Last revised by Mateusz Wilczek on 14 Nov 2023

Fluoroscopy is an imaging modality that allows real-time x-ray viewing of a patient with high temporal resolution. It is based on an x-ray image intensifier coupled to a still/video camera. In recent years flat panel detectors (like those used in direct digital radiography) have been replacing the image intensifiers.

Fluoroscopic apparatus uses low current (0.5-5 mA) for continuous or near-continuous x-ray exposures. Resultant images have relatively low signal to noise ratio (SNR) but are of sufficient quality for patient positioning and certain diagnostic/therapeutic procedures.

Overview of a fluoroscopy system

  • x-ray generator

  • x-ray tube, including filters and collimation

  • patient table (which may be horizontal or erect)

  • image intensifier: converts x-rays emerging from the patient into an optical image

  • optical distributor: used to couple the output image from the image intensifier to receiving devices:

    • video camera: converts the image into an electronic signal, which can be fed into the image display/record device

    • spot-film camera recording static images onto film, which may incorporate a film changer (radiography and fluoroscopy (R&F) system)

    • cine camera: to record a sequence of images onto a roll of film/digital medium

    • image displaying/recording device

      • video monitor: for immediate display of image (videofluoroscopy)

      • videotape recorder: for storage and subsequent replay

    • computer: for digital image processing, analysis and storage (digital fluorography), e.g. digital subtraction angiography (DSA)

Design of the x-ray tube and image intensifier assembly

There are various setups of fluoroscopy machines: 

  • ceiling-suspended image intensifier and under-table tube (most common)

  • ceiling-suspended tube and under-table image intensifier

  • C-arm assembly: either ceiling-suspended or floor-mounted (for DSA and interventional procedures)

  • mobile C-arm system (for operating theater)

See also

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