Flat Panel Detector (FPD)

A flat panel detector (FPD) is an X-ray camera (X-ray imaging device) used in digital radiography. In a digital camera, a CCD or CMOS sensor receives visible light formed through a lens and converts it into electrical signals to create an image. Similarly, an X-ray FPD converts X-rays that pass through an object into electrical signals to generate a radiographic image.

Flat panel detectors are used in X-ray CT, medical X-rays, and mammography, replacing conventional image intensifiers (I.I.) and imaging plates (IP). FPDs offer a wider dynamic range than image intensifiers and provide real-time imaging capabilities, unlike IPs which require a separate reading process.

There are two types of X-ray FPDs: indirect conversion flat panel detectors and direct conversion flat panel detectors.
In the indirect method, the scintillator is laid flat and the emission is detected by a PD (photodiode). It does not use a high-voltage power supply.
There are two methods of direct type, one using amorphous selenium (a-Se) and the other using cadmium telluride (CdTe). In the amorphous selenium method, a high-voltage bias is applied across the selenium film. When X-rays strike the film, they generate electrical charges. These charges are collected by an array of TFTs (Thin-Film Transistors), which act as switches to read out the signal and form an image.

Matsusada Precision handles power supplies for applying high voltages to amorphous selenium films.