Abstract
Objective: To examine the imaging capability of a novel small field of view hybrid gamma camera (HGC) using I-125 seeds prior to surgical use.
Methods: The imaging performance of the camera system was assessed quantitatively and qualitatively at different source depths, source to collimator distances (SCD), activity levels, acquisition times and source separations, utilising bespoke phantoms.
Results: The system sensitivity and spatial resolution of the HGC for I-125 were 0.41 cps/MBq (at SCD 48 mm) and 1.53 +/- 0.23 mm (at SCD 10 mm) respectively. The camera was able to detect the I-125 seed at a SCD of 63 mm (with no scattering material in place) in images recorded within a 1-min acquisition time. The detection of the seeds beneath scattering material (simulating deep-seated tumours) was limited to depths of less than 20 mm beneath the skin surface with a SCD of 63 mm and seed activity of 2.43 MBq. Subjective assessments of the hybrid images acquired showed the capability of the HGC for localising the I-125 seeds.
Conclusion: This preliminary ex vivo study demonstrates that the HGC is capable of detecting I-125 seeds and could be a useful tool in radioactive seed localisation with the added benefit of providing hybrid optical gamma images for guiding breast conserving surgery.
Advances in knowledge: The SFOV HGC could provide high resolution fused optical-gamma images of I-125 radioactive seeds indicating the potential use in intraoperative surgical procedure such as RSL.