We examine the feasibility of inferring the internal geometry of an object based on passive measurements of the radiation emitted by that object. The approach taken in this paper is one designed to produce the radiation source density as well as the attenuation of the materials making up the object, herein referred to as f and a respectively. We refer to this problem, of recovering a and f from radiation measurements, as radiation tomography. The work is motivated by the need to determine the internal structure of devices containing
radioactive material entirely from passive measurements for the inspection requirements associated with the enforcement of potential nuclear arms treaties.