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Model of the spatial‐frequency‐dependent detective quantum efficiency of phosphor screens
Author(s) -
Nishikawa Robert M.,
Yaffe Martin J.
Publication year - 1990
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.596583
Subject(s) - phosphor , detective quantum efficiency , physics , medical imaging , optics , computer science , optoelectronics , computer vision , artificial intelligence , image quality , image (mathematics)
We have developed a theoretical model to predict the modulation transfer function (MTF), the shape of the x‐ray quantum noise power spectrum (NPS), and the spatial‐frequency‐dependent detective quantum efficiency (DQE) of an x‐ray phosphor screen. The transfer of energy through the screen is modelled as a series of cascaded stochastic processes assuming that the screen consists of many thin phosphor layers. In this way, the model is able to account for the possibility of secondary‐quantum noise and the difference in shape between MTF 2 and the x‐ray quantum NPS. Modelling a Kodak Min‐R screen we were able to predict both the number of light quanta emitted per absorbed x‐ray and MTF( f ) to better than ±5%, and the scintillation efficiency to within 10% of experimentally measured values. The shape of the x‐ray quantum NPS is predicted to within ±5% for spatial frequencies less than about 6 mm ‐1 and to within ±20% for higher frequencies.