Department of Radiation Oncology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Department of Oncology, The Affiliated Lianyungang Hospital of Xuzhou Medical University, Lianyungang, China.
Technol Cancer Res Treat. 2021 Jan-Dec;20:15330338211011964. doi: 10.1177/15330338211011964.
To evaluate the dosimetric accuracy of the default couch model of the QFix kVue Calypso couch top in the treatment planning system.
With the gantry 180°, field size 20 × 20 cm, 6 MV, we measured the depth dose, off-axis dose, and dose plane of different depths in the phantom with the couch rails in and out, respectively. Isocenter doses at different angles were also obtained. The results were compared to the doses calculated using the default couch top model and the real scanned couch top model. Then we revised the default model according to the measured results.
With "Rails In," the depth dose, off-axis dose, and dose plane of the default couch top model had a big difference with the dose of the real scanned couch top model and the measured result. The dose of the real scanned couch top model was much closer to the measured result, but in the region of the rail edge, the difference was still significant. With "Rails Out," there was a minor difference between the measured result, the dose of the default couch top model and the real scanned couch top model. The difference between the measurement and the default couch top model became very small after being revised.
It is better to avoid the beam angle passing through the couch rails in treatment plans, or you should revise the parameter of the QFix kVue Calypso couch top model based on the measured results, and verify the treatment plan before clinical practice.
评估 QFix kVue Calypso 治疗床顶部默认床模型在治疗计划系统中的剂量学准确性。
在机架 180°、射野大小为 20×20cm、6MV 条件下，我们分别测量了有和无治疗床轨的情况下模体中的深度剂量、离轴剂量和不同深度的剂量平面，以及不同角度的等中心剂量。将结果与使用默认床顶模型和实际扫描床顶模型计算的剂量进行比较。然后，根据测量结果对默认模型进行了修正。
在“轨内”状态下，默认床顶模型的深度剂量、离轴剂量和剂量平面与实际扫描床顶模型和测量结果的剂量有很大差异。实际扫描床顶模型的剂量更接近测量结果，但在轨道边缘区域，差异仍然显著。在“轨外”状态下，测量结果、默认床顶模型和实际扫描床顶模型的剂量之间存在较小差异。经过修正后，测量值与默认床顶模型之间的差异变得非常小。
在治疗计划中应尽量避免束流角度穿过治疗床轨，或者应根据测量结果修正 QFix kVue Calypso 治疗床顶模型的参数，并在临床实践前验证治疗计划。
