Calibration Procedures For Remote Afterloading Selectron (LDR) Unit

Remote afterloading machines provide a viable alternate to manual afterloading for brachytherapy, in view of increased radiation safety and of selective source positioning for the given application geometry. Quality assurance program for these machines are essential in terms of accurate dose delivery. As a part of this program, output calibration is to be carried out in a precise manner to evaluate the effective activity of the source being used. In our centre, this is carried out in terms of activity, with Nucletron Source Dosimetry System (NSDS) and in terms of air kerma rate with an air kerma calibrated dosimeter, using a 0.6 cc ion chamber. The effective activity thus arrived at is comparable with the quoted activity by the source manufacturer. This paper describes the calibration procedure for Selectron LDR remote afterloading system.