McGill University, Department of Radiation Oncology, Montréal, Québec, Canada.
Med Phys. 2011 Nov;38(11):6074-83. doi: 10.1118/1.3651482.
A radiochromic film based dosimetry system for high dose rate (HDR) Iridium-192 brachytherapy source was described. A comparison between calibration curves established in water and Solid Water™ was provided.
Pieces of EBT-2 model GAFCHROMIC™ film were irradiated in both water and Solid Water™ with HDR (192)Ir brachytherapy source in a dose range from 0 to 50 Gy. Responses of EBT-2 GAFCHROMIC™ film were compared for irradiations in water and Solid Water™ by scaling the dose between media through Monte Carlo calculated conversion factor for both setups. To decrease uncertainty in dose delivery due to positioning of the film piece with respect to the radiation source, traceable calibration irradiations were performed in a parallel-opposed beam setup.
The EBT-2 GAFCHROMIC™ film based dosimetry system described in this work can provide an overall one-sigma dose uncertainty of 4.12% for doses above 1 Gy. The ratio of dose delivered to the sensitive layer of the film in water to the dose delivered to the sensitive layer of the film in Solid Water™ was calculated using Monte Carlo simulations to be 0.9941 ± 0.0007.
A radiochromic film based dosimetry system using only the green color channel of a flatbed document scanner showed superior precision if used alone in a dose range that extends up to 50 Gy, which greatly decreases the complexity of work. In addition, Solid Water™ material was shown to be a viable alternative to water in performing radiochromic film based dosimetry with HDR (192)Ir brachytherapy sources.
描述了一种基于放射色胶片的高剂量率（HDR）铱-192 近距离放射治疗源剂量测定系统。提供了在水中和 Solid Water™中建立的校准曲线之间的比较。
将 EBT-2 型 GAFCHROMIC™胶片的若干部分在水中和 Solid Water™中用 HDR（192）Ir 近距离放射治疗源进行照射，剂量范围从 0 到 50 Gy。通过使用蒙特卡罗计算的两种设置的转换因子来缩放介质之间的剂量，比较 EBT-2 GAFCHROMIC™胶片在水中和 Solid Water™中的辐射响应。为了减少由于胶片相对于辐射源的位置而导致的剂量传递不确定度，在平行对置光束设置中进行了可追溯的校准照射。
本工作中描述的 EBT-2 GAFCHROMIC™胶片剂量测定系统在剂量超过 1 Gy 时可以提供总体一个标准差剂量不确定度为 4.12%。使用蒙特卡罗模拟计算水和 Solid Water™中胶片敏感层的剂量比，结果为 0.9941±0.0007。
仅使用平板文档扫描仪的绿色通道的基于放射色胶片的剂量测定系统，如果单独在剂量范围扩展至 50 Gy 时使用，具有更高的精度，大大降低了工作的复杂性。此外，Solid Water™材料被证明是在使用 HDR（192）Ir 近距离放射治疗源进行放射色胶片剂量测定时替代水的可行选择。
