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Title: Optimization of dual-energy imaging systems using generalized NEQ and imaging task

Abstract

Dual-energy (DE) imaging is a promising advanced application of flat-panel detectors (FPDs) with a potential host of applications ranging from thoracic and cardiac imaging to interventional procedures. The performance of FPD-based DE imaging systems is investigated in this work by incorporating the noise-power spectrum associated with overlying anatomical structures (''anatomical noise'' modeled according to a 1/f characteristic) into descriptions of noise-equivalent quanta (NEQ) to yield the generalized NEQ (GNEQ). Signal and noise propagation in the DE imaging chain is modeled by cascaded systems analysis. A Fourier-based description of the imaging task is integrated with the GNEQ to yield a detectability index used as an objective function for optimizing DE image reconstruction, allocation of dose between low- and high-energy images, and selection of low- and high-kVp. Optimal reconstruction and acquisition parameters were found to depend on dose; for example, optimal kVp varied from [60/150] kVp at typical radiographic dose levels ({approx}0.5 mGy entrance surface dose, ESD) but increased to [90/150] kVp at high dose (ESD{approx}5.0 mGy). At very low dose (ESD{approx}0.05 mGy), detectability index indicates an optimal low-energy technique of 60 kVp but was largely insensitive to the choice of high-kVp in the range 120-150 kVp. Similarly, optimal dose allocation, definedmore » as the ratio of low-energy ESD and the total ESD, varied from 0.2 to 0.4 over the range ESD=(0.05-5.0) mGy. Furthermore, two applications of the theoretical framework were explored: (i) the increase in detectability for DE imaging compared to conventional radiography; and (ii) the performance of single-shot vs double-shot DE imaging, wherein the latter is found to have a DQE approximately twice that of the former. Experimental and theoretical analysis of GNEQ and task-based detectability index provides a fundamental understanding of the factors governing DE imaging performance and offers a framework for system design and optimization.« less

Authors:
;  [1];  [2]
  1. Department of Medical Biophysics, University of Toronto, Ontario, M5G 2M9 (Canada)
  2. (Canada)
Publication Date:
OSTI Identifier:
20853903
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 1; Other Information: DOI: 10.1118/1.2400620; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; DOSIMETRY; IMAGE PROCESSING; IMAGES; NOISE; OPTIMIZATION; PERFORMANCE; RADIATION DOSES; SYSTEMS ANALYSIS

Citation Formats

Richard, S., Siewerdsen, J. H., and Ontario Cancer Institute, Princess Margaret Hospital, Ontario, M5G 2M9, Canada, Department of Medical Biophysics, University of Toronto, Ontario, M5G 2M9, Canada, and Department of Radiation Oncology, University of Toronto, Ontario, M5G 2M9. Optimization of dual-energy imaging systems using generalized NEQ and imaging task. United States: N. p., 2007. Web. doi:10.1118/1.2400620.
Richard, S., Siewerdsen, J. H., & Ontario Cancer Institute, Princess Margaret Hospital, Ontario, M5G 2M9, Canada, Department of Medical Biophysics, University of Toronto, Ontario, M5G 2M9, Canada, and Department of Radiation Oncology, University of Toronto, Ontario, M5G 2M9. Optimization of dual-energy imaging systems using generalized NEQ and imaging task. United States. doi:10.1118/1.2400620.
Richard, S., Siewerdsen, J. H., and Ontario Cancer Institute, Princess Margaret Hospital, Ontario, M5G 2M9, Canada, Department of Medical Biophysics, University of Toronto, Ontario, M5G 2M9, Canada, and Department of Radiation Oncology, University of Toronto, Ontario, M5G 2M9. Mon . "Optimization of dual-energy imaging systems using generalized NEQ and imaging task". United States. doi:10.1118/1.2400620.
@article{osti_20853903,
title = {Optimization of dual-energy imaging systems using generalized NEQ and imaging task},
author = {Richard, S. and Siewerdsen, J. H. and Ontario Cancer Institute, Princess Margaret Hospital, Ontario, M5G 2M9, Canada, Department of Medical Biophysics, University of Toronto, Ontario, M5G 2M9, Canada, and Department of Radiation Oncology, University of Toronto, Ontario, M5G 2M9},
abstractNote = {Dual-energy (DE) imaging is a promising advanced application of flat-panel detectors (FPDs) with a potential host of applications ranging from thoracic and cardiac imaging to interventional procedures. The performance of FPD-based DE imaging systems is investigated in this work by incorporating the noise-power spectrum associated with overlying anatomical structures (''anatomical noise'' modeled according to a 1/f characteristic) into descriptions of noise-equivalent quanta (NEQ) to yield the generalized NEQ (GNEQ). Signal and noise propagation in the DE imaging chain is modeled by cascaded systems analysis. A Fourier-based description of the imaging task is integrated with the GNEQ to yield a detectability index used as an objective function for optimizing DE image reconstruction, allocation of dose between low- and high-energy images, and selection of low- and high-kVp. Optimal reconstruction and acquisition parameters were found to depend on dose; for example, optimal kVp varied from [60/150] kVp at typical radiographic dose levels ({approx}0.5 mGy entrance surface dose, ESD) but increased to [90/150] kVp at high dose (ESD{approx}5.0 mGy). At very low dose (ESD{approx}0.05 mGy), detectability index indicates an optimal low-energy technique of 60 kVp but was largely insensitive to the choice of high-kVp in the range 120-150 kVp. Similarly, optimal dose allocation, defined as the ratio of low-energy ESD and the total ESD, varied from 0.2 to 0.4 over the range ESD=(0.05-5.0) mGy. Furthermore, two applications of the theoretical framework were explored: (i) the increase in detectability for DE imaging compared to conventional radiography; and (ii) the performance of single-shot vs double-shot DE imaging, wherein the latter is found to have a DQE approximately twice that of the former. Experimental and theoretical analysis of GNEQ and task-based detectability index provides a fundamental understanding of the factors governing DE imaging performance and offers a framework for system design and optimization.},
doi = {10.1118/1.2400620},
journal = {Medical Physics},
number = 1,
volume = 34,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}