Development of GAGG gamma camera system for high-energy photon imaging

GAGG結晶を用いた高エネルギー線対応型ガンマカメラの開発

河地 有木; 藤巻 秀; 渡部 浩司*; 山本 誠一*

Kawachi, Naoki; Fujimaki, Shu; Watabe, Hiroshi*; Yamamoto, Seiichi*

We have developed a gamma camera that employs a newly developed single-crystal scintillator, Ce-doped GdAlGaO (Ce:GAGG), which has no natural radioactivity, a relatively high density, and a large light output, as well as being nonhygroscopic. A 44 44 matrix of the Ce:GAGG pixels, 0.85 mm 0.85 mm 10 mm in size, was coupled to a high quantum efficiency position sensitive photomultiplier tube (HQE-PSPMT), and performance measurements indicate that almost all of the Ce:GAGG pixels were separated in the two-dimensional position histograms of Cs (662 keV) photons with an average peak-to-valley (P/V) ratio of 2. An energy resolution of 12.50.62% relative to the 662-keV photons was achieved. The camera was constructed by encasing the GAGG detector in a 20-mm-thick tungsten container with a pinhole collimator mounted on the front and setting the device on a positioning stand for both horizontal and vertical movement. Using the camera, we successfully imaged photons emitted from Cs (600 and 800 keV) and Cs (662 keV) solutions. Image data obtained at a distance of 300 mm from a Cs point source indicated that the position resolution was 13 mm, and the sensitivity obtained with a 1-mm-diameter collimator was 20 cpm/300 kBq.