This cross-sectional scanning method allows the radiologist to look at different levels of the skull bones, specifically the bone ridge behind the ear. A rotating X-ray beam creates images that resemble slices and allow the radiologist to assess the skull bones for injury, infection, fluid levels and abnormalities.

This exam may include injecting an iodine substance in the vein. Diabetic patients and those with allergies must inform the radiology staff and may need clearance from their doctor before the exam. Blood tests may also be required prior to the administration of contrast materials. Patients whose exam includes an injection may not to eat or drink anything four hours before the test. During the injection the patient may experience a warm sensation throughout the body and a metal taste in the mouth. This is normal.

This procedure is done in two positions. For both positions, the head is positioned in a holder, and the patient is asked to lie very still. For the first position, patients lie on their back with arms at the sides. For the second position, the patient lies on the stomach with the head resting on the chin. Only the head is covered by the scanner, and the scanner is open at the back and the front, allowing the patient to see out. This procedure usually takes approximately 30 minutes.