Brachytherapy strand visibility in reflected power ultrasound images: Comparison of EchoStrand vs. regular strands using 3D visibility profiles

Poor visibility of the implanted brachytherapy seeds in ultrasound images is an obstacle for real time ultrasound-based dosimetry. A common practice in brachytherapy is to encapsulate the seeds in a structure called strand, manufactured from a synthetic bioabsorbable polymer. A possible solution to the visibility problem of the brachytherapy seeds is to localize the strand polymers, as opposed to the seeds, by using an echogenic strand polymer as in the EchoStrand product from BrachySciences. We extract and compare the 3D visibility profiles of EchoStrand with those of regular strands, at different angles between the ultrasound probe and the strand. The results show that the ultrasound visibility of both strand types decreases when the angle of orientation between the ultrasound transducer and the strand increases. However, at non-parallel orientations, the EchoStrand is significantly (p-value <; 0.03) more visible compared to regular strands.