AbstractObjective To study the iso-center point coincidence of two accelerators with treatment planning system (TPS) based on γ passing rates of intensity-modulated radiotherapy (IMRT) plan verification. Methods Twenty-one IMRT plans were verified by Varian accelerator and twenty by Elekta accelerator with a gamma criterion of 3 mm/3%. The passing rates were measured when the iso-center point of TPS had -2,-1, 0, 1, and 2 mm shift in the x or y direction. A binomial curve of γ was fit to figure out the values of the two accelerators on the x and y axes when γ value reached the maximum. The γ pass rate difference was analysed by χ2 test. Results The mean values of γ-2,γ-1, γ0, γ1, and γ2 in the x direction were (92.56±3.27)%,(96.53±1.82)%,(96.13±1.41)%,(90.14±2.87)%, and (82.28±4.69)% for Varian accelerator, and (94.82±2.04)%,(97.05±2.02)%,(98.38±1.33)%,(97.96±1.44)%, and (94.49±2.34)% for Elekta accelerator. There was no significant difference in the mean value of γ0between the two accelerators (P=0.332). When γ value reached the maximum, the values on the x and y axes were-0.65 and-0.30 mm for Varian accelerator and 0.01 and 0.30 mm for Elekta accelerator, respectively. Conclusions In the same TPS, different accelerators have different degrees of coincidence of the actual field center point with the iso-center point of TPS, to which more attention should be paid in clinical practice.
Corresponding Authors:
Yang Bo,Email:yangbo_lz@163.com
Cite this article:
Sun Xiaoyang,Yang Bo,Pang Haowen et al. A study of the iso-center point coincidence between accelerator and radiotherapy planning system[J]. Chinese Journal of Radiation Oncology, 2016, 25(6): 625-627.
Sun Xiaoyang,Yang Bo,Pang Haowen et al. A study of the iso-center point coincidence between accelerator and radiotherapy planning system[J]. Chinese Journal of Radiation Oncology, 2016, 25(6): 625-627.
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2016, Vol. 25 
