Van Uytven E, Van Beek T, Chytyk K, McCurdy Bmc
CancerCare Manitoba, Winnipeg, Manitoba, Canada.
Nova Scotia Cancer Centre, Halifax, Nova Scotia, Canada.
Med Phys. 2012 Jul;39(7Part3):4634. doi: 10.1118/1.4740159.
As radiation treatment delivery becomes more complex, including dynamic IMRT and VMAT, the argument for routine patient dose verification becomes more compelling. This work demonstrates a technique that utilizes our pre-existing portal dose image prediction algorithm to compute 3D patient dose from recorded on-treatment portal images. This approach can be applied on CT simulation data or daily cone-beam CT data sets. Here we demonstrate the robustness of our dose reconstruction technique with phantom and patient examples, with delivery schemes including IMRT and VMAT. For an example prostate treatment site, 3D dose distributions reconstructed in the patient model are computed for each fraction, and DVHs presented. Results indicate that the patient dose reconstruction algorithm compares well with treatment planning system computed doses for controlled test situations. For patient examples the 3D chi comparison values (similar to the gamma comparison) ranged from 94.5% to 100% agreement for voxels > 10% maximum dose for all treatments and phantom cases. We show an example where the DVH for fraction nine of a prostate treatment fails acceptability criteria, due to a previously unnoticed positioning error. Future work involves building our patient dose reconstruction into a QA package, subsequently integrating it into a clinical workflow. We are also investigating the use of this tool as a backbone for an in-house adaptive radiotherapy implementation. This work is supported by Varian Medical Systems.
随着放射治疗的实施变得更加复杂，包括动态调强放疗（IMRT）和容积调强弧形放疗（VMAT），常规患者剂量验证的必要性变得更加迫切。这项工作展示了一种技术，该技术利用我们预先存在的射野剂量图像预测算法，根据记录的治疗中射野图像计算三维患者剂量。这种方法可应用于CT模拟数据或每日锥形束CT数据集。在这里，我们通过模体和患者实例展示了我们剂量重建技术的稳健性，治疗方案包括IMRT和VMAT。对于一个前列腺治疗部位的示例，在患者模型中重建的三维剂量分布针对每个分次进行计算，并给出剂量体积直方图（DVH）。结果表明，在受控测试情况下，患者剂量重建算法与治疗计划系统计算的剂量相比效果良好。对于患者实例，所有治疗和模体病例中，对于体素>最大剂量10%的情况，三维卡方比较值（类似于伽马比较）的一致性范围为94.5%至100%。我们展示了一个例子，由于之前未被注意到的定位误差，前列腺治疗第九分次的DVH不符合可接受标准。未来的工作包括将我们的患者剂量重建纳入质量保证（QA）软件包，随后将其整合到临床工作流程中。我们还在研究将该工具用作内部自适应放疗实施的基础。这项工作得到了瓦里安医疗系统公司的支持。
