How many detectors does a flat panel detector?

The basis of two digital detector types, direct and indirect detectors, is given. The direct and indirect detectors, made as the active-matrix flat-panel detectors containing sensing/storage elements, switching elements (diodes or thin film transistors (TFTS)) and image processing module, are described.

What is a flat panel image detector?

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

What are the two classes of flat panel detectors?

There are currently two main types of flat-panel detectors, direct and indirect. The main difference between the two types is the conversion process.

What is a TFT in radiology?

The TFT is a photosensitive array made up of small (about 100 to 200 µm) pixels, also called a detector element (del) in these TFT arrays. Each pixel contains a photodiode that absorbs the electrons and generates electrical charges.

How does a flat panel detector ( FPD ) work?

Flat panel detectors FPDs are digital radiography (DR) devices that either convert x-rays into an electric charge (direct conversion) or light (indirect conversion) which is then read out through TFTs (Thin Film Transistors). The imaging principles used in FPDs are similar to those of imaging sensors used in digital photography and video cameras.

How are indirect conversion detectors similar to direct detectors?

Indirect-conversion detectors are similar to direct detectors in that they use TFT technology. Unlike direct conversion, indirect conversion is a two-step process: x-ray photons are converted to light, and then the light photons are converted to an electrical signal.

What kind of semiconductor is used in flat panel detectors?

The substrate of choice for many of the detectors we will be investigating is ordinary glass; the semiconductor used in flat-panel detectors is hydrogenated amorphous Si (a-Si:H), and for direct conversion x-ray detectors, the only material that has developed into commercial systems is a-Se.

What kind of material is used in Indirect detectors?

Indirect detectors contain a layer of scintillator material, typically either gadolinium oxysulfide or cesium iodide, which converts the x-rays into light. Directly behind the scintillator layer is an amorphous silicon detector array manufactured using a process very similar to that used to make LCD televisions and computer monitors.