X-ray detector

An instrument that registers incoming X-ray photons and converts them into measurable signals. Its design determines how those signals represent photon energy, arrival time, or spatial distribution.

Photoelectric effect: The absorption of a photon by matter, transferring its energy to an electron. In many detectors, this interaction converts an incoming X-ray into an energetic electron.
X-ray: Electromagnetic radiation with wavelengths shorter than ultraviolet light and photon energies high enough to penetrate many materials. X-rays are the photons the detector must register.
Digital radiography: Medical imaging that records X-ray transmission as digital data rather than on photographic film. Flat-panel detectors capture the transmitted X-rays used to form radiographic images.
Film radiography: Radiographic imaging that records X-ray exposure as a latent image in photographic film. It records exposure chemically, unlike digital detectors that produce electronic signals.
Detector dead time: The interval after a detection event during which a detector cannot reliably register another event. Dead time can cause missed counts when X-ray flux is high.
Scintillation: The emission of brief flashes of light from a material excited by ionizing radiation. Scintillators turn absorbed X-ray energy into light that a photodetector can measure.
Ionizing radiation: Radiation energetic enough to remove electrons from atoms or molecules. X-rays produce detectable charge by ionizing atoms in sensing materials.
Computed tomography: An imaging method that reconstructs cross-sectional views from measurements taken at multiple angles. Its projections depend on detectors measuring transmitted X-rays during rotation.
Indirect-conversion detector: An X-ray detector that first converts X-rays into visible light and then converts that light into charge. It contrasts with direct-conversion designs, which create charge from X-ray interactions in the sensor.
Charge sharing: The division of charge from one radiation event among multiple neighboring detector pixels. It can blur photon localization and distort energy estimates in pixelated detectors.

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