A fluorescent screen is a type of transparent screen that is coated on one side with a phosphor that fluoresces when exposed to cathode rays or X-rays. Fluoroscopy is an imaging method that uses X-rays and a fluoroscope to produce real-time moving pictures of the internal organs of a patient.
A simple fluoroscope includes an X-ray source and fluorescent screen between which a patient is placed. As the X-rays pass through the patient's body, they are attenuated by different amounts as they come in contact with different organs of the body, displaying a shadow of the organs on the fluorescent screen.
Modern fluoroscopes, however, have an X-ray image intensifier and CCD video camera that allow the images to be recorded and displayed on a monitor. X-rays are a type of ionizing radiation, which pose a potential high risk of radiation-induced cancer, and they therefore require caution to avoid applying high doses to a patient during fluoroscopic procedures. Longer fluoroscopic procedures, however, unavoidably lead to absorption of relatively high rates by a patient.
Technological developments, such as digitization of captured images and flat panel detector systems, help reduce the patient's exposure to radiation. Radiation doses may vary according to the size of the patient and the length of the procedures. Exposure times vary based on the procedure.