Effects of spine tracking parameters on the positioning errors of cyberknife / 中华放射肿瘤学杂志

ABSTRACT

Objective To investigate the effects of spine region of interest (ROI),tracking range,and real-time image contrast ratio on the positioning errors of cyberknife.Methods The LTT dynamic phantom was used to develop a spine tracking plan and perform treatment,and the target positioning system was used to preset the phantom and obtain real-time preset image and positioning error.Based on the realtime preset image,spine ROI,tracking range,and real-time image contrast ratio were changed to observe the changes in positioning error and related parameters.Pearson correlation analysis was performed.Results The change in tracking range did not change the positioning error in spine tracking,and tracking range was not correlated with positioning error (R =0,P =1).The changes in ROI and image contrast ratio did not affect the translation error,but affected the rotation error,especially the rotation error in left-right direction (r =0.533 and 0.693,P=0.002 and 0.026).The image contrast ratio had the most obvious effect,with an amplitude of variation up to 2.2°.Conclusions The change in tracking range does not affect the positioning errors in spinal tracking,but the changes in ROI and image contrast ratio can cause varying degrees of changes in positioning errors,which should be taken seriously in cyberknife treatment.