CAMRT Radiography Practice Exam

Which component of the image intensifier is responsible for focusing the electron beam?

1. Optical Lens

2. Electrostatic Lens

3. Photocathode

4. Image Receptor

The correct answer is: Electrostatic Lens

The component responsible for focusing the electron beam within the image intensifier is the electrostatic lens. This device uses an electric field to manipulate the path of the electrons emitted from the photocathode. When light photons hit the photocathode, they liberate electrons, which then travel through the image intensifier. The electrostatic lens, created by carefully arranged electrodes, focuses these electrons onto a specific area, improving the spatial resolution and brightness of the resulting image on the output phosphor. Each of the other components has distinct functions: the optical lens is involved in converting the light emitted from the output phosphor into a viewing format, while the photocathode is where the initial conversion of light to electrons occurs. The image receptor plays a role in capturing or displaying the final image but does not focus the electron beam. Understanding the roles of these components provides clarity on the function of the image intensifier and the process of image enhancement in radiography.