An Innovative Approach to Intraoperative Quality Assurance for Low Dose Rate Brachytherapy

BrachyView is a novel in-body imaging system, aimed to accurately localise brachytherapy sources using high-resolution pixelated silicon detectors and a pinhole collimator. In the recent years, many research projects have studied the different possibilities for real-time, intra-operative, dynamic dose treatment planning to increase the quality of brachytherapy implants. The capabilities of this pinhole camera were tested through a proof of concept study using four active seeds. A more clinically realistic scenario, using twenty active seeds implanted in a PMMA phantom, was the clear next step. To further imitate a clinical scenario, 20 seeds were implanted and imaged using a single pinhole lead collimator with a diameter of 400 μm. BrachyView was successful at locating the seeds within 1-2 mm of their expected positions which was verified via co-registration with a full clinical post-implant CT scan with 0.8 mm width. The first BrachyView prototype to feature a triple-chip detector embedded within a tungsten collimator with three single cone pinholes was used to localise 30 active seeds embedded within 11 needles, implanted in a soft gel prostate phantom, under ultrasound guidance. For verification, a full post implant CT was also performed. The BrachyView was able to accurately resolve the all the seeds with a maximum discrepancy of 1.78 m