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.
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
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