用两种方法确定磁场输出校正因子,用于中央轴上的两个探测器
Stephan Frick1, Moritz Schneider2, Daniela Thorwarth2,3
1Physikalisch-Technische Bundesanstalt, Braunschweig, Germany.
Physics in medicine and biology
|February 21, 2025
概括
对于MR-linac投入使用,确定了输出校正因数 (kB→,Qclin,Qmsrfclin,fmsr). 对于较大的领域,这些因素始终是1,简化了剂量计. 较小的磁场需要仔细考虑磁场效应.
科学领域:
- 医学物理 医学物理
- 辐射瘤学 辐射瘤学
- 剂量测量方法 剂量测量方法
背景情况:
- 精确测量linac输出对于MR-linac治疗计划至关重要.
- 检测器需要输出校正因子,特别是kB→,Qclin,Qmsrfclin,fmsr,以考虑磁场和小场效应.
研究的目的:
- 用两个不同的方法来确定kB→,Qclin,Qmsrfclin,fmsr.
- 为了研究kB→,Qclin,Qmsrfclin,fmsr在各种光子能量和磁流密度的行为.
- 在1.5 T MR-linac.linac上评估确定因素的临床适用性.
主要方法:
- 用实验设施的电离室和固态探测器进行了测量.
- 蒙特卡洛模拟被用来确定吸收剂量变化到水与现场大小.
- 通过在1.5 T MR-linac.l上进行额外的测量来评估临床适用性.
主要成果:
- 这两种方法都产生了可比的kB→,Qclin,Qmsrfclin,fmsr结果.
- 对于场面大小>3 × 3 cm2,kB→,Qclin,Qmsrfclin,fmsr 对于6和8 MV光子能量没有对磁场的依赖.
- 对于3 × 3 cm2的场大小,kB→,Qclin,Qmsrfclin,fmsr取决于光子能量和磁场强度,在1.5 T和6 MV下降值高达3% (电离室) 和7% (固态探测器).
结论:
- 对两个探测器成功确定了kB→,Qclin,Qmsrfclin,fmsr,使其能够在1.5 T MR-linac.中使用.
- 对于场尺寸>3 × 3 cm2,kB→,Qclin,Qmsrfclin,fmsr在大多数探测器中大约为一个,简化了MR-linac系统中的小场剂量计.
- 未来的研究应该集中在较小的磁场尺寸上,因为它们依赖磁场和光子能量.
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