Abstract: The invention relates to a method of assessing an optical density gradient in one or more radiologic images of a non-uniformly composed material for purpose of using the optical density gradient to assess a characteristic of the non-uniformly composed material. Optical density gradient is calculated as a function of the difference in optical density between a first and second region on the one or more images. The method finds particular application in predicting occurrence or likelihood of non-union of a bone fracture and for predicting occurrence of likelihood of a disorder or disease of the bone, such as osteoporosis.