title: In-phantom calibration of Selectron-LDR sources.
abstract: Source strength measurements were performed for cesium-137 spherical sources of nine Selectron-LDR remote afterloading systems in The Netherlands. The mean reference air kerma rate of a set of sources was obtained from air kerma rate measurements in a phantom at a distance of about 5.5 cm from a large number (24 to 30) of sources. The results were compared with the source strengths specified by the manufacturer. Discrepancies between measured and manufacturers data ranging from -2.3% to +3.9% were observed. The frequency distribution of the strength of the sources within a set was measured by the use of a well-type ionisation chamber. The root mean square deviations of the nine source sets ranged from 1.0 to 3.2%. Application of the in-phantom calibration method would improve the precision of source strength measurements and therefore reduce the differences in dose delivery between institutes. The uncertainty of the in-phantom method, which could be estimated by statistical methods, was 0.3% (one standard deviation). That part of the uncertainty, which could not be evaluated by statistical methods, was estimated to be about 1.2% (one effective standard deviation). This latter part in the uncertainty needs further investigation in order to reduce the overall uncertainty.
authors.affiliation: Netherlands Cancer Institute, Amsterdam.
authors.forename: H
authors.initials: H
authors.lastname: Meertens
mesh_terms: D001918:Brachytherapy / Q000379:methods* / Q000592:standards; D002138:Calibration; D002588:Cesium Radioisotopes / Q000627:therapeutic use; D006801:Humans; D008433:Mathematics; D008961:Models, Structural
chemical_list: D002588:Cesium Radioisotopes