1. A method for obtaining a panoramic image similar to a panoramic radiography obtained from a patient through X-ray emission by processing an acquired 3D digital volume in voxel, each voxel having values of X-ray absorption, the method comprising the steps of a) selecting a curved surface in 3D volume; b) identifying a plurality of first points on said curved surface and connecting each point of said identified first points with a corresponding pixel of the panoramic image to be obtained to map said first points of said curved surface on corresponding pixels of said panoramic image; c) associating for each identified point of said first points a respective set of lines passing through said identified point, each line having a different angle of incidence, said lines being contained in a solid angle having said identified point as vertex; d) calculating an absorption value in the 3D volume along each of said lines; e) attributing to said identified point of said first points an absorption value calculated as a function of all of the absorption values calculated for each of said lines of said set; and f) attributing to said pixel linked to said identified point of said first points a value expressed in grayscale calculated as a function of the absorption value of said identified point.