1131 - Performance of a Novel Frameless and Maskless Robotic Head Motion Compensation System for Stereotactic Radiosurgery in a Realistic Clinical Environment with Human Volunteers

08:30am - 08:35am PT

Room 160

Presenter(s)

Rodney Wiersma, PhD - University of California Los Angeles, Los Angeles, CA

X. Liu¹, A. Sakaamini², W. Gu², C. Denis³, M. Alonso-Basanta², and R. D. Wiersma¹; ¹Department of Radiation Oncology, UCLA, Los Angeles, CA, ²Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, ³CDR Systems Inc, Calgary, AB, Canada

Purpose/Objective(s):

Stereotactic radiosurgery (SRS) is a non-surgical technique used to treat functional abnormalities and small tumors of the brain. For the most accurate forms of SRS, a metal head ring is rigidly fixated to the patient’s skull using screws under local anesthesia, and then bolted to the treatment couch. The discomfort, inconvenience, and invasive nature associated with frame preparation have been identified as a serious cause of poor patient compliance and poor clinical efficiencies. Eliminating the frame using thermoplastic face masks have resulted in SRS with less accuracy as mask flex can lead to systematic drift away from the intended target. Additionally, it has been reported that many patients find the thermoplastic mask invasive and psychologically confining as it greatly restricts natural head motion. To address these issues, we report on a novel robotic head motion compensation (RHMC) device for SRS system that does not require a frame or mask.

Materials/Methods:

A compact RHMC device was built as a portable accessory that can be quickly attached and detached from the end of the Linac treatment table. Real-time 6D head position tracking was performed using 3D surface imaging that was inputted into the robot control computer. To mimic the actual SRS treatment environment, both phantom and a 20 human volunteer studies were performed for a virtual SRS treatment without use of the treatment beam.

Results:

Of the 20 volunteers enrolled 2 were excluded due to incompatibility with the RHMC device. For the remaining 18 volunteers, the RHMC system maintained head motion below a 1.0 mm and 0.5 degrees threshold 99% of the treatment time for a mock mid-brain lobe target, compared to 45% of the time without robotic compensation.

Conclusion:

The RHMC device was successfully demonstrated in a clinical environment for maintaining accurate head motion control. It has the potential to allow frameless and maskless SRS while still delivering frame-like accuracies.