This publication complements an online tool available on the IAEA Human Health Campus website and the IAEA's International Research Integration System (IRIS). Together they address and calculate staffing requirements for the optimal and safe delivery of nuclear medicine services, based on current standards of practice and relevant IAEA guidance. Users can assess their current performance as well as additional staffing needs depending on their case-mix -- the type or mix of studies or treatments performed by their nuclear medicine department -- or when acquiring new technologies. This publication and the online tool are intended for hospital administrators, department heads and all nuclear medicine practitioners to support the planning of new departments, introduction of new technologies and periodic reviews of resources.