Combined PET and CT detector and method for using same

A method for detecting radiation emitted from a computed tomography source (CT source), said method comprising the steps of:

• (a) sensing radiation from a CT source as sensed radiation with a scintillator crystal and a photodetector in optical communication with said scintillator crystal;
• (b) processing said sensed radiation, wherein said step of processing is accomplished with a discrete event circuit including a fast amplifier connected to said photodetector;
• an energy discriminator connected to said fast amplifier, said energy discriminator filtering out a signal corresponding to an x-ray energy level outside a specified range;
• and
• a counter/timer responsive to said energy discriminator and having an output proportional to a count rate corresponding to a plurality of x-rays detected from the CT source within a specified energy level range sensed over a preset time period.

A detector for sensing radiation emitted from a computed tomography source (CT source), said detector comprising:

• a scintillator crystal responsive to radiation emitted from a CT source;
• a photodetector in optical communication with said scintillator crystal, said photodetector responsive to said scintillator crystal;
• a fast amplifier connected to said photodetector;
• an energy discriminator connected to said fast amplifier, said energy discriminator filtering out a signal corresponding to an x-ray energy level outside a specified range;
• and
• a counter/timer responsive to said energy discriminator and having an output proportional to a count rate corresponding to a plurality of x-rays detected from the CT source within a specified energy level range sensed over a preset time period.

A detector for sensing radiation resulting from a positron emission tomography source (PET source) and from a computed tomography source (CT source), said detector comprising:

• a means for sensing radiation from a PET source and from a CT source with a single device;
• a means for determining a gamma ray energy level and a time of event from the PET source;
• and
• a means for determining a number of x-ray events per a specified period from the CT source.

A detector for sensing radiation emitted from a positron emission tomography source (PET source), and from a computed tomography source (CT source), said detector comprising:

• a scintillator crystal responsive to radiation emitted from a PET source and responsive to radiation emitted from a CT source, said scintillator crystal formed of lutetium oxyorthosilicate;
• a photodetector in optical communication with said scintillator crystal, said photodetector responsive to said scintillator crystal;
• a first discrete event circuit for PET scanning including a charge amplifier connected to said photodetector, said charge amplifier having an output corresponding to a gamma ray energy level, and a fast amplifier connected to said photodetector, said fast amplifier having an output corresponding to a detection time;
• a second discrete event circuit for CT scanning, said second discrete event circuit including said fast amplifier connected to said photodetector, an energy discriminator connected to said fast amplifier, and a counter/timer responsive to said energy discriminator and having an output proportional to a count rate corresponding to a plurality of x-rays detected from the CT source within a specified energy level range sensed over a preset time period;
• and
• an integrator for CT scanning, said integrator in communication with said photodetector.