1. A method for 3-D volume image reconstruction of a subject, comprising: obtaining a plurality of 2-D projection images over a range of scan angles; identifying one or more truncated images from the obtained plurality of 2-D projection images; forming, from each of the one or more truncated images, a corrected truncated image by a repeated process comprising: (i) identifying a row of image data values in the one or more truncated images; (ii) assigning an extension length to one or both ends of the row according to the row location in the truncated image; and (iii) extending the truncated image data for the row of image data values by applying a cosine function to each value in the extension length; and reconstructing the 3-D volume image using one or more of the corrected truncated images.