Quality assurance of radiotherapy and its clinical assessment

Background: We investigated the clinical quality assurance (QA) of radiotherapy in Japan since 1981. The aim of this study was to establish the QA of a radiotherapy system and its clinical assessment in Japan. Methods: We introduced the Patterns of Care Study (PCS) into Japan to perform this study in 1996. The PCS is a retrospective study designed to establish the national practice for cancer patients during a specific period and should be a complementary study to a prospective randomized controlled study. We collected precise data for 4399 patients with carcinomas of the breast, cervix, esophagus, lung and prostate by means of external audits for 96 institutes from 1998 through 2001. Patients were randomly sampled with two-stage cluster sampling. We stratified 556 institutes into four categories according to the academic condition and annual number of radiotherapy patients. National and regional averages of various factors of radiotherapy could be calculated and were used to measure QA of radiotherapy. Results: Using a standard score, we could compare the process of individual institutions with national averages and feed back the evaluation score to each institution. With a PCS process survey, we could observe the dissemination of the treatment method under evidence-based medicine from the prospective randomized controlled study. We proposed future prediction of the number of radiotherapy patients and a counter plan for equipment and personnel. The first US–Japan PCS Workshop was held at San Francisco in 2001. Conclusion: We could establish QA of a radiotherapy system using PCS 1995–97 in Japan.