What is the function of the flat panel thin film transistor detectors (FDP/TFT) when using the direct method to produce an image?

The function of flat panel thin film transistor detectors (FDP/TFT) in the direct method of image production is to convert X-rays to electrons. This process occurs when X-rays penetrate the detector material, typically made of a photoconductive layer, such as amorphous selenium (a-Se). In this scenario, the energy from the incoming X-rays frees electrons in the photoconductive material, creating an electric signal.

This conversion process is vital because it forms the basis for capturing the image data. The electrons generated are then collected by the TFT array, which plays a key role in reading out these signals, thus enabling the formation of a digital image. This direct conversion method allows for high-quality images with excellent spatial resolution and improved efficiency compared to indirect methods, which involve additional steps.

Understanding this mechanism helps clarify how the FDP/TFT systems efficiently transform X-ray data into usable image form, emphasizing the role of direct conversion in modern radiographic technology.