*FLUOROSCOPY*

Source:  *FLUOROSCOPY*    Tag:  fluoroscopy tube
WHAT IS FLUOROSCOPY?

Fluoroscopy is a study of moving body structures - similar to an x-ray "movie." A continuous x-ray beam is passed through the body part being examined, and is transmitted to a TV-like monitor so that the body part and its motion can be seen in detail.




HISTORY OF FLUOROSCOPY



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. 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.
















PURPOSE

Fluoroscopy, as an imaging tool, enables physicians to look at many body systems, including the skeletal, digestive, urinary, respiratory, and reproductive systems. Fluoroscopy may be performed to evaluate specific areas of the body, including the bones, muscles, and joints, as well as solid organs such as the heart, lung, or kidneys.















EXAMINATIONS

Fluoroscopy is used in many types of examinations and procedures, such as barium x-rays, cardiac catheterization, and placement of intravenous (IV) catheters (hollow tubes inserted into veins or arteries). In barium x-rays, fluoroscopy allows the physician to see the movement of the intestines as the barium moves through them. In cardiac catheterization, fluoroscopy enables the physician to see the flow of blood through the coronary arteries in order to evaluate the presence of arterial blockages. For intravenous catheter insertion, fluoroscopy assists the physician in guiding the catheter into a specific location inside the body.











X ray- 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. 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.









four principal components

* A vacuum bottle to keep the air out
*An input layer that converts the x-ray signal to electrons
*electronic lens that focus the electrons and,
*An output phosphorus that converts the accelerated electrons into visible light.












EQUIPMENT

fluoroscopy machine includes an x-ray source and detector mounted in spaced relation to a support arm, an image processor and a display device. The display device includes image optics attached to a head mount wearable by a person, such as a physician or technician. The image displayed by the image optics can be processed by the image processor to present an orientationally accurate image corresponding to the head mount wearer's field of view. For example, the image can be processed to correct for angle of rotation, translation and/or perspective distortion.