Effect of spatial noise of medical grade Liquid Crystal Displays (LCD) on the detection of micro-calcification

Abstract

This presentation describes work in progress that is the result of an NIH SBIR Phase 1 project that addresses the wide-spread concern for the large number of breast-cancers and cancer victims [1,2]. The primary goal of the project is to increase the detection rate of microcalcifications as a result of the decrease of spatial noise of the LCDs used to display the mammograms [3,4]. Noise reduction is to be accomplished with the aid of a high performance CCD camera and subsequent application of local-mean equalization and error diffusion [5,6]. A second goal of the project is the actual detection of breast cancer. Contrary to the approach to mammography, where the mammograms typically have a pixel matrix of approximately 1900 x 2300 pixels, otherwise known as FFDM or Full-Field Digital Mammograms, we will only use sections of mammograms with a pixel matrix of 256 x 256 pixels. This is because at this time, reduction of spatial noise on an LCD can only be done on relatively small areas like 256 x 256 pixels. In addition, judging the efficacy for detection of breast cancer will be done using two methods: One is a conventional ROC study [7], the other is a vision model developed over several years starting at the Sarnoff Research Center and continuing at the Siemens Corporate Research in Princeton NJ [8].Keywords: Detection of micro-calcification, threshold detection of anatomical noise, power law as function of lesion size, spatial noise, noise reduction by Error Diffusion, noise free template pixel, Siemens Visual Discrimination Model. I. Background A. Mammography and the relation between detection of breast cancer and various noisesThe detection of abnormalities in medical images is generally understood to be limited by the amount of noise in the image [11]. In the context of this research project, noise is defined as the ensemble of all variations present in the image that interfere with the detection of the "true" signal that is sought, namely the developing cancer. These variations include spatial noise introduced into the image by the very display used to view the developing cancer.To be sure, there are other sources of noise in radiographic images: • Anatomical noise, which reflects the highly correlated variations formed by the projection of breast tissue.