1. A three-dimensional image-generating device comprising: a radiation source configured to irradiate an object with gamma rays to generate a three-dimensional representation of said object; a modulating unit configured to encode gamma flux scattered from the inspected object as said gamma rays interact wherein said object generates scattered gamma rays, said modulating unit configured to identify spatial origins of said scattered gamma rays as said scattered gamma rays pass through said modulating unit; and a radiation detector configured to detect gamma rays scattered from said object, and passing through said modulating unit.