Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

Objective: The purpose of this study was to evaluate spot scanning proton therapy with an anthropomorphic prostate phantom at the Proton Therapy Center of The University of Texas MD Anderson Cancer Center at Houston, TX (PTCH). Methods: An anthropomorphic prostate phantom from the Radiological Physics Center (RPC), The University of Texas MD Anderson Cancer Center, Houston, TX, was used, which contained thermoluminescent dosemeters and GAFCHROMIC (R) EBT2 film (ISP Technologies, Wayne, NJ). The phantom was irradiated by the Hitachi synchrotron (Hitachi America, Ltd, Tarrytown, NY), and the results were compared between the treatment planning system (TPS) and RPC measurements. Results: RPC results show that the right/left, inferior/superior and posterior/anterior aspects of the coronal/sagittal and EBT2 film measurements were within 67%/64mm of the TPS. The RPC thermoluminescent dosemeter measurements of the prostate and femoral heads were within 3% of the TPS. Conclusion: The RPC prostate phantom is a useful mechanism to evaluate spot scanning beam proton therapy within certain confidence levels. Advances in knowledge: The RPC anthropomorphic prostate phantom could be used to establish quality assurance of spot scanning proton beam for patients with prostate cancer.