The side of the patient’s dental arches closest to the receptor is recorded in focus while the side closest to the x-ray source is blurred out of focus (Figure 19). The x-ray source has a vertical slit aperture and directs the x-ray beam in a lingual to labial direction through the structures. Panoramic machines vary in style but operate according to the principles outlined above. Some models allow the patient to sit-down and while in others the patient stands. The resulting image is uniformly magnified due to the long object-receptor distance with some premolar contact overlapping. However, this technique produces reasonably good overall representations of the teeth and surrounding anatomical structures.
Figure 19. Schematic diagram of simple panoramic motion incorporating slit beam radiography and linked motion of x-ray tubehead and receptor.