Contrast Enhancement of Mammograms By Optical Polarization of the Viewing Environment

摘要

To investigate the possibility that commercially available brands of mammography film may possess optical polarimetric properties and whether any observed polarimetric behavior displayed a dependence on film optical density. A polarimeter was constructed for performing optical experiments using the method of Azzam(sup 2). The Mueller matrix formalism was used to describe the results of the experiments. A prototype viewing device was constructed and evaluated by two radiologists. Polarimetric behavior was observed for all brands of film tested. Further investigation isolated the probable source of this behavior to the base of the film, rather than to the emulsion (which is responsible for the production of the image one sees). There is thus no observed evidence that mammography films display polarimetric behavior which is dependent on the optical density of the film. Results of the evaluation of the prototype suggest that the device may aid in the reading of films having low optical density (i.e. , films that appear too light). However, the polarimetry results do not support the possibility that polarimetric behavior played a major role in this outcome.