Continuous sampling and digital integration for PET scintillation
AssigneeCTI PET Systems, Inc.
InventorsJ. Clifton Moyers, John W. Young, Mark Musrock
Life of this patent
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Abstract
An apparatus and method for determining the total energy of a continuously under-sampled energy signal resulting from an annihilation event detected by a positron emission tomograph (PET) scanner. An annihilation event is detected by a scintillator crystal and photomultiplier tube, which produces an energy signal that is continuously under-sampled by an analog-to-digital converter. The start time of the energy signal is determined by a constant fraction discriminator and time-to-digital converter. The start time is used to calculate a new amplitude for each sample, from which the total energy can be calculated.
Claims14
An apparatus for determining a total energy level for an event detected in a tomograph scanner, said apparatus comprising:
- a detector responsive to the event and producing an energy signal;
- a shaping circuit responsive to said energy signal and producing a shaped signal;
- an analog-to-digital converter continuously sampling said shaped signal, said analog-to-digital converter producing a plurality of sample data;
- a constant fraction discriminator responsive to said energy signal;
- a time-to-digital converter in communication with said constant fraction discriminator, said time-to-digital converter producing a time value related to a start time of the event;
- and
- a processor receiving said time value and said plurality of sample data, wherein said processor determines the total energy level resulting from the event.
An apparatus for determining a total energy level for an event detected in a tomograph scanner, said apparatus comprising:
- a detector responsive to the event and producing an energy signal;
- a shaping circuit responsive to said energy signal and producing a shaped signal;
- an analog-to-digital converter continuously sampling said shaped signal, said analog-to-digital converter producing a plurality of sample data;
- a constant fraction discriminator responsive to said energy signal;
- a time-to-digital converter in communication with said constant fraction discriminator, said time-to-digital converter producing a time value related to an arrival time of the event, said time-to-digital converter resolving a time interval less than a sampling time interval of said analog-to-digital converter;
- and
- a processor receiving said plurality of sample data and said time value, said processor time-shifting said plurality of sample data based on said time value and producing a plurality of time-shifted data, said processor calculating a new amplitude for each of said plurality of time-shifted data, said processor producing an output of the total energy level resulting from the event.
An apparatus for determining a total energy level for an event detected in a tomograph scanner, said apparatus comprising:
- a means for detecting the event and producing an energy signal;
- a means for determining a starting time of the event;
- a means for producing a plurality of measured energy levels corresponding to a regular time interval;
- a means for correlating said starting time to said plurality of measured energy levels;
- and
- a means for determining the total energy level of the event from said starting time and said plurality of measured energy levels.
A method for determining a total energy level for an event detected in a tomograph scanner, said method comprising the steps of:
- a) detecting the event;
- b) determining a start time of the event;
- c) producing a shaped energy signal of the event;
- d) producing a plurality of measured energy levels from said shaped energy signal, each of said plurality of measured energy levels corresponding to a regular time interval;
- and
- e) determining the total energy level from said plurality of measured energy levels and said start time.
Dependencies are inferred from the claim text.