Purpose: Medical device performance checks are essential following changes to control system software. This work investigates the effects of new software on the performance of a high dose rate (HDR) brachytherapy treatment unit.

Methods and Materials: A performance assessment was undertaken of the Eckert & Ziegler BEBIG GmbH MultiSource® HDR treatment unit following software upgrade. Video recordings of source transits were used to calculate transit doses, and autoradiography used to measure source dwell positions. Results were compared to a previous study.1

Results: All results showed improved performance with the new compared to old control software. Optimal source movement profiles were observed with maximum transit speeds of 63 (+/−4) mm s−1 between dwells of 5.0 mm separation. The maximum error in transit dose correction with the new software was 2.5 % at 10.0 mm perpendicular from the source axis, compared to 5.6 % previously. The new software eliminated a causal relationship between curvature of the source transfer tubes and dwell position uncertainty.

Conclusions: This work demonstrates the need for comprehensive medical device system checks following software changes. Technical improvements in HDR device performance have been achieved with the new software; reducing transit doses, improving transit dose correction, and improving source positioning accuracy.