Multiplexing readout scheme for a gamma ray detector

A method for producing a PET image of a tissue using a PET scanner, the scanner comprising a plurality of scintillation crystals and a plurality of detectors, the method comprising:

• forming a first crystal group including a first subset of the plurality of crystals;
• forming a second crystal group including a second subset of the plurality of crystals, wherein crystals comprising the first crystal group are different from crystals comprising the second crystal group;
• converting beams striking one or more crystals of the first crystal group to to a like number of electrical signals;
• determining a time of occurrence of the leading edge of each electrical signal;
• determining corrected electrical signals by correcting the time determined at the determining step according to a respective amplitude of each electrical signal;
• and
• creating an image of the tissue using the corrected electrical signals.

An apparatus for producing a PET image using a PET scanner, the apparatus comprising;

• scintillation crystals segregated into a plurality of mutually exclusive crystal groups;
• detectors, one detector coupled to each scintillation crystal, each detector for producing an energy signal responsive to the energy in a gamma ray striking a crystal associated with the detector;
• comparators responsive to the detectors, each comparator for producing a signal representative of a time when a energy signal crosses a threshold;
• a number of time-to-digital converters equal to the number of crystal groups, wherein a signal produced by each comparator is supplied as an input to the time-to-digital converter for the respective crystal group for producing a digital timing signal representative of the time when the energy signal crosses the threshold;
• and
• a correction element responsive to the energy signal and to the digital timing signal for correcting the energy signal responsive to the digital timing signal.