Background
Fluoroscopy is an imaging technique that uses x-rays to obtain real-time moving images of the interior of an object. By using a fluoroscope, a physician can see the internal structure and function of body systems. Essentially, a fluoroscope consists of an x-ray source and a fluorescent screen, between which a patient is placed. For many decades, fluoroscopy produced live pictures that were not recorded; since the 1960s, recording and playback has become standard. Fluoroscopy combined with videotaping is especially useful for evaluating the kinematics of joints.1
Historical Overview
In 1895, Wilhelm Röntgen noticed a barium platinocyanide screen fluorescing after being exposed to x-rays. Within months, the first experimental fluoroscopes were developed. In the late 1890s, Thomas Edison began investigating materials such as calcium tungstate for their ability to fluoresce when x-rayed. By the early 1900s, he had invented a fluoroscope with sufficient image intensity to be commercialized. The introduction of analog electronics revolutionized fluoroscopy. The development of the x-ray image intensifier in the late 1940s and of closed-circuit TV cameras in the 1950s produced brighter pictures and better protection from radiation, allowing the radiologist to view the images in a separate room. In the early 1960s, digital electronics were used to produce the first image to be digitally generated in real-time; square-wave signals were detected by the pixels of a cathode ray tube to create the image. After the late 1980s, digital imaging technology was reintroduced to fluoroscopy with the development of improved detector systems. Modern advancements continue to increase image quality while minimizing radiation exposure.2
Description
X-rays can penetrate a wide variety of objects, but they are invisible to the naked eye. Conventional, film-based radiography makes the x-ray penetrations visible through chemical changes in the film, and classic fluoroscopy achieves this by fluorescence, whereby certain materials convert x-ray energy into visible light. As the x-rays pass through the patient, they are attenuated as they pass through or reflect off different tissues of the body and cast an x-ray shadow of the radiopaque tissues on the fluorescent screen. Images on the screen are produced as the unattenuated x-rays from radiolucent tissues interact with atoms in the screen through the photoelectric effect.2
