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 very small amounts of electromagnetic radiation to create images of structures inside the body that can be viewed on film or digitally. X-rays often are done to view bones and teeth, making them useful for diagnosing breaks, fractures, and diseases such as arthritis. A healthcare provider may order an X-ray to look at organs and structures inside the chest, including the lungs, heart, and breasts, and in the abdomen to evaluate the digestive tract.

How to Read an X-Ray
 Verywell / Cindy Chung 

Purpose of Test

The tiny particles of electromagnetic radiation emitted by an X-ray machine pass through all but the most solid of objects in the body. As such, the image it creates, known as a radiograph, is useful for healthcare providers interested in visualizing significant internal structures. Sometimes a contrast medium, a type of dye, is introduced into the body to help images show up in greater detail.

The individual elements render 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. Skin, muscle, blood and other fluids, and fat will be grey because they allow the largest amount of radiation to pass through.

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

X-ray technology is used throughout the medical world for a multitude of purposes.

Conventional X-ray images can be very useful to healthcare providers in evaluating symptoms that originate inside the body as well as diagnosing injuries. Among the most common uses of conventional X-ray are:

  • Identifying fractures (cracks) and breaks or infections in bones and teeth
  • Diagnosing cavities and evaluating structures in the mouth and jaw
  • Picking up on signs of joint changes that indicate arthritis using a special type of X-ray image called an arthrogram
  • Revealing tumors on bones
  • Measuring bone density as a means of diagnosing osteoporosis
  • Finding evidence of pneumonia, tuberculosis, or lung cancer (chest X-rays)
  • Examining breast tissue for signs of cancer using a special X-ray technique called mammography
  • 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 is also used to support other types of diagnostic procedures:

  • Fluoroscopy: For this imaging technique, an X-ray image is displayed on a monitor in real time. This makes it possible to follow the progression of a procedure (such as the placement of a stent) or the movement of a contrast agent as it passes through the body.
  • Computed tomography (CT): This technique takes a series of individual images called “slices” of internal organs and tissues that are combined to allow for three-dimensional visualization.

Risks and Contraindications

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

Radiation Exposure

Having frequent X-rays can carry a very low risk of developing cancer later in life. This 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 U.S. Food and Drug Administration (FDA) says that the risk of cancer from exposure to X-rays depends on:

  • Dose: 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.
  • Age: The lifetime risk of cancer is larger for someone who's exposed to radiation at a younger age than for a person who has X-rays when older.
  • Sex: Women are at a somewhat higher lifetime risk than men for developing radiation-associated cancer after receiving the same exposures at the same ages.
  • Area of the body: Some organs are more sensitive to radiation than are others.

It is important 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 results of the X-ray, then it will most likely be worth the small risk.

Contrast Mediums

There may be some small 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, but there are some circumstances that can put a person at an increased risk of serious side effects such as throat swelling, difficulty breathing, and more. These include:

  • A history of asthma, hay fever, or other allergies, which increases the risk of an allergic reaction to additives in the barium sulfate agent
  • Cystic fibrosis, which will increase the risk of blockage in the small bowel
  • Severe dehydration, which may cause severe constipation
  • An intestinal blockage or perforation that could be made worse by a barium sulfate agent

After being injected with a contrast dye made from iodine, a small percentage of people may develop a delayed reaction hours or even days later. Most are mild, but some can be more severe and cause skin rash or hives, wheezing, abnormal heart rhythms, high or low blood pressure, shortness of breath, or difficulty breathing. A person having a severe response may experience difficulty breathing, swelling of the throat or other parts of the body, profound low blood pressure, cardiac arrest, or convulsions.

Your healthcare provider will help you determine if use of a contrast agent is necessary and right for you given your overall health profile.


Women who are expecting a baby usually are discouraged from having an X-ray unless it's absolutely vital. That said, this recommendation is largely precautionary. These problems are associated with very high doses of radiation. A regular diagnostic X-ray will not expose a pregnant woman to high-dose radiation, and the benefits of what an X-ray could reveal will usually outweigh any risks. In addition, most X-ray tests, including those of the arms, legs, head, teeth, or chest, won't expose your uterus and other reproductive organs to radiation; you can be covered with a leaded apron or collar to block any scattered radiation.

The exception is abdominal X-rays, which may expose your baby to direct X-ray beams. The risk of harm to your baby depends on your baby's gestational age and the amount of radiation exposure.

Before having an X-ray, tell your healthcare provider if you're expecting or if there's even a chance you could be pregnant. It might be possible to postpone the test or modify it to reduce the amount of radiation. In addition, if you have a child who needs an X-ray, don't hold your child during the exam if you are or might be pregnant.

Before the Test

Often, an X-ray will be done as part of a visit to your practitioner or emergency room to diagnose symptoms or evaluate an injury. X-rays are also taken as part of certain routine exams, such as dental checkups. At other times, as in screening tests such as mammograms, an X-ray is performed as a single procedure, usually at regularly prescribed intervals.

The setting in which you get an X-ray, and the reasons for it, will dictate your overall testing experience.


It's impossible to generalize about how long an entire X-ray procedure will take. It can take just a few minutes to get an image or two of an injured bone in an emergency room, while 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 allot.


Most of the time, X-rays are done in hospital imaging departments (particularly in the case of emergency situations) or freestanding radiology and medical imaging clinics. Some practitioners' offices are equipped to do X-rays, particularly those with certain specialties such as orthopedics and dental care. Many times urgent care centers have onsite X-ray machines as well.

What to Wear

Your clothing choices for an X-ray will depend on the type of test you're having, the body part being imaged, and the purpose of the test. Generally speaking, you will be asked to remove any clothing covering the part of the body to be X-rayed. For some procedures that involve X-ray imaging, you'll need to wear a hospital gown, so you may want to choose clothing that's easy to change into and out of.

You may need to take off your jewelry and eyeglasses before an X-ray depending, again, on where on your body the radiation will be directed; metal can show up on the image.

Food and Drink

If you will be having an X-ray using barium contrast dye, which is used most often to highlight structures in the digestive system, you will be told not to eat for at least three hours before your appointment. People with diabetes usually are allowed to eat a light meal three hours before receiving barium. If the barium will be administered via an enema, you also may 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 type of X-ray imaging that's medically necessary if you've met your deductible, though you may be responsible for a copay or co-insurance. 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 the body part being imaged, the number of images taken, whether a contrast dye is used, and many other factors. Similarly, if you are paying for your X-ray and have time to research the fees, do that so that you know what you'll be obligated to pay for.

What to Bring

You will need to have your insurance card with you at your X-ray. If your healthcare provider wrote a prescription for the procedure, bring that as well.

During the Test

Because X-ray procedures vary widely based on the purpose of the test, the parts of the body being imaged, the type of X-ray, and more, it's difficult to generalize the experience. In addition to reading through the broad description of what is likely to take place during an X-ray procedure that follows, ask your practitioner to give you as much detail as possible about what to expect in your specific case.


Depending on the part of your body to be imaged, you may need to remove some or all of your clothing. You'll be escorted to a dressing room or other private area where you can change into a hospital gown. There probably will be a locker where you can safely store your clothing and other belongings.

If you will be having a test that involves a contrast dye, you will either swallow it in a special drink or it will be put into your body via injection, intravenous line, or enema, depending on the substance being used and what internal organs or structures are to be viewed. For example, iodine-based contrast dye may be injected into a joint for an arthrogram, which is often used to diagnose bursitis or to discover the reason for shoulder pain. A contrast medium containing barium may be swallowed to help illuminate how a part of the digestive system is functioning in real time during 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 are given barium rectally, you may have a feeling of abdominal fullness and an urgency to expel the liquid. The mild discomfort will not last long.

With the exception of IV contrast dye, which allows for a constant stream of the material, injectable, oral, and rectally administered contrasts will be given just prior to the X-ray images being taken. In other words, you will not have to wait for the dye to "take" before your imaging test.

During the Test

A conventional X-ray will be taken in a special room where you will be asked to stand, sit, or lie down on an X-ray table. In order to capture the part of the body to be imaged, the technician will ask you to position your body in specific ways. They may move parts of your body for you or use props such as sandbags or pillows to position you properly.

Once you're positioned correctly you will need to be very still: Even slight movement can cause an X-ray image to come out blurry. You may even be asked to hold your breath. Note that young children having an X-ray may need to be gently restrained to help them hold still.

The technician also may cover body parts that are not being imaged with a lead apron to protect them from exposure to radiation. For their own protection, they will then step behind a protective window from where they can operate the X-ray machine while also watching you. It will take no longer to take an X-ray than it does to take a photograph—a few seconds.

If multiple views of a body part are necessary, you may need to be positioned in different ways, or the machine may be moved to capture images at different angles. For each X-ray taken, the technician will set you up, adjust the machine, step behind the window, and take the image.

Note that mammograms are done using special X-ray machines with special plates that compress the breast so that the tissue spreads as flat as possible. This can be uncomfortable, but only for a few seconds per image taken. According to the American Cancer Society, a mammogram usually involves imaging each breast from two different angles for a total of four X-rays.

For a CT scan, you will lie down on a table that moved you into a cylindrical machine that rotates around you in order 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.


When all the required images have been taken, the lead apron (if one was used) will be removed and you will be allowed to leave the room. If you need to change back into your street clothes, you'll be directed 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 were given a contrast medium, you may be instructed to drink extra fluids to help flush the substance out of your system.

If you had barium-based dye, it will be expelled in your bowel movements, which will be white in color 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 may be asked to stop taking your medication for at least 48 hours after the contrast is administered, as it may cause a condition called metabolic acidosis, or an unsafe change in your blood pH.

Managing Side Effects

Keep an eye on the injection site if you received contrast dye by injection and call your healthcare provider if you experience pain, swelling, or redness.

Barium contrast materials can cause a number of digestive tract problems, including stomach cramps, nausea and vomiting, diarrhea, or constipation. If these become severe or don't go away, see your practitioner.

Call your healthcare provider immediately or go to the emergency room if you experience any of these symptoms after having had a barium-based contrast dye, which are signs of a more severe reaction:

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

Likewise, iodine contrast can cause symptoms such as nausea and vomiting, a headache, itching, flushing, mild skin rash, and hives. Even if you begin to have mild symptoms after receiving iodine contrast, let your healthcare provider know. If you're having a reaction that's more severe, go to the emergency room.

Interpreting Results

The images from your X-ray usually are interpreted by a practitioner called a radiologist, who specializes in analyzing these tests. The results are then sent to your healthcare provider, who will call you or have you come in to discuss the findings. In emergency situations, you should receive these results soon after your X-ray.


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 may need to be set. A breast tumor revealed during a mammography may need to be followed by a biopsy so the type and stage of cancer can be diagnosed.

A Word From Verywell

X-ray technology has been an indispensable part of medical care for a very long time. It has myriad uses, from diagnosing an injury to a bone during an emergency room visit to identifying a tumor on a lung to evaluating a problem with the digestive process. 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 an increased risk of cancer. As such, it's important 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.

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6 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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  2. U.S. Food & Drug Administration. Medical x-ray imaging. Updated June 14, 2019.

  3. RadiologyInfo.org. Contrast materials. Updated July 23, 2018.

  4. U.S. Food & Drug Administration. X-Rays, pregnancy and you. Updated December, 9, 2017.

  5. RadiologyInfo.org. X-ray (radiography).

  6. American Cancer Society. Mammogram basics. Updated October 3, 2019.

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