There are two main technologies available inDirect Digital Radiography (DR):
The Charge Coupled Device (CCD) based detectors and Flat Panel (either direct or indirect capture) detectors are the two choices when considering your Direct Digital X-ray System
The CCD technology uses a very high density CCD (VHD CCD), a lens and a scintillator. Light from the scintillator is deflected by a mirror into the lens. The lens focuses light onto the 6-19 Megapixels of the CCD. A crucial difference between this and Flat Panel technology is CCD based detector does not have any electronics in the radiation field.
Flat Panel systems – either direct or indirect – use a thin film transistor (TFT), layers that capture the X-ray generated electrons. Unlike CCD technology, the electronics in Flat Panel systems are in the direct radiation beam which is damaging and can cause the electronics to fail. To protect the electronics and reduce the risk of failure, Flat Panel manufacturers “harden” them, a process which reduces the efficiency.
Additionally, these complex electronic devices have layers of components that are surrounded by protective casings. In order to produce these Flat Panel Digital X-ray Systems, arrays of smaller devices are tiled together which prevents an entirely seamless image.
Another important difference between CCD and Flat Panel technology pertains to fill factor. CCD has 100% fill factor which means 100% of the pixel area is used. Flat Panel systems have far lower fill factors because they have electronics running through each pixel reducing the X-ray capture surface area. The higher the fill factor, the higher the resolution of the image and the lower the dose needed. CCD 100% fill factor provides maximum efficiency with lower radiation.

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