Fluoroscopy
Encyclopedia
Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray
source and fluorescent screen between which a patient is placed. However, modern fluoroscopes couple the screen to an X-ray image intensifier
and CCD
video camera
allowing the images to be recorded and played on a monitor.
The use of X-rays, a form of ionizing radiation
, requires the potential risks from a procedure to be carefully balanced with the benefits of the procedure to the patient. While physicians always try to use low dose
rates during fluoroscopic procedures, the length of a typical procedure often results in a relatively high absorbed dose
to the patient. Recent advances include the digitization of the images captured and flat panel detector
systems which reduce the radiation dose to the patient still further.
platinocyanide
screen fluorescing as a result of being exposed to what he would later call x-ray
s. Within months of this discovery, the first fluoroscopes were created. Early fluoroscopes were simply cardboard funnels, open at narrow end for the eyes of the observer, while the wide end was closed with a thin cardboard piece that had been coated on the inside with a layer of fluorescent metal salt. The fluoroscopic image obtained in this way is rather faint. Thomas Edison
quickly discovered that calcium tungstate screens produced brighter images and is credited with designing and producing the first commercially available fluoroscope. In its infancy, many incorrectly predicted that the moving images from fluoroscopy would completely replace the still x-ray radiographs, but the superior diagnostic quality of the earlier radiographs
prevented this from occurring.
Ignorance of the harmful effects of x-rays resulted in the absence of standard radiation safety procedures which are employed today. Scientists and physicians would often place their hands directly in the x-ray beam resulting in radiation burns. Edison's assistant Clarence Madison Dally
(1865–1904) died as a result of exposure to radiation from fluoroscopes, and in 1903, Edison abandoned his work on fluoroscopes, saying "Don't talk to me about X-rays, I am afraid of them.". Trivial uses for the technology also resulted, including the shoe-fitting fluoroscope
used by shoe stores in the 1930s-1950s.
Due to the limited light produced from the fluorescent screens, early radiologists were required to sit in a darkened room, in which the procedure was to be performed, accustomizing their eyes to the dark and thereby increasing their sensitivity to the light. The placement of the radiologist behind the screen resulted in significant radiation doses to the radiologist. Red adaptation goggles
were developed by Wilhelm Trendelenburg
in 1916 to address the problem of dark adaptation of the eyes, previously studied by Antoine Beclere. The resulting red light from the goggles' filtration correctly sensitized the physician's eyes prior to the procedure while still allowing him to receive enough light to function normally.
The development of the X-ray image intensifier
and the television camera in the 1950s revolutionized fluoroscopy. The red adaptation goggles
became obsolete as image intensifiers allowed the light produced by the fluorescent screen to be amplified, allowing it to be seen even 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
.
More modern improvements in screen phosphors, image intensifiers and even flat panel detectors have allowed for increased image quality while minimizing the radiation dose to the patient. Modern fluoroscopes use CsI
screens and produce noise-limited images, ensuring that the minimal radiation dose results while still obtaining images of acceptable quality.
, all fluoroscopic procedures pose a potential health risk to the patient. Radiation doses to the patient depend greatly on the size of the patient as well as length of the procedure, with typical skin dose rates quoted as 20–50 mGy
/min. Exposure times vary depending on the procedure being performed, but procedure times up to 75 minutes have been documented. Because of the long length of some procedures, in addition to standard cancer
-inducing stochastic radiation effects, deterministic radiation effects have also been observed ranging from mild erythema
, equivalent of a sun burn, to more serious burns.
A study has been performed by the Food and Drug Administration
(FDA) entitled Radiation-induced Skin Injuries from Fluoroscopy with an additional publication to minimize further fluoroscopy-induced injuries, Public Health Advisory on Avoidance of Serious X-Ray-Induced skin Injuries to Patients During Fluoroscopically-Guided Procedures.
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 intensifier
s generally have radiation-reducing systems such as pulsed rather than constant radiation, and last image hold which is "freezing" the screen and availing for examining the screen without exposing the patient to unnecessary radiation.
of the structures on the fluorescent screen. Images on the screen are produced as the unattenuated x rays interact with atoms in the screen through the photoelectric effect
, giving their energy to the electrons. While much of the energy given to the electron
s is dissipated as heat
, a fraction of it is given off as visible light, producing the images. Early radiologists would adapt their eyes to view the dim fluoroscopic images by sitting in darkened rooms, or by wearing red adaptation goggles
.
s in the 1950s 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, CCD cameras
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 105 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 100. 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.
Image intensifiers are available with input diameters of up to 45 cm, and a resolution of approximately 2-3 line pairs mm−1.
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.g., vascular imaging and cardiac catheterization
.
, 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 blur
ring for moving objects. Temporal blurring also complicates measurements of system performance for fluoroscopic systems.
Another common procedure is the modified barium swallow study during which barium
-impregnated liquids and solids are ingested by the patient. A radiologist records and, with a speech pathologist, interprets the resulting images to diagnose oral and pharyngeal swallowing dysfunction. Modified barium swallow studies are also used in studying normal swallow function.
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
source and fluorescent screen between which a patient is placed. However, modern fluoroscopes couple the screen to an X-ray image intensifier
X-ray image intensifier
An x-ray image intensifier , is an imaging component which converts x-rays into a visible image.The term image intensifier refers to a specific component of an x-ray imaging system, which allows low intensity x-rays to be converted to a visible light output...
and CCD
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
video camera
Video camera
A video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in...
allowing the images to be recorded and played on a monitor.
The use of X-rays, a form of ionizing radiation
Ionizing radiation
Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
, requires the potential risks from a procedure to be carefully balanced with the benefits of the procedure to the patient. While physicians always try to use low dose
Dose (biochemistry)
A dose is a quantity of something that may impact an organism biologically; the greater the quantity, the larger the dose. In nutrition, the term is usually applied to how much of a specific nutrient is in a person's diet or in a particular food, meal, or dietary supplement...
rates during fluoroscopic procedures, the length of a typical procedure often results in a relatively high absorbed dose
Absorbed dose
Absorbed dose is a measure of the energy deposited in a medium by ionizing radiation per unit mass...
to the patient. Recent advances include the digitization of the images captured and flat panel detector
Flat panel detector
Flat panel detectors are a class of solid-state x-ray imaging devices similar in principle to the image sensors used in digital photography and video, but due to the impracticability of focusing x-rays, the sensors are hundreds of times larger than those used in digital cameras.- Mechanics :X-rays...
systems which reduce the radiation dose to the patient still further.
History
The beginning of fluoroscopy can be traced back to 8 November 1895 when Wilhelm Röntgen noticed a bariumBarium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
platinocyanide
Platinocyanide
A platinocyanide is a salt containing the anion Pt42-. Barium platinocyanide, BaPt4, was important in the discovery of X-rays, and in the development of the fluoroscope. One platinocyanide salt with interesting conductive properties is Krogmann's salt....
screen fluorescing as a result of being exposed to what he would later call x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
s. Within months of this discovery, the first fluoroscopes were created. Early fluoroscopes were simply cardboard funnels, open at narrow end for the eyes of the observer, while the wide end was closed with a thin cardboard piece that had been coated on the inside with a layer of fluorescent metal salt. The fluoroscopic image obtained in this way is rather faint. Thomas Edison
Thomas Edison
Thomas Alva Edison was an American inventor and businessman. He developed many devices that greatly influenced life around the world, including the phonograph, the motion picture camera, and a long-lasting, practical electric light bulb. In addition, he created the world’s first industrial...
quickly discovered that calcium tungstate screens produced brighter images and is credited with designing and producing the first commercially available fluoroscope. In its infancy, many incorrectly predicted that the moving images from fluoroscopy would completely replace the still x-ray radiographs, but the superior diagnostic quality of the earlier radiographs
prevented this from occurring.
Ignorance of the harmful effects of x-rays resulted in the absence of standard radiation safety procedures which are employed today. Scientists and physicians would often place their hands directly in the x-ray beam resulting in radiation burns. Edison's assistant Clarence Madison Dally
Clarence Madison Dally
Clarence Madison Dally was an American glassblower, noted as an assistant to Thomas Edison in his work on X-rays and as an early victim of radiation dermatitis and its complications.- Early life and education :...
(1865–1904) died as a result of exposure to radiation from fluoroscopes, and in 1903, Edison abandoned his work on fluoroscopes, saying "Don't talk to me about X-rays, I am afraid of them.". Trivial uses for the technology also resulted, including the shoe-fitting fluoroscope
Shoe-fitting fluoroscope
Shoe-fitting fluoroscopes, also Pedoscopes, were X-ray fluoroscope machines installed in shoe stores from the 1920s until about the 1960s in the United States , and into the mid-1970s in the United Kingdom. In the UK, they were known as Pedoscopes, after the company based in St. Albans that...
used by shoe stores in the 1930s-1950s.
Due to the limited light produced from the fluorescent screens, early radiologists were required to sit in a darkened room, in which the procedure was to be performed, accustomizing their eyes to the dark and thereby increasing their sensitivity to the light. The placement of the radiologist behind the screen resulted in significant radiation doses to the radiologist. Red adaptation goggles
Red adaptation goggles
Red adaptation goggles were first invented by Wilhelm Trendelenburg in 1916 for early radiologists to use to adapt their eyes to view the light produced by fluorescent screens during fluoroscopic procedures. The concept is based on the work by Antoine Beclere on dark adaptation of the eye, where it...
were developed by Wilhelm Trendelenburg
Wilhelm Trendelenburg
Ernst Wilhelm Theodor Trendelenburg was a German physiologist.- References :...
in 1916 to address the problem of dark adaptation of the eyes, previously studied by Antoine Beclere. The resulting red light from the goggles' filtration correctly sensitized the physician's eyes prior to the procedure while still allowing him to receive enough light to function normally.
The development of the X-ray image intensifier
X-ray image intensifier
An x-ray image intensifier , is an imaging component which converts x-rays into a visible image.The term image intensifier refers to a specific component of an x-ray imaging system, which allows low intensity x-rays to be converted to a visible light output...
and the television camera in the 1950s revolutionized fluoroscopy. The red adaptation goggles
Red adaptation goggles
Red adaptation goggles were first invented by Wilhelm Trendelenburg in 1916 for early radiologists to use to adapt their eyes to view the light produced by fluorescent screens during fluoroscopic procedures. The concept is based on the work by Antoine Beclere on dark adaptation of the eye, where it...
became obsolete as image intensifiers allowed the light produced by the fluorescent screen to be amplified, allowing it to be seen even in a lighted room. The addition of the camera
Camera
A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...
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
Radiation exposure
The term radiation exposure commonly has several uses:* Absorption of high-energy ionizing radiation by an object. In living beings a high absorbed dose can lead to radiation poisoning.* Absorption by an object of non-ionizing radiation...
.
More modern improvements in screen phosphors, image intensifiers and even flat panel detectors have allowed for increased image quality while minimizing the radiation dose to the patient. Modern fluoroscopes use CsI
Caesium iodide
Caesium iodide is an ionic compound often used as the input phosphor of an x-ray image intensifier tube found in fluoroscopy equipment....
screens and produce noise-limited images, ensuring that the minimal radiation dose results while still obtaining images of acceptable quality.
Risks
Because fluoroscopy involves the use of x-rays, a form of ionizing radiationIonizing radiation
Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
, all fluoroscopic procedures pose a potential health risk to the patient. Radiation doses to the patient depend greatly on the size of the patient as well as length of the procedure, with typical skin dose rates quoted as 20–50 mGy
Gray (unit)
The gray is the SI unit of absorbed radiation dose of ionizing radiation , and is defined as the absorption of one joule of ionizing radiation by one kilogram of matter ....
/min. Exposure times vary depending on the procedure being performed, but procedure times up to 75 minutes have been documented. Because of the long length of some procedures, in addition to standard cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
-inducing stochastic radiation effects, deterministic radiation effects have also been observed ranging from mild erythema
Erythema
Erythema is redness of the skin, caused by hyperemia of the capillaries in the lower layers of the skin. It occurs with any skin injury, infection, or inflammation...
, equivalent of a sun burn, to more serious burns.
A study has been performed by the Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
(FDA) entitled Radiation-induced Skin Injuries from Fluoroscopy with an additional publication to minimize further fluoroscopy-induced injuries, Public Health Advisory on Avoidance of Serious X-Ray-Induced skin Injuries to Patients During Fluoroscopically-Guided Procedures.
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 intensifier
X-ray image intensifier
An x-ray image intensifier , is an imaging component which converts x-rays into a visible image.The term image intensifier refers to a specific component of an x-ray imaging system, which allows low intensity x-rays to be converted to a visible light output...
s generally have radiation-reducing systems such as pulsed rather than constant radiation, and last image hold which is "freezing" the screen and availing for examining the screen without exposing the patient to unnecessary radiation.
Equipment
The first fluoroscopes consisted of an x-ray source and fluorescent screen between which the patient would be placed. As the x-rays pass through the patient, they are attenuated by varying amounts as they interact with the different internal structures of the body, casting a shadowShadow
A shadow is an area where direct light from a light source cannot reach due to obstruction by an object. It occupies all of the space behind an opaque object with light in front of it. The cross section of a shadow is a two-dimensional silhouette, or reverse projection of the object blocking the...
of the structures on the fluorescent screen. Images on the screen are produced as the unattenuated x rays interact with atoms in the screen through the photoelectric effect
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...
, giving their energy to the electrons. While much of the energy given to the electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s is dissipated as heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
, a fraction of it is given off as visible light, producing the images. Early radiologists would adapt their eyes to view the dim fluoroscopic images by sitting in darkened rooms, or by wearing red adaptation goggles
Red adaptation goggles
Red adaptation goggles were first invented by Wilhelm Trendelenburg in 1916 for early radiologists to use to adapt their eyes to view the light produced by fluorescent screens during fluoroscopic procedures. The concept is based on the work by Antoine Beclere on dark adaptation of the eye, where it...
.
X-ray image intensifiers
The invention of X-ray image intensifierX-ray image intensifier
An x-ray image intensifier , is an imaging component which converts x-rays into a visible image.The term image intensifier refers to a specific component of an x-ray imaging system, which allows low intensity x-rays to be converted to a visible light output...
s in the 1950s 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, CCD cameras
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
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
Caesium iodide
Caesium iodide is an ionic compound often used as the input phosphor of an x-ray image intensifier tube found in fluoroscopy equipment....
phosphor is deposited directly on the photocathode of the intensifier tube. On a typical general purpose system, the output image is approximately 105 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 100. This level of gain is sufficient that quantum noise
Quantum noise
Quantum noise is uncertainty of some physical quantity due to its quantum origin.In the case of number of particles , the quantum noise is also called shot noise. Most optical communications use amplitude modulation...
, due to the limited number of x-ray photons, is a significant factor limiting image quality.
Image intensifiers are available with input diameters of up to 45 cm, and a resolution of approximately 2-3 line pairs mm−1.
Flat-panel detectors
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: flat-panel detectors are linear over a very wide latitude, whereas image intensifiers have a maximum contrast ratio of about 35:1. 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.g., vascular imaging and cardiac catheterization
Cardiac catheterization
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done for both investigational and interventional purposes...
.
Imaging concerns
In addition to spatial blurring factors that plague all x-ray imaging devices, caused by such things as Lubberts effectLubberts effect
Lubberts effect refers to the non-uniform response of an imaging system to x-rays that are absorbed at different depths within the input phosphor. It indicates an input phosphor depth-dependent response of the imaging system....
, K-fluorescence reabsorption and electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
range, fluoroscopic systems also experience temporal blurring due to system lag
Lag
Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
. This temporal blurring has the effect of averaging frames together. While this helps reduce noise in images with stationary objects, it creates motion blur
Motion blur
Motion blur is the apparent streaking of rapidly moving objects in a still image or a sequence of images such as a movie or animation. It results when the image being recorded changes during the recording of a single frame, either due to rapid movement or long exposure.- Photography :When a camera...
ring for moving objects. Temporal blurring also complicates measurements of system performance for fluoroscopic systems.
Common procedures using fluoroscopy
- Investigations of the gastrointestinal tractGastrointestinal tractThe human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
, including barium enemaBarium enemaA lower gastrointestinal series, also called a barium enema, is a medical procedure used to examine and diagnose problems with the human colon . X-ray pictures are taken while barium sulfate fills the colon via the rectum.-Procedure:...
s, defecating proctogramDefecating proctogramThe defecating proctogram or defecography is an imaging study performed by a radiologist in which the mechanics of a patient's defecation are visualized in real time using a fluoroscope.-History:...
s, barium mealBarium mealA barium meal, also known as an upper gastrointestinal series is a procedure in which radiographs of the esophagus, stomach and duodenum are taken after barium sulfate is ingested by a patient...
s and barium swallowBarium swallowA barium swallow is a medical imaging procedure used to examine the upper GI tract, which includes the esophagus and, to a lesser extent, the stomach.-Principle:...
s, and enteroclysisEnteroclysisEnteroclysis is a fluoroscopic X-ray of the small intestine. Radiocontrast is infused through a tube inserted through the nose to the duodenum, and images are taken in real time as the contrast moves through aided by administration of methyl cellulose. Enteroclysis is also known by the confusing...
. - Orthopaedic surgery to guide fracture reduction and the placement of metalwork.
- Angiography of the leg, heart and cerebral vessels.
- Placement of a PICC (peripherally inserted central catheterPeripherally inserted central catheterA peripherally inserted central catheter is a form of intravenous access that can be used for a prolonged period of time...
) - Placement of a weighted feeding tube (e.g. Dobhoff) into the duodenum after previous attempts without fluoroscopy have failed.
- Urological surgeryUrologyUrology is the medical and surgical specialty that focuses on the urinary tracts of males and females, and on the reproductive system of males. Medical professionals specializing in the field of urology are called urologists and are trained to diagnose, treat, and manage patients with urological...
– particularly in retrograde pyelography. - Implantation of cardiac rhythm management devices (pacemakersArtificial pacemakerA pacemaker is a medical device that uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart...
, implantable cardioverter defibrillators and cardiac resynchronization devices) - DiscographyLumbar provocative discographyLumbar provocative discography is an invasive diagnostic procedure for evaluation for intervertebral disc pathology...
, an invasive diagnostic procedure for evaluation for intervertebral discIntervertebral discIntervertebral discs lie between adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.-Structure:...
pathology.
Another common procedure is the modified barium swallow study during which barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
-impregnated liquids and solids are ingested by the patient. A radiologist records and, with a speech pathologist, interprets the resulting images to diagnose oral and pharyngeal swallowing dysfunction. Modified barium swallow studies are also used in studying normal swallow function.
See also
- Absorbed doseAbsorbed doseAbsorbed dose is a measure of the energy deposited in a medium by ionizing radiation per unit mass...
- Ionizing radiationIonizing radiationIonizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
- Medical imagingMedical imagingMedical imaging is the technique and process used to create images of the human body for clinical purposes or medical science...
- X-rayX-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
- RadiologyRadiologyRadiology is a medical specialty that employs the use of imaging to both diagnose and treat disease visualized within the human body. Radiologists use an array of imaging technologies to diagnose or treat diseases...
- RadiographyRadiographyRadiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition....
External links
- Fluoroscopy FDA Radiological Health Program
- "Were those old shoe store fluoroscopes a health hazard?" at Straight DopeStraight DopeThe Straight Dope is a popular question-and-answer newspaper column published in the Chicago Reader, syndicated in thirty newspapers in the United States and Canada, as well as being available and archived at the .-Newspapers:...
, 27 November 1987 - Fluoroscopy Equipment and Information from Siemens Medical
- Fluoroscopy video in the medical field
- Fluoroscopy video in the Nondestructive Testing field