Physical aspects of cobalt 60 teletherapy using wedge filters

Abstract

Wedge filters for use with a Picker C 3000 cobalt unit are described. Measurements were made of build-up, transverse field distributions, percentage depth doses, isodose curves and absolute dose-rates. The presence of a wedge filter does not appreciably alter build-up characteristics of the radiation. For a given wedge (i.e. a given field width) a single isodose chart suffices for all field lengths, within limits of [plus or minus] 5%.