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A simple quality assurance method to check dwell times in high dose rate (HDR) remote after loading intracavitary applications


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Abstract

Calculated dwell times for approved treatment plans are usually uploaded from treatment planning system (TPS) to the control console of remote after loading High Dose Rate (HDR) brachytherapy machines for treatment execution. These TPS dwell times needs validation, also to check correctness of applications. In the event of image transfer problems, the patients’ treatment cannot be cancelled, when they are on a fixed protocol of treatments. An attempt was made to arrive at ‘dwell times’ by manually calculated tables.
 
Published Monte-Carlo doserate table for single HDR Iridium-192 source from Ir-192 source manufacturers were referred. By a manual method, contributions of doses for Manchester Points A and B from Intra-Uterine (IU) tandem and Intra-vaginal (IV) ovoids, for standard irradiation geometry are generated. To validate the use of these tables, the dwell times of retrospective patient records in the department were verified.
 
Manually calculated dwell times for intra-cavitary treatments for different combinations of dwell positions are found to be accurate within a mean deviation ±5% for the treatments. This method will help in busy radiotherapy departments for rapid check of dwell times obtained from TPS, before executing treatments.

Keywords

high dose rate brachytherapy, dwell times, remote afterloading, quality assurance

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