An improved way of using radiographic imagery to locate inclusions within concrete. Radiographic film is placed on one side of a concrete structure and X-rays are transmitted towards the film from the other side. A target which is selectively radiographically impervious is interposed to generate location indicia on the film. Once developed, the film may be used to generate an image display such as a paper bearing indicia from the film or may be used directly to mark the location of inclusions on the concrete. The target may comprise a metallic plate with a viewing window and location indicia rendered in radiographically impervious material to establish measurement indicia in the final film image.