Real-time, programmable, digital signal-processing electronics for extracting the information from a detector module for multi-modality PET/SPECT/CT scanners

Measurements performed by manufacturers on their PET devices reveal a limitation of the electronics in extracting the properties of particles hitting the detector. As a consequence, either a lead collimator with holes is placed in front of the detector (2-D mode) preventing many photons which are not sufficiently aligned with the holes from ever reaching the detector, or many photons are lost because the electronics cannot fully process the data and separate the good event from the bad events. In order to overcome the above limitation, a data acquisition system based on the programmable 3D-Flow processor has been designed for acquiring data from modules for multi-modality PET/SPECT/CT. The modular electronics allows for digital data to be acquired from all sensors included in a given view angle of the detector. Each channel can sustain an input data rate of 20 MHz, 64-bit word; 40 MHz, 32-bit word; or 80 MHz, 16-bit word. The bits at each electronic channel correspond to spatial, timing, and energy information from photomultipliers, avalanche photodiodes (APD), photodiodes, or other sensors. The programmable circuit performs digital signal-processing operations on the incoming bit string such as: (a) variable digital integration time (or pileup identification/correction) which allows for the maximum count rate capabilities while preserving spatial resolution; (b) depth of interaction which reduces the parallax error based on pulse shape discrimination (PSD), and/or pulse height discrimination (PHD); (c) improvement of the signal-to-noise ratio; (d) centroid calculation to improve spatial resolution or/and techniques of most likely position given the statistical nature of the signals; (e) correlation with neighboring signals; and (f) improving the timing resolution from the information received from the time-to-digital converter and pulse shape analysis