Heart imaging by cadmium telluride gamma camera: European Program “BIOMED” consortium

Cadmium telluride semiconductor detectors (CdTe) operating at room temperature are attractive for medical imaging because of their good energy resolution providing excellent spatial and contrast resolution. The compactness of the detection system allows the building of small light camera heads which can be used for bedside imaging. A mobile pixellated gamma camera based on 2304 CdTe (pixel size: 3×3mm, field of view: 15cm×15cm) has been designed for cardiac imaging. A dedicated 16-channel integrated circuit has also been designed. The acquisition hardware is fully programmable (DSP card, personal computer-based system). Analytical calculations have shown that a commercial parrallel hole collimator will fit the efficiency/resolution requirements for cardiac applications. Monte-Carlo simulations predict that the Moire effect can be reduced by a 15° tilt of the collimator with respect to the detector grid. A 16×16CdTe module has been built for the preliminary physical tests. The energy resolution was 6.16±0.6keV (mean ± standard deviation, n=30). Uniformity was ±10%, improving to ±1% when using a correction table. Test objects (emission data: letters 1.8mm in width) and cold rods in scatter medium have been acquired. The CdTe images have been compared to those acquired with a conventionnal gamma camera.