1. A method for the three dimensional image reconstruction of single plane 2-dimensional X-ray image projection of an object having at least one plane of symmetry comprising: a) substantially uniformly filling the object with an X-ray contrast agent said contrast agent having a pre-selected concentration and absorption coefficient; b) irradiating said contrast agent-filled object with X-rays substantially perpendicular to said at least one plane of symmetry of the object; c) detecting said X-rays transmitted through said contrast agent-filled object to define a 2-dimensional projection image with pixels (x,y) having an intensity related to the absorbance of said contrast agent-filled object; d) processing said 2-dimensional projection image to reconstruct the 3-dimensional image of said object, said processing including determining a distance D(x,y) travelled by said X-rays in the contrast agent-filled object by dividing the absorbance corresponding to the intensity of each pixel (x,y) by the concentration of the contrast agent within said object and multiplying the result thus obtained by the absorption coefficient of said contrast agent; dividing said distance D(x,y) by 2 to define a (&plus;z) coordinate (equals to &plus;D(x,y)/2) and a (−z) coordinate (equals to −D(x,y)/2) for each pixel (x,y); such that for each pixel (x,y) there is: 1) a (&plus;z) coordinate &equals;&plus;D(x,y)/2 and 2) a (−z) coordinate&equals;−D(x,y)/2; e) using the x,y,z coordinates thus determined to reconstruct the 3 dimensional image in a 3-dimensional axis system in which the x-y plane is parallel to the plane of symmetry of said object;