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The detective quantum efficiency (often abbreviated as DQE) is a measure of the combined effects of the signal (related to image contrast) and noise performance of an imaging system, generally expressed as a function of spatial frequency. This value is used primarily to describe imaging detectors in optical imaging and medical radiography.
In medical radiography, the DQE describes how effectively an x-ray imaging system can produce an image with a high signal-to-noise ratio (SNR) relative to an ideal detector. It is sometimes viewed to be a surrogate measure of the radiation dose efficiency of a detector since the required radiation exposure to a patient (and therefore the biological risk from that radiation exposure) decreases as the DQE is increased for the same image SNR and exposure conditions.
The DQE is also an important consideration for CCDs, especially those used for low-level imaging in light and electron microscopy, because it affects the SNR of the images. It is also similar to the noise factor used to describe some electronic devices. The concept has been extended to chemical sensors,[1] in which case the alternative term detectivity[2] is more appropriate.