AAMD 2024
The Correlation of Modulation, QA Pass Rate and Delivery Time for SBRT Treatments
There is a long-standing idea that QA plan analysis failure can be directly correlated to the modulation of the plan itself. But often, this is communicated to the planner by a physicist with little more than anecdotal evidence to support the claim. Planners are frequently put in a position where they are asked to replan cases due to QA failures without direct guidance as to how to change the plan and what an acceptable amount of modulation will be needed to create a passable QA plan. Our hope was to investigate the correlation between modulation (as defined by MU/dose for a given field) and the QA pass rate using 2%2mm and 3%3mm gamma criteria.
Also, because modulation is often thought to be related to delivery efficiency, the estimated delivery time for each beam, as stated in the optimization console in the planning system, was also compared to the actual delivery time. This was done in the hopes that cases where beam-on time mattered most (breath-hold, patients under sedation, etc.) could be prospectively analyzed, and assuming a low correlation of pass rate to modulation, the lowest possible beam-on-time could be prioritized, with less regard to possible QA failures.
Learner Outcomes
- identify which planning parameters and metrics influence the QA pass rate
- correlate estimated with actual delivery time
- Explain the relative importance of Plan Modulation on patient experience
CE credit = 1.0
Matthew Goss, DABR
Senior Medical Physicist
Allegheny Health Network
Prior to joining Allegheny Health Network in 2018 as senior medical physicist, Mr. Goss gained valuable experience by working for RadAmerica, LLC for four years as a clinical physicist and then at Memorial Sloan Kettering Cancer Center for seven years in the external beam treatment planning division. Matthew is a member of the board of trustees of the Radiating Hope Foundation, a nonprofit organization dedicated to providing access to radiation cancer care in developing and underserved areas around the world. He enjoys traveling, mountaineering, playing rugby, home-brewing, and restoring (extremely) old automobiles. He is the former president of the Duke Medical Physics Alumni Association, and the Associate Program Director for the Allegheny Health Network Medical Physics Residency Program.
Mr. Goss received his MS from Duke University as part of the first class to graduate from the medical physics program. His clinical training was completed at both Duke University and Brigham and Women’s Hospital/Dana Farber Cancer Center. He is board-certified in Therapeutic Radiological Physics by the American Board of Radiology (DABR) and holds a NY State license for Medical Therapeutic Physics.
Danielle Waters, CMD, RT(T)
Dosimetrist
Allegheny Health Network
Danielle Waters, CMD, RT(T), is a senior dosimetrist at AHN. She began as a therapist in 1994 and has been a Dosimetrist since 2007. She specializes in SBRT Lung, Prostate and Breast Planning and is the dosimetry liaison to the medical physics residency program.
Ryan Turner, MS
Medical Physics Resident
Allegheny Health Network
Ryan Turner, MS, is a first-year medical physics resident in the Allegheny Health Network (AHN). His graduate school practicum involved commissioning a 6 MV FFF beam. His interests include brachytherapy, particle therapy, SBRT, and MR-guided radiotherapy. He is a member of the American Association of Physicists in Medicine.
Ryan received his undergraduate degree in Chemistry from Rutgers University. His Master’s studies were completed at Vanderbilt University in Medical Physics.
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