Radiation Safety

What Are X-rays and What Do They Do?

X-rays are forms of radiant energy, like light or radio waves. Unlike light, X-rays can penetrate the body, which allows a radiologist to produce pictures of internal structures. The radiologist can view these on photographic film or on a television or computer monitor.

X-ray examinations provide valuable information about your health and play an important role in helping your doctor make an accurate diagnosis. In some cases X-rays are used to assist with the placement of tubes or other devices in the body or with other therapeutic procedures.

Measuring Radiation Dosage

The scientific unit of measurement for radiation dose, commonly referred to as effective dose, is the millisievert (mSv). Other radiation dose measurement units include rad, rem, roentgen, sievert, and gray. Because different tissues and organs have varying sensitivity to radiation exposure, the actual radiation risk to different parts of the body from an X-ray procedure varies. The term “effective dose” is used when referring to the radiation risk averaged over the entire body.

According to the Environmental Protection Agency, most people in the United States receive an annual radiation dose of 360 millirem (a measure of radiation exposure). About 80% of that exposure amount is from natural sources such as soil, rocks, radon gas, human bodies, or plane trips. Diagnostic imaging procedures typically account for only 20% of the average Americans’ yearly exposure.

Radiation Exposure Risks Associated With Common Imaging Procedures

Magnetic Resonance Imaging (MRI): An MRI does NOT use X-rays or other ionizing radiation to image patients.

Ultrasound (US): An Ultrasound does NOT use X-rays or other ionizing radiation to image patients.

X-ray: A small dose of radiation is used to perform most X-ray examinations. As an example, the radiation exposure from a typical chest X-ray is comparable to the radiation exposure received during a cross-country plane trip.

Mammogram: A small dose of radiation is used to perform this study – approximately equal to the radioactivity your own body naturally produces each year.

Computed Tomography (CT): A CT scan requires more radiation than conventional X-ray examinations; however, it also provides more detailed pictures. Total radiation exposure varies greatly by CT procedure; a typical chest CT is comparable to the radiation exposure the average American receives from radon gas naturally occurring in their home.

Positron Emission Tomography (PET): Positron Emission Tomography uses small amounts of radioactive isotope-labeled materials which are injected to target the area of the body being imaged. The radiation dose varies by procedure.

Please visit our Imaging Questions and Precautions page for more information on things to discuss with your doctor, radiologist or technician.

Radiation Exposure Risks Associated With Common Imaging Procedures

According to recent estimates, the average person in the U.S. receives an effective dose of about 3mSv per year from naturally occurring radioactive materials and cosmic radiation from outer space. These natural “background” doses vary throughout the country.

What Is ACR Accreditation?

American College of Radiology (ACR) accreditation is recognized as the gold standard in medical imaging. Patients concerned about radiation safety should seek out facilities that display ACR accreditation seals.

ACR accreditation ensures the highest level of radiation care. It means:

• The facility has undergone a rigorous review process and meets nationally accepted standards of patient safety and image quality
• Personnel are well qualified to perform your radiation procedure and interpret your medical images
• All equipment is assessed by a medical imaging expert who verifies that the equipment functions properly, takes optimal images, and utilizes appropriate radiation dose levels

ACR accreditation demonstrates your doctor’s commitment to quality care and patient safety. For more than three quarters of a century, ACR has devoted its resources to making imaging safe, effective, and accessible to those who need it. ACR is the oldest and most experienced imaging accreditation body and is comprised of physicians, physicists, and experts in radiology technology.