A robotic 3-D motion simulator for enhanced accuracy in CyberKnife stereotactic radiosurgery

The purpose of this study was to develop a respiratory motion simulator and evaluate its accuracy. The simulator is intended for use in the CyberKnife radiosurgery suite for phantom treatments, dose verifications, and future technical developments. CyberKnife is a radiation treatment system that incorporates a robotic arm to precisely position a linear accelerator. For enhanced accuracy in the treatments of a tumor in an internal organ that is subject to a patient's respiratory motion, the CyberKnife robot must be commanded to move the radiation beam in real-time to compensate for such motion. The motion simulator described in this study was specifically developed to serve the CyberKnife technical requirements for better treatment accuracies. The motion simulator consists of two platforms that may be programmed independently to reproduce different three-dimensional (3-D) respiratory motions at both the skin over the patient's abdomen and at the internal tumor site. The simulator meets the spatial restrictions of the CyberKnife suite with a position accuracy better than ±0.1 mm.