LET三难题:在碳疗法中,强大的目标覆盖率,均剂量和剂量平均的 LET之间存在冲突
Albin Fredriksson1, Lars Glimelius1, Rasmus Bokrantz1
1RaySearch Laboratories, Stockholm, Sweden.
Medical physics
|October 11, 2023
概括
增加剂量平均线性能量转移 (LETd) 可以改善瘤治疗,但与范围不确定性强度相冲突. 对于大型瘤来说,同时实现范围强度,均剂量和高LETd是具有挑战性的.
科学领域:
- 医学物理和辐射瘤学.
- 电离辐射及其生物学影响.
- 先进的辐射疗法技术.
背景情况:
- 线性能量转移 (LET) 与电离辐射对生物的影响相关.
- 在目标体积中提高剂量平均的LET (LETd) 是治疗缺氧瘤的一种策略.
- 然而,增加LETd可能会损害对范围不确定性的稳定性.
研究的目的:
- 量化评估强大的目标覆盖,剂量均性和LETd之间的相互作用.
- 使用基于剂量和LETd的目标进行强大的优化.
- 调查不同目标非统一性的影响.
主要方法:
- 采用强大的碳疗法优化用于不同目标尺寸 (1-5厘米半径) 的幻象病例.
- 分析范围和设置不确定性对目标LETd的影响.
- 在临床目标体积 (CTV) 或总瘤体积 (GTV) 中实施过量剂量策略,以增强目标LETd.
主要成果:
- 增加的范围不确定性 (0-5%) 降低了目标大小的近最小名义LETd17% - 29%.
- 设置不确定性对LETd.有很小的影响.
- 与统一剂量计划相比,允许10%的CTV过量剂量增加了接近最低的最坏情况下的LETd9%-29%.
结论:
- 在范围不确定性强度和高目标LETd之间存在一个基本的权衡,由较大的瘤大小加剧.
- 对于实质性瘤,同时实现所有三个目标 - - 范围稳定性,剂量均性和高LETd - - 是不可能的.
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