Development and evaluation of high-resolution gamma camera for animal imaging

In recent years, 211 At has garnered significant attention in the field of targeted radionuclide therapy, owing to its potential for localized and highly effective cancer treatment. This alpha-emitting radionuclide is particularly promising as it emits alpha particles with 100% probability and can be produced easily in cyclotron facilities. Additionally, 211 At emits 79 keV X-rays, which can be used for imaging purposes. Imaging these X-rays enables tracking of 211 At dynamics, which is critical for visualizing therapeutic effects and optimizing treatment strategies. Consequently, the development of high-resolution imaging technologies for 211 At is of great importance. Currently, human SPECT systems are used for 211 At imaging in animal studies and typically provide a resolution of 5–10 mm. However, the small size of the organs in animals necessitates a resolution below 1 mm for detailed imaging. Although various high-resolution imaging devices have been proposed, achieving a balance among high resolution, low cost, and ease of use remains a challenge. To address this need, we are developing an easy-to-use, affordable, and high-resolution gamma camera with an active area of 100 × 100 mm 2 , specifically designed for small-animal imaging. The detector incorporates four 50 × 50 mm 2 multi-pixel photon counter arrays optically coupled to diced Gd 3 Al 2 Ga 3 O 12 scintillators with a pixel size of 0.5 mm. The system was designed to target low-energy X-rays and gamma rays, including the 79 keV X-rays emitted from 211 At. We conducted experiments using 133 Ba and 241 Am sources, that emit low-energy gamma rays. Our resolution evaluation demonstrated the ability to resolve 0.6 mm slits. In addition, we confirmed the capability of the detector for imaging complex radiation sources.