A computerized method and system for determining an optimum amount of Internal Radionuclide Therapy (IRT) and External Radiation Therapy (XRT) to administer, comprising: obtaining activity image information for an imaged object from a detector running a Monte Carlo simulation for the activity image information to obtain absorbed dose-rate image information at multiple times adding the absorbed dose-rate image information from each time to obtain IRT total absorbed dose image information and utilizing the IRT total dose image information to obtain total dose image information that is equivalent to XRT dose image information in terms of dose-rate, wherein the IRT dose information is converted to equivalent XRT dose information without having to generate BED dose maps.
