1. A method of processing patient data using a radiation detector and a computer, said method comprising the steps of: using said radiation detector to acquire image data representing an image, said acquiring performed for some period of time using the radiation detector; using the computer for automatically detecting and isolating a feature portion of the image; identifying at least one region of interest of the image based on said feature portion; generating an activity versus time array corresponding to the at least one region of interest from said image data; and analyzing the activity versus time array for generating an output for use by a user, wherein said output represents a quality of a bolus of an injected radiotracer through the central circulatory system of the patient, and wherein said quality of the bolus includes one or both of compactness or fragmentation of the bolus.