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M T F MODULATION TRANSFER FUNCTION ()

D Q E Detective Quantum Efficiency

S / N - SIGNAL / NOISE RATIO

Detective Quantum EfficiencyDQE Definition The simplest definition of detective quantum efficieny can be stated in the formula. It shows that the DQE is the ratio of the output SNR squared to the input SNR squared. . DQE SNR , SNR .

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MASKVP &Filtration

MAS( HKV)

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MAS 2 4 6 8 10 12 14 16 18 20 MASCR

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Digital radiography systems can be operated with speed classes higher than that conventionally used in SF. Film-based imaging provides immediate feedback to the technologist and radiologist concerning the delivery of the proper radiation exposure to the patient. If the optical densities in the film image are too great, the patient received too much radiation relative to the proper value, while reduced optical densities indicates a reduced radiation exposure. When digital image receptors replace SF image receptors, the brightness and contrast in the displayed image on the monitor are independent of the exposure used during acquisition. Only the noise in the image changes with the exposure. Radiologists react negatively to digital images with excessive noise (low patient exposure), but rarely complain about images with reduced noise due to excessive patient exposures. This leads to the potential for dose creep in CR and DR. SF ( = ). . () , , . SF, . . ( ), . CR DR. PRACTICE GUIDELINE FOR DIGITAL RADIOGRAPHYACR 2007 (Res. 42)*

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