Radiation therapy dosimetry reviews by the centers for radiological physics

Six Centers for Radiological Physics (CRP) have performed over 250 dosimetric site reviews at institutions participating in the Division of Cancer Control and Rehabilitation therapy networks and/or as affiliates in Oncology Group Clinical trials. For the initial site visits, institution stated output calibration was within ±3% of that measured by the CRPs for 87 % of the therapy machines reviewed. The accuracy of methods utilized in calculating tumor dose were assessed by using a set of reference cases of varying complexity. At the time of the first visit, 90% of the calculated doses for these reference cases were within ±5% of that prescribed by the CRPs. Other parameters, important for the accurate delivery of prescribed dose, were also checked as part of the review protocol. Many institutions have received multiple reviews and a significant reduction in the variance of machine calibration and calculated tumor dose for the reference cases is evident.