Performance evaluation of three-dimensional position-sensitive CdTe detector blocks for an ultra-high resolution brain PET scanner

We have developed an ultra-high resolution human brain positron emission tomography (PET) scanner with the resolution of less than 1 mm FWHM, in which cadmium telluride (CdTe) semiconductor detectors were used. As the detector of the scanner, we have developed a two-dimensional position-sensitive CdTe detector (2D-PSD) which was developed in our previous study. The 2D-PSD can detect gamma rays with a position resolution of approximately 1.2 mm. We developed a three-dimensional position-sensitive CdTe detector block (3D-PSD block) by stacking 80 2D-PSDs which were connected to subsequent circuits (amplifiers, analog to digital converters, and other data processing circuits). We constructed an ultra-high resolution semiconductor brain PET gantry placing the ten 3D-PSD blocks in decagonal arrangement. In this paper, we checked all 2D-PSDs and classified their performance. As the results, we confirmed that our 3D-PSD blocks can be used to the ultra-high resolution human brain PET. We made a circuit to reduce the dead time due to restoration from polarization phenomena in CdTe detector and we could stabilize count rates. (author)