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A Survey of IMRT QA Practices for More Than 800 Institutions

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K Pulliam

K Pulliam1*, J Kerns2 , R Howell3 , D Followill4 , J O'Daniel5 , S Kry6 , (1)(2)(3)(4)(6) UT MD Anderson Cancer Center, Houston, TX, (5) Duke University Medical Center, Durham, NC


MO-G-BRE-2 Monday 4:30PM - 6:00PM Room: Ballroom E

Purpose: A wide range of techniques and measurement devices are employed for IMRT QA, causing a large variation of accepted action limits and potential follow up for failing plans. Such procedures are not well established or accepted in the medical physics community. To achieve the goal of proving insight into current IMRT QA practices, we created an electronic IMRT QA survey. The survey was open to a variety of the most common QA devices and assessed the type of comparison to measurement, action limits, delivery methods, and clinical action for failing QA plans.

Methods: We conducted an online survey through the Radiological Physics Center’s (RPC) annual survey with the goal of ascertaining elements of routine patient-specific IMRT QA. A total of 874 institutions responded to the survey. The questions ranged from asking for action limits, dosimeter type(s) used, delivery techniques, and actions taken when a plan fails IMRT QA.

Results: The most common (52%) planar gamma criteria was 3%/3 mm with a 95% of pixels passing criteria. The most common QA device were diode arrays (48%). The most common first response to a plan failing QA was to re-measure at the same point the point dose (89%), second was to re-measure at a new point (13%), and third was to analyze the plan in relative instead of absolute mode (10%) (Does not add to 100% as not all institutions placed a response for each QA follow-up option). Some institutions, however, claimed that they had never observed a plan failure.

Conclusion: The survey provided insights into the way the community currently performs IMRT QA. This information will help in the push to standardize action limits among dosimeters.

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