Can Electromagnetic Tracking be Used to Enhance Treatment Accuracy and Aid Applicator Insertion in High Dose Rate Brachytherapy

Abstract

Introduction: The treatment for high dose rate (HDR) cervix brachytherapy relies on accurate placement of applicators and interstitial needle positions inside the uterus and target volume. Positioning of needles is performed by transabdominal or transrectal ultrasound, and the use of electromagnetic (EM) tracking could help with positioning of needles during insertion. Inter-fractional needle migration during the treatment course is also a challenge and the use of EM tracking serves as a promising tool to identify the magnitude of needle migration as well as assist as a verification tool to ensure accuracy of throughout the treatment process. Methods: The Aurora EM tracking system was evaluated using a series of phantoms designed to test the basic functionality and characterise the tracking system under different clinical environments. Three phantoms were designed for the experiments: one to test characterise the EM tracking system within the ideal environment and the clinical environment; the second to assess needle tracking for cervix brachytherapy insertions; and a third phantom was used to test the sensitivity of the EM tracking solution for error detection and needle migration in HDR prostate brachytherapy. Results: It has been demonstrated the Aurora EM tracking system has a geometric accuracy to within 2mm within the 50x50x50cm2 working volume and has the potential to be used in the clinical environment for HDR brachytherapy. Under ideal conditions the EM tracking performed with a geometric accuracy of 0.29±1.55mm (95% CI) with an overall experimental error of 0.7mm. The phantoms could be tracked at 15cm above the brachytherapy and CT treatment couch with mean geometric differences of -0.68±1.62mm and -1.09±1.00mm (95% CI) for the gynae phantom, respectively. The results for titanium prostate needle phantom were -1.90±1.88mm and -2.04±0.36mm (95% CI) for the brachytherapy and CT couch, respectively. The height of the tracking relative to the CT and brachytherapy couch was demonstrated to affect tracking in the clinical environment and future work is required to minimise interference at

Date of Award	5 Apr 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Stephen Bolton (Main Supervisor) & Lisa Hallett (Co Supervisor)