Methods for routine calibration of brachytherapy sources.
- 1 February 1982
- journal article
- research article
- Published by Radiological Society of North America (RSNA) in Radiology
- Vol. 142 (2) , 511-515
- https://doi.org/10.1148/radiology.142.2.7054845
Abstract
Two types of routine geometry calibrators, the nuclear medicine dose calibrator and a Lucite jig holding a 30-ml external beam ion chamber with the source in a rigid geometry, were compared with open-air measurements for 137Cs, 192Ir and 226Ra brachytherapy sources. The proximity of scattering surfaces in the 2nd apparatus resulted in significant distortion of the buildup effect and deviation from the inverse square law (5-15%). For the dose calibrator, the response/Roentgen was dependent on source energy and source capsule thickness. Approximately 1/2 of the observed variation (27%) in calibration factors was accounted for by differences in filtration among sources. A mathematical logarithm that corrects for these geometric and filtration effects is presented. In addition, the activity assay procedure provided by the manufacturer of the dose calibrator is unsuitable for brachytherapy sources. Steps to overcome these problems are discussed.This publication has 2 references indexed in Scilit:
- Standardization of iridium-192 gamma-ray sources in terms of exposureJournal of Research of the National Bureau of Standards, 1980
- Standardization of cesium-137 gamma-ray sources in terms of exposure units (Roentgens)Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry, 1970