Verification of the range calculation accuracy of a commercial proton treatment planning system
Sun Xiangshang1,2, Pu Yuehu3, Liao Wentao1,2, Kong Haiyun1, Chen Mei4, Wu Chao5, Yan Nan1,2, An Chaofan1,2, Liu Junya1,2
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; 2University of Chinese Academy of Sciences, Beijing 100049, China; 3Medical Equipment Innovation Research Center, West China Hospital, Sichuan University, Chengdu 610041, China; 4Department of Radiotherapy, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200025, China; 5Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
Abstract：Objective In Shanghai Advanced Proton Therapy Facility (SAPT) of Ruijin Hospital Proton Therapy Center, the calculation accuracy of the commercial proton treatment planning system RayStation (V10), especially the accuracy of the proton range calculation, was measured and verified, aiming to provide reference for the clinical application of the treatment planning system. Methods A head phantom was used to verify the calculation accuracy of RayStation. The phantom CT was imported into treatment planning system (TPS). The phantom was followed closely by a water tank with a one-liter cubic target. A single field verification plan with the prescribed dose of 200 cGy (relative biological effectiveness) was designed and implemented. Then, the measured distribution results were compared with the calculation results. Results When the verification plan of the phantom was designed with the default settings of RayStation, the measured longitudinal dose distribution was approximately 4 mm deeper than that of TPS, indicating that RayStation overestimated the water equivalent thickness (WET) of the tissue substitute materials in the phantom. To study the range error, the actual beam was used to measure the WET of the soft tissue substitute material. The default setting of RayStation was fine-tuned according to the measured results. It was found that the error between the measured SOBP and TPS calculations was reduced to only 2 mm. Conclusions Using the default setting of RayStation to calculate the stopping power of the phantom may cause a large range error. A method that combines tissue segmentation with the measured WET of the tissue substitute material is proposed to improve the range calculation accuracy of the TPS. The results show that the proposed method can improve the dose and range accuracy of the commercial TPS including RayStation for tissue substitute materials.
Sun Xiangshang,Pu Yuehu,Liao Wentao et al. Verification of the range calculation accuracy of a commercial proton treatment planning system[J]. Chinese Journal of Radiation Oncology, 2022, 31(11): 1028-1033.
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