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15. Appendices
180 vatech A9 (Model name: PHT-30CSS) User Manual
The most critical component in producing a diagnostically acceptable panoramic
image is patient positioning. All panoramic x-ray machines have guidelines to assist
with positioning the dental arches within the three dimensions of the focal trough, an
area where the anatomical structures will be imaged in relative clarity. Most
panoramic x-ray machines have a bite block to indicate the correct anterior-posterior
position, or how far forward or back the patient should be positioned, side positioner
guides for determining the correct lateral alignment, and chin rest to correctly locate
the superior-inferior dimension or how far up or down the chin should be
positioned.
4,10 Panoramic x-ray machines are available with a mirror and laser light
beam guide that shines on the patient's face to illustrate various anatomical planes
(Figure 2)
. Incorrectly positioning the patient in any of these three dimensions will
produce unique and distinct radiographic image errors (Table 1) .