University of Twente Student Theses


The feasibility of EM navigation for gynecologic brachytherapy catheter insertion

Venix, L.P.J. (2023) The feasibility of EM navigation for gynecologic brachytherapy catheter insertion.

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Abstract:Introduction: Accurately inserting catheters for gynecologic brachytherapy (GBT) can be difficult and time-consuming, especially for complex GBT procedures involving placement of one or more freehand catheters next to the applicator, through the perineal or vaginal tissue. Electromagnetic (EM) tracking for real-time visualization during catheter placement might improve catheter placement accuracy and procedure time. This study aims to develop and evaluate an EM-navigation system for 3D assistance during GBT catheter insertion. Method: A new EM-navigation workflow was proposed, involving EM-tracked transrectal ultrasound, an in-house developed catheter insertion stylet, and dedicated software. The accuracy of the EM system, the US calibration, and the EM-tracked insertion stylet was measured. Phantom tests were conducted to assess initial accuracy and system usability. Additionally, a case study was conducted with ‘regular’ GBT procedures to test the first part of the proposed workflow in a clinical setting. The accuracy of gold marker (GM) localization, registration techniques, and overlay discrepancies were examined. Results: The average EM-system accuracy was 0.64 mm, and the average jitter was 0.02. The transverse US calibration had a fiducial registration error (FRE) of 1.47 mm and a target registration error (TRE) of 1.59 mm. The sagittal US calibration had an FRE of 0.67 mm and a TRE of 0.72 mm. The calibration RMS of the EM-tracked stylet was 0.23 mm and the mean position error was 0.54 mm. For the phantom tests, the mean FRE was 0.83 mm for the initial registration and 0.74 mm for the tumor tracker registration. The mean overall US-catheter to EM-catheter distance was 1.69 mm. The mean US-catheter tip to EM-catheter tip distance was 3.04 mm. During the clinical cases, a mean FRE of 2.4 mm was acquired for both the MRI-US registration and the CT-US registration. Besides, the inserted catheters were tracked with an inter-catheter geometry accuracy of 3.4 mm. Conclusion: This study showed that EM-navigation for gynecological brachytherapy catheter insertion is feasible in a research setting and has potential in a clinical setting. The proposed workflow has potential benefits that eliminate the need for intraoperative CBCT. This workflow can only truly be analyzed after the prospective clinical study in our institution.
Item Type:Essay (Master)
NKI-AVL, Amsterdam, Netherlands
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
Keywords:Electromagnetic tracking, Gynecological Brachytherapy, Ultrasound, Freehand catheters
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