A method of quantitative reconstruction of an image of a human breast of predetermined thickness comprising the steps of: using an x-ray source to obtain a plurality of projection views of the human breast where each the projection views is offset from another of the projection views by an angle (θ); forming an image comprised of pixels from each projection view, the pixels representing a level of attenuation of x-rays passed through the breast from the x-ray source; using a reference point in a reference projection view to obtain a reference value ( P fat o) for the reference projection view, estimating a pixel to source breast tissue thickness (Z j) between a pixel (x) and the x-ray source for each of the other projection views using a total thickness estimation equation; compressing the breast so as to decrease in thickness across the breast from the chest wall towards the nipple by a paddle tilted at a paddle tilt angle corresponding to the decrease in thickness along the length; using a tilt estimation algorithm to find the paddle tilt angle across the breast and thus the variation in breast tissue thickness (Z j) due to the projection views and the paddle, wherein the tilt estimation algorithm comprises the steps of: using regression to fit a first plane to the x-ray attenuation corresponding to all of the pixels in a first portion of the breast compressed by the paddle and obtaining an all tilt angle from the slope of the first plane and taking the all tilt angle as the paddle tilt angle, if a preselected fraction of the pixels in the first portion are within a preselected distance of the first plane; characterized by using regression to fit a second plane to the x-ray attenuation corresponding to pixels in a second portion of the breast compressed by the paddle having less than a preselected percentage of fat and obtaining a fatty tilt angle from slope of the second plane, and taking the fatty tilt angle as the paddle tilt angle, if a preselected fraction of the pixels in the second portion are within a preselected distance of the second plane; estimating a reference value (P fatj) for each of the other projection views I j using a reference value estimation equation which is a function of the reference value (P fat o), and breast tissue thickness (Z j); using the estimated reference value (P fatj) for each projection view I j to obtain a respective volume of fibroglandular tissue (V j) for the projection view; and adjusting the estimated reference value (P fatj) for each projection view using a volumetric difference equation to determine the volume of fibroglandular tissue in the human breast to a preselected accuracy. using an x-ray source to obtain a plurality of projection views of the human breast where each the projection views is offset from another of the projection views by an angle (θ); forming an image comprised of pixels from each projection view, the pixels representing a level of attenuation of x-rays passed through the breast from the x-ray source; using a reference point in a reference projection view to obtain a reference value ( P fat o) for the reference projection view, estimating a pixel to source breast tissue thickness (Z j) between a pixel (x) and the x-ray source for each of the other projection views using a total thickness estimation equation; compressing the breast so as to decrease in thickness across the breast from the chest wall towards the nipple by a paddle tilted at a paddle tilt angle corresponding to the decrease in thickness along the length; using a tilt estimation algorithm to find the paddle tilt angle across the breast and thus the variation in breast tissue thickness (Z j) due to the projection views and the paddle, wherein the tilt estimation algorithm comprises the steps of: using regression to fit a first plane to the x-ray attenuation corresponding to all of the pixels in a first portion of the breast compressed by the paddle and obtaining an all tilt angle from the slope of the first plane and taking the all tilt angle as the paddle tilt angle, if a preselected fraction of the pixels in the first portion are within a preselected distance of the first plane; characterized by using regression to fit a second plane to the x-ray attenuation corresponding to pixels in a second portion of the breast compressed by the paddle having less than a preselected percentage of fat and obtaining a fatty tilt angle from slope of the second plane, and taking the fatty tilt angle as the paddle tilt angle, if a preselected fraction of the pixels in the second portion are within a preselected distance of the second plane; estimating a reference value (P fatj) for each of the other projection views I j using a reference value estimation equation which is a function of the reference value (P fat o), and breast tissue thickness (Z j); using the estimated reference value (P fatj) for each projection view I j to obtain a respective volume of fibroglandular tissue (V j) for the projection view; and adjusting the estimated reference value (P fatj) for each projection view using a volumetric difference equation to determine the volume of fibroglandular tissue in the human breast to a preselected accuracy.