X-ray: Everything You Need to Know

Medically Reviewed By Kevin Martinez, M.D.
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An X-ray is a common method of scanning the body. Doctors and dentists use X-rays to get clear images of bones, tissue, organs, or teeth. X-rays use a form of ionizing radiation to take images. This is similar to light, except X-rays have higher energy, meaning they can pass through the body. X-rays then hit a detector on the other side of the person, and this creates shadows, which appear on the scan to show a detailed image. These images are called radiographs.

Doctors and dentists can use X-rays to check for cavities, fractures, and tumors, among many other diagnostic factors.

Read on to learn more about X-rays, including how they work, any risks they may cause, and what to expect during an X-ray.

How do X-rays work?

a man is looking at an X ray
Vradiy Art/Stocksy United

To take an X-ray, radiographers will position a person between an X-ray source and an X-ray detector. The X-ray source sends waves of electromagnetic radiation through the body. Your body parts absorb the waves in different amounts depending on how dense they are.

For example, bones contain high amounts of calcium, which is dense. Therefore, bones absorb more of the X-rays as the X-rays pass through, and the detector picks up fewer X-rays at the other end. That means that the bones show up as being white on the image, which has a black background.

Fat, muscle, and air are less dense and absorb fewer X-rays. This means they do not show up as clearly as bones and may appear translucent or gray on the image.


X-rays are especially useful in diagnoses that require clear images of the hard tissues in the body. This can include conditions such as:

Sometimes, doctors may inject you with a contrast dye before an X-ray. This dye helps certain parts of the body, including soft tissue, appear more clearly on the scan. For example, doctors may use this dye alongside X-rays to examine the gastrointestinal tract or the uterus.

Doctors also use X-rays to help in certain procedures. X-rays give doctors a clearer image and they can carry out procedures more accurately and easily, including:

  • catheter angiography
  • stereotactic breast biopsies
  • intra-articular steroid injection

Learn about chest X-rays here.


Several examinations or procedures use X-rays for a range of diagnostic and treatment-based benefits.

Diagnostic types of X-rays

The following types and examples are common uses of X-rays in a diagnostic setting:

X-ray radiographybone fractures, tumors, pneumonia, injuries, calcifications, foreign objects, and dental issues, such as cavities
Mammographytumors and cancers of the breast tissue, and microcalcifications, which can be benign or indicative of cancer
CT (computed tomography) scancross-sectional images that come together to form a 3D X-ray and can be more detailed than regular X-rays
Fluoroscopyshows movements and diagnostic processes within the body, including real-time blood flow through the heart, blood vessels, or organs

Treatment-based types of X-rays

The following types and examples are common uses of X-rays in a therapeutic setting:

Cardiac angioplastyuses contrast dye and fluoroscopy to help doctors thread a catheter through the body to the heart, opening up clogged arteries
Radiation therapyuses high doses of high-energy X-rays to destroy cancerous cells by changing their cell DNA


According to the Centers for Disease Control and Prevention (CDC), the radiation exposure X-rays could lead to some short-term and long-term risks, but the benefits of X-rays usually outweigh the possible risks.

The dose of ionizing radiation that X-rays use can damage cell DNA. Usually, however, this damage is so small that the body repairs itself. If the body receives too much radiation over a period of time, it can lead to more permanent changes in cell DNA, such as cancer.

It is also important to remember that everyone experiences daily exposure to radiation. When performing X-rays, doctors will use the lowest dose of radiation necessary for a clear image, and they will protect the other parts of the body that do not need X-rays.

Fluoroscopies use higher doses of radiation and can cause short-term side effects, such as flushed skin and hair loss.

If you are concerned about the risks of X-rays, discuss them with your doctor. It may be possible for you to undergo a different type of scan that does not use ionizing radiation, such as an MRI scan or an ultrasound.

You should always inform your doctor before an X-ray if you think you may be pregnant.

Technological developments of X-rays

Experts from the National Institute of Biomedical Imaging and Bioengineering are currently undertaking research to improve X-rays by:

  • reducing the amount of radiation needed for a clear image
  • improving the clarity of images
  • improving materials and methods of applying contrast to the procedure

Preparing for an X-ray

You will normally receive an appointment time for your X-ray in advance. Staff may ask you to arrive a little early to fill out a questionnaire before the scan.

You should always tell your doctor or the radiologist performing the scan if you believe you could be pregnant. You should also mention any metal you may have inside your body, including piercings, implants, or items such as bullets.

Before the scan begins, staff will ask you to take off any metallic clothing or accessories you are wearing, including jewelry or zippers. You may need to remove underwear if it contains metal. Staff may give you a hospital gown to wear during the scan if necessary.

If you need contrast dye during the scan, you may receive this as a pill or through an IV cannula.

Learn six questions to ask before getting a medical scan here.

What to expect during an X-ray

Staff may ask you to lie down or sit at a certain angle or position while they perform the X-ray.

Dentists may give you a device to put between your teeth and bite down on while the X-ray is happening.

Sometimes, staff will give you a lead covering to place over parts of the body that need extra protection from radiation.

You will need to keep as still as possible during the X-ray. This helps the images to appear more clearly. X-rays are not as noisy as MRI scans but you can keep in contact with radiographers during the scan if you feel concerned or uncomfortable at any point.

The duration of the X-ray will depend on the type of scan radiologists are performing and whether they need to use contrast dye.

Receiving the results of an X-ray

You will usually receive the results of your X-ray at a follow-up appointment, over a phone call, or through your online health portal.

Radiographers will provide a report of their findings and send them to your doctor or the person who referred you for the X-ray.

After this, you will receive treatment depending on the findings of the X-ray. If doctors ordered the scan to rule out a certain condition but are still not sure of a particular diagnosis, you may need to undergo further testing.


X-rays are useful for the diagnosis of certain medical conditions, such as fractures, cavities, and pneumonia. They use low doses of ionizing radiation to produce shadows that show up as images of certain parts of the body.

The radiation from X-rays can lead to some short-term and long-term side effects, and radiation can lead to cancer in high doses. However, X-rays use the lowest possible dose of radiation and the body can usually heal any cell damage itself. The benefits of X-rays in diagnosing conditions generally outweigh their possible risks.

If you feel concerned, you can discuss the pros and cons of X-rays for your specific case with your doctor.

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Medical Reviewer: Kevin Martinez, M.D.
Last Review Date: 2022 Feb 25
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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