Multi-head gamma camera system with CdZnTe semiconductor detectors

The purpose of our research is to develop a new brain single photon emission CT (SPECT) system with a semiconductor detector. For the detector we adopted CdZnTe semiconductor modular detectors to improve the energy resolution and spatial resolution. The size of a module was 39 × 39 mm² (16 × 16 pixels) and the thickness of the CdZnTe crystal was 5 mm. With this modular detector we made three detector units each consisting of ten CdZnTe modules. In each detector unit we set 5 × 2 (=10) detector modules, and thus the maximum active field became 195 × 78 mm². And to increase the sensitivity we used a multi-pinhole collimator with a hole size of 2 mmφ and the thickness of 1 cm. These pinholes were located on the surface of the hexagonal gantry around the object to be reconstructed. In this paper we evaluated the performance of our proposed system with several phantoms (a cold channel phantom, hot rod phantom and brain phantom). The results obtained with the experiments confirmed the validity of the proposed brain SPECT system.