What Is an X-ray?
By Lynn Marks
Medically Reviewed by Sanjai Sinha, MDLast Updated: 10/23/2015
This longstanding form of medical imaging is still one of the most useful.
An X-ray is a procedure that produces images of the inside of your body.
X-ray beams are a form of electromagnetic radiation, first discovered by German professor Wilhelm Conrad Roentgen in 1895.
In the procedure, a machine sends X-ray beams through your body.
The resulting images are recorded either on film or by a computer.
X-ray images show the body in shades of black and white, because different tissues absorb different amounts of radiation.
Dense materials in the body (such as bones or metal) show up as white on an X-ray image.
Parts of the body that contain air appear as black, while muscle, fat, and fluids show up as shades of gray.
Sometimes, a contrast medium (containing iodine or barium) is injected, swallowed, or delivered as an enema to provide more detail on X-ray images.
X-rays can examine many parts of the body. Some of the most common reasons X-rays are given are to view or diagnose:
- Bone fractures or infections
- Tooth decay
- Bone cancer
- Lung infections such as pneumonia
- Breast cancer
- Blocked blood vessels
- Swallowed objects
- Digestive tract problems
- An enlarged heart
The X-ray Procedure
X-rays can be performed at a doctor’s office, dentist’s office, hospital, or other medical facility.
The procedure can take anywhere from a few minutes to more than an hour, depending on the type of image your doctor or dentist needs.
A technician will position your body and the X-ray machine.
You will need to remain still and may have to hold your breath during the X-ray. Movement can cause blurry images.
The machine will capture images of your body as you sit, stand, or lie still. The process is painless.
If you need a contrast medium for your X-ray, you’ll swallow it or receive it by an intravenous injection or enema ahead of time.
Before an X-ray
Follow all instructions your doctor provides before an X-ray.
Be sure to let your doctor know if you’re pregnant or may become pregnant.
Also, tell your doctor if you’re using an intrauterine device (IUD) for birth control.
You may have to remove all jewelry and other metal objects from your body before having an X-ray.
After an X-ray
Typically, you can resume normal activities after an X-ray.
Be sure to drink plenty of fluids if you had an X-ray with a contrast medium.
X-rays expose your body to radiation, which some people worry could raise the risk of developing cancer.
However, the level of exposure in adults is usually very low, and the benefits typically outweigh the risks.
Let your doctor know if you’re pregnant, because radiation exposure may not be safe for an unborn baby.
If you receive a contrast medium for your X-ray, you could experience the following side effects:
- Metallic taste
- Lightheadedness or nausea
- Hives or itching
- Flushing of face and neck
In rare cases, the contrast medium can cause a serious reaction, such as:
- Severe low blood pressure
- Cardiac arrest
- Anaphylactic shock (a severe allergic reaction)