Flat Panel X-ray DetectorFlat panel X-ray detector (FPXD) technology has developed rapidly in the last decade, fueled by improvements in large-area amorphous Silicon (α-Si) thin-film transistor (TFT) arrays, and innovations in deposition techniques for scintillators and photoconductors. Several types of FPXD are commercially available today for digital medical imaging. ANRAD detectors are based on amorphous Selenium technology on TFT arrays, which enable high resolution, excellent contrast, and a high frame rate. Direct vs. Indirect X-ray Conversion Two conversion methods can be used in digital X-ray imaging: direct and indirect. The direct conversion method transforms X-ray energy directly into electrical charges within a semiconductor. The indirect conversion requires an intermediate step: X-ray energy is first converted into light by a scintillating medium before conversion into electrical charges by a photodiode.
With indirect detection, the light generated by the X-ray interaction in the scintillator spreads in every direction and consequently degrades the spatial resolution. Needle-type scintillators can greatly help in guiding the light to a pixel, but a certain degree of light still will spread to neighboring pixels. The direct X-ray conversion method has the main benefit of having a higher modulation transfer function (MTF), leading to a high spatial resolution and highly contrasted images. ANRAD Amorphous Selenium TechnologyThe patented ANRAD Selenium structure includes blocking layers that permit fast image readout and high dynamic range. ANRAD Selenium technology is suitable for both static and dynamic imaging. To learn more about ANRAD’s direct X-ray detectors, click here. To find out what kind of solutions ANRAD can offer, click here.
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