Skull and maxillofacial radiography
Radiographs of the whole head were traditionally required for a variety of purposes and because of the complexity of the structure of the maxillofacial skeleton a range of projections was devised. In some cases these techniques have been superseded by computed tomography (CT) (see Ch. 18) and cone beam computed tomography (CBCT) (see Ch. 16). However, this sophisticated CT equipment is not universally available. This chapter therefore provides a brief summary of the original main maxillofacial/skull projections, why and how each is taken, what the resultant radiograph looks like and which normal anatomical features are shown.
Equipment, patient positioning and projections
Most skull radiographs are taken using an isocentric skull unit such as the Orbix®, often with the patient lying down, or using a conventional skull unit such as the Craniotome® with the patient sitting up, as shown in Fig. 13.1.
The main maxillofacial/skull projections are:
• Standard occipitomental (0° OM)
• Posteroanterior of the skull (PA skull) or occipitofrontal (OF)
• Posteroanterior of the jaws (PA jaws)
Standard occipitomental (0° OM)
Main indications
Technique and positioning
This can be summarized as follows:
1. The patient is positioned facing the image receptor with the head tipped back so the radiographic baseline is at 45° to the image receptor, the so-called nose–chin position. This positioning drops the dense bones of the base of the skull downwards and raises the facial bones so they can be seen.
2. The X-ray tubehead is positioned with the central ray horizontal (0°) centred through the occiput (see Fig. 13.3B).
30° occipitomental (30° OM)
Main indications
The main clinical indications include:
Note: Ideally for fracture diagnosis two views at right angles are required (see Ch. 29), but the 0° OM and 30° OM provide two views of the facial bones at two different angles – therefore in cases of suspected facial fracture both views are needed.
Technique and positioning
This can be summarized as follows:
1. The patient is in exactly the same position as for the 0° OM, i.e. the head tipped back, radiographic baseline at 45° to the image receptor, in the nose–chin position.
2. The X-ray tubehead is aimed downwards from above the head, with the central ray at 30° to the horizontal, centred through the lower border of the orbit (see Fig. 13.6).
