Commissioning a newly developed treatment planning system, VQA Plan, for fast-raster scanning of carbon-ion beams.
Commissioning a newly developed treatment planning system, VQA Plan, for fast-raster scanning of carbon-ion beams.
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DOI：
10.1371/journal.pone.0268087
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发表时间：
2022
期刊：
影响因子：
3.7
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中科院分区：
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在这项研究中，我们报告了我们的经验，在调试一个商业治疗计划系统（TPS）的快速光栅扫描的碳离子束。该TPS使用分析剂量计算算法、具有用于横向剂量分布的三重高斯形式的双射束模型以及考虑介质中的横向异质性的射束分裂算法。采用混合束模型作为计算扫描碳离子束相对生物效应的模型。为了验证模型的物理剂量，我们比较了计算与测量的各种相关的量作为字段的大小，范围和宽度的扩展布拉格峰（SOBP），和深度剂量和横向剂量分布为6毫米SOBP在水中的函数。为了模拟生物剂量，我们将使用新开发的TPS计算的RBE与使用先前验证的TPS计算的RBE进行了比较，该TPS在临床使用中并使用相同的RBE模型概念。我们还进行了患者特异性测量，以验证临床情况下的剂量模型。物理束模型再现了测量的绝对剂量在SOBP的中心作为字段大小，范围和SOBP宽度的函数，并再现了在水中的6毫米SOBP的剂量分布。然而，为异质体模计算的配置文件在预测碳离子束剂量方面有一定的局限性，尽管生物剂量与经验证的TPS计算的值一致。使用这种剂量模型进行快速光栅扫描，我们从2018年10月到2020年10月成功治疗了900多名患者，TPS计算的剂量分布和测量的剂量分布之间具有可接受的一致性。我们的结论是，新开发的TPS可以在临床上使用的理解，它具有有限的准确性异质介质。
In this study, we report our experience in commissioning a commercial treatment planning system (TPS) for fast-raster scanning of carbon-ion beams. This TPS uses an analytical dose calculation algorithm, a pencil-beam model with a triple Gaussian form for the lateral-dose distribution, and a beam splitting algorithm to consider lateral heterogeneity in a medium. We adopted the mixed beam model as the relative biological effectiveness (RBE) model for calculating the RBE values of the scanned carbon-ion beam. To validate the modeled physical dose, we compared the calculations with measurements of various relevant quantities as functions of the field size, range and width of the spread-out Bragg peak (SOBP), and depth–dose and lateral-dose profiles for a 6-mm SOBP in water. To model the biological dose, we compared the RBE calculated with the newly developed TPS to the RBE calculated with a previously validated TPS that is in clinical use and uses the same RBE model concept. We also performed patient-specific measurements to validate the dose model in clinical situations. The physical beam model reproduces the measured absolute dose at the center of the SOBP as a function of field size, range, and SOBP width and reproduces the dose profiles for a 6-mm SOBP in water. However, the profiles calculated for a heterogeneous phantom have some limitations in predicting the carbon-ion-beam dose, although the biological doses agreed well with the values calculated by the validated TPS. Using this dose model for fast-raster scanning, we successfully treated more than 900 patients from October 2018 to October 2020, with an acceptable agreement between the TPS-calculated and measured dose distributions. We conclude that the newly developed TPS can be used clinically with the understanding that it has limited accuracies for heterogeneous media.