X-rays are a form of radiation, like light or radio waves, that are focused into a beam, much like a flashlight beam. X-rays can pass through most objects, including the human body. X-rays make a picture by striking a detector that either exposes a film or sends the picture to a computer. Dense tissues in the body, such as bones, block (absorb) many of the X-rays and look white on an X-ray picture. Less dense tissues, such as muscles and organs, block fewer of the X-rays (more of the X-rays pass through) and look like shades of grey on an X-ray. X-rays that pass only through air, such as through the lungs, look black on the picture.
A skull X-ray may help find head injuries, bone fractures, or abnormal growths or changes in bone structure or size.
Why It Is Done
Skull X-rays have largely been replaced by CT scans. A skull X-ray may be done to:
- Find fractures.
- Find a metallic foreign object stuck in the skull.
- Check problems on a baby's head, such as an odd shaped skull.
How To Prepare
Before the X-ray test, tell your doctor if you are or might be pregnant. Pregnancy and the risk of radiation exposure to your unborn baby (fetus) must be considered. The risk of damage from the X-rays is usually very low compared with the potential benefits of the test. If a skull X-ray is absolutely necessary, a lead apron will be placed over your abdomen to shield your baby from exposure to the X-rays.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form ( What is a PDF document? ).
You don't need to do anything else before you have this test.
How It Is Done
A skull X-ray is taken by a radiology technologist. The X-ray pictures are usually read by a doctor who specializes in interpreting X-rays (radiologist).
You will need to remove any jewellery that may be in the way of the X-ray picture. You will also need to remove glasses or dentures.
You may be asked to lie on an X-ray table or sit in a chair. The bones of the skull and face are so detailed that several views from different angles are needed. A series of X-ray pictures is usually taken from the front, back, top, and sides of your head. You should hold your head completely still while the pictures are being taken. A padded brace, foam pads, a headband, or sandbags may be used to hold your head in place while the pictures are taken.
Skull X-rays usually take about 10 to 20 minutes. You will wait about 5 minutes until the X-rays are processed in case repeat pictures need to be taken. In some clinics and hospitals, X-ray pictures can be shown immediately on a computer screen (digitally).
How It Feels
You will feel no discomfort from the X-rays. The X-ray table may feel hard and the room may be cool. You may find that the positions you need to hold are uncomfortable or painful, especially if you have an injury.
There is always a slight risk of damage to cells or tissue from being exposed to any radiation, including the low levels of radiation used for this test. But the risk of damage from the X-rays is usually very low compared with the potential benefits of the test.
For example, the radiation exposure from a chest X-ray is about equal to the natural radiation exposure received during a round-trip airline flight from Montreal to Vancouver or 10 days in the Rocky Mountains.
A skull X-ray is a series of pictures of the bones of the skull. In an emergency, the doctor can see the initial results of a skull X-ray in a few minutes. Otherwise, a radiologist usually has the official X-ray report ready the next day.
The bones of the skull are normal in size and appearance.
No foreign objects, abnormal growths, or bone abnormalities are present.
No broken bones are present.
Foreign objects, such as fragments of metal or glass, may be present.
Abnormal growths, such as tumours, may be present.
Broken bones may be present.
Signs of a disease that affects the bones of the skull may be present.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- If you can't remain still during the test. The pictures may not be clear.
- If you have a possible neck injury. In this case, it may not be possible to do a complete set of skull X-rays.
- If you have a false eye (prosthetic eye) or other artificial or metal objects on the head. These can make a shadow on the X-ray picture that hides part of the bones.
What To Think About
- A computed tomography (CT) scan may be done instead of a skull X-ray. A CT scan shows more detail than an X-ray does. It may show tiny fractures better than an X-ray and can also show injuries to the brain and other tissues. CT scans are more expensive than skull X-rays and may not be available in some areas. To learn more, see the topic Computed Tomography (CT) Scan of the Head and Face.
- Your X-ray results may be different from earlier test results because you were tested at a different medical centre or you had a different kind of test.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Current as ofJune 25, 2018
Author: Healthwise Staff
Medical Review: Adam Husney, MD - Family Medicine
Brian O'Brien, MD, FRCPC - Internal Medicine
Martin J. Gabica, MD - Family Medicine
Howard B. Schaff, MD - Diagnostic Radiology