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http://dx.doi.org/10.5573/ieie.2016.53.12.120

Noise Power Spectrum of Radiography Detectors: I. Measurement Using the Averages of Images  

Kim, Dong Sik (Hankuk University of Foreign Studies)
Lee, Eunae (Hankuk University of Foreign Studies)
Publication Information
Journal of the Institute of Electronics and Information Engineers / v.53, no.12, 2016 , pp. 120-127 More about this Journal
Abstract
In order to acquire digital x-ray images, developing radiography detectors have been recently conducted based on the DR (digital radiography) technology. The noise property of the radiography detector can be observed from measuring the NNPS (normalized noise power spectrum) using uniform exposure images. Here, the image difference of two images is used to remove the fixed pattern noise in measuring the detector NNPS. In this paper, two average images are first calculated using several images and then their difference is used to calculate an NNPS value. Here, the obtained NNPS value is usually lower than the true detector NNPS due to the average. Hence, a compensation constant, which is a function of the number of used images, is also proposed to compensate the NNPS value to obtain the true detector NNPS. Furthermore, another measurement method, in which the ratio of the average images is used, is proposed. Through NNPS measuring experiments using real x-ray images, it is observed that the proposed method can provide further accurate NNPS measurements.
Keywords
Average image difference; Average image ratio; Noise power spectrum; Radiography detector;
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