Development and performance evaluation of large-area hybrid gamma imager (LAHGI)

• Published in: Nuclear engineering and technology 2021, 53(8), , pp.2640-2645
• Main Authors: Lee, Hyun Su, Kim, Jae Hyeon, Lee, Junyoung, Kim, Chan Hyeong
• Format: Article
• Language: English
• Subjects: Coded aperture imaging; Compton imaging; Hybrid imaging; Scintillation detector; 원자력공학
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2021.01.036

We report the development of a gamma-ray imaging device, named Large-Area Hybrid Gamma Imager (LAHGI), featuring high imaging sensitivity and good imaging resolution over a broad energy range. A hybrid collimation method, which combines mechanical and electronic collimation, is employed for a stable imaging performance based on large-area scintillation detectors for high imaging sensitivity. The system comprises two monolithic position-sensitive NaI(Tl) scintillation detectors with a crystal area of 27 × 27 cm2 and a tungsten coded aperture mask with a modified uniformly redundant array (MURA) pattern. The performance of the system was evaluated under several source conditions. The system showed good imaging resolution (i.e., 6.0–8.9° FWHM) for the entire energy range of 59.5–1330 keV considered in the present study. It also showed very high imaging sensitivity, successfully imaging a 253 μCi 137Cs source located 15 m away in 1 min; this performance is notable considering that the dose rate at the front surface of the system, due to the existence of the 137Cs source, was only 0.003 μSv/h, which corresponds to ∼3% of the background level.