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Evaluation of multi-leaf collimator performance of TrueBeam accelerator using high-resolution trajectory log files
Ma Yangguang1, Mai Rizhen2, Hu Jinyan1, Han Bin1, Jia Fei1, Xu Dandan1, Liu Shuaipeng1, Guo Yuexin1
1Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China; 2Department of Medical Equipment, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
AbstractObjective To evaluate the multi-leaf collimator (MLC) performance of TrueBeam accelerator using trajectory log files. Methods All tests were performed 5 times under different gantry-collimator angle combination. The 1 mm picket fences were constructed by static or dynamic MLC. The control ability for small-field accuracy of accelerator was evaluated. Repeatability was assessed by MLC repeat motion. The movement performance of difference velocities along one direction and the opposite direction were evaluated via a 1 cm picket fences which slipped from -7 cm to 7 cm with a uniform velocity and stopped or immediately back at 7 cm. The MLC performance in a complex program was evaluated by a cross movement test. Results Both the static and the dynamic picket fences yielded high accuracy. The deviation spectrums of MLC in different gantry angle were consistent, however, an absolute difference of 0.0011 mm was found. For uniform velocity movement tests with 0°gantry, the RMSE of MLC was increased from 0.0150 mm to 0.0598 mm when the speed was accelerated from 5 mm/s to 25 mm/s. Similar results were obtained in non-zero gantry angle. The “overspeed” effect caused by the direction change movement of MLC was less obvious than that caused by speed changed from zero to a uniform velocity movement state. There was no significant change in speed before and after the MLC crossing. The MLC speed fluctuated around the set value, which was independent of the gantry angle. Conclusion A method for evaluating the performance of MLC using trajectory log files is established, which can evaluate the MLC performance of TrueBeam accelerator and be used for MLC rapid quality control in clinical practice.
Fund:Henan Provincial Science and Technology Department Research Project (182102310369);Key Research and Development Project of Henan Colleges and Universities (19B416005)
Ma Yangguang,Mai Rizhen,Hu Jinyan et al. Evaluation of multi-leaf collimator performance of TrueBeam accelerator using high-resolution trajectory log files[J]. Chinese Journal of Radiation Oncology, 2020, 29(12): 1080-1085.
Ma Yangguang,Mai Rizhen,Hu Jinyan et al. Evaluation of multi-leaf collimator performance of TrueBeam accelerator using high-resolution trajectory log files[J]. Chinese Journal of Radiation Oncology, 2020, 29(12): 1080-1085.
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2020, Vol. 29 
