Oblique lateral radiography
Oblique lateral radiographs are extraoral views of the jaws that can be taken using a dental X-ray set (see Fig. 10.1). Before the development of panoramic equipment they were the routine extraoral radiographs used both in hospitals and in general practice. In recent years, their popularity has waned, but the limitations of panoramic radiographs (see Ch. 12) have ensured that oblique lateral radiographs still have an important role.
The image receptor and the sagittal plane of the patient’s head are parallel and the X-ray beam is perpendicular to both of them. This is the positioning for the true lateral skull radiograph taken in a cephalostat unit described in Chapter 11.
The image receptor and the sagittal plane of the patient’s head are not parallel. The X-ray beam is aimed perpendicular to the image receptor but is oblique to the sagittal plane of the patient. As a result, a variety of different oblique lateral projections is possible with different head and X-ray beam positions.
Fig. 10.3 Equipment used for oblique lateral radiography. (i) An 11 × 18 cm cassette A and lead shield B. (ii) An example of an angle board showing the cassette A, lead shield B and the plastic earpieces P for patient positioning.