The events of 9/11 sparked a revitalization of civil defense in the U.S. for emergency planning and preparedness for future radiological or nuclear event scenarios and specifically for mass casualty medical management of radiation exposure and injury. Research in medical countermeasure development in the form of novel pharmaceuticals to treat radiation injury and new radiation biodosimetry diagnostics, primarily focused on development of research models of uniform total-body irradiation (TBI). With the success of those models, it was recognized that most radiation exposures in the field will involve non-uniform heterogeneous irradiations and many partial-body or organ-specific irradiation models have been utilized. This review examines partial-body models of irradiations developed in the last decade for heterogeneous radiation exposures and organ-specific radiation exposure patterns. These research models have been used to further our understanding of radiation injury, novel medical countermeasures and biodosimetry diagnostics in development for future radiological and nuclear event scenarios.