The present specification describes a compact, hand-held probe or device that uses the principle of X-ray backscatter to provide immediate feedback to an operator about the presence of scattering and absorbing materials, items or objects behind concealing barriers irradiated by ionizing radiation, such as X-rays. Feedback is provided in the form of a changing audible tone whereby the pitch or frequency of the tone varies depending on the type of scattering material, item or object. Additionally or alternatively, the operator obtains a visual scan image on a screen by scanning the beam around a suspect area or anomaly.