What Is an X-Ray?

What to Expect When Undergoing This Test

An X-ray, also known as radiography, is a medical imaging technique. It uses tiny amounts of electromagnetic radiation to create images of structures inside the body. These images can then be viewed on film or digitally.

X-rays often are done to view bones and teeth, making them helpful in diagnosing fractures (broken bones) and diseases such as arthritis. A healthcare provider may also order an X-ray to look at organs and structures inside the chest, including the lungs, heart, breasts, and abdomen.

This article explains when X-rays are used, how to prepare for one, and what to expect. It also covers the risks and benefits of the imaging test.

How to Read an X-Ray
 Verywell / Cindy Chung 

How It Works

The tiny particles of electromagnetic radiation that an X-ray machine emits pass through all but the most solid objects in the body. As such, the image it creates, known as a radiograph, allows healthcare providers to visualize internal structures in your body.

What Is Electromagnetic Radiation?

Electromagnetic radiation (EMR) is a type of radiation that travels in waves and has electric and magnetic fields. Devices that use this type of radiation include X-rays, microwaves, radio waves, ultraviolet light, infrared light, visible light, and gamma rays.

Sometimes a contrast medium, a type of dye, is given to help images appear in greater detail. You might receive these via injection into a blood vessel, orally, or rectally.

X-ray images appear in various shades of white and grey. Because bones and metal objects are solid, less radiation passes through them, making them appear white on the radiograph. On the other hand, skin, muscle, blood and other fluids, and fat are grey because they allow most radiation to pass through.

Areas where there is nothing to stop the beam of radiation, such as air, or even a fracture, appear black compared to surrounding tissue.

When It's Used

X-ray technology is used for a multitude of purposes. For example, it can help healthcare providers evaluate symptoms and diagnose injuries.

Among the most common reasons for X-rays include:

  • Identifying fractures
  • Identifying infections in bones and teeth
  • Diagnosing cavities and evaluating structures in the mouth and jaw
  • Revealing bone tumors
  • Measuring bone density (the amount of mineral in your bones) to diagnose osteoporosis (a bone disease caused by bone loss)
  • Finding evidence of pneumonia, tuberculosis, or lung cancer
  • Looking for signs of heart failure or changes in blood flow to the lungs and heart
  • Revealing problems in the digestive tract, such as kidney stones, sometimes using a contrast medium called barium
  • Locating swallowed items such as a coin or tiny toy

This technology can also support other types of diagnostic procedures.

Fluoroscopy

During fluoroscopy, an X-ray image displays on a monitor in real-time. Unlike X-ray images, which are still pictures, fluoroscopy is a moving image. Often, you will receive a contrast dye intravenously (in your vein) during this procedure.

Seeing moving images allows healthcare providers to follow the progression of a procedure (such as the placement of a stent). They can also view the contrast agent passing through the body.

CT Scan

Computed tomography (CT scan) is a technique that takes a series of individual images of internal organs and tissues. These “slices” are then combined to show a three-dimensional visualization.

CT scans can identify organ masses, see how well blood is flowing, observe brain hemorrhage and trauma, view lung structures, and diagnose injuries and diseases of the skeletal system.

Mammography

A mammogram is a breast cancer screening test that uses X-ray imaging. Mammograms can also diagnose breast lumps and other breast changes.

During a mammogram, your breasts are placed one at a time between two plates. A technician then presses them together to flatten your breast to get a clear picture. Finally, they X-ray your breasts from the front and sides.

Arthrogram

Arthrography allows healthcare providers to identify signs of joint changes that indicate arthritis. It uses an X-ray and a special contrast dye injected directly into the joint.

Sometimes instead of X-rays, an arthrogram uses CT scan, fluoroscopy, or magnetic resonance imaging (MRI) technology.

Risks

Having an X-ray doesn't hurt and isn't particularly dangerous. However, there are a few things to be aware of and discuss with your healthcare provider.

Radiation Exposure

Having frequent X-rays carries a very low risk of developing cancer later in life. That is because the radiation has enough energy to potentially damage DNA.

There are varying estimates as to how significant this risk is. What is known is that fluoroscopy and computed tomography both expose the body to more radiation than a single conventional X-ray. The Food and Drug Administration (FDA) says that the risk of cancer from exposure to X-rays depends on:

  • Exposure frequency
  • Age at exposure
  • Which reproductive organs a person has
  • Area of the body exposed

The more times a person is exposed to radiation from medical imaging throughout their life and the larger the dose, the greater the risk of developing cancer. In addition, the lifetime risk of cancer is more significant for someone who's exposed to radiation at a younger age than for a person who has X-rays when they're older.

Studies have shown that those with female reproductive organs are at a somewhat higher lifetime risk for developing radiation-associated cancer. Researchers believe that since reproductive organs absorb more radiation and people with ovaries typically have more reproductive organs than those with testicles, this may be why.

It is essential to weigh the risks and benefits of having an X-ray, CT scan, or fluoroscopy with your healthcare provider. Ask if the imaging study will make an impact on your care. If not, it may be advisable to skip the test. However, if a diagnosis or potential changes in your treatment are likely to depend on the X-ray results, it will most likely be worth the minor risk.

Barium Sulfate Risks

There may be some minor risks associated with contrast mediums used during X-ray procedures, particularly for people who have asthma or other conditions.

Barium sulfate contrast materials are perfectly safe for most people. However, some circumstances can put a person at an increased risk of severe side effects such as throat swelling, difficulty breathing, and more. These include:

  • Having asthma or allergies, which increases the risk of an allergic reaction
  • Cystic fibrosis, which increases the risk of small bowel blockage
  • Severe dehydration, which may cause severe constipation
  • An intestinal blockage or perforation that could be made worse by the contrast agent

Iodine Risks

Iodine is another contrast medium used for X-rays. After exposure to this dye, a small percentage of people may develop delayed reaction hours or even days later. Most reactions are mild, but some can be more severe and cause the following:

  • Skin rash or hives
  • Wheezing
  • Abnormal heart rhythms
  • High or low blood pressure
  • Shortness of breath
  • Difficulty breathing
  • Throat swelling
  • Cardiac arrest
  • Convulsions

Given your overall health profile, a healthcare provider can help you determine if using a contrast agent is necessary and suitable for you.

Contraindications

Pregnant people are usually discouraged from having an X-ray unless it's vital. That's because there is a risk that the radiation from an X-ray could cause changes in developing fetal cells and thereby increase the risk of birth defects or cancer later in life. The risk of harm depends on a fetus's gestational age and the amount of radiation exposure.

That said, this recommendation is mainly precautionary. These risks are associated with very high doses of radiation, and a regular diagnostic X-ray does not expose you to high-dose radiation. Therefore, the benefits of what an X-ray could reveal often outweigh any risks.

If you need an X-ray during pregnancy, the following can reduce your risks:

  • Cover with a leaded apron or collar to block any scattered radiation
  • Avoid abdominal X-rays
  • Inform the X-ray technician if you are or could be pregnant

In addition, if you have a child who needs an X-ray, don't hold them during the procedure if you are or might be pregnant.

How To Prepare

Often, an X-ray is done as part of a visit to a healthcare provider or emergency room to diagnose symptoms or evaluate an injury. X-rays also complement specific routine exams, such as dental checkups. These types of X-rays usually take place in a medical office or the hospital.

Other times, a healthcare provider recommends screening X-rays, like mammograms, at regular intervals. These are often performed at imaging centers or hospitals by appointment.

The setting in which you get an X-ray and its reasons will determine your overall testing experience.

Timing

It's impossible to generalize how long an entire X-ray procedure will take. For example, it can take just a few minutes to get an image or two of an injured bone in an emergency room. On the other hand, a CT scan appointment can take longer.

If you're scheduling an X-ray, ask your healthcare provider to give you an idea of how much time you should allow.

Location

X-ray tests may take place in various locations, including:

  • Hospital imaging departments
  • Freestanding radiology and imaging clinics
  • Medical offices, particularly specialists such as orthopedics and dentists
  • Urgent care centers

What to Wear

Generally speaking, the X-ray tech will ask you to remove any clothing covering the X-rayed area. For some procedures that involve X-ray imaging, you'll need to wear a hospital gown. Therefore, you may want to choose clothing that's easy to change in and out of.

In addition, since metal can show up on an X-ray, you may need to remove your jewelry and eyeglasses before an X-ray.

Food and Drink

If you have an X-ray without contrast, you can usually eat and drink normally. However, if you are receiving a contrast agent, you may need to avoid consuming food and liquids for some time before.

For example, healthcare providers use barium to highlight structures in the digestive system. Therefore, they may tell you not to eat for at least three hours before your appointment.

People with diabetes are usually advised to eat a light meal three hours before receiving barium. However, suppose you receive the barium via an enema (a tube inserted into the rectum). In that case, you may also be asked to eat a special diet and take medication to cleanse your colon beforehand.

Cost and Health Insurance

Most health insurance policies will cover any medically necessary X-ray imaging. Of course, out-of-pocket costs vary and depend on the type of plan you have. For example, you may be responsible for a copay, or for the entire cost if you haven't met your deductible. Check with your insurance company to learn the specifics of your plan.

If you don't have insurance or you're paying out-of-pocket for an X-ray, the fee will depend on several things, including:

  • Which body part is imaged
  • The number of images taken
  • Whether a contrast dye is used

Similarly, if you are paying for your X-ray and have time to research the fees, you can call the hospital's billing department ahead of time to get a quote for the procedure. Doing so can help you know the cost you're obligated to pay.

What to Bring

You will need to have your insurance card with you at your X-ray. In addition, if your healthcare provider gave you a written order for the procedure, bring that as well.

During the Test

Because X-ray procedures vary widely, it isn't easy to generalize the experience. So instead, ask your healthcare provider for details about what to expect in your specific case.

Pre-Test

You may need to remove some or all of your clothing before the X-ray. A technician will escort you to a dressing room or other private area where you can change into a hospital gown. There will probably be a locker where you can safely store your clothing and other belongings.

If you have a test involving a contrast dye, you will receive that before your imaging procedure.

Healthcare providers may give contrast dyes in the following ways:

  • In a special drink you swallow
  • Injection
  • Intravenous (IV) line
  • Enema

Except for IV contrast dye, which allows for a constant stream of the material to be given, contrasts are administered before the X-ray. In other words, you will not have to wait for the dye to "take" before your imaging test.

How you receive the contrast depends on the substance used and what internal organs or structures your healthcare provider needs to view. For example, you might receive an iodine-based contrast dye injection into a joint for an arthrogram.

On the other hand, you might swallow a barium contrast to help illuminate your digestive system for fluoroscopy. Oral barium contrast dye may not taste good, but most people can tolerate the flavor long enough to swallow the prescribed amount.

If you have a barium enema, you may feel abdominal fullness and urgency to expel the liquid. However, the mild discomfort will not last long.

During the Test

A conventional X-ray is taken in a special room with an X-ray machine. During the test, you will:

  • Place a leaded apron or cover over your torso
  • Stand, sit, or lie down on an X-ray table
  • Position your body in specific ways
  • Use props such as sandbags or pillows to adjust your position

Once positioned correctly, you will need to be very still. That's because even slight movement can cause an X-ray image to come out blurry. A technician may even ask you to hold your breath.

Infants and young children may need support being still. Guardians often accompany small children into the procedure room for this reason. If you attend your child for support, you will wear a leaded apron to limit your radiation exposure.

For their protection, the technician will step behind a protective window to operate the X-ray machine while also watching you. It only takes a few seconds to take the picture. However, often multiple angles of the body part are necessary. So, after your first image, the technician will likely adjust you or the machine and take another picture.

For a CT scan, you will lie down on a table that moved you into a cylindrical machine that rotates around you to take many pictures from all directions. You won't feel anything during a CT scan, but it may be uncomfortable for you if you dislike being in enclosed spaces.

Post-Test

When the tech has all the required images, you will remove the lead apron (if used) and leave the room. If you need to change back into your clothes, they'll direct you to the dressing area to change out of your hospital gown.

After the Test

After you leave your appointment, you can return to your regular activities. If you received a contrast medium, a healthcare provider might instruct you to drink extra fluids to help flush the substance out of your system.

The barium-based dye comes out in your bowel movements, which will be white for a few days. You also may notice changes in your bowel movement patterns for 12 to 24 hours after your X-ray.

If you take Glucophage (metformin) or a related medication to treat type 2 diabetes, you need to stop taking your medicine for at least 48 hours after receiving contrast. That's because it may cause a condition called metabolic acidosis—an unsafe change in your blood pH (the balance of acidic or alkaline substances in the body).

Barium Side Effects

Keep an eye on the injection site if you received contrast dye by injection. Call your healthcare provider if you experience signs of infection, like pain, swelling, or redness.

Barium contrast materials can cause some digestive tract problems. If these become severe or don't go away, see your healthcare provider. These side effects include:

  • Stomach cramps
  • Nausea and vomiting
  • Diarrhea
  • Constipation

Iodine Side Effects

Likewise, iodine contrast can cause symptoms. Let your healthcare provider know if you begin to have even mild symptoms after receiving iodine contrast. These symptoms include:

  • Nausea and vomiting
  • Headache
  • Itching
  • Flushing
  • Mild skin rash and hives

Severe Side Effects

Call your healthcare provider immediately or go to the emergency room if you experience signs of anaphylaxis, a severe allergic reaction, including:

  • Hives
  • Itching
  • Red skin
  • Swelling of the throat
  • Difficulty breathing or swallowing
  • Hoarseness
  • Agitation
  • Confusion
  • Fast heartbeat
  • Bluish skin color

Interpreting Results

A radiologist specializing in analyzing imaging tests interprets the images from your X-ray. They then send the results and a report to your healthcare provider. Often, they will call you or have you come in to discuss the findings. In emergencies, you should receive these results soon after your X-ray.

Follow-Up

Any follow-up tests or treatment will depend on your particular situation. For example, if you have an X-ray to determine the extent of an injury to a bone and it reveals you have a break, the bone will need to be set. Likewise, a breast tumor revealed during mammography may require a follow-up biopsy to determine if it is malignant (cancerous) or benign (non-cancerous).

Summary

X-rays are imaging tests that use small amounts of electromagnetic radiation to view the inside structures of your body. In addition to conventional X-rays, several other specialized forms of X-rays capture images in more precise ways. Sometimes a contrast agent can help healthcare providers see things better. These dyes might be given via injection, IV, orally, or rectally.

X-rays don't typically require preparation unless you are receiving contrast. In that case, you may need to avoid food and drinks for a few hours beforehand. X-rays do not take long—usually just a few minutes. Often, a technician takes multiple angles and images of the area. Afterward, you will be able to leave right away. If you received contrast, you might notice side effects. You should tell your healthcare provider about any symptoms you experience.

A Word From Verywell

For the majority of people, X-rays are harmless. However, if you have to have multiple X-rays over a lifetime, you may be at increased cancer risk. As such, it's essential to talk to your healthcare provider before you have an X-ray to make sure you have all the information you need to make an informed decision. And if you are or could be pregnant, tell the technician before undergoing the procedure.

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9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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