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X-ray
Definition:
X-rays are a form of electromagnetic radiation, just like visible light. In a health care setting, x-rays are emitted by a machine as individual "particles" (photons) that pass through the body and then get detected by a sensitive film. Structures that are dense (such as bone) will block most of the photons, and will appear white on developed film. Structures containing air will be black on film, and muscle, fat, and fluid will appear as shades of gray. Metal and contrast media (intravenous or oral contrast) blocks almost all the photons and will appear bright white.
The basic science of x-ray generation and detection is the key behind general radiographs of the body, mammography, fluoroscopy (real-time imaging on video screens), and computed tomography (CT).
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Alternative Names:
General Radiography; Plain films How the test is performed:
The test is performed in a hospital radiology department or in the health care provider's office by an x-ray technologist. The positioning of the patient, x-ray machine, and film depends on the type of study and area of interest. Multiple individual views may be requested. Much like conventional photography, motion causes blurry images on radiographs, and thus, patients may be asked to hold their breath or not move during the brief (approximately 1 second) exposure. How to prepare for the test:
Inform the health care provider prior to the exam if you are pregnant, may be pregnant, or have an IUD inserted. If abdominal studies are planned and you have had a barium contrast study (such as a barium enema, upper GI series, or barium swallow) or taken medications containing bismuth (such as Pepto-Bismol) in the last 4 days, the test may be delayed until the contrast has fully passed.
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