A compact SPECT detector based on a quad PMT

Traditionally, the technology of general purpose SPECT cameras has been based on a large panel of NaI:Tl scintillator, optically coupled with a number of 2” or 3” PMTs [1]. With its rather good performance at low cost, the SPECT camera design has not changed essentially since Hal Anger invented it in the late 1950's. For the last decade, however, with progress in new scintillators and photosensors, there have been renewed efforts to improve spatial and energy resolutions. A series of new compact detectors have been mostly designed for small animal or organ specific SPECT cameras. In this paper, we present a concept of a compact SPECT detector design using a NaI:Tl crystal array and a quad anode PMT. By using a crystal array and a light guide, we demonstrate that all individual crystals can be identified without any dead area at the edge of the detector. This proves the possibility of a compact SPECT detector having high spatial resolution using an array of regular types of PMTs, for example, a 2×2 or 3×3 array of PMTs. Also, we show that this block structure design enables very small gaps at the edge of the detectors resulting in a more compact geometry when packed in full size SPECT cameras.