Ultra-high Resolution SPECT with CdTe Detectors

Abstract

Semiconductor detectors such as CdTe and CdZnTe that work at room temperature have facilitated the realization of an ultra-high resolution SPECT system. These semiconductor detectors are used as pixellated detectors, and so the intrinsic resolution can be equal to the size of the pixel used for measurement. The size of the detector pixel can be as small as 0.5 × 0.5 mm2 with state-of-the-art semiconductor technology, so that the spatial resolution of a reconstructed SPECT image with an ultra-high resolution parallel-hole collimator may be less than 1 – 2 mm FWHM in clinical studies. And if we apply this detector to a pinhole SPECT system, we can obtain ultra-high resolution SPECT images in small animal studies. To clarify the feasibility of an ultra-high resolution SPECT system, we conducted experiments with a commercially available semiconductor detector. The size of the pixel used in the experiments was 0.5 × 0.5 mm2. In this real SPECT system we newly developed an ultra-high resolution parallel-hole collimator and pinhole collimator that were made of tungsten. The results of the experiments with the parallel-hole collimator and pinhole collimator showed that our SPECT system could resolve 1.0 mm hot-rods and 1.6 mm cold rods.Keywordssemiconductor detectorultra-high spatial resolutionSPECT