Flat Panel Detector (FPD) is a precision device used to convert radiation signals such as X-rays into electrical or digital signals that can be analyzed and generate images.
Flat panel detector (FPD) is the core component of X-ray detection system, mainly used to convert X-ray energy into electrical signals and generate digital images, widely used in industrial detection, medical imaging and other fields.
FPD converts X-rays that penetrate objects into photons or electrons through semiconductor materials such as amorphous silicon or cesium iodide, and then converts the signals into electrical signals through devices such as photodiodes. After amplification and analog-to-digital conversion, these electrical signals are used to generate two-dimensional images of the interior of the object through image reconstruction algorithms.
working principle
Indirect conversion type: When X-rays pass through the detected object and reach the detector, the scintillation layer (such as cesium iodide or gadolinium oxysulfide) first converts the X-ray energy into visible light. Then, the visible light is sensed by the photodiode array below and converted into an electrical signal. The electrical signal is read out through a thin film transistor (TFT) matrix, converted into a digital signal through an analog-to-digital converter (ADC), and then reconstructed by a computer.
Direct conversion type: When X-rays are irradiated onto the detector, the special semiconductor material inside (such as amorphous selenium) directly converts X-ray photons into electron hole pairs. Under the action of an external electric field, electrons and holes move in opposite directions to form current, which is stored in the inter electrode capacitance of the TFT. After being read and digitized by the TFT, the image reconstruction is completed by the computer.
Flat panel detectors complete imaging through three key stages: photoelectric conversion, signal acquisition, and digital processing
Photoelectric conversion: After X-rays penetrate an object, they are absorbed by scintillation materials on the surface of the detector (such as cesium iodide or gadolinium oxysulfide) and converted into visible light.
Signal acquisition: Visible light is converted into electrical signals by photodiode arrays (such as amorphous silicon) or photoconductive materials (such as amorphous selenium).
Digital processing: Electrical signals are read out through a thin film transistor (TFT) array and converted into digital signals through an A/D converter to generate images.