Program Information
Towards Frameless Maskless SRS Through Real-Time 6DOF Robotic Head Motion Stabilization
AH Belcher*, X Liu , S Chmura , K Yenice , RD Wiersma , The University of Chicago, Chicago, IL
Presentations
MO-DE-FS1-11 (Monday, July 31, 2017) 1:45 PM - 3:45 PM Room: Four Seasons 1
Purpose: Stereotactic radiosurgery (SRS) uses precise dose placement to treat conditions of the CNS. Frame-based SRS uses a metal head ring fixed to the patient’s skull to provide high treatment accuracy, but patient comfort and clinical workflow may suffer. Frameless SRS, while potentially more convenient, may increase uncertainty of treatment accuracy and be physiologically confining to some patients. By incorporating highly precise robotics and advanced software algorithms into SRS treatments, we present a novel frameless and maskless SRS system where a robot provides real-time 6DOF head motion stabilization allowing positional accuracies to match or exceed those of traditional frame-based SRS.
Methods: A 6DOF parallel kinematics robot was developed and integrated with a real-time infrared camera in a closed loop configuration. A novel compensation algorithm was developed based on an iterative closest-path correction approach. The robotic SRS system was tested on six volunteers, whose motion was monitored and compensated for in real-time over 15-minute simulated treatments. The system’s effectiveness in maintaining the target’s 6DOF position within preset thresholds was determined by comparing volunteer head motion with and without compensation.
Results: Comparing corrected and uncorrected motion, the 6DOF robotic system showed an overall improvement of 2100% in terms of maintaining target position duty cycle within 0.5 mm and 0.5 degree thresholds. Although the system’s effectiveness varied among the volunteers examined, for all volunteers tested the target position remained within the preset tolerances 99.0% of the time when robotic stabilization was used, compared to 4.7% without robotic stabilization.
Conclusion: The pre-clinical robotic SRS compensation system was found to be effective at responding to sub-millimeter and sub-degree cranial motions for all volunteers examined. The system’s success with volunteers has demonstrated its capability for implementation with frameless and maskless SRS treatments, potentially able to achieve the same or better treatment accuracies than frame-based approaches.
Funding Support, Disclosures, and Conflict of Interest: This work was funded in part by the National Institutes of Health T32-EB002103 Training Grant from the National Institute of Biomedical Imaging and Bioengineering, and by American Cancer Society grant RSG-13-313-01-CCE. Volunteers were recruited on IRB 14-0040.
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