Unified deadtime correction model for PET.

A model of deadtime for emission and transmission scans in positron emission tomography (PET) scanners with two-dimensional detectors has been developed. The model takes into account coincidence losses due to singles losses and multiple events, as well as mispositioning errors at higher count rates caused by pulse pile-up, within a detector block. The model is applicable to emission distributions and to spatially varying singles distributions seen with a rotating pin transmission source. An automatic procedure to determine the parameters of this model based on decaying emission studies has also been developed. Different singles dead time factors are required for emission and blank distributions due to differences in their energy spectra. The model was tested on emission and pin transmission data taken on the Scanditronix PC2048-15B scanner.