Gafchromic EBT film dosimetry in proton beams
Gafchromic EBT film dosimetry in proton beams
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DOI：
10.1088/0031-9155/55/10/n04
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发表时间：
2010-05-21
影响因子：
3.5
通讯作者：
Das, Indra J.
中科院分区：
文献类型：
--
作者：
Zhao, Li;Das, Indra J.
对于用于束数据调试和患者特定测量的电离室测量，主动扫描质子束的深度剂量验证非常耗时。随着 Gafchromic EBT 薄膜的广泛使用，人们在均匀扫描质子束中探索了二维高分辨率剂量测定。 EBT 薄膜在固体水体模中平行于射束轴曝光，以便在单次测量中获得深度-剂量曲线，并与水中平行板离子室的金标准测量进行比较。我们的结果表明，EBT 薄膜在确定质子束范围方面表现良好，不确定度为 0.5 mm。还发现EBT薄膜响应是能量的函数，超过50-160 MeV质子束的有效能量，变化小于10%。然而，在布拉格曲线的峰值处观察到剂量不足高达 20%。提出了一个根据经验得出的校正因子来解释 EBT 能量依赖性。通过校正，EBT 胶片可以成为主动扫描质子束深度剂量验证的有用工具，从而节省宝贵的质子束时间。
The depth dose verification of active scanning proton beams is extremely time consuming with ion chamber measurements for beam data commissioning and patient specific measurements. With widespread use of Gafchromic EBT films, two-dimensional high-resolution dosimetry is explored in a uniform scanning proton beam. The EBT films were exposed parallel to the beam axis in a solid water phantom in order to obtain the depth-dose curve in a single measurement and compared with the gold standard measurement with a parallel plate ion chamber in water. Our results demonstrate that EBT films perform well in determining the proton beam range, with uncertainty of 0.5 mm. It is also found that EBT film response is a function of energy over the effective energy of 50-160 MeV proton beams with the variations less than 10%. However, an under-dosage of up to 20% was observed at the peak of the Bragg curve. An empirically derived correction factor is proposed to account for the EBT energy dependence. With corrections, EBT films can be a useful tool for the depth dose verification of active scanning proton beams, thus saving valuable proton beam time.