Dose delivery accuracy of advanced radiotherapy: 30 years of end-to-end dosimetry audits.

Abstract

The MD Anderson Radiation Quality Assurance Lab (including its IROC activities) monitors more than 2500 radiotherapy facilities worldwide to ensure accurate radiotherapy delivery. This study reviews the 30-year history of the RQALab's anthropomorphic phantom program for advanced photon therapy. The RQALab offers anthropomorphic phantoms as end-to-end tests of the accuracy of advanced radiotherapy. Phantoms are mailed to the institution where they are treated like a patient, including planning and delivery, and are returned to the RQALab for analysis. Several types of phantoms exist that test IMRT, motion management, SBRT, SRS, multi-target delivery, and more. Institutions may perform this audit as an internal quality assurance test or as a credentialing requirement to participate in clinical trials. Passing criteria typically require the dose to be within 5-7% and 3-4 mm. A total of 9,879 photon phantoms have been irradiated since 1996, most frequently the IMRT H&N phantom (3,429), moving lung phantom (2,788), and SRS phantom (1,898). Overall, the average pass rate is 86.4%, with the highest pass rate seen for the IMRT H&N phantom (89%) and the lowest pass rate seen for the moving multi-target liver phantom (73%). Overall, pass rates have significantly increased with time, which is particularly noteworthy because treatments have gotten more complex over this time period. Independent audits of radiotherapy practice continue to highlight challenges in implementing advanced radiotherapy. As such, they serve an important role in the community, helping guide individual clinics and the community at large, to achieve best practice.