A CT scan of the head produces an image of a cross section of the head. It is a safe procedure. It uses X-ray beams, but provides much more detail than a standard X-ray film. It can help diagnose various problems, such as tumors, blood clots, or injured tissue.

CT is short for computerized tomography. Tomography means that the X-ray tube travels in an arc around the head. It sends many beams though the same flat plane. The beams are altered by the nature of tissues they pass through. These changes are detected on the other side of the head and analyzed by computer. The computer translates the image to a film that contrasts various tissue types in different shades.

CT scans of the head are used to:
* diagnose various brain abnormalities,
* monitor the effects of surgery or cancer therapy,
* assess nerve problems that suggest a brain tumor, and
* find internal bleeding after a head injury.

Scanning typically lasts from 15 to 30 minutes. It is painless. The person may receive an injection of dye to create contrast. If so, the person is instructed to fast for 4 hours before the test. Some people are sensitive to the contrast dye. A sign of this is past reactions to shellfish. The dye may cause warm feelings, flushed face, temporary headache, salty taste, or nausea and vomiting.

During a CT scan, the person lies still on a table. It is important not to move the head during the scan. A device or straps hold the head in place, but does not cover the face. The person removes all jewelry and metal from head and neck. The table slides into the CT unit, which is like a small tunnel. The scanner rotates around the head, and may make clacking noises. Communication is maintained throughout the procedure. If a person becomes panicky, the procedure may be stopped at any time. Some people have a fear of enclosed spaces. The doctor may give a mild sedative to restless or anxious people.

After a CT scan, one should watch for signs of delayed reaction to the contrast dye. These include itching, rash, sweating, or difficulty breathing. The patient should drink plenty of fluids to rid the body of the dye.

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