A method for improving clinical data quality in Positron Emission Tomography (PET). The method provides for the processing of PET data to accurately and efficiently determine a data signal-to-noise ratio (SNR) corresponding to each individual clinical patient scan, as a function of a singles rate in a PET scanner. The method relates an injected dose to the singles rate to determine SNR(Dinj), and provides an accurate estimate of a quantity proportional to SNR, similar in function to the SNR(Dinj). Knowledge of SNR(Dinj) permits determination of peak SNR, optimal dose, SNR deficit, dose deficit, and differential dose benefit. The patient dose is fractionated, with a small calibration dose given initially. After a short uptake, the patient is pre-scanned to determine T, S, and R. An optimal dose is then determined and the remainder injected.