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They are no longer used because the radiation exposure risk outweighs the trivial benefit. Analog electronics revolutionized fluoroscopy. The development of the X-ray image intensifier by Westinghouse in the late s [29] in combination with closed circuit TV cameras of the s allowed for brighter pictures and better radiation protection. The red adaptation goggles became obsolete as image intensifiers allowed the light produced by the fluorescent screen to be amplified and made visible in a lighted room.

The addition of the camera enabled viewing of the image on a monitor, allowing a radiologist to view the images in a separate room away from the risk of radiation exposure. The commercialization of video tape recorders beginning in allowed the TV images to be recorded and played back at will.

Digital electronics were applied to fluoroscopy beginning in the early s, when Frederick G. Weighart [30] [31] and James F. McNulty [32] at Automation Industries, Inc. Square wave signals were detected on a fluorescent screen to create the image. From the late s onward, digital imaging technology was reintroduced to fluoroscopy after development of improved detector systems.

Modern improvements in screen phosphors , digital image processing , image analysis , and flat panel detectors have allowed for increased image quality while minimizing the radiation dose to the patient. Modern fluoroscopes use caesium iodide CsI screens and produce noise-limited images, ensuring that the minimal radiation dose results while still obtaining images of acceptable quality.

Many names exist in the medical literature for moving pictures taken with X-rays. They include fluoroscopy , fluorography , cinefluorography , photofluorography , fluororadiography , kymography electrokymography , roentgenkymography , cineradiography cine , videofluorography , and videofluoroscopy. Today the word fluoroscopy is widely understood to be a hypernym of all the aforementioned terms, which explains why it is the most commonly used and why the others are declining in usage.

As soon as X-rays and their application of seeing inside the body were discovered in the s, both looking and recording were pursued. But the quest for recorded moving images was a more complex challenge. In the s, moving pictures of any kind whether taken with visible light or with invisible radiation were emerging technologies. Soon several new words were coined for achieving moving radiographic pictures.

This was often done either by filming a simple fluoroscopic screen with a movie camera variously called fluorography , cinefluorography , photofluorography , or fluororadiography or by taking serial radiographs rapidly to serve as the frames in a movie cineradiography.

Either way, the resulting film reel could be displayed by a movie projector. Another group of techniques were various kinds of kymography, whose common theme was capturing recordings in a series of moments, with a concept similar to movie film although not necessarily with movie-type playback; rather, the sequential images would be compared frame by frame a distinction comparable to tile mode versus cine mode in today's CT terminology. Thus electrokymography and roentgenkymography were among the early ways to record images from a simple fluoroscopic screen.

Television also was under early development during these decades s—s , but even after commercial TV began widespread adoption after World War II , it remained a live-only medium for a time. In the mids, a commercialized ability to capture the moving pictures of television onto magnetic tape with a video tape recorder was developed.

This soon led to the addition of the video- prefix to the words fluorography and fluoroscopy , with the words videofluorography and videofluoroscopy attested since Thus, over time the cameras and recording media for fluoroscopic imaging have progressed as follows. The original kind of fluoroscopy, and the common kind for its first half century of existence, simply used none, because for most diagnosis and treatment, they weren't essential.

For those investigations that needed to be transmitted or recorded such as for training or research , movie cameras using film such as 16 mm film were the medium. In the s, analog electronic video cameras at first only producing live output but later using video tape recorders appeared. Since the s, there have been digital video cameras , flat panel detectors , and storage of data to local servers or more recently secure cloud servers. Late-model fluoroscopes all use digital image processing and image analysis software, which not only helps to produce optimal image clarity and contrast but also allows that result with a minimal radiation dose because signal processing can take tiny inputs from low radiation doses and amplify them while to some extent also differentiating signal from noise.

Cineradiography records frame-per-second fluoroscopic images of internal organs such as the heart taken during injection of contrast dye to better visualize regions of stenosis , or to record motility in the body's gastrointestinal tract.

The predigital technology is being replaced with digital imaging systems. Some of these decrease the frame rate but also decrease the absorbed dose of radiation to the patient.

As they improve, frame rates will likely increase. Today, owing to technological convergence , the word fluoroscopy is widely understood to be a hypernym of all the earlier names for moving pictures taken with X-rays, both live and recorded. Also owing to technological convergence, radiography, CT, and fluoroscopy are now all digital imaging modes using X-rays with image analysis software and easy data storage and retrieval. Just as movies, TV, and web videos are to a substantive extent no longer separate technologies but only variations on common underlying digital themes, so too are the X-ray imaging modes.

And indeed, the term X-ray imaging is the ultimate hypernym that unites all of them, even subsuming both fluoroscopy and four-dimensional CT 4DCT 4DCT is the newest form of moving pictures taken with X-rays. Because fluoroscopy involves the use of X-rays, a form of ionizing radiation , fluoroscopic procedures pose a potential for increasing the patient's risk of radiation-induced cancer.

A study of radiation induced skin injuries was performed in by the Food and Drug Administration FDA [38] [39] followed by an advisory to minimize further fluoroscopy-induced injuries. While deterministic radiation effects are a possibility, radiation burns are not typical of standard fluoroscopic procedures. Most procedures sufficiently long in duration to produce radiation burns are part of necessary life-saving operations.

X-ray image intensifiers generally have radiation-reducing systems such as pulsed rather than constant radiation, and last image hold , which "freezes" the screen and makes it available for examination without exposing the patient to unnecessary radiation. Image intensifiers have been introduced that increase the brightness of the screen, so that the patient needs to be exposed to a lower dose of X-rays.

The invention of X-ray image intensifiers in the s allowed the image on the screen to be visible under normal lighting conditions, as well as providing the option of recording the images with a conventional camera. Subsequent improvements included the coupling of, at first, video cameras and, later, digital cameras using image sensors such as charge-coupled devices or active pixel sensors to permit recording of moving images and electronic storage of still images.

Modern image intensifiers no longer use a separate fluorescent screen. Instead, a caesium iodide phosphor is deposited directly on the photocathode of the intensifier tube. On a typical general purpose system, the output image is approximately 10 5 times brighter than the input image. This brightness gain comprises a flux gain amplification of photon number and minification gain concentration of photons from a large input screen onto a small output screen each of approximately This level of gain is sufficient that quantum noise , due to the limited number of X-ray photons, is a significant factor limiting image quality.

The introduction of flat-panel detectors allows for the replacement of the image intensifier in fluoroscope design. Flat panel detectors offer increased sensitivity to X-rays, and therefore have the potential to reduce patient radiation dose. Temporal resolution is also improved over image intensifiers, reducing motion blurring.

Contrast ratio is also improved over image intensifiers: Spatial resolution is approximately equal, although an image intensifier operating in 'magnification' mode may be slightly better than a flat panel. Flat panel detectors are considerably more expensive to purchase and repair than image intensifiers, so their uptake is primarily in specialties that require high-speed imaging, e.

A number of substances have been used as radiocontrast agents , including silver , bismuth , caesium , thorium , tin , zirconium , tantalum , tungsten and lanthanide compounds. The use of thoria thorium dioxide as an agent was rapidly stopped as thorium causes liver cancer. Most modern injected radiographic positive contrast media are iodine-based.

Iodinated contrast comes in two forms: Non-ionic contrast is significantly more expensive than ionic approximately three to five times the cost , however, non-ionic contrast tends to be safer for the patient, causing fewer allergic reactions and uncomfortable side effects such as hot sensations or flushing.

Most imaging centers now use non-ionic contrast exclusively, finding that the benefits to patients outweigh the expense. Negative radiographic contrast agents are air and carbon dioxide CO 2.

The latter is easily absorbed by the body and causes less spasm. It can also be injected into the blood, where air absolutely cannot.

In addition to spatial blurring factors that plague all X-ray imaging devices, caused by such things as Lubberts effect , K-fluorescence reabsorption and electron range, fluoroscopic systems also experience temporal blurring due to system lag.

This temporal blurring has the effect of averaging frames together. While this helps reduce noise in images with stationary objects, it creates motion blurring for moving objects.

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