Implementation of needle-tracking technology for real-time transrectal ultrasound-guided interstitial gynecological...

To investigate the feasibility of adapting a commercial prostate biopsy system for transrectal ultrasound (TRUS)-guided hybrid gynecological (GYN) high-dose-rate (HDR) brachytherapy (BT). Leveraging 3D-TRUS and MR image fusion, the prototype system aims to improve real-time needle placement accuracy.

A second-generation, multi-imaging modality female pelvic phantom was developed to validate the system's feasibility. Software and hardware modifications, including user-accessible calibration modules and a redesigned needle guide for multi-needle insertion, were made to the pre-existing commercial system to enable use for GYN BT applications. An end-to-end feasibility test was performed to acquire 3D-TRUS images, perform contour-based registration with pre-implant MR, and insert six needles to targeted locations under real-time TRUS guidance. A 30° tandem without ovoids was added to mimic a hybrid GYN implant. The most proximal and most distal distances between the planned needle track and the visible portion of each inserted needle were measured. A CT/MR image-based treatment plan with a prescribed dose of 6 Gy was generated for the resulting 3D-TRUS-guided implant (tandem and needles) within the phantom.

The modified phantom improved needle visualization and insertion range by de-gassing the silicone and increasing the window size. The system accuracy for average ± standard deviations from intended needle tracks was 1.31 ± 1.36 mm (proximal) and 2.04 ± 2.05 mm (distal). Post-implant imaging confirmed needle placement and good target coverage. Needle placement was verified on CT/MR images and treatment plan quality was clinically acceptable.

With enhanced needle placement accuracy and integrated clinical workflow, this study demonstrates the feasibility of adapting a commercially available prostate biopsy system for 3D-TRUS-guided hybrid GYN HDR BT.