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Program Information

The Radiological Physics Center (RPC): 45 Years of Improving Radiotherapy Dosimetry

D Followill

D Followill*, J Lowenstein , A Molineu , P Alvarez , P Summers , S Kry , UT MD Anderson Cancer Center, Houston, TX


SU-C-BRD-7 Sunday 1:00PM - 1:55PM Room: Ballroom D

Purpose:The RPC, established in 1968 has contributed to the development, conduct, and QA of NCI funded multi-institutional cooperative group clinical trials and institutions, primarily in the USA/Canada and 242 other countries, participating in trials.

Methods:The RPC QA program components were designed to audit the radiation dose calculation chain from the NIST traceable reference beam calibration, to inclusion of dosimetry parameters used to calculate tumor doses, to the delivery of the radiation dose. The QA program included: 1) remote TLD/OSLD audit of machine output, 2) on-site dosimetry review visits, 3) credentialing for advanced technologies, and 4) review of patient treatment records. The RPC presented and published their findings to the radiation oncology community.

Results:The number of institutions monitored by the RPC increased from around 1200 in the late 90s, to ~2000 in 2013. There were over 4000 megavoltage therapy machines and ~28,000 therapy beams in the 1991 institutions monitored by the RPC by the end of 2013. Within the 14,000 photon, electron and proton beam outputs remotely monitored with TLD/OSLD annually, between 10-20% of the institutions have one or more beams outside the RPC 5% criterion. Dosimetry site visits to photon and proton centers continue to result in 2-4 recommendations affecting key dosimetry parameters that impact patient treatment times. One in four patient treatment records reviewed by the RPC have their dose data corrected by >5% before trial groups use them for outcomes analysis. Twelve of fourteen clinically active proton centers are approved to participate in NCI funded clinical trials. The RPC published 222 peer reviewed articles since 1972.

Conclusion:Findings from the RPC suggest that human errors continue to play a role in radiotherapy discrepancies and without the RPC independent QA program, the number of undetected errors and time elapsed before their discovery would have been greater.

Funding Support, Disclosures, and Conflict of Interest: Work supported by MGH C06 CA059267 and grants CA10953, CA081647 awarded by NCI, DHHS.

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