Abstract：Objective To explore the application of the electronic portal imaging device (EPID) to test on MLC leaves position accuracy instead of EBT3 film, and the feasibility analysis under any gantry angle. Methods RIT113 software was used to analyze the image data of radiochromic film EBT3 and EPID of Siemens ARTISTE accelerator. The replacement process from EBT3 film to EPID for the test MLC leaves positioning was completed by defining the positions of 50% isodose curve of the field edge of EBT3 after radiation as the actual positions of MLC leaves, therefore finding out the percentage isodose value of the same position in the EPID portal imaging from the corresponding radiation field. Results When the accelerator gantry angle was 0, the mean percentage isodose value was 44% at the MLC leaves positions determined by EBT3, and the maximum position error of MLC leaves is 0.12 mm. When the accelerator gantry was any other angles, the results were compared with the zero angle situation through DTA, all of the points passed when the DTA radium was 0.5 mm. Conclusions Using EPID instead of EBT3 to do the test MLC leaves positioning is feasible, furthermore, it is suitable under any gantry angle with excellent accuracy for the clinical practive, which deserves to be widely spread.
Cao Zheng*,Li Hongxia,Bao Yangyi et al. The study of electronic portal imaging devices for the position accuracy of multi-leaf collimator instead of the film[J]. Chinese Journal of Radiation Oncology, 2015, 24(5): 573-574.
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