In search for the third dimension: from radiostereoscopy to three-dimensional imaging.

The radiographic image is the bidimensional projection of a tridimensional volume. Interpretation of such an image is sometimes uneasy as we cannot determine ot which level the shadows are located. To dissociate the superimposed shadows, the radiologist may rely on different techniques including fluoroscopy, profile view, radiosteoroscopy, conventional tomography, transverse axial tomography or really three-dimensional imaging techniques such as computer assisted (axial) tomography, ultrasound, and magnetic resonance imaging. This paper makes a short historical overview of these different techniques.