Development of MRI-Compatible Nuclear Medicine Imaging Detectors

The value of pre-clinical PET and MRI is established, and SPECT also is now routinely used in drug development, disease treatment, and molecular biology research. The aim of this research is to prepare and test imaging prototypes of both SPECT and PET with similar form-factors for use within the core of a pre-clinical MRI. To test the imaging properties of the SPECT detector in a magnetic field a prototype based on CZT semiconductor detectors has been fabricated. This detector has a field-of-view of 2.54 times 12.7 cm² and is fitted with a parallel hole collimator for mouse imaging. The prototype is designed to obtain a tomographic dataset by manual positioning within a 90-degree projection range. Shielding, support, positioning, and cooling materials were selected to minimally influence the magnetic field homogeneity. Fabrication of a stationary, polygonal ring of CZT has commenced. An APD-based, light-sharing detector has been evaluated for use in PET. The detector configuration is a 2 times 2 array of 10 mm times 10 mm Hamamatsu S8664-1010 APDs used to read out multi-crystal LYSO blocks. The design of the detector and front-end electronics is optimized for spectroscopic and timing performance, minimization of power dissipation, and low electromagnetic interference. Current plans are for assembling five rings, each with 17 modules, to give a 13.0 cm axial FOV with a 14 cm inner diameter. The results on the tests and performance of both types of modules are reported.