X-rays are a form of radiation, like light or radio waves, that can be focused into a beam, much like a flashlight beam. But unlike a beam of light, X-rays can pass through most objects, including the human body. When X-rays strike a piece of photographic film, they produce a picture. Dense tissues in the body, such as bones, block (absorb) many of the X-rays and appear 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 appear in shades of gray. Space that contains no tissue appears black on an X-ray picture.

To evaluate symptoms of possible sinusitis, X-rays of the sinuses may be taken from several directions.

Why It Is Done

An X-ray of the sinuses may sometimes be used to confirm a suspected diagnosis of acute sinusitis.

An X-ray of the sinuses was formerly the standard method of diagnosing acute sinusitis in the sinuses behind the cheeks (maxillary sinuses) or behind the eyebrows (frontal sinuses). Because a computed tomography (CT) scan shows a much clearer picture of the sinuses and other structures, the use of standard X-rays has declined.

However, standard X-rays are commonly used to help distinguish uncomplicated sinusitis from other problems that may cause similar symptoms, such as problems with the jaw joint, dental infections, or headache. The findings are often not reliable, though, so they should be evaluated with caution.

If complications of sinusitis develop or if it becomes necessary to see more of the sinuses or bones that surround them, a CT scan may be needed.

Results

Findings of an X-ray of the sinuses may include the following.

Normal

Normal findings on an X-ray of the sinuses will show:

• Normal bone structure.
• No evidence of fluid in the sinuses.
• No thickening of the mucous membrane.

Standard X-rays are fairly good at showing the frontal and maxillary sinuses (those in the cheek and forehead). They do not show the ethmoid and sphenoid sinuses as well. See a picture of the location of the facial sinuses .

Abnormal

Abnormal findings on an X-ray of the sinuses may show evidence of fluid in the sinus or a thickened mucous membrane. This is strong evidence of a sinus infection.

What To Think About

• X-rays of the sinuses may be unreliable in diagnosing sinusitis in babies under 1 year of age. The sinus cavities are not completely developed in children. A partly developed sinus on X-ray can look like it is infected.
• X-rays provide limited information about the sinuses located at the bridge of the nose (ethmoid sinuses), at the back of the nasal passage (sphenoid sinuses), or about the bony structure that surrounds the drainage openings of the sinuses (ostiomeatal complex).
• It can be difficult to interpret the results of a sinus X-ray. The X-ray may suggest sinusitis when the problem is actually something else.
• A sinus X-ray is less expensive than a CT scan, but it will also provide less detail.
• There is a slight risk of exposure to radiation.

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