1. A method of acquiring medical data using a data acquisition system including a radiation detector, said method comprising the steps of: acquiring a first set of data from a monitored region that is a first region of interest; for n=2 to N, performing the steps of: a) detecting an (n-1) th trigger condition based on said (n-1) th set of data, b) defining an n th region of interest in response to said (n-1) th trigger condition; c) acquiring an n th set of data from the n th region of interest; and d) repeating steps (a) and (c) for each value of n, where N is equal to or greater than 3; and then recording said N th set of data for including in said medical data.