Clinical Characterization of a Novel Handheld Coded Aperture Gamma/Compton Camera
Abstract
Purpose
To evaluate a novel dual-mode handheld gamma camera (RAVIN, M3D Inc.) utilizing coded aperture and Compton imaging for clinical radiopharmaceutical applications.
Methods
The tests assessed minimum detectable activity-time, spatial resolution, and isotope identification capabilities. A 4 µCi Pluvicto sample was imaged at various distances to determine detection limits (minimum observable after 30 minutes). Two 30 µCi cylindrical sources (7×8 mm) were placed at varying horizontal separations at 60 cm distance to assess spatial resolution. A 200 mCi Pluvicto syringe was imaged through varying solid water thicknesses at 100 cm to evaluate shielding effects on the spectrum and isotope identification. Spectra were normalized by imaging time.
Results
A 4 µCi sample at 100 cm was observable within 6.5 minutes, yielding a minimum detectable time-activity <1400 µCi-seconds. Sub-uCi activity measurement were not feasible due to substantial uncertainties. The camera resolved the cylindrical sources separated by 2 cm, but not 1 cm. Isotope identification succeeded in all scenarios, including through 25 cm of solid water. The FWHM for 113 keV and 208 keV peaks were 2.7% and 1.7%, respectively. The camera imaged a Pluvicto droplet on a glove but could not image trace contamination from gauze transfer, though it did measure an increased count rate and identify isotope present.
Conclusion
The RAVIN camera excels at imaging and identifying non-trace contamination in low-background environments at centimeter-to-meter distances, making it well-suited for safety surveillance of moderate- to high-activity sources in brachytherapy or radiopharmaceutical therapy. Performance is limited for distributed low-activity sources and trace contamination detection in high-background environments (e.g., on workers or patients). However, isotope identification remains functional even when imaging is insufficient, improving contamination detection capabilities.