Search

We describe a single photon emission computed tomograph (SPECT) which can be operated inside state-of-the-art magnetic resonance imaging (MRI) systems. The combined SPECT/MRI system allows one to acquire simultaneously the data from both modalities and co-register the images in space and time. The new SPECT is based on the semiconductor cadmium zinc telluride (CZT) and application specific integrated circuits (ASICs) — two technologies which are MR-compatible and almost insensitive to magnetic fields. The SPECT camera has an energy resolution of 5.4 keV full-width-half-maximum (FWHM) at the 140-keV photo peak from 99mTc for either inside or outside of the MRI. We acquired the first SPECT and MR images from resolution phantoms and mice in-vivo. The experiments show that the MRI is minimally affected by the SPECT camera inside the bore. Preliminary results for the SPECT camera show high sensitivity of about 1.6% and a spatial resolution of 4 mm FWHM.

We describe a digital line-camera that can be used for computed tomography (CT) with energy resolved x-ray photon counting (XPC) capability. The camera is based on pixellated cadmium telluride (CdTe) radiation sensors and application specific integrated circuits (ASICs). Each camera pixel simultaneously counts x-rays in multiple energy bins providing the capability for “color” x-ray imaging and energy weighted x-ray CT. The camera can be used in pre-clinical x-ray microCT, where energy resolved photon counting is capable of improving contrast in the image and reducing radiation dose to the subject. We began testing the camera using 120-kVp polychromatic x-rays illuminating a phantom consisting of different test materials. Projection data of x-ray intensity transmitted through the phantom at different views were acquired and reconstructed to obtain tomographic images. This article describes the functionality and performance of the camera, and presents preliminary results from x-ray microCT with phantoms.