Raj Sathiya, Shree Nithya, Ganesh K M
Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, India.
Rep Pract Oncol Radiother. 2024 Jul 22;29(3):357-361. doi: 10.5603/rpor.101095. eCollection 2024.
EBT-XD film specially designed for high dose verifications such as stereotactic treatments. The dose response of the film can be affected by several factors, the curly nature of the film being one of them. In this study this curly nature of the film was investigated for stereotactic body radiotherapy (SBRT) plan verifications.
For this study, 18 SBRT (11 prostate, 3 spines, and 4 lungs) cases were enrolled. For all the cases, VMAT plans were created in the Monaco treatment planning system and plan was delivered in Elekta Versa HD linear accelerator and delivered fluence was captured by EBT-XD films. All films were scanned with and without a compression plate. All the films were analyzed using the single-channel film method using the red channel.
A significant difference in the gamma passing rates (GPR) for the films scanned with and without the compression plate was observed. The maximum percentage differences in GPR between using and not using a compression plate were 12.7% for 1% 1 mm, 8.1% for 2% 2 mm, 7.5% for 3% 2 mm, and 5% for 3% 3mm criteria. Similarly, the mean %difference in GPR was 5.8% for 1% 1 mm, 2.4% for 2% 2 mm, 1.6% for 3% 2 mm and 0.96% for 3% 3 mm criteria.
The results suggest that placing a compression plate over the film during scanning provided a great advantage in achieving a more accurate gamma passing rate irrespective of gamma criteria.
EBT-XD 胶片是专门为立体定向治疗等高剂量验证而设计的。胶片的剂量响应会受到多种因素的影响，胶片的卷曲特性就是其中之一。在本研究中，针对立体定向体部放射治疗（SBRT）计划验证对胶片的这种卷曲特性进行了研究。
本研究纳入了 18 例 SBRT 病例（11 例前列腺癌、3 例脊柱和 4 例肺癌）。对于所有病例，在 Monaco 治疗计划系统中创建容积调强弧形治疗（VMAT）计划，并在 Elekta Versa HD 直线加速器中实施计划，EBT-XD 胶片捕获实施的注量。所有胶片在有和没有压板的情况下进行扫描。所有胶片均使用单通道胶片法通过红色通道进行分析。
观察到有和没有压板扫描的胶片在伽马通过率（GPR）上存在显著差异。对于 1% 1mm、2% 2mm、3% 2mm 和 3% 3mm 标准，使用和不使用压板时 GPR 的最大百分比差异分别为 12.7%、8.1%、7.5%和 5%。同样，对于 1% 1mm、2% 2mm、3% 2mm 和 3% 3mm 标准，GPR 的平均百分比差异分别为 5.8%、2.4%、1.6%和 0.96%。
结果表明，在扫描过程中在胶片上方放置压板无论伽马标准如何，在实现更准确的伽马通过率方面都具有很大优势。
