A mobile X-ray image intensifier (XRII), sometimes referred to as a C-Arm or Fluoroscope in medical settings, is a highly complex piece of equipment which uses x-rays and produces a 'live' image feed which is displayed on a TV screen. The term image intensifier refers to a special component of the machine, which allows low intensity x-rays to be amplified, resulting in a smaller dose to the patient. The overall system consists of an x-ray source, input window, input phosphor, photocathode, vacuum and electron optics, output phosphor and output window. It allows for lower x-ray doses to be used on patients by magnifying the intensity produced in the output image, enabling the viewer to easily see the structure of the object being imaged. They were introduced by Philips in 1955.