1. A method for digital radiographic 3D volume image processing of a subject, executed at least in part on a computer, comprising: obtaining image data for a plurality of 2D projection images over a range of scan angles; generating, for each of the plurality of 2D projection images, a first scatter intensity distribution by: estimating a first scatter distribution in an air region from at least one 2D current projection image, segmenting the at least one 2D current projection image to determine an object shadow portion, and determining a coarse scatter intensity within the object shadow portion based on an interpolation of the first scatter distribution; generating, for said each of the plurality of 2D projection images, a second scatter intensity distribution for the 2D projection image by: modulating the first scatter intensity distribution for the plurality of 2D projection images by a rescaled processed object intensity in log space, where the modulating comprises, determining a first scaling factor for at least one point in the range of scan angles that occurs within the object shadow portion using a scatter-to-primary ratio, dividing all the projections by the first scaling factor to get scaled projections, inverting the scaled projections to determine a moderating function, and applying the moderating function to the plurality of first scatter intensity distributions for the plurality of 2D projection images to generate the plurality of second scatter intensity distribution for the plurality of 2D projection images for the range of scan angles, and combining the plurality of second scatter intensity distribution for the plurality of 2D projection images to the plurality of 2D projection images to determine a plurality of scatter corrected 2D projection images; and storing the scatter corrected plurality of 2D projection images in a computer-accessible memory.