Department of Radiotherapy Physics, Northern Centre for Cancer Care, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
Department of Radiotherapy Physics, Northern Centre for Cancer Care, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
Med Dosim. 2023;48(4):216-224. doi: 10.1016/j.meddos.2023.04.004. Epub 2023 May 8.
This work describes the experimental validation of the RadCalc (Lifeline software Inc, Tyler) collapsed cone dose calculation algorithm against measured data for a range of scenarios. 6 MV photon beam data were measured in a large water tank on a Varian TrueBeam linear accelerator. These were input into the RadCalc software, in conjunction with head geometry and output calibration information, then used to create a collapsed cone beam model. The model performance was assessed by comparison against measurement, using a selection of homogeneous and inhomogeneous geometries not incorporated into the original beam model. Dose calculations generated using the collapsed cone algorithm are generally in good agreement with measurement. However, the primary collimating of the linac is not accounted for in the RadCalc model and hence dose in the corners of large fields is significantly overestimated. Percentage depth doses were within 0.5% beyond a depth of 2 cm. The dose in the build-up region was underestimated by RadCalc Version 7.1.4.1, with (Distance To Agreement) discrepancies of up to 3 mm which were corrected in Version 7.2.2.0. Beam profiles for homogeneous phantom comparisons were within 2% in the central 80% of the field with out of field dose underestimated by no more than 3%. Dose comparisons in heterogeneous geometries were acceptable and generally within 3.5%. The largest observed differences were found at density interfaces and a result of the RadCalc dose resolution of 2 mm against 1 mm measured. Absolute dose comparisons demonstrated that RadCalc agreed with measurement to within 1.2% under homogeneous media irradiation geometries. For static beam IMRT deliveries agreement was within 2% or 2 mm of measured data, and for complex VMAT deliveries within 3% or 2 mm. The implementation of the (model-based) photon collapsed cone algorithm in RadCalc shows generally good agreement with measured data over a range of simple and complex scenarios considered.
这项工作描述了 RadCalc（Lifeline software Inc，Tyler）坍塌圆锥剂量计算算法的实验验证，针对各种情况的测量数据。在瓦里安 TrueBeam 直线加速器上的大水罐中测量了 6 MV 光子束数据。将这些数据输入 RadCalc 软件，结合头部几何形状和输出校准信息，然后用于创建坍塌圆锥束模型。通过与未包含在原始光束模型中的均质和非均质几何形状的选择进行比较，评估模型性能。使用坍塌圆锥算法生成的剂量计算通常与测量值非常吻合。然而，直线加速器的主要准直器未包含在 RadCalc 模型中，因此大野角的剂量被显著高估。在超过 2 厘米的深度，深度剂量百分比在 0.5%以内。RadCalc 版本 7.1.4.1 低估了建区剂量，（符合协议的距离）差异最大可达 3 毫米，在版本 7.2.2.0 中得到纠正。对于均匀体模比较的射束轮廓，在中央 80%的射野内，偏差在 2%以内，场外剂量的偏差不超过 3%。非均匀几何形状的剂量比较是可以接受的，通常在 3.5%以内。在密度界面处发现了最大的观察差异，这是由于 RadCalc 剂量分辨率为 2 毫米，而测量值为 1 毫米。绝对剂量比较表明，在均质介质辐照几何形状下，RadCalc 与测量值的一致性在 1.2%以内。对于静态射束 IMRT 输送，与测量数据的一致性在 2%或 2 毫米以内，对于复杂的 VMAT 输送，在 3%或 2 毫米以内。在考虑的一系列简单和复杂情况下，RadCalc 中基于模型的光子坍塌圆锥算法的实现与测量数据具有很好的一致性。
