在连续和脉冲扫描质子束中进行参考剂量计的圆柱形和平面平行离子化室的实验比较
Gloria Vilches-Freixas1, Geert Bosmans1, Alexandros Douralis2
1Department of Radiation Oncology (Maastro), GROW Research Institute for Oncology and Reproduction, Maastricht University Medical Centre+, Maastricht, The Netherlands.
Physics in medicine and biology
|April 19, 2024
概括
四个电离室在质子束中显示了1.53.7%的剂量差异. 新的光束质量 (k) 值减少了室内扩散,但仍然存在不一致性,特别是在IBA-PPC05室内.
科学领域:
- 医学物理 医学物理
- 辐射剂量计 辐射剂量计
- 微粒疗法是一种微粒疗法.
背景情况:
- 精确的吸收剂量确定对于有效的质子疗法至关重要.
- 电离室 (IC) 是剂量计的标准工具,但它们的性能可能有所不同.
- 质子束具有独特的剂量测量挑战,因为它们的范围有限和能量依赖.
研究的目的:
- 为了实验性地比较吸收剂量与水的测量,使用四个不同的电离室.
- 评估不同光束质量 (k) 校正因子对质量测定对质子束剂量的影响.
- 在扫描的质子束中识别剂量测量协议和室内性能中的潜在不一致.
主要方法:
- 四个电离室 (PTW-34045高级马库斯,PTW-34001罗斯,IBA-PPC05,PTW-30012农民) 在扫描的质子束 (80220 MeV) 中被辐射.
- 在水幻影中,ICs被放置在特定的深度,考虑到水等效厚度和有效测量点.
- 剂量测量使用了国际原子能机构的TRS-398,新计算的蒙特卡洛 (MC) 值,以及更新的TRS-398对光束质量 (k) 校正因子的建议.
主要成果:
- 四个IC之间的剂量差异在TRS-398和新推的k值之间为1.5%至3.7%.
- 随着新推的k值的应用,剂量测量的差异减少了.
- 与其他室相比,IBA-PPC05 IC 总是产生较低的剂量读数.
结论:
- 观察到IC之间的剂量差异表明k值的确定不一致,特别是对扫描的质子束.
- 对于平面平行IC的蒙特卡洛模拟应该考虑物理窗口厚度,而不是水等效厚度.
- 需要进一步的研究,包括热量计测量,以解决k值的不一致性和MC计算的基准.
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