US-guided EM tracked system for HDR brachytherapy: A first in-men randomized study for whole prostate treatment

Purpose: An electromagnetic tracking device (EMT) has been integrated in an HDR 3D ultrasound guidance system for prostate HDR. The aim of this study was to compare the efficiency of HDR workflows with and without EM tracking.

Methods and materials: A total of 58 patients with a 15 Gy HDR prostate boost were randomized in two arms and two operation room (OR) procedures using: (1) the EMT investigational device, and (2) the Oncentra prostate system (OCP). OR times were compared for both techniques.

Results: The overall procedure median time was about 20% shorter for EMT (63 min) compared to OCP (79 min). The US acquisition and contouring was longer for OCP compared to EMT (23 min vs. 16 min). The catheter reconstruction's median times were 23 min and 13 min for OCP and EMT respectively. For the automatic reconstruction with EMT, 62% of cases required no or few manual corrections. Using the EM technology in an OR environment was challenging. In some cases, interferences or the stiffness of the stylet introduced errors in the reconstruction of catheters. The last step was the dosimetry with median times of 11 min (OCP) and 15.5 min (EMT). Finally, it was observed that there was no learning curve associated with the introduction of this new technology.

Conclusions: The EMT device offers an efficient solution for automatic catheter reconstruction for HDR prostate while reducing the possibility of mis-reconstructed catheters caused by issues of visualization in the US images. Because of that, the overall OR times was shorter when using the EMT system.