Flat panel detectors

Flat panel detectors (FPD) are used in direct digital radiography (DDR) for conversion of X-rays to light (indirect conversion) or charge (direct conversion) which is read out using thin film transistors (TFT array).


They are of two types:

  1. indirect conversion FPDs
    • outermost layer is scintillator: phosphor screen (caesium iodide or gadolinium oxysulfide)
    • detector: based on amorphous silicon photodiode
    • convert X-rays to light and then to charge (hence called indirect FPDs)
  2. direct conversion FPDs
    • outermost layer: high voltage bias electrode
    • detector: based on amorphous selenium 
    • convert X-rays to charge directly (hence called direct FPDs)

It is important to note that indirect conversion can also be detected using charge-coupled devices (CCDs). These are small and require optical coupling.

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Article information

rID: 26365
Section: Physics
Tag: refs
Synonyms or Alternate Spellings:
  • FPDs

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