Optimized readout of small gamma cameras for high resolution single gamma and positron emission imaging

Using a novel resistive readout scheme and off-the-shelf PCI ADC data acquisition cards, a compact readout and control system for mini gamma cameras based on position sensitive photomultiplier tubes (PMTs) has been developed. This economical resistive readout incorporates a special fractional subtraction technique to greatly expand the useful field of view of the PMTs to the very edges of their active area as compared to standard resistive readout methods such as charge division or Anger logic. This allows one to obtain the same quality images as those obtained with much more expensive and bulky individual wire readout data acquisition systems. The four output signals from the readout circuit can be digitized by a PCI ADC card in a computer to achieve high counting rates. Results will be shown for this readout applied to a dual modality breast biopsy system currently undergoing clinical trials and an ultra high resolution single gamma small animal imaging system for studies on mice and rats.