Determination of Ir-192 micrselectron-V2 HDR/PDR dwell position reproducibility using a slit camera.

ABSTRACT

PURPOSE: To examine the limits of dwell position reproducibility of an ELEKTA microSelectron-V2 HDR/PDR remote afterloader. METHODS AND MATERIALS The variability in source dwell position of an ELEKTA Microselectron mHDR - V2 HDR/PDR Microselectron was assessed using a slit camera. 100 consecutive extensions each of the source were made to positions of 1200 mm and 1470 mm and the variations in dwell position were observed. RESULTS: Maximum deviations of 0.4 mm from the median dwell position were observed. 72% of all deviations from median dwell position were 0.15 mm or less while 96% were no greater than 0.3 mm. CONCLUSION: Guide wire flexibility makes buckling over the length of source extension an unavoidable reality which, in turn, produces variability in the dwell position achieved. Fortunately these deviations in source dwell position are small and may be compensated for using margins along the dose distribution length.