Evaluation of Real-time Target Positioning Accuracy in Spinal Radiosurgery

Lee, Dong Joon

Abstract

Stereotactic Radiosurgery require high accuracy and precision of patient positioning and target localization. We evaluate the real time positioning accuracy of isocenter using optic guided patient positioning system, ExacTrac (BrainLab, Germany), during spinal radiosurgery procedure. The system is based on real time detect multiple body markers attached on the selected patient skin landmarks. And a custom designed patient positioning verification tool (PPVT) was used to check the patient alignment and correct the patient repositioning before radiosurgery. In this study, We investigate the selected 8 metastatic spinal tumor cases. All type of tumors commonly closed to thoracic spinal code. To evaluate the isocenter positioning, real time patient alignment and positioning monitoring was carried out for comparing the current 3-dimensional position of markers with those of an initial reference positions. For a selected patient case, we have check the isocenter positioning per every 20 millisecond for 45 seconds during spinal radiosurgery. In this study, real time average isocenter positioning translation were 0.07+/-0.17 mm, 0.11+/-0.18 mm, 0.13+/-0.26 mm, and 0.20+/-0.37 mm in the x (lateral), y (longitudinal), z (vertical) directions and mean spatial error, respectively. And body rotations were 0.14+/-0.07degrees, 0.11+/-0.07degrees, 0.03+/-0.04degrees in longitudinal, lateral, table directions and mean body rotation 0.20+/-0.11degrees, respectively. In this study, the maximum mean deviation of real time isocenter positioning translation during spinal radiosurgery was acceptable accuracy clinically.