In accordance with one or more embodiments, the present invention provides a series of identified radiopharmaceuticals herein termed “imaging surrogates” whose pharmacokinetic behavior matches that of the alphaRPT for several alphaRPTs currently under investigation as cancer therapeutics. Methods for identifying imaging surrogates are also provided. These imaging surrogates can be used to implement a treatment planning approach to radiopharmaceutical therapy of alpha-emitters, enabling treatment to the maximum tolerated organ absorbed dose for individual patients.