Author: Diandra Ayala-Peacock, Lindsey Hendricks Bloom, Oana I. Craciunescu, Julie A. Raffi, Megan K. Russ, Ryan Sanford, Rajesh Venkarataman 👨🔬
Affiliation: Clinical Imaging Physics Group, Department of Radiology, Duke University Health System, Duke University Medical Center, Duke University, Eigen Health, Duke Univesity 🌍
Purpose: To establish a robust QA framework to characterize and ensure accuracy, reliability, and reusability of a transrectal ultrasound (TRUS)-based needle tracking system (NTS) for clinical HDR GYN brachytherapy using two novel in-house phantoms (QA and GYN).
Methods: The framework, based in part on AAPM TG-128 recommendations, assessed four components of the NTS-generated 3DUS: (1) imaging characteristics, (2) geometric accuracy, (3) needle fidelity, and (4) tracking accuracy. Imaging characteristics were evaluated using the CIRS Model 45A phantom (Sun Nuclear). Geometric accuracy was assessed with both the CIRS phantom and an in-house QA phantom, comparing 3DUS measurements to known ground truth values. The US location accuracy of four Ti needles was investigated with fiducial-based CT-3DUS rigid registration of the QA phantom. Needle tracking accuracy was evaluated using an in-house GYN phantom containing relevant female anatomy, with six Ti needles inserted under NTS guidance.
Results: The NTS is a modified version of the Artemis prostate biopsy system (Eigen Health), adapted for GYN applications. Imaging characteristics, geometric accuracy, and validation with the QA phantom were all within TG-128 tolerances. CT-3DUS registration of the QA phantom with four inserted needles showed needle deviations of 0.975 ± 0.15mm (axial) and 0.35 ± 0.41mm (sagittal), confirming needle fidelity. Needle tracking accuracy met clinical standards (2–5mm from intended placement), with deviations averaging 1.31 ± 1.36mm (proximal) and 2.04 ± 2.05mm (distal). Throughout this work, a “lateral stretching” effect specific to the in-house phantoms was identified and addressed by imaging phantoms at room temperature, which reduced average deviations from 4.02% to 0.31% (QA) and 4.34% to 0.68% (GYN).
Conclusion: We have developed a novel QA framework to effectively characterize the TRUS-based needle tracking system, with results meeting tolerances and demonstrating accuracy and reliability for GYN brachytherapy.