中沉积的能量联系起来的重要量。在这项研究中，我们应用了基于 Geant4 的新工具 DoseCalcs，使用 ICRP 出版物 107 中的核数据来估计 [Formula: see text]F 的 S 值。ICRP 出版物 110 和 143 的几何数据用于选择四个模型，代表成年男性和女性以及 15 岁的成年人和 15 岁的成年人，以研究由于解剖结构和初始能量验证的变化而导致的 S 值变化的可变性，因为我们使用的是 [Formula: see text] 平均能量而不是全β谱。使用 Geant4 Livermore 包跟踪来自 26 个源器官的 [Formula: see text]F 释放光子和 [Formula: see text]。因此，为 141 个靶器官计算了 S 值。将成年男性和女性模型的结果与 OpenDose 参考数据进行了比较。这些结果与 OpenDose 吻合较好，自吸收 S 值的平均比值为 1.015，交叉照射的平均比值分别为 AM 和 AF 的 1.2 和 1.22。这表明 DoseCalcs 可用于随后使用体素化几何形状估计 [Formula: see text]F S 值。
