Adac Laboratories, Inc.

Peter Nelleman

Horace H Hines

Hugo Bertelsen

Lingxiong Shao

A method of correcting for deadtime and for emission contamination of a transmission scan in a nuclear camera system is provided. The transmission scan is used to correct positron emission tomography (PET) images for attenuation. The camera system includes two detectors and two corresponding single-photon point sources that are collimated to produce fanbeam illumination profiles. A transmission detection window and an emission contamination detection window is defined on each detector. Radiation from each source is scanned axially across the field of view of the corresponding detector in synchronization with the corresponding transmission detection window to acquire transmission projection data. The emission contamination detection windows are also scanned axially concurrently with, but offset from, the transmission detection windows to acquire emission data. Events detected in the transmission detection windows are used to add counts from appropriate locations of the transmission projection on an event-by-event basis in real-time. Events detected in the emission contamination detection windows are used to subtract counts from appropriate locations of the transmission projection on an event-by-event basis as those events are detected. The number of counts by which a given location is incremented or decremented for each detected event is determined event-by-event from a look-up table based on the current singles rate.

Method and apparatus for performing correction of emission contamination and deadtime loss in a medical imaging system

A method of correcting for deadtime and for emission contamination of a transmission scan in a nuclear camera system is provided. The transmission scan is used to correct positron emission tomography (PET) images for attenuation. The camera system includes two detectors and two corresponding single-photon point sources that are collimated to produce fanbeam illumination profiles. A transmission detection window and an emission contamination detection window is defined on each detector. Radiation from each source is scanned axially across the field of view of the corresponding detector in synchronization with the corresponding transmission detection window to acquire transmission projection data. The emission contamination detection windows are also scanned axially concurrently with, but offset from, the transmission detection windows to acquire emission data. Events detected in the transmission detection windows are used to add counts from appropriate locations of the transmission projection on an event-by-event basis as those events are detected. Events detected in the emission contamination detection windows are used to subtract counts from appropriate locations of the transmission projection on an event-by-event basis as those events are detected. The number of counts by which a given location is incremented or decremented for each detected event is determined event-by-event from a look-up table based on the current singles rate.

Method and apparatus for performing correction of emission contamination

The present invention provides an apparatus and method for enhancing the resolution of a Positron Emission Tomography (PET) image in a Nuclear Camera System that is configurable to performs both PET and SPECT imaging. The apparatus includes a crystal that interacts with a gamma ray to create a scintillation event within the surface of the crystal. The gamma rays that impinge the crystal have an incident angle that is limited by a field of view of the crystal. Positioned behind the crystal is a detector that responds to the light photons released by the scintillation event and registers a coordinate value of the scintillation event. Coupled to the detector is a resolution enhancer that generates an in-crystal plane displacement correction value for the coordinate value registered by the detector. The in-crystal plane displacement correction value is then combined with the coordinate value to compute the actual entry point of the gamma ray into the crystal.

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Pleasanton, CA, United States of America

Peter Nelleman