A study of the signal-to-noise ratio using Time-of-Flight information on a positron emission tomograph

We present a study of the signal-to-noise ratio (SNR), conducted on the Time-of-Flight (TOF) positron emission tomograph (PET) CEA-LETI TTV03. An element of the pixel covariance matrix has been calculated. It includes the reconstruction process as well as statistical fluctuations in emission and transmission scans. Using this expression, we found that the SNR of a 20 cm diameter uniform cylinder is independent of the number of coincidences in the transmission scan when the emission scan contains less than 6 × 10⁶ coincidences. With a 750 ps TOF resolution and a 2 mm pixel size, one pixel is only correlated with its nearest neighbours.