Estimate of the real-time respiratory simulation system in CyberKnife image-guided radiosurgery

The purpose of this study was to evaluate the target accuracy according to the movement with respiration of an actual patient in a quantitative way by developing a real-time respiratory simulation system (RRSS), including a patient customized 3D moving phantom. The real-time respiratory simulation system (RRSS) consists of two robots in order to implement both the movement of body surfaces and the movement of internal organs caused by respiration. The quantitative evaluation for the 3D movement of the RRSS was performed using a real-time laser displacement sensor for each axis. The average difference in the static movement of the RRSS was about 0.01 ∼ 0.06 mm. Also, in the evaluation of the dynamic movement by producing a formalized sine wave with the phase of four seconds per cycle, the difference between the measured and the calculated values for each cycle length in the robot that was in charge of body surfaces and the robot that was in charge of the movement of internal tumors showed 0.10 ∼ 0.55 seconds, and the correlation coefficients between the calculated and the measured values were 0.998 ∼ 0.999. The differences between the maximum and the minimum amplitudes were 0.01 ∼ 0.06 mm, and the reproducibility was within ±0.5 mm. In the case of the application and non-application of respiration, the target errors were 0.05 ∼ 1.05 mm and 0.13 ∼ 0.74 mm, respectively, and the entire target errors were 1.30 mm and 0.79 mm, respectively. Based on the accuracy in the RRSS system, various respiration patterns of patients can be reproduced in real-time. Also, this system can be used as an optimal tool for applying patient customized accuracy management in image-guided radiosurgery.