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FAQ: What is digital radiography?

   

What is digital radiography?

Frequently Asked Questions

A digital radiograph is stored and displayed on a PC, rather than a radiographic film. The advantage of this is that the image can be processed, enhanced and communicated much faster than a conventional film. There are three typical methods of capturing a digital radiograph:

  • The first method is to scan a conventional wet film radiograph in a specialist scanner, similar to a document scanner.
  • The second method is known as Computed Radiography (CR). CR uses a flexible imaging plate in the place of film. A chemical process in the imaging plate captures the radiograph. The imaging plate is then attached to a drum and placed in a scanner. This scanner reads the latent image off the plate. Exposing the plate to bright light erases the plate.
  • The third method is to use a digital 'flat-panel' (similar to a digital camera) or ‘linear’ digital detector.  These detectors convert the X-ray quanta directly into electric charge.  The conversion is either direct (through an X-ray photo conductor) or indirect (a scintillator converts the X-ray quanta to visible light) and an array of photo diodes or charge couple device camera converts the light to a digital signal. The detector is positioned in the same place as the film and is connected to a PC.

The use of digital flat panels offers many advantages over conventional radiography. This includes quick setup, fast acquisition of X-ray images and automated inspection for multiple components or production inspection.  Using a flat panel also typically requires lower values of kV and smaller exposure times. The disadvantage is a slightly poorer resolution compared with fine-grain film. However, the technology is improving with time.

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