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Monte Carlo evaluation of the dose sparing and dose enhancement by combination of Gd-infused tumor and 241Am source for an endocavitary brachytherapy geometry.
Applied Radiation and Isotopes ( IF 1.6 ) Pub Date : 2020-05-04 , DOI: 10.1016/j.apradiso.2020.109194
M Fuentealba 1 , M Santibáñez 2
Affiliation  

In this work, the benefits in terms of dose enhancement and dose sparing via radiation shielding are evaluated, for a combined irradiation scheme with sources of 241Am and tumor-infused with Gd agents, regarding conventional 192Ir treatment. Monte Carlo simulations using PENELOPE code were implemented for endocavitary brachytherapy geometries, configuring a pelvis phantom of 15 cm radius and 30 cm length. Inside, it was defined cylindrical tumor phantoms of 2 cm radius and 4 cm–6 cm length (simulating initial stages) as well as tumors of extensive volume (2.5 and 3.0 cm radius) and difficult coverage. Tumor phantoms were doped with 68 mM and 138 mM of Gd in order to assess the effects of enhancement and protection based on the concentration and emission energy of the isotope. Obtained results for the first tumor group, shown the feasibility of achieving dose enhancements of 94.3%–117% and 160%–194% for 68 mM and 138 mM of Gd infused into the tumor and irradiation with 241Am, respectively. Similarly, reduced dose enhancements of 3.5–5.7% y 8.9%–11.2% for 68 mM and 138 mM of Gd are attained with 192Ir. In terms of dose sparing outer the tumor, the radiation shielding and dose enhancement allowed a higher reduction in the dose by 241Am of 17%–24% for 68 mM and 21%–32% for 138 mM of Gd, and non-negligible dose sparing are produced too by 192Ir of 2% and 5% for the same concentration of Gd. For the second tumors group, the combined use of 241Am and Gd agents simultaneously allowed to improve coverage and reduce the healthy tissue dose, showing the obtained results the possibility of achieving coverage of 95% of the prescribed dose in 100% of tumor volume together with dose sparing factor of 6–21% reduction in isodose of the studied point and dose enhancements of 75%–158% at the prescription point.



中文翻译:

通过结合 Gd 注入肿瘤和 241Am 源对腔内近距离放射治疗几何形状的剂量保留和剂量增强进行蒙特卡罗评估。

在这项工作中,在剂量增强方面的好处和剂量经由辐射屏蔽节约被评估,对于具有源的组合照射方案241 AM到肿瘤并入以Gd剂,关于常规192红外线治疗。使用 PENELOPE 代码对腔内近距离放射治疗几何结构进行蒙特卡罗模拟,配置半径为 15 厘米、长度为 30 厘米的骨盆体模。在内部,它被定义为半径为 2 cm 和长度为 4 cm–6 cm(模拟初始阶段)的圆柱形肿瘤模型,以及体积大(半径为 2.5 和 3.0 cm)且难以覆盖的肿瘤。肿瘤体模掺杂了 68 mM 和 138 mM 的 Gd,以评估基于同位素浓度和发射能量的增强和保护效果。获得的第一个肿瘤组的结果表明,将 68 mM 和 138 mM 的 Gd 注入肿瘤并用241分别是。同样,使用192 Ir可将 68 mM 和 138 mM Gd 的剂量增强降低 3.5–5.7% y 8.9%–11.2% 。就肿瘤外部的剂量保留而言,辐射屏蔽和剂量增强允许剂量降低241 Am,68 mM的剂量降低17%–24%,Gd 的 138 mM 降低 21%–32%,并且不可忽略剂量节省也由192产生对于相同浓度的 Gd,Ir 为 2% 和 5%。对于第二个肿瘤组,241Am和Gd剂的联合使用可以提高覆盖率并减少健康组织剂量,表明获得的结果有可能在100%的肿瘤体积内实现95%的处方剂量覆盖研究点的等剂量减少 6-21% 的剂量保留因子和处方点的剂量增加 75%-158%。

更新日期:2020-05-04
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