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
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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
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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)
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