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Beyond TG119: Providing Multiple Institutional Planning and Dosimetry Comparisons for Stereotactic Radiosurgery Commissioning

J Burmeister1*, R Culcasi2, G Baran3, M Dominello4, A Molineu5, S Benedict6, R Popple7, B Salter8, K Yenice9, (1) Karmanos Cancer Center / Wayne State University School of Medicine, Detroit, MI, (2) Karmanos Cancer Center / Wayne State University School of Medicine, Detroit, MI, (3) Karmanos Cancer Center, Detroit, MI, (4) Wayne State University School of Medicine, Detroit, MI, (5) UT MD Anderson Cancer Center, Houston, TX, (6) UC Davis Cancer Center, Sacramento, CA, (7) Univ Alabama Birmingham, Birmingham, AL, (8) University Utah, Salt Lake City, UT, (9) University of Chicago, Chicago, IL

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: Stereotactic radiosurgery (SRS) was historically delivered at a small number of facilities using specialized equipment and techniques. Today, more than half of radiotherapy facilities in the US are delivering SRS. Such rapid proliferation of a complex technique raises concerns regarding practitioner expertise, commissioning, and adherence to established quality assurance guidelines. The current widespread use of complex delivery techniques using conventional linacs, including single-isocenter multi-target VMAT, represents a significant increase in planning and delivery complexity and warrants additional attention. AAPM TG-119 facilitated a standardized approach to IMRT commissioning and evaluation, addressing the rapid implementation of IMRT and low pass rates on credentialing tests. We characterize the current state of SRS and advocate for a TG-119 equivalent test suite for SRS commissioning.


Methods: We evaluated SRS practice patterns in the US and results from Imaging and Radiation Oncology Core (IROC) SRS phantom irradiation to identify current shortcomings and/or needs related to commissioning and quality assurance in SRS.


Results: Over 1,000 facilities in the US currently deliver SRS. This number increased by 60% from 2004-2014 and currently includes nearly 500 dedicated SRS systems. The percentage of patients treated using linac-based SRS increased from 3% to >30% from 2003-2011 and continues to increase. In 2013, tolerances for the IROC SRS phantom became 5%(point dose), and 85% gamma pass(5%/3mm). From 2013-present, phantom pass rates are 83% and 93% for linac and Gamma Knife, respectively.


Conclusion: IROC SRS phantom results reveal a substantial fraction of facilities failing to meet relatively lenient dosimetric tolerances for a relatively simple target. Numerous high profile treatment deviations associated with SRS delivery have already occurred. We propose that a standardized SRS planning and dosimetry comparison, including a suite of complex and clinically relevant plans, would improve our ability to accurately deliver SRS, and potentially mitigate future quality and safety incidents.

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Keywords

Stereotactic Radiosurgery, Commissioning

Taxonomy

TH- External Beam- Photons: intracranial stereotactic/SBRT

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