By introducing wide-aperture detectors, the efficiency of the conventional Compton scatter imaging technique can be greatly improved. A Monte Carlo method has been developed to investigate the imaging process of this enhanced Compton imaging technique. Using this technique, a conceptual design of a pipe inspection system has been completed. This system features the use of dual wide-aperture detectors and a photon source of two energy components. In practice, a source of more than two energy components is allowed. With this inspection system, the inner surface contours of the pipe can be reconstructed in a rather straightforward manner, and the inner surface can be fully mapped. The measured data together with the associated geometry parameters such as size and curvature will serve to provide a two- or three-dimensional contour mapping of the pipe.