A modern fluoroscope.

Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time images of the internal structures of a patient through the use of a fluoroscope. A physician, medical practitioner or medical doctor who practices Medicine, and is concerned with maintaining or restoring human Health In its simplest form, a fluoroscope consists of an x-ray source and fluorescent screen between which a patient is placed. X-radiation (composed of X-rays) is a form of Electromagnetic radiation. However, modern fluoroscopes couple the screen to an x-ray image intensifier and CCD video camera allowing the images to be played and recorded on a monitor. An X-ray image intensifier (XRII sometimes referred to as a C-Arm or Fluoroscope in medical settings is a highly complex piece of equipment which uses A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors A video camera is a Camera used for electronic Motion picture acquisition initially developed by the Television industry but now common in other applications The use of x-rays, a form of ionizing radiation, requires that the potential risks from a procedure be carefully balanced with the benefits of the procedure to the patient. Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation While physicians always try to use low dose rates during fluoroscopy procedures, the length of a typical procedure often results in a relatively high absorbed dose to the patient. Absorbed dose (also known as total ionizing dose, TID is a measure of the energy deposited in a medium by Ionizing radiation. Recent advances include the digitization of the images captured and flat-panel detector 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 barium platinocyanide screen fluorescing as a result of being exposed to what he would later call x-rays. Events 1519 - Hernán Cortés enters Tenochtitlán and Aztec ruler Moctezuma welcomes him with great a Celebration Year 1895 ( MDCCCXCV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar (or a Common year Wilhelm Conrad Röntgen (27 March 1845 &ndash 10 February 1923 was a German physicist, who on 8 November 1895 produced and detected Electromagnetic Barium (ˈbɛəriəm is a Chemical element. It has the symbol Ba, and Atomic number 56 X-radiation (composed of X-rays) is a form of Electromagnetic radiation. 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. Scheelite is a Calcium Tungstate Mineral with the Chemical formula Ca[[tungsten W]] O 4 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. For medical radiography see Radiology Radiography is the use of X-rays to view unseen or hard-to-image objects

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. A radiation burn is damage to the Skin or other Biological tissue caused by exposure to radio frequency energy or Ionizing radiation. Trivial uses for the technology also resulted, including the shoe-fitting fluoroscope used by shoe stores in the 1930s-1950s. Shoe-fitting Fluoroscopes were X-ray machines installed in Shoe stores from the early 20th century up until about 1960 in the United States by Year 1930 ( MCMXXX) was a Common year starting on Wednesday (link will display 1930 calendar of the Gregorian calendar. Year 1950 ( MCML) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar. [1]

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. Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases The placement of the radiologist behind the screen resulted in significant radiation doses to the radiologist. Absorbed dose (also known as total ionizing dose, TID is a measure of the energy deposited in a medium by Ionizing radiation. 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. Red adaptation goggles were first invented by Wilhem Trendelenburg in 1916 for early Radiologists to use to adapt their eyes to view the light produced by fluorescent Ernst Wilhelm Theodor Trendelenburg 16 July 1877 &ndash 16 March 1946) was a German Physiologist. Year 1916 ( MCMXVI) was a Leap year starting on Saturday (link will display the full calendar of the Gregorian calendar (or a Leap year In ocular physiology adaptation is the ability of the Eye to adjust to various levels of darkness and light 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. An X-ray image intensifier (XRII sometimes referred to as a C-Arm or Fluoroscope in medical settings is a highly complex piece of equipment which uses A professional Video camera (often called a television camera even though the use has spread is a high-end device for recording electronic moving images (as opposed Year 1950 ( MCML) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar. 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. Red adaptation goggles were first invented by Wilhem Trendelenburg in 1916 for early Radiologists to use to adapt their eyes to view the light produced by fluorescent 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. A camera is a device used to capture images either as still Photographs or as sequences of moving images ( Movies or Videos. Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment

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. A phosphor is a substance that exhibits the phenomenon of Phosphorescence (sustained glowing after exposure to energized particles such as Electrons Modern fluoroscopes use CsI screens and produce noise-limited images, ensuring that the minimal radiation dose results while still obtaining images of acceptable quality. Caesium iodide (CsI is an Ionic compound often used as the input Phosphor of an X-ray image intensifier tube found in Fluoroscopy equipment

Risks

Because fluoroscopy involves the use of x rays, a form of ionizing radiation, all fluoroscopic procedures pose a potential health risk to the patient. Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation 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. The gray (symbol Gy is the SI unit of absorbed radiation dose. 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. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled Erythema is redness of the Skin caused by Capillary congestion A sunburn is a burn to living tissue such as Skin produced by overexposure to Ultraviolet (UV radiation commonly from the Sun 's rays

A study has been performed by the Food and Drug Administration (FDA) entitled Radiation-induced Skin Injuries from Fluoroscopy[2] 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[3].

While deterministic radiation effects are a possibility, radiation burns are not typical of standard fluoroscopic procedures. A radiation burn is damage to the Skin or other Biological tissue caused by exposure to radio frequency energy or Ionizing radiation. Most procedures sufficiently long in length to produce radiation burns are part of necessary life-saving operations.

Fluoroscopy 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 shadow of the structures on the fluorescent screen. In Physics, attenuation (in some context also called extinction) is the gradual loss in intensity of any kind of Flux through a medium A shadow is an area where direct light from a light source cannot reach due to obstruction by an object 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. Introduction When a Metallic surface is exposed to Electromagnetic radiation above a certain threshold Frequency, the light is absorbed and Electrons The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J While much of the energy given to the electrons is dissipated as heat, a fraction of it is given off as visible light, producing the images. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Early radiologists would adapt their eyes to view the dim fluoroscopic images by sitting in darkened rooms, or by wearing red adaptation goggles. Radiology is the medical specialty directing Medical imaging technologies to diagnose and treat diseases Red adaptation goggles were first invented by Wilhem Trendelenburg in 1916 for early Radiologists to use to adapt their eyes to view the light produced by fluorescent

X-ray Image Intensifiers

Main article: Image intensifier

The invention of X-ray image intensifiers 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. A night vision device (NVD is an Optical instrument that allows images to be produced in levels of light approaching total darkness An X-ray image intensifier (XRII sometimes referred to as a C-Arm or Fluoroscope in medical settings is a highly complex piece of equipment which uses Year 1950 ( MCML) was a Common year starting on Sunday (link will display the full calendar of the Gregorian calendar. 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. A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors

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. Caesium iodide (CsI is an Ionic compound often used as the input Phosphor of an X-ray image intensifier tube found in Fluoroscopy equipment 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. Quantum noise is uncertainty of some physical quantity due to its quantum origin

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. Angiography or arteriography is a Medical imaging technique in which an X-ray image is taken to visualize the inside or lumen, of blood vessels Cardiac catheterization ( heart cath) is the insertion of a Catheter into a chamber or vessel of the Heart.

Imaging concerns

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. 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. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Computing and especially Computer networks lag (slang is a symptom where the result of an action appears later than expected 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. 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. Temporal blurring also complicates measurements of system performance for fluoroscopic systems.

Common procedures using fluoroscopy

• Investigations of the gastrointestinal tract, including barium enemas, barium meals and barium swallows, and enteroclysis. lower gastrointestinal series, also called a barium enema, is a medical procedure used to examine and diagnose problems with the human colon (large intestine A barium meal, also known as an upper gastrointestinal series is a procedure in which radiographs of the Esophagus, A barium swallow is a Medical imaging procedure used to examine the upper GI (gastrointestinal tract which includes the esophagus and to a lesser extent the stomach Enteroclysis is a Fluoroscopic X-ray of the Small intestine. Radiocontrast is infused through a tube inserted through the nose to the Duodenum
• Orthopaedic surgery to guide fracture reduction and the placement of metalwork. Orthopedic surgery or orthopedics (also spelled orthopaedics) is the branch of Surgery concerned with injuries to or conditions involving the
• Angiography of the leg, heart and cerebral vessels. Angiography or arteriography is a Medical imaging technique in which an X-ray image is taken to visualize the inside or lumen, of blood vessels
• Placement of a PICC (peripherally inserted central catheter)
• Placement of a weighted feeding tube (e. A peripherally inserted central catheter ( PICC or PIC line) is a form of Intravenous access that can be used for a prolonged period of time e g. Dobhoff) into the duodenum after previous attempts without fluoroscopy have failed.
• Urological surgery – particularly in retrograde pyelography. Urology is the branch of Surgery that focuses on the Urinary tracts of males and females and on the reproductive system of males An intravenous pyelogram (also known as IVP, pyelography, intravenous urogram or IVU) is a radiological procedure used to visualize
• Implantation of cardiac rhythm management devices (pacemakers, implantable cardioverter defibrillators and cardiac resynchronization devices)

Another common procedure is the modified barium swallow study during which barium-impregnated liquids and solids are ingested by the patient. For other uses see Pacemaker (disambiguation A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker An implantable cardioverter-defibrillator ( ICD) is a small battery -powered electrical impulse generator which is implanted in patients who are at risk of Sudden Barium (ˈbɛəriəm is a Chemical element. It has the symbol Ba, and Atomic number 56 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 dose
• Ionizing radiation
• Medical Imaging
• X Ray
• Radiology
• Radiography

External links

• "Were those old shoe store fluoroscopes a health hazard?" at Straight Dope, 27 November 1987

• - Fluoroscopy Equipment and Information from Siemens Medical