在临床MR-linac光束中实验测量的磁场质量转换因子,用于七种MR兼容的电离室模型
Nathan Orlando1,2, Jennie Crosby3, Carri Glide-Hurst3,4
1Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
这项研究实验验证了MR-linac系统的MR兼容的电离室. 测量的磁场质量转换因子 (kB,Q) 与传统室相比显示出几乎相同的性能,这对于准确的剂量测量至关重要.
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:
- 磁共振线性加速器 (MR-linacs) 将MRI与linac技术集成在一起,用于图像引导的放射治疗.
- 精确的剂量测量对于有效的MR-linac治疗提供至关重要,需要精确地描述辐射输出.
- 对于MR-linac系统的体内剂量测量和质量保证,需要兼容MR的电离室.
研究的目的:
- 在1.5T Elekta Unity和0.35T ViewRay MRIdian MR-linac系统上实验量化MR兼容的电离室的响应.
- 为了确定这些室的磁场质量转换系数 (kB,Q).
- 为了比较MR兼容室的性能与它们的常规对应器.
主要方法:
- 通过交叉校准方法评估了七种MR兼容的电离室模型.
- 磁场质量转换因子 (kB,Q) 通过将参考室的剂量测量与测试室的校正输出进行比较来确定.
- 在1.5T Elekta Unity上评估了kB,Q的角度依赖性,通过改变相对于磁场的电池方向.
主要成果:
- 对于MR兼容室的光束质量转换因子 (kQ) 与常规室的计算值非常接近 (平均差异为-0.09 ± 0.18%).
- 磁场质量转换因子 (kB,Q) 在MR兼容和常规腔之间显示出极小的差异:Elekta Unity -0.1 ± 0.3%,ViewRay MRIdian -0.0 ± 0.2%.
- 室内反应在不同的角度是一致的,表明kB,Q没有显著的角度依赖.
结论:
- 兼容MR的电离室的性能几乎相当于传统的电离室.
- 对kB,Q的实验性确定为开发MR-linac剂量计协议提供了关键数据.
- 这次验证是确保MR-linac系统准确输出校准的重要一步.
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