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Program Information

Quality Assurance for GammaPod: A Novel Dedicated Breast Stereotactic Radiosurgery Device

S Becker

S Becker1*, Y Niu2 , Y Mutaf3 , K Prado1 , C Yu1,2 , B Yi1 , (1) Univ. of Maryland School Of Medicine, Baltimore, MD, (2) Xcision Medical Systems, Columbia, MD, (3) Boston University Medical Center, Boston, MA


SU-I-GPD-T-528 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: The GammaPod (Xcision Medical System) is a novel breast-specific stereotactic radiotherapy device that has been developed at the University of Maryland and is currently activated on clinical trial. GammaPod dynamically dose-paints the target by rotating 36 non-overlapping Co-60 beams while the patient is translated continuously in three axes on the couch during delivery. From simulation to treatment, the patient’s breast is immobilized using mild negative pressure (150 mmHg) through a device-specific dual cup system with stereotactic fiducials. The cup is secured to both the simulation and treatment tables functioning as a stereotactic frame. The objective of this study is to create a comprehensive quality assurance program for this device.

Methods: In the course of clinically implementing Gamma Pod (2016-2017), we have developed a quality assurance system comprising of daily, monthly, and annual tests. University of Maryland along with advice from Xcision Medical Systems broke down the systems of the machine and determined based off of relevant regulations and past AAPM guidance what should be tested and how often. This comprised of tests on the dosimetric, geometric, and safety systems.

Results: The daily QA comprises of output verification, table motion accuracy, and beam interrupt tests. This resulted in the creation of the PodScope to test these parameters. The monthly QA expands on the daily tests by testing the PodScope itself, checking the proper rotation of the collimator and therefore the profile of the beams, and tests on the pressure lock system. The annual QA completes the program by testing the dose linearity, table speed, a more expansive tests on table positioning and sag, the coincidence of the radiation and geometric isocenter, and a check of the dose profiles.

Conclusion: The University of Maryland has created a comprehensive QA for the GammaPod which will ensure that treatments are safe and reliable.

Funding Support, Disclosures, and Conflict of Interest: Dr Cedric Yu is the founder of Xcision Medical System, LLC

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