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Title: Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system

Abstract

Purpose: Undertaking observer studies to compare imaging technology using clinical radiological images is challenging due to patient variability. To achieve a significant result, a large number of patients would be required to compare cancer detection rates for different image detectors and systems. The aim of this work was to create a methodology where only one set of images is collected on one particular imaging system. These images are then converted to appear as if they had been acquired on a different detector and x-ray system. Therefore, the effect of a wide range of digital detectors on cancer detection or diagnosis can be examined without the need for multiple patient exposures. Methods: Three detectors and x-ray systems [Hologic Selenia (ASE), GE Essential (CSI), Carestream CR (CR)] were characterized in terms of signal transfer properties, noise power spectra (NPS), modulation transfer function, and grid properties. The contributions of the three noise sources (electronic, quantum, and structure noise) to the NPS were calculated by fitting a quadratic polynomial at each spatial frequency of the NPS against air kerma. A methodology was developed to degrade the images to have the characteristics of a different (target) imaging system. The simulated images were created by firstmore » linearizing the original images such that the pixel values were equivalent to the air kerma incident at the detector. The linearized image was then blurred to match the sharpness characteristics of the target detector. Noise was then added to the blurred image to correct for differences between the detectors and any required change in dose. The electronic, quantum, and structure noise were added appropriate to the air kerma selected for the simulated image and thus ensuring that the noise in the simulated image had the same magnitude and correlation as the target image. A correction was also made for differences in primary grid transmission, scatter, and veiling glare. The method was validated by acquiring images of a CDMAM contrast detail test object (Artinis, The Netherlands) at five different doses for the three systems. The ASE CDMAM images were then converted to appear with the imaging characteristics of target CR and CSI detectors. Results: The measured threshold gold thicknesses of the simulated and target CDMAM images were closely matched at normal dose level and the average differences across the range of detail diameters were -4% and 0% for the CR and CSI systems, respectively. The conversion was successful for images acquired over a wide dose range. The average difference between simulated and target images for a given dose was a maximum of 11%. Conclusions: The validation shows that the image quality of a digital mammography image obtained with a particular system can be degraded, in terms of noise magnitude and color, sharpness, and contrast to account for differences in the detector and antiscatter grid. Potentially, this is a powerful tool for observer studies, as a range of image qualities can be examined by modifying an image set obtained at a single (better) image quality thus removing the patient variability when comparing systems.« less

Authors:
; ; ; ; ;  [1]
+ Show Author Affiliations
  1. National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom)
Publication Date:
OSTI Identifier:
22098856
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 39; Journal Issue: 5; Other Information: (c) 2012 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BIOMEDICAL RADIOGRAPHY; CORRELATIONS; DETECTION; DOSIMETRY; IMAGE PROCESSING; KERMA; MAMMARY GLANDS; MODULATION; NEOPLASMS; PATIENTS; POLYNOMIALS; RADIATION DOSES; SIMULATION; SPECTRA; THICKNESS; TRANSFER FUNCTIONS; TRANSMISSION; X RADIATION

Citation Formats

Mackenzie, Alistair, Dance, David R., Workman, Adam, Yip, Mary, Wells, Kevin, Young, Kenneth C., Northern Ireland Regional Medical Physics Service, Forster Green Hospital, Belfast, BT8 4HD, Department of Physics, University of Surrey, Guildford, GU2 7XH, Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, and National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford, GU2 7XH. Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system. United States: N. p., 2012. Web. doi:10.1118/1.4704525.
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Mackenzie, Alistair, Dance, David R., Workman, Adam, Yip, Mary, Wells, Kevin, Young, Kenneth C., Northern Ireland Regional Medical Physics Service, Forster Green Hospital, Belfast, BT8 4HD, Department of Physics, University of Surrey, Guildford, GU2 7XH, Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, & National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford, GU2 7XH. Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system. United States. https://doi.org/10.1118/1.4704525
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Mackenzie, Alistair, Dance, David R., Workman, Adam, Yip, Mary, Wells, Kevin, Young, Kenneth C., Northern Ireland Regional Medical Physics Service, Forster Green Hospital, Belfast, BT8 4HD, Department of Physics, University of Surrey, Guildford, GU2 7XH, Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, and National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford, GU2 7XH. 2012. "Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system". United States. https://doi.org/10.1118/1.4704525.
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@article{osti_22098856,
title = {Conversion of mammographic images to appear with the noise and sharpness characteristics of a different detector and x-ray system},
author = {Mackenzie, Alistair and Dance, David R. and Workman, Adam and Yip, Mary and Wells, Kevin and Young, Kenneth C. and Northern Ireland Regional Medical Physics Service, Forster Green Hospital, Belfast, BT8 4HD and Department of Physics, University of Surrey, Guildford, GU2 7XH and Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH and National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford, GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford, GU2 7XH},
abstractNote = {Purpose: Undertaking observer studies to compare imaging technology using clinical radiological images is challenging due to patient variability. To achieve a significant result, a large number of patients would be required to compare cancer detection rates for different image detectors and systems. The aim of this work was to create a methodology where only one set of images is collected on one particular imaging system. These images are then converted to appear as if they had been acquired on a different detector and x-ray system. Therefore, the effect of a wide range of digital detectors on cancer detection or diagnosis can be examined without the need for multiple patient exposures. Methods: Three detectors and x-ray systems [Hologic Selenia (ASE), GE Essential (CSI), Carestream CR (CR)] were characterized in terms of signal transfer properties, noise power spectra (NPS), modulation transfer function, and grid properties. The contributions of the three noise sources (electronic, quantum, and structure noise) to the NPS were calculated by fitting a quadratic polynomial at each spatial frequency of the NPS against air kerma. A methodology was developed to degrade the images to have the characteristics of a different (target) imaging system. The simulated images were created by first linearizing the original images such that the pixel values were equivalent to the air kerma incident at the detector. The linearized image was then blurred to match the sharpness characteristics of the target detector. Noise was then added to the blurred image to correct for differences between the detectors and any required change in dose. The electronic, quantum, and structure noise were added appropriate to the air kerma selected for the simulated image and thus ensuring that the noise in the simulated image had the same magnitude and correlation as the target image. A correction was also made for differences in primary grid transmission, scatter, and veiling glare. The method was validated by acquiring images of a CDMAM contrast detail test object (Artinis, The Netherlands) at five different doses for the three systems. The ASE CDMAM images were then converted to appear with the imaging characteristics of target CR and CSI detectors. Results: The measured threshold gold thicknesses of the simulated and target CDMAM images were closely matched at normal dose level and the average differences across the range of detail diameters were -4% and 0% for the CR and CSI systems, respectively. The conversion was successful for images acquired over a wide dose range. The average difference between simulated and target images for a given dose was a maximum of 11%. Conclusions: The validation shows that the image quality of a digital mammography image obtained with a particular system can be degraded, in terms of noise magnitude and color, sharpness, and contrast to account for differences in the detector and antiscatter grid. Potentially, this is a powerful tool for observer studies, as a range of image qualities can be examined by modifying an image set obtained at a single (better) image quality thus removing the patient variability when comparing systems.},
doi = {10.1118/1.4704525},
url = {https://www.osti.gov/biblio/22098856}, journal = {Medical Physics},
issn = {0094-2405},
number = 5,
volume = 39,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2012},
month = {Tue May 15 00:00:00 EDT 2012}
}
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Journal Article:
https://doi.org/10.1118/1.4704525
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