1. A program code storage device, comprising: a machine-readable storage medium; and machine-readable program code, stored on the machine readable storage medium, the machine-readable program code having instructions to: receive, at a location determination module, a plurality of distance readings and a plurality of reference readings from at least one subject sensor located in an imaging gantry, the at least one subject sensor located within an inner circumference of the imaging gantry to provide the plurality of distance readings and the plurality of reference readings; calculate a subject location and a subject volume, relative to at least one image source and at least one image receptor, from the plurality of distance readings and the plurality of reference readings, and output the subject location and the subject volume; receive, at a map module, the subject location and the subject volume; and create, at the map module, a base three-dimensional map from the subject location and the subject volume.