We’re all exposed to radiation every day. Background radiation occurs naturally in the ground, the soil, and water. It also comes from various other natural and man-made sources.

X-rays are common medical imaging tests. They use a type of radiation called ionizing radiation. This type of radiation can lead to cancer but only in higher doses.

Medical tests that involve X-rays generally expose us to only small amounts of radiation. However, with the increase in imaging tests being used, people are becoming more concerned about radiation risks.

Ionizing radiation is classified as a human carcinogen. It can damage cells and DNA and cause cancer. However, many common imaging tests use very low doses of radiation and pose only a minimal risk when performed properly.

Experts agree that the benefits far outweigh the risks. X-rays have saved millions of lives by helping doctors diagnose, monitor, and treat many medical conditions.

Several types of medical imaging procedures use X-ray technology. They use an X-ray beam to view the internal structures of the body for different purposes. Each procedure poses a different associated risk depending on the type of X-ray used and the area of the body being viewed.

We’ll take a look at different types of imaging procedures and their effective dose for an average-sized adult. The dose for each X-ray is compared to the natural background radiation that we’re all exposed to daily.

Radiographs

A radiograph — commonly known simply as an X-ray — provides a quick static image of a body part. Simple X-rays use very little radiation. Studies have not found an increased risk of cancer in people who’ve received very low doses of radiation.

x-rays and radiation dose

The radiation dose varies depending on the body part. Here are three examples:

  • Chest X-ray. 0.1 mSv, comparable to 10 days of natural background radiation
  • Extremity X-ray. 0.001 mSv, comparable to 3 hours of natural background radiation
  • Spine X-ray. 1.5 mSv, comparable to 6 months of natural background radiation

Mammograms

A mammogram is a low-dose X-ray that’s used to look for changes in breast tissue. The radiation dose from a mammogram is 0.4 mSv, which is comparable to 7 weeks of natural background radiation.

Computed tomographic (CT) scans

CT scans create 3-D pictures that allow doctors to view your organs and other tissues. They use higher doses of radiation than most other types of imaging tests, leading to an increased risk of cancer.

Experts agree that while the benefits are worth the risk, CT scans should be ordered only when medically necessary and no other lower-radiation alternatives exist. This is especially the case for children under the age of 20 because children are more sensitive to the effects of radiation and have more years to develop cancer.

The effective doses from diagnostic CT scans are estimated to range from 1 to 10 mSv, which is comparable to a few months to several years of background radiation.

Positron emission tomography (PET) scans

PET scans use gamma rays, which have a higher energy than X-rays. Instead of a view of an organ, they show how an organ or system is functioning. A small amount of radioactive material is injected or swallowed before the test. PET is often combined with CT for more detailed images. This is called a PET/CT.

A PET/CT exposes you to about 25 mSv of radiation, which is equal to approximately 8 years of background radiation.

Dental X-rays

There have been concerns about the risk from radiation from dental X-rays, but the amount of radiation used by a typical dental X-ray has always been very low.

Today the radiation dose is even lower thanks to digital X-rays and more precise beams. Dental professionals also take extra measures to limit the exposure to other parts of your head and neck by using special collars and shields.

A dental X-ray uses 0.005 mSv, which equals 1 day of background radiation.

Fluoroscopy

Fluoroscopy provides a continuous image of your body instead of just still images. A dye is consumed or injected before the test to create a more detailed outline of your organs, arteries, and joints.

The radiation dose used during fluoroscopy is higher than many other tests because it uses continuous X-ray beams over an extended period, typically 20 to 60 minutes.

Fluoroscopy of the kidneys, ureters, and bladder uses 15 mSv, which is equal to approximately 5 years of background radiation.

Medical professionals take measures to limit the amount of radiation you’re exposed to during X-rays.

protection during X-rays

Medical professionals limit the amount of radiation you’re exposed to by:

  • carefully weighing the risks and benefits and only ordering tests that are considered medically necessary
  • opting for tests with the lowest radiation dose or finding alternatives when possible
  • using the lowest amount of radiation possible to get the required view
  • minimizing the length of fluoroscopy
  • using digital X-ray technology and X-ray beam filters
  • limiting the area being X-rayed or scanned to the smallest possible
  • placing shielding devices on your body to protect your organs

An alternative may not exist depending on the type of imaging you require, but some medical tests use lower doses of radiation or no radiation at all.

Simple radiographs use the least amount of radiation, and digital X-ray even less. Ultrasound and magnetic resonance imaging (MRI) do not use X-rays.

Ultrasound is often used to examine the abdomen and pelvis, breasts, soft tissues, and testes. MRI is often used instead of CT scans, when available, for the head, spine, joints, and other tissues.

Imaging tests are of particular concern for children because:

  • children are more sensitive to radiation than adults
  • they have many more years to develop cancer and other issues related to radiation exposure
  • machines settings not properly adjusted for a child’s size can result in higher exposure levels
protecting children during x-rays

As a parent or caregiver, you can limit the amount of radiation your child is exposed to by:

  • only allowing X-rays or scans when there’s a clear medical benefit
  • avoiding repeating tests whenever possible
  • ask the healthcare provider if there’s another test that uses less radiation

Exposure to X-rays and gamma rays can lead to cancer, but medical imaging procedures have a relatively low risk. The risk of death from cancer caused by 10 mSv from an imaging test is estimated at 1 chance in 2000.

Medical professionals make every effort to limit your radiation risk during testing and the benefits of these tests far outweigh any risk. Talk to your doctor or radiologist if you have concerns about your risk.