Skip NavigationFDA Logo links to FDA home pageCenter for Devices and Radiological Health, U.S. Food and Drug AdministrationHHS Logo links to Department of Health and Human Services website
FDA Home Page | CDRH Home Page | Search | A-Z Index U.S. Food and Drug AdministrationCenter for Devices and Radiological Health Questions?
horizonal rule
Radiological Health Home
Products and Procedures
Radiation Safety
News & Highlights
Regulated Industry
FDA's Role in Radiation Protection
Other Resources
CeSub Electronic Submission Program
SubscribeSubscribe to Email Updates on Radiological Health
Contact Us

Medical X-Rays


X-rays refer to radiation, waves or particles that travel through the air like light or radio signals. X-ray energy is high enough that some radiation passes through objects (such as internal organs, body tissues, and clothing) and onto x-ray detectors (such as film or a detector linked to a computer monitor). In general, objects that are more dense (such as bones and calcium deposits) absorb more of the radiation from the x-rays and don’t allow as much to pass through them. These objects leave a different image on the detector than less dense objects. Specially trained or experienced physicians can read these images to diagnose medical conditions or injuries.


Medical x-rays are used in many types of examinations and procedures. Some examples include

  • x-ray radiography (to find orthopedic damage, tumors, pneumonias, foreign objects, etc);
  • mammography (to image the internal structures of breasts)
  • CT (computed tomography) (to produce cross-sectional images of the body)
  • fluoroscopy (to dynamically visualize the body for example to see where to remove plaque from coronary arteries or where to place stents to keep those arteries open)
  • radiation therapy in cancer treatment


Medical x-rays have increased the ability to detect disease or injury early enough for a medical problem to be managed, treated, or cured. When applied and performed appropriately, these procedures can improve health and may even save a person’s life.

X-ray energy also has a small potential to harm living tissue. The most significant risks are:

  • a small increase in the possibility that a person exposed to x-rays will develop cancer later in life; and
  • cataracts and skin burns only at very high levels of radiation exposure and in only very few procedures.

The risk of developing cancer from radiation exposure is generally small, and it depends on at least three factors—the amount of radiation dose, the age at exposure, and the sex of the person exposed:

  • The lifetime risk of cancer increases the larger the dose and the more x-ray exams a patient undergoes.
  • The lifetime risk of cancer is larger for a patient who received x-rays at a younger age than for one who receives them at an older age.
  • Women are at a somewhat higher lifetime risk than men for developing radiation-associated cancer after receiving the same exposures at the same ages.

Information for Patients

You can reduce your radiation risks and contribute to your successful examination or procedure by:

  • Keeping a “medical x-ray history” with the names of your radiological exams or procedures, the dates and places where you had them, and the physicians who referred you for those exams;
  • Making your current healthcare providers aware of your medical x-ray history;
  • Asking your healthcare provider about whether or not alternatives to x-ray exams would allow the provider to make a good assessment or provide appropriate treatment for your medical situation;
  • Providing interpreting physicians and referring physicians with recent x-ray images and radiology reports; and
  • Informing radiologists or x-ray technologists in advance if you are pregnant or think you may be pregnant.

See also: RadiologyInfo: The Radiology Information Resource for Patients.

Information for Professionals

Laws, Regulations & Standards

Manufacturers of electronic radiation-emitting products sold in the United States are responsible for compliance with the Federal Food, Drug and Cosmetic Act (FFDCA), Chapter V, Subchapter C - Electronic Product Radiation Control.

Manufacturers of medical x-ray products are responsible for compliance with all applicable requirements of Title 21 Code of Federal Regulations (Subchapter J, Radiological Health) Parts 1000 through 1005:

1000 - General

1002 - Records and Reports

1003 - Notification of defects or failure to comply

1004 - Repurchase, repairs, or replacement of electronic products

1005 - Importation of electronic products

In addition, medical x-ray products must comply with radiation safety performance standards in Title 21 Code of Federal Regulations (Subchapter J, Radiological Health) Parts 1010 and 1020.

1010 - Performance standards for electronic products: general

1020.30 - Diagnostic x-ray systems and their major components

1020.31 - Radiographic equipment

1020.32 - Fluoroscopic equipment

1020.33 - Computed tomography (CT) equipment

Because they are medical devices, medical x-ray equipment must also comply with the medical device regulations. For more information, see Getting to Market with a Medical Device.

Industry Guidance

Other Resources

Updated January 6, 2009

horizonal rule

CDRH Home Page | CDRH A-Z Index | Contact CDRH | Accessibility | Disclaimer
FDA Home Page | Search FDA Site | FDA A-Z Index | Contact FDA | HHS Home Page

Center for Devices and Radiological Health / CDRH