Question

How does fluoroscopy work? (to answer this properly you will need to draw a diagram and explain how it works; brief answers won't be acceptable). Be sure to explain in detail how the image intensifier works. Assu

Answer 1

The fluoroscope is a type of x-ray machine that can use either a pulsing or continuous x- ray beam. The x-ray tube in this machine is made of glass and sometimes metal, the tube has a vacuum seal inside. The machine creates x- rays by converting electricity from its line that supplies power( power line). The power line has a current of 120-480 volts, however to use it in the x-ray the current is converted into 25-150 kilo volt range. Then it creates a stream of electrons that are shot against a tungsten target which is a target made from the element tungsten. When the electrons hit this target the electrons stop because of its surface. The result is a release of x-ray energy, then the energy is focused by the x-ray tube into an area of the body to be imaged.

he electromagnetic waves can pass through the body and create images of the internal structures. However, because of the different tissues within the body have different densities the waves are weakened as they pass through certain tissues. An example of this is that bones absorb a lot of x-rays because it is very dense, in contrast the tissues around the bone absorb less x-ray because it is less dense. The difference in the amount of x-rays absorbed creates the light and dark colors in the image that is produced. When the beam passes through the body it hits an image intensifier which is a device that increases the amount of light produced. This then makes the image more brighter so that it can be viewed on the display screen. The image intensifier also contains a video camera that captures the two-dimensional patterns of light as a video, afterwards the image is seen on the monitor. The image can be changed for computer image enhancements. The doctor has a switch that controls the amount of x-rays passed through the body. The fluoroscope produced a little higher radiation than regular x-ray.

Working diagram of fluoroscopy

The function of an image intensifier is to convert incident x-ray photons to light photons of sufficient intensity to provide a viewable image. This occurs in several stages. The first is conversion of x-ray photons to light photons by the input phosphor. Sodium activated Cesium Iodide is typically used due to its high conversion efficiency thanks to high atomic number and mass attenuation coefficient.^[2] The light photons are then converted to electrons by a photocathode. A potential difference (25-35 kilovolts) created between the anode and photocathode then accelerates these photoelectrons while electron lenses focus the beam down to the size of the output window. The output window is typically made of silver-activated zinc-cadmium sulfide and converts incident electrons back to visible light photons.^[2] At the input and output phosphors the number of photons is multiplied by several thousands, so that overall there is a large brightness gain. This gain makes image intensifiers highly sensitive to x-rays.