The Standard Attenuation Rate for Quantitative Mammography
We introduce the Standard Attenuation Rate (SAR), a quantitative, and normalised measure of radiodensity per unit distance traversed by the primary beam incident on each pixel of an x-ray mammogram is presented. We sketch an algorithm to compute the SAR. The calculation utilises a physics model of image formation, including consideration of photon production in the x-ray tube, photon detection within the image receptor, and photon scattering occurring within the tissues of the breast. Using the model, the difference in the flux incident upon, and exiting from, the breast is quantified relative to a reference material. Experimental validation of the SAR representation is presented, based on a tissue equivalent phantom designed and manufactured specifically for the purpose. The observed performance across the clinical range of acquisition parameters is very promising, supporting the suitability of this approach to form the basis of a next generation of diagnostic techniques based on quantitative tissue measurement.
KeywordsQuantitative mammography measuring radiodensity acquisition physics modelling scatter removal
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