Monday, March 30, 2009

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.

When was Fluoro Invented?
Fluoroscopy was invented by Thomas Edison in 1896, just one year after Wilhelm Roentgen discovered x-rays. 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 searching for practical ways to use x-rays, Edison developed the first medical fluoro screen. Like many other concepts pioneered by this peerless scientist, fluoroscopy was a revolutionary development that permanently altered the course of medical science. John Coltman created the image amplifier in the late 1940s, which today is known as the image intensifier.

Its Designs and Functions
Fluoroscopy is actually a rather routine type of x-ray examination except for its application in angiography. The x-ray tube is usually hidden under the patient table. The image intensifier and other image detection devices are set over the patient table. With some fluoroscopes, the x-ray tube is over the patient table. Some fluoroscopes are operated remotely from outside the x-ray room. Many different arrangements are provided for fluoroscopy. During image intensified fluoroscopy, the radiologic image is displayed on a television monitor.
Input phosphor receives incident x-rays from the x-ray tube and converts them into light composed of cesium iodide. The photocathode is attached to the input phosphor by an adhesive layer and it converts light from input phosphor to electrons by photoemission.

Intensification Principals / Characteristics
The image-intensifier tube is a complex electronic device that receives the image-forming x-ray bean and converts it into a visible light image of high intensity. The tube components are contained in a glass or metal envelope that provides support but more importantly contains a vacuum. Since the images are dark brightness gain comes into effect. Brightness gain is the ability for the fluoroscope to increase the brightness. Brightness gain is the product of the minification gain and the flux gain. The flux gain is the ratio of the number of light photons at the output phosphor to the number of x-rays at the input phosphor. The minification gain is the ration of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor and minification factor is the reduction in size on the input phosphor screen. . The conversion factor is the ability for the image intensifier to convert x-rays into visible light and the output phosphor illumination/input exposure rate. Automatic Brightness Control (ABC) controls the brightness of the image by automatically varying the KVP and mA.

Viewing and Recording Systems
The television camera consists of a cylindrical housing approximately 15 mm in diameter by 25 cm in length.The television camera tube converts the light image from the output phosphor of the image intensifier into an electrical signal that is sent to the televisions monitor, where it is reconstructed as an image on the television screen.

Digital Fluoroscopy
Digital fluoroscopy is a form of x-ray that allows us to view deep structures of the body in real time. It provides very detailed images of function and structure of areas like the intestines, the bladder, the cardiac muscle and stomach. Unlike regular x-ray which records the image to film, digital fluoroscopy records a series of images to a computer. Once digitized, we can view the area being examined in real time on a computer monitor. It is used to visualize the digestive tract, observe cardiac movement, assess joint movement, and in infertility testing. Digital fluoroscopy uses a controlled beam of energy that is passed through the body and captured by an image detector. Because the bones, organs and tissues within our bodies are composed of differing densities, the beams move through them differently. Bones for instance will absorb more of the beam than an organ or soft tissue making them appear white or gray on the image while the tissue appears darker.

Monday, March 16, 2009

Linear Tomography is the most basic form of tomography; it is a tomographic examination that is designed to image only that anatomy that lies in a plane of interest while blurring structures on either side of that plane. It is basically a procedure to obtain a sharper image, although this procedure is beneficial for better contrast images, it does have a higher patient dose.

Principals of Tomography

Equipment

The equipment used for Linear Tomography are similar to that of x-ray except that the tube and the film tray move in opposit directions; the top of the rod moves in one direction as the bottom moves in the opposite.

Applications

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