Progress Toward a Quantitative Scale for Describing Radiodensity in Mammographic Images

A technique is presented for computing a normalised imagein which each pixel directly describes the radiodensity of the underlying anatomy. Precisely, each pixel quantifies the equivalent thickness of reference material per unit traversal distance required to match the radiodensity of the breast tissues present within the traversal between the focal spot and the image receptor pixel. Measurements are computed using a model of image formation, which includes consideration of both the attenuation and scattering phenomena that occur. In view of the complexity of the underlying model, substantial computational optimisation has been made to yield clinically realistic execution times. Validation experiments are described using a purpose designed and manufactured tissue equivalent test object which allows both the assessment of the performance of the image normalisation, and a comparison with "ground truth".