Comparison between three gamma cameras based on cadmium telluride and cadmium zinc telluride detector arrays

For clinical investigations, several small cameras equipped with cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe or CZT) material have been developed, with the objective to reach better contrast and spatial resolution than the conventional Anger cameras. Taking a clinical gamma camera as a reference, the aim of this work is to document progresses made in this field by comparing physical and imaging characteristics of three devices based on 16×16 detector arrays with different geometrical configurations: pixel sizes ranging from 2.46 mm to 3.07 mm and thickness of the semiconductor detectors from 2 mm to 5 mm. One probe is a CdTe multi-element instrument, while the other two include CdTe and CZT recent pixelized arrays. The experimental comparative imaging tests used cold lesions in a radioactive solution of ^99mTc, using an MRI "Jaszczak" contrast phantom module. All the three SC probes yield considerably better pictures compared to the Anger camera with higher efficiency, which will be a significant advantage in clinical conditions. Other two results are, first: in our experimental conditions, the pitch is the main factor of image quality, whereas the influence of the energy resolution is not estimable and second: discrete detectors exhibit similar results than those of monolithic pixelized detector array. These experiments didn't allow us to investigate the putative difference among SC material character on the image quality. Intrinsic material uniformity is the other crucial parameter which still need improvement. Despite this last requirement, the results underline the highly significant diagnostic gain expected from SC based pixelized gamma cameras.