Abstract：Objective To validate the accuracy of physical model of in-vivo 3D dose verification based on electronic portal imaging device (EPID) using the phantom and preliminarily analyze the clinical application. Methods Two phantoms (uniform and non-uniform phantoms) were involved in this study. The system of in-vivo 3D dose verification based on EPID was employed to acquire the images of square fields (SF) and combined fields of intensity-modulated radiotherapy (CFIMRT). The physical model of different media was constructed using the system. The factor of γ passing rate under different dose/distance criteria was statistically compared. For clinical cases, the dose-volume histograms were adopted to analyze the dose distribution of target volume and organs at risk (OARs). Results For the SF in the uniform phantom, the average γ passing rate (3%/3mm) was (97.49±1.11)%, and (94.06±5.11)% for the SF in the non-uniform phantom (P>0.05). No statistical significance was noted in IMRT using different delivery methods (all P>0.05). For clinical cases, the average γ passing rate (3%/2mm) was (97.96±1.84)% in the pre-treatment dose verification, and (90.51±6.96)%(3%/3mm) for the in-vivo 3D dose verification. For clinical cases, significant dose deviation was observed in OARs with small size and large volume changes. Conclusion The in-vivo 3D dose verification model based on EPID can be effectively applied in inter-fraction dose verification, providing technical support for adaptive radiotherapy in clinical practice.
Mao Ronghu,Guo Wei,Li Bing et al. Preliminary study of physical model test and clinical application based on EPID-based in-vivo dose verification system[J]. Chinese Journal of Radiation Oncology, 2021, 30(10): 1065-1070.
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