Size and positioning reproducibility of an 192 Ir brachytherapy stepping source

In this paper we describe techniques for measuring the dimensions and position reproducibility of an 192 Ir brachytherapy stepping source. Measurements were carried out using a 0.25×10×152 mm3 collimator placed in front of a detector of our own design. The brachytherapy source was translated past the collimator in 0.025 mm increments using a stepper motor. The source was found to be 3.58 mm long and 0.69 mm wide, which is in good agreement with the manufacturer’s values of 3.5×0.6 mm2. The source position was reproducible to within 0.12 mm.