1. An emission computed tomography system comprising: means for illuminating a plurality of secondary emitters within an object of interest by using an external non-parallel source beam while the object of interest is moving relative to said external non-parallel source beam; means, coupled to receive radiation emitted from the plurality of secondary emitters, for providing a localization signal representing the emitted radiation; means, coupled to receive the localization signal, for determining a location for each of the plurality of secondary emitters; means for producing a 3D reconstruction of the object of interest; and means for combining the location with a computed 3D reconstruction of the object of interest so as to create an image of the plurality of secondary emitters.