Preliminary Performance Evaluation of a Hand-Held Magic-Cube Spectral Intraoperative Gamma Camera

Portable gamma cameras are valuable tools for intraoperative imaging guidance. However, existing intraoperative cameras primarily rely on mechanical collimation, resulting in limited clinical impact and sensitivity, particularly during real-time or short-time-framed imaging. Additionally, imaging high-energy radionuclides is often necessary for certain applications, but the stronger collimator penetration results in degraded imaging performance.In this work, we develop a novel gamma camera prototype that consists of a magic-cube detector composed of scintillator, optical glass, and metal elements. The geometrical configuration and composition of the detector enable the application of a hybrid collimation concept, that is, mixing collimations formed by the inter-layer scintillator, optical glass, and metal, to achieve high sensitivity and resolution simultaneously, overcoming the intrinsic limitation of mechanical collimation. The prototype magic-cube assembly has a size of 67.2 mm × 67.2 mm × 20.0 mm, weighs 0.7 kg, and records detected gamma events with spatial and energy information.We conducted imaging experiments on the prototype using
^99m
Tc and
¹⁸
F point sources. The energy resolution of the camera as a single detector is 13.5% and 24.5% for 511 keV and 140 keV gamma rays, respectively. The average sensitivity is 1700 cps/MBq and 703 cps/MBq for
^99m
Tc and
¹⁸
F point sources, respectively, at a distance of 15 cm from the camera. The spatial resolutions (FWHM) are less than 9.4 mm and 14.8 mm, respectively, when measured with a 20 μCi
^99m
Tc and 1 mCi
¹⁸
F source at 15 cm from the detector for 1 s. The camera clearly resolves a 3 × 3
^99m
Tc point source array (each point source 4.3 mCi, 10 s) with a 2-cm point-to-point separation and a 2 × 2
¹⁸
F point source array (each point source 1.5 mCi, 10 s) with a 4-cm separation. The prototype’s high sensitivity and hybrid collimation concept offer significant potential for practical intraoperative applications.