National average for the process of radiation therapy in Japan by Patterns of Care Study.

Abstract

A nationwide effort is in progress to establish the actual state of radiotherapy and its quality assurance (QA) in Japan by using the Patterns of Care Study (PCS). In this study, national averages are calculated with a limited number of patients. A calculation program for national averages was prepared and applied to the radiotherapeutic processes used for esophageal cancer patients entered in the PCS. The calculation program for national averages, which were revised on the basis of differences between individual facilities and institutional strata, was developed in accordance with Sedransk's equation for the original PCS in the USA. National averages for several aspects concerning the sampled patients who had esophageal cancer between 1992 and 1994 were calculated with these procedures. Data for facilities and stratification of institution were simulated from a national structure survey of radiation oncology in 1990. Values of the national average by Sedransk's equation were different from those of the simple sample average. There were significant differences in radiotherapeutic processes among stratification of institutions. For esophageal cancer, national averages were 0.129 for applications of endoscopic ultrasound, 0.599 for 'all fields treated each day' and 0.088 for application of brachytherapy. National averages for radiotherapy could be calculated. The values obtained in this PCS will be a useful measure for future QA in radiation oncology and in other specialties in Japan.