Correction of emission contamination and deadtime loss

摘要

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.