Measurement of correlated noise in images of computed radiography systems and its influence on the detective quantum efficiency

Hartmut Illers; Dirk Vandenbroucke; Egbert Buhr

doi:10.1117/12.535807

6 May 2004 Measurement of correlated noise in images of computed radiography systems and its influence on the detective quantum efficiency

Hartmut Illers, Dirk Vandenbroucke, Egbert Buhr

Author Affiliations +

Proceedings Volume 5368, Medical Imaging 2004: Physics of Medical Imaging; (2004) https://doi.org/10.1117/12.535807
Event: Medical Imaging 2004, 2004, San Diego, California, United States

Abstract

The contributors to image noise of two computed radiography (CR) detector systems-a state-of-the-art and a wellchosen laboratory CR image plate-were studied by two different methods. Method 1 analyzes the image noise content of a series of images obtained at a wide range of different X-ray exposure levels. It uses a model to fit the observed exposure dependence of the normalized noise power spectrum (NNPS): It distinguishes between an NNPS component that is independent of the exposure level and mainly due to correlated noise, and an NNPS component which is inversely proportional to the exposure level and consists mainly of quantum noise. Method 2 analyzes several images taken at the same exposure level and distinguishes between correlated noise, which remains unchanged in repeated exposures, and uncorrelated noise which is different in each image. The results of the two methods allowed the relevant noise contributions in CR images to be quantitatively determined. The novel laboratory image plate showed a significant reduction of correlated noise with an accompanying increase in the DQE. The results also served to estimate a possible improvement of DQE if an appropriate flat field correction is made for these CR systems.

Citation Download Citation

Hartmut Illers, Dirk Vandenbroucke, and Egbert Buhr "Measurement of correlated noise in images of computed radiography systems and its influence on the detective quantum efficiency", Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); https://doi.org/10.1117/12.535807

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