Development and performance evaluation of a high-speed gamma-ray imaging system

Gamma-ray imaging is an emerging technology for radiation surveillance at customs sites, supporting critical homeland security operations. However, existing handheld and vehicle-borne systems face challenges in balancing the high sensitivity and mobility required in complex customs environments. To address these limitations, we developed a fast gamma imager (FGI) comprising a high-sensitivity gamma-ray imaging system based on large-area monolithic NaI(Tl) scintillators integrated onto a motorized trolley platform. The FGI achieved an energy resolution of 6.6% and an angular resolution of 8.0° for 137 Cs (662 keV). Owing to its enhanced detection volume, it demonstrated high sensitivity, identifying and localizing a 10 μCi 137 Cs source at 1 m in only 0.044 ± 0.034 s and 0.55 ± 0.42 s ( k = 2 ), respectively. These response times were approximately 350 and 150 times faster than those of the commercial handheld imager H420 (H3D, Inc.) and were comparable to those of a large vehicle-borne system under identical conditions. Field tests at a bonded warehouse in Korea validated the FGI’s capability to localize concealed sources and track a moving source on a conveyor belt. While further refinements are ongoing, the FGI shows strong potential for improving radiation surveillance efficiency in safeguarding global logistics.