What are X-rays and how are they used?
X-rays are the oldest, most commonly used form of medical imaging and are a vital tool in diagnosing and monitoring illness and injury.1 X-rays utilize electromagnetic radiation that passes through the body to reveal images of bones and other parts of the body.2 As a diagnostic technology, X-rays are particularly good at penetrating through dense structures like bone in order to produce clear images of fractures and infections, as well as reveal signs of arthritis, measure bone density in osteoporosis, and detect bone tumors.2,3 X-rays are also used to examine many other areas of the body, such as mammograms, which are a specific type of low-dose X-ray used to screen for breast cancer.4 X-rays can also provide important information about the heart, including changes in blood flow and blockages. Chest X-rays can detect if a patient has pneumonia, emphysema, or lung cancer.5 Depending on the type of imaging, X-rays are generally quick and painless, while more detailed imaging procedures may take longer and require special preparation.
What are the most common types of X-rays?
Medical radiography is the most common type of X-ray and covers a broad range of X-ray examinations that require static (i.e., non-moving) images of bone and certain internal organs and structures, such as the lungs, heart, and abdomen.1 Radiography emits the smallest amount of ionizing radiation, the high-energy wavelengths that are absorbed by the body to produce images.6 Radiographic X-rays are used by healthcare professionals in numerous settings and situations to image broken bones, obtain images of the chest, locate foreign objects in soft tissue, and evaluate and monitor a wide variety of medical conditions.1 Common types of radiographic X-rays include: routine dental X-rays that check for cavities, as well as panoramic X-rays that image the entire mouth; mammograms, used for both symptom screening as well as to aid in diagnosing breast abnormalities; chest X-rays, also used for screening as well as to monitor or diagnose lung conditions; bone densitometry, used in diagnosing or evaluating the risk for osteoporosis; abdominal X-rays used to assess acute pain and other symptoms; and bone X-rays, a key tool in diagnosing and evaluating an injury. Because they are fast, painless and require little or no preparation, radiographic X-rays are particularly useful in making an emergency diagnosis and determining the most appropriate treatment.
When referred by your doctor for an X-ray exam, you will be asked to position your body in the most optimal way possible for the technician to get the best view, including lying on a table, sitting, or standing. When having a mammogram, for example, the technician will compress and position the breast in order to image from several angles. Depending on the type of X-ray, you may also be given a lead apron, or other protective cover, to minimize any unnecessary radiation exposure. Radiographic X-rays can be performed in a doctor's office or any outpatient setting where an X-ray machine, qualified physician, and licensed or certified X-ray technician (depending on the state) are available to perform the imaging and report the findings.
Fluoroscopy is a type of medical imaging that produces a continuous, or moving, X-ray image to assist in diagnosing diseases or guiding physicians while performing certain procedures.7 The image is transmitted to a monitor, allowing the physician to see the internal structure in detail of a body part in motion. In certain procedures, such as a barium enema, a contrast agent may be used to more clearly highlight the moving image. As an imaging tool, fluoroscopy allows physicians to examine and evaluate the health and functioning of various regions of the body, including digestive, urinary, and pulmonary (lung) systems, as well as perform a variety of therapeutic procedures. Some fluoroscopy procedures may require special preparations, such as the use of laxatives, along with sedation, for imaging the digestive tract. Most procedures can be performed on an outpatient basis. The radiation dose for fluoroscopy varies depending on the type of procedure. Longer, more complex procedures, such as placing a stent, require a higher dose.7 However, if the procedure is determined to be medically necessary, the risks of radiation exposure are outweighed by the benefit to the patient.7 In fact, according to the U.S. Food & Drug Administration, the radiation risk is usually lower than other risks not associated with radiation, such as the use of anesthesia or risks from the treatment itself.7
Common fluoroscopy procedures:
• Barium enemas to view the gastrointestinal tract;
• Insertion of catheters (flexible tubes) through blood vessels or the urinary system;
• Guiding the placement of artificial joints or to repair fractures during orthopedic surgery.
Computed tomography (CT) uses specialized X-ray equipment to produce highly detailed cross-sectional images of the body that are used for a variety of diagnostic and therapeutic purposes. A painless, accurate and noninvasive test, a CT scan can detect many types of cancers, diagnose heart disease or abnormalities, and provide images of the head to locate injuries, tumors, or clots that can lead to potentially life-threatening conditions.8 Computed tomography angiography (CTA) is another form of a CT scan that combines an injection of iodine-containing contrast material and CT scanning to examine the arteries that supply blood to the heart to determine if they have been narrowed or blocked.
CT scans require much larger radiation doses than traditional X-rays. However, in one 2009 study that looked at more than 30,000 records of patient data over 22 years, researchers only estimated a slight increased risk in the potential to develop cancer from CT scans — 0.7 percent above the overall lifetime risk of cancer in the U.S., which is about 40 percent.6 CT scans also have the advantage of being viewed on a computer monitor, printed on film, or transferred to electronic media.1
How safe are X-rays?
According to the most current evidence, unless you were exposed to high doses of radiation during childhood, any increase in your risk for cancer due to medical radiation from traditional X-ray exams appears to be very small.6 Radiologists and other doctors who perform X-ray exams are trained to determine the appropriate imaging exam for common medical conditions and may use evidence-based guidelines, such as the American College of Radiology’s Appropriateness Criteria, to assist in making the most appropriate imaging or treatment decision for a specific clinical condition.9 Adverse effects from X-rays are rare and the radiation dose from a simple radiographic X-ray exam of the chest, skull, abdomen, pelvic region, or joints is very low; the average person receives more radiation annually from natural sources.3 However, even at these low levels—and with no real evidence from any human studies to date—in theory, the possibility that the radiation from an X-ray could cause changes to healthy cells can't be ruled out.3
The most important safety measure you can take as a patient is to ensure that you discuss the need for any potentially high-dose diagnostic imaging with your doctor, keep track of your X-ray history, including holding onto copies of older X-rays, and always make sure that your doctor has determined that the benefits of the procedure outweigh any risks.3,6
- Radiology.org for patients. X-Ray. 2018 Radiological Society of North America, Inc. https://www.radiologyinfo.org/en/submenu.cfm?pg=xray. Accessed August 9, 2018.
- Radiology.org for patients. Bone X-ray. Radiological Society of North America. http://www.radiologyinfo.org/en/info.cfm?PG=bonerad. Accessed August 9, 2018
- X-rays - what patients need to know. International Atomic Energy Agency, Radiation Protection of Patients. https://www.iaea.org/resources/rpop/patients-and-public/x-rays. Accessed August 9, 2018.
- Radiology.org for patients. Mammography. Radiological Society of North America. https://www.radiologyinfo.org/en/info.cfm?pg=mammo . Accessed August 9, 2018
- Radiology.org for patients. Chest X-ray. Radiological Society of North America. http://www.radiologyinfo.org/en/info.cfm?pg=chestrad. Accessed August 9, 2018.
- Radiation risk from medical imaging. Harvard Health Publishing. Harvard Medical School. Updated 2018. https://www.health.harvard.edu/cancer/radiation-risk-from-medical-imaging. Accessed August 9, 2018.
- U.S. Food & Drug Administration. Radiation-Emitting Products. Fluoroscopy. https://www.fda.gov/radiation-emittingproducts/radiationemittingproductsandprocedures/medicalimaging/medicalx-rays/ucm115354.htm#description. Accessed August 10, 2018
- Computed Tomography (CT). National Institute of Biomedical Imaging and Bioengineering. National Institutes of Health. Department of Health & Human Services. https://www.nibib.nih.gov/science-education/science-topics/computed-tomography-ct#1026. Accessed August 10, 2018
- ACR Appropriateness Criteria. American College of Radiology. https://www.acr.org/Clinical-Resources/ACR-Appropriateness-Criteria. Accessed August 10, 2018