Needle path detection for brachytherapy dosimetry based on lateral power imaging and template matching

Brachytherapy is a treatment for prostate cancer with highly successful outcomes. During brachytherapy, radioactive seeds are implanted in and around the prostate based on a designed plan. Accurate detection of the implanted seeds and their position relative to prostate are important for dosimetry during and after brachytherapy. We propose a method to identify the needle paths in ultrasound images based on reflected power imaging and matching the temporal profile of the potential seeds with that of a set of template seed images. These needle tracks are used for line to line registration to needle tracks extracted from five fluoroscopy images. The needle tracks in fluoroscopy data are extracted based on the random sample consensus algorithm. Very accurate results in phantom studies and a promising patient study are reported. In the patient study, 16 out of 22 needle tracks were successfully extracted from ultrasound data.