Abstract: The method is for inspecting an infrastructure having a corrugated pipe at least partially surrounded by soil. The corrugated pipe has a cylindrical wall which is corrugated along a length thereof and forming a longitudinally extending series of corrugations. The method generally has the steps of emitting, outwardly from the interior of the corrugated pipe, a beam of radiation particles directed towards a given voxel positioned beyond an inner face of the cylindrical wall and along a scanning plane parallel to an orientation of individual ones of the corrugations of the cylindrical wall; detecting backscattered photons scattered back from the given voxel and along the scanning plane; and generating inspection data based on the detected backscattered photons associated with the given voxel for use in inspecting the corrugated pipe.