Feasibility Study on an Ultra-High-Resolution SPECT With CdTe Detectors

The development of semiconductor detectors such as CdTe and CdZnTe, which work at room temperature, has led us to study the design of a new single photon emission computed tomography (SPECT) system. These semiconductor detectors have a high energy resolution. Moreover, they are used as pixellated detectors, and so the intrinsic resolution can be equal to the size of the pixel used for measurement. The detector pixel is as small as 0.5 mm, and so the spatial resolution of a reconstructed SPECT image can be less than 3 mm full-width at half-maximum. To clarify the feasibility of an ultra-high-resolution SPECT system, we conducted some simulations and evaluated the quality of images. In these simulations, we used a diverging collimator to enlarge the field of view of the detector and compared the quality of the reconstructed images of a pixellated SPECT system with a conventional SPECT system with a scintillation detector and parallel-hole collimator under the same sensitivity and reduced sensitivity. The results showed that the improvement of the spatial resolution in the pixellated semiconductor detector yielded high-quality images even under the low sensitivity condition due to the small size of the pixels.