Dose-response of EBT3 radiochromic films to proton and carbon ion clinical beams
Dose-response of EBT3 radiochromic films to proton and carbon ion clinical beams
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DOI：
10.1088/1361-6560/aa5078
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发表时间：
2017-01-21
影响因子：
3.5
通讯作者：
Russo, Paolo
中科院分区：
文献类型：
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作者：
Castriconi, Roberta;Ciocca, Mario;Russo, Paolo
我们研究了质子和碳离子临床射束的外部射束治疗3（EBT 3）薄膜的剂量响应，与传统的放射治疗射束相比，我们还测量了薄膜响应沿着水中的能量沉积曲线。我们进行了测量，在三个强子治疗中心提供单能笔束（质子：63-230 MeV;碳离子：115-400 MeV/u），在0.4-20戈伊剂量的水，在高原的深度-剂量曲线。我们还用临床MV-光子和电子束照射胶片。我们将EBT 3薄膜放置在水中沿着整个深度-剂量曲线为148.8 MeV的质子和398.9 MeV/u的碳离子，与测量提供的平面平行电离室。对于质子，在实验不确定性范围内，EBT 3在深度-剂量曲线的平台中的响应与光子的响应没有不同。对于碳离子，我们观察到EBT 3膜的能量依赖性响应不足，相对于光子束从16%到29%。此外，我们观察到的布拉格峰区域的响应不足约10%的148.8 MeV的质子和约42%的398.9 MeV/u的碳离子。对于质子和碳离子临床束，在布拉格峰处发生响应不足。对于碳离子，我们还观察到EBT 3在深度-剂量曲线的平台中的响应不足。这种效应在临床射束的最低初始能量处最高，这是与胶片敏感层中相应的较高LET相关的现象。当使用EBT 3胶片进行精确的3D剂量测定时，应正确模拟这种行为。
We investigated the dose-response of the external beam therapy 3 (EBT3) films for proton and carbon ion clinical beams, in comparison with conventional radiotherapy beams; we also measured the film response along the energy deposition-curve in water. We performed measurements at three hadrontherapy centres by delivering monoenergetic pencil beams (protons: 63-230 MeV; carbon ions: 115-400 MeV/u), at 0.4-20 Gy dose to water, in the plateau of the depth-dose curve. We also irradiated the films to clinical MV-photon and electron beams. We placed the EBT3 films in water along the whole depth-dose curve for 148.8 MeV protons and 398.9 MeV/u carbon ions, in comparison with measurements provided by a plane-parallel ionization chamber. For protons, the response of EBT3 in the plateau of the depth-dose curve is not different from that of photons, within experimental uncertainties. For carbon ions, we observed an energy dependent under-response of EBT3 film, from 16% to 29% with respect to photon beams. Moreover, we observed an under-response in the Bragg peak region of about 10% for 148.8 MeV protons and of about 42% for 398.9 MeV/u carbon ions. For proton and carbon ion clinical beams, an under-response occurs at the Bragg peak. For carbon ions, we also observed an under-response of the EBT3 in the plateau of the depth-dose curve. This effect is the highest at the lowest initial energy of the clinical beams, a phenomenon related to the corresponding higher LET in the film sensitive layer. This behavior should be properly modeled when using EBT3 films for accurate 3D dosimetry.