Current research on the ARO-positron emission tomography

We are presently constructing `AROPET', a rotating PET scanner for imaging small animals. The design of the system has flexible geometry, using four detectors. Each detector is made of a position-sensitive PMTs (Hamamatsu R3941) coupled with 18×16 small individual BGO scintillator crystals of dimension 2.6×2.6×25 mm³. Animals can be imaged in two modes. One is similar to a gamma camera in which the detectors are stationary, and a 2-D planar projection imaging is obtained. This mode is used for initial characterization of the bio-distribution of tracers. In the other mode the detectors are rotated through 90°, and the diameter can be adjusted between 22 cm to approximately 40 cm. This mode resembles a conventional 3-D PET scan using a partial detector ring. Thirty-one tomographic images can be obtained after rebinning and reconstruction. The field of view is 51.3 mm (transaxial) by 45.6 mm (axial). The spatial resolution of the planar projection mode, and the results of the planar image of a phantom and the dynamical images of the bio-distribution of F18-FDG in a mouse are discussed.