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 plurality of first points with a corresponding pixel of the panoramic image to be obtained to map said plurality of first points on said curved surface to each corresponding pixel of said panoramic image; c) associating, for each identified point of said plurality of first points, a respective set of lines passing through the identified point, each line of the respective set of lines having a different angle of incidence, the angle of incidence defined as an angle between a line of the respective set of lines and a line perpendicular to the curved surface passing through the identified point, each line of the respective set of lines being contained in a solid angle having the identified point as the vertex of the solid angle; d) calculating an absorption value in the 3D volume along each line; e) attributing, to each identified point, an absorption value calculated as a function of all of the absorption values calculated for each line of the respective set of lines; and f) attributing, to each corresponding pixel linked to each identified point, a value expressed in grayscale calculated as a function of the absorption value of each identified point.