Development of a Prototype Intraoperative Safety Device for HDR Brachytherapy Channel Verification
Abstract
Purpose
Modern brachytherapy afterloaders have a capacity of up to 50 channels for complex high dose rate (HDR) treatments. For interstitial treatments, needles must be accurately matched to the correct channel on the afterloader, else the dwell times will be erroneously delivered. Incorrect catheter connection is a failure mode of HDR brachytherapy that is challenging to detect. The inadvertent swapping of channels can result in a consequential loss of target coverage while simultaneously delivering excessive dose to normal tissues. In this work, a prototype brachytherapy template attachment is demonstrated that detects and alerts clinicians of an erroneous catheter connection prior to delivery.
Methods
As a pre-delivery safety measure, clinical afterloaders advance a non-radioactive 'dummy' wire through each catheter channel to verify an unobstructed source path. To independently verify correct channel-needle correspondence during this process, a custom HDR template attachment was developed incorporating embedded solenoid inductors driven by a micro-controller operating a metal-detecting circuit. The system detects the presence of a dummy wire within a solenoid and compares to the expected. Confirmation is made that channel-needle assignments are connected in the predefined order, and the user is notified if a wire is detected in a needle out of the expected sequence.
Results
The prototype template attachment consistently detected the dummy wire within gynecological interstitial needles. Comparison between the planned delivery sequence and connections were actively made by the device, and an error signal was reliably produced in real time when there was an erroneous connection.
Conclusion
This work introduces a prototype design for a brachytherapy HDR template attachment that provides intraoperative safety validation of appropriate catheter connection, which could assist in minimizing human error during HDR treatment delivery, particularly in complex cases with multiple catheters.