RESUMO
Objective To evalutate the accuracy of CyberKnife system and measure its relative output factor.Methods The accuracy of target localization of the system was measured with E2E test,film dosimetry,6D-skull tracking mode and fiducial tracking mode.Six kinds of detectors were used to detect the collimators of the system.Results The positioning errors were (0.531 ±0.293) and (0.482±0.297) mm respectively by 6D-skull tracking mode and fiducial tracking mode.The detectors proved the relative output factors of 5-mm collimator were 0.133 ±0.006,0.320±0.010,0.635 ±0.010,0.656±0.009,0.777± 0.013 and 0.680±0.014,and those of 35-mm collimator were 0.983±0.002,0.990±0.002,0.987±0.001,0.992±0.002,0.990± 0.010 and 0.981 ±0.010.Conclusion The total error of CyberKnife system was less than 1 mm.Large collimater has high consistencies between the output factors of the detectors,while there are significant differences between the output factors in case of the collimater with the diameter less than 15 mm.