A method and system for identifying foreign objection (FOD) in items such as aircraft are disclosed. The item may be imaged using x-ray backscatter before and after work is performed thereon. The image taken before work may be subtracted from the image taken after the work to provide a resultant image....http://www.google.co.uk/patents/US7463714?utm_source=gb-gplus-sharePatent US7463714 - Foreign object detection
