FLUOROSCOPY

What is fluoroscopy?

• Fluoroscopy is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an x-ray source and fluorescent screen between which a patient is placed. Fluoroscopy is used for examination of moving internal structures and fluids.

FLUOROSCOPY AND ASSOCIATED PARTS

SPECIAL DEMANDS OF FLUOROSCOPY

• Fluoroscopy is a dynamic process; thus, the radiologist must adapt to moving images that are sometimes dim.
• Illumination- levels are measured in units of lumen per square meter or lux.
• Radiographs are visualized under illumination levels of 100 to 100 lux

Image-Intensifier Tube

Image Intensification

• Input phosphor
  •Made of cesium iodide (CsI)
  •Receives radiation exiting patient
  •Emits light photons


• Photo cathode
  •Responds to light exiting input phosphor
  •Emits electrons
  
• Electrostatic lenses
• •Focus electrons
  
• Output phosphor
  •Receives electrons from photocathode
  •Emits 50-75× more light than received by photocathode

Flux Gain

Flux Gain=Number of output light photons/
Number of input x-ray photons

Brightness Gain

Brightness gain = Minification gain × Flux gain

Magnification Modes

• Better spatial resolution
• Better contrast resolution
• Higher patient dose
  

Vidicon Television Camera Tube

Fiber Optics vs Lens System Coupling

A Television Picture Tube (CRT)