Compositions and methods for treating and imaging vulnerable plaque and otherinflammatory conditions in a patient rely on the delivery of conversionelectron-emitting sources and other radionuclides to regions of exposedcollagen in the vasculature or other body lumens. The conversion electron-emitting sources or other radionuclides are coupled to a collagen-bindingsubstance and administered to the vasculature or other body lumen to permitbinding for imaging and/or therapeutic purposes.