SU-E-T-199: The Radiological Physics Center's Credentialing Dosimetry Reviews: Their Effect on Clinical Trial...

To describe the Radiological Physics Center's (RPC) methods to evaluate an institution's ability to meet protocol guidelines in order to decrease NCI clinical trial deviation rate.

The RPC's dosimetry group utilizes 3 methods of assessing an institutions ability to meet the protocol treatment specifications. These methods involve a clinical and dosimetric review of a treatment plan submitted by the institution prior to the first patient being treated on a protocol. The three evaluation methods include use of site/treatment modality specific benchmark cases, evaluation of a previous patient treated in a similar fashion and a rapid review of the first patient placed on a trial prior to start of treatment. The dosimetric review consists of an independent dose recalculation using RPC measured data or RPC standard dosimetry data. The clinical review assesses the patient's DVHs and contouring of the tumor volume and critical structures, typically in conjunction with a radiation oncologist.

Over the past 5 years the RPC has performed these QA reviews for several of the clinical trial groups for several different disease sites and treatment modalities. We have reviewed 1366 treatment plans as a part of credentialing (97 gynecological, 223 prostate, 1046 breast) where 222 failed the first submission requiring the RPC to interact with the submitting institution to resolve the discrepancy. The review of the benchmarks has resulted in 18% of the institutions requiring intervention by the RPC. Performing these reviews has identified potential clinical and dosimetric problem areas that could possibly have resulted in 17% of the charts reviewed to receive a minor or major deviation.

The RPC's clinical and dosimetry review of submitted treatment plans before or early in the treatment process has helped to reduce the deviation rates on protocols. Work supported by PHS grant CA 10953 awarded by NCI, DHHS.