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Title: Imaging Using Energy Discriminating Radiation Detector Array

Abstract

Industrial X-ray radiography is often done using a broad band energy source and always a broad band energy detector. There exist several major advantages in the use of narrow band sources and or detectors, one of which is the separation of scattered radiation from primary radiation. ARDEC has developed a large detector array system in which every detector element acts like a multi-channel analyzer. A radiographic image is created from the number of photons detected in each detector element, rather than from the total energy absorbed in the elements. For high energies, 25 KeV to 4 MeV, used in radiography, energy discriminating detectors have been limited to less than 20,000 photons per second per detector element. This rate is much too slow for practical radiography. Our detector system processes over two million events per second per detector pixel, making radiographic imaging practical. This paper expounds on the advantages of the ARDEC radiographic imaging process.

Authors:
; ; ; ;  [1];  [2]
  1. U.S. Army Tank-Automotive and Armaments Command (TACOM) -Armaments Research, Development and Engineering Center (ARDEC) Picatinny Arsenal, NJ 07806 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20634243
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 680; Journal Issue: 1; Conference: 17. international conference on the application of accelerators in research and industry, Denton, TX (United States), 12-16 Nov 2002; Other Information: DOI: 10.1063/1.1619857; (c) 2003 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DIGITAL SYSTEMS; DISCRIMINATORS; KEV RANGE; MEV RANGE; MULTI-CHANNEL ANALYZERS; RADIATION DETECTORS; X-RAY RADIOGRAPHY

Citation Formats

Willson, Paul D., Clajus, Martin, Tuemer, Tuemay O., Visser, Gerard, Cajipe, Victoria, and NOVA R and D, Inc., 1525 Third Street, Suite C, Riverside, CA 92507. Imaging Using Energy Discriminating Radiation Detector Array. United States: N. p., 2003. Web. doi:10.1063/1.1619857.
Willson, Paul D., Clajus, Martin, Tuemer, Tuemay O., Visser, Gerard, Cajipe, Victoria, & NOVA R and D, Inc., 1525 Third Street, Suite C, Riverside, CA 92507. Imaging Using Energy Discriminating Radiation Detector Array. United States. doi:10.1063/1.1619857.
Willson, Paul D., Clajus, Martin, Tuemer, Tuemay O., Visser, Gerard, Cajipe, Victoria, and NOVA R and D, Inc., 1525 Third Street, Suite C, Riverside, CA 92507. 2003. "Imaging Using Energy Discriminating Radiation Detector Array". United States. doi:10.1063/1.1619857.
@article{osti_20634243,
title = {Imaging Using Energy Discriminating Radiation Detector Array},
author = {Willson, Paul D. and Clajus, Martin and Tuemer, Tuemay O. and Visser, Gerard and Cajipe, Victoria and NOVA R and D, Inc., 1525 Third Street, Suite C, Riverside, CA 92507},
abstractNote = {Industrial X-ray radiography is often done using a broad band energy source and always a broad band energy detector. There exist several major advantages in the use of narrow band sources and or detectors, one of which is the separation of scattered radiation from primary radiation. ARDEC has developed a large detector array system in which every detector element acts like a multi-channel analyzer. A radiographic image is created from the number of photons detected in each detector element, rather than from the total energy absorbed in the elements. For high energies, 25 KeV to 4 MeV, used in radiography, energy discriminating detectors have been limited to less than 20,000 photons per second per detector element. This rate is much too slow for practical radiography. Our detector system processes over two million events per second per detector pixel, making radiographic imaging practical. This paper expounds on the advantages of the ARDEC radiographic imaging process.},
doi = {10.1063/1.1619857},
journal = {AIP Conference Proceedings},
number = 1,
volume = 680,
place = {United States},
year = 2003,
month = 8
}
  • Purpose: Breast CT is an emerging imaging technique that can portray the breast in 3D and improve visualization of important diagnostic features. Early clinical studies have suggested that breast CT has sufficient spatial and contrast resolution for accurate detection of masses and microcalcifications in the breast, reducing structural overlap that is often a limiting factor in reading mammographic images. For a number of reasons, image quality in breast CT may be improved by use of an energy resolving photon counting detector. In this study, the authors investigate the improvements in image quality obtained when using energy weighting with an energymore » resolving photon counting detector as compared to that with a conventional energy integrating detector.Methods: Using computer simulation, realistic CT images of multiple breast phantoms were generated. The simulation modeled a prototype breast CT system using an amorphous silicon (a-Si), CsI based energy integrating detector with different x-ray spectra, and a hypothetical, ideal CZT based photon counting detector with capability of energy discrimination. Three biological signals of interest were modeled as spherical lesions and inserted into breast phantoms; hydroxyapatite (HA) to represent microcalcification, infiltrating ductal carcinoma (IDC), and iodine enhanced infiltrating ductal carcinoma (IIDC). Signal-to-noise ratio (SNR) of these three lesions was measured from the CT reconstructions. In addition, a psychophysical study was conducted to evaluate observer performance in detecting microcalcifications embedded into a realistic anthropomorphic breast phantom.Results: In the energy range tested, improvements in SNR with a photon counting detector using energy weighting was higher (than the energy integrating detector method) by 30%–63% and 4%–34%, for HA and IDC lesions and 12%–30% (with Al filtration) and 32%–38% (with Ce filtration) for the IIDC lesion, respectively. The average area under the receiver operating characteristic curve (AUC) for detection of microcalcifications was higher by greater than 19% (for the different energy weighting methods tested) as compared to the AUC obtained with an energy integrating detector.Conclusions: This study showed that breast CT with a CZT photon counting detector using energy weighting can provide improvements in pixel SNR, and detectability of microcalcifications as compared to that with a conventional energy integrating detector. Since a number of degrading physical factors were not modeled into the photon counting detector, this improvement should be considered as an upper bound on achievable performance.« less
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  • No abstract prepared.
  • Purpose: To evaluate quantitatively dose distributions from helical, axial and cone-beam CT clinical imaging techniques by measurement using a two-dimensional (2D) diode-array detector. Methods: 2D-dose distributions from selected clinical protocols used for axial, helical and cone-beam CT imaging were measured using a diode-array detector (MapCheck2). The MapCheck2 is composed from solid state diode detectors that are arranged in horizontal and vertical lines with a spacing of 10 mm. A GE-Light-Speed CT-simulator was used to acquire axial and helical CT images and a kV on-board-imager integrated with a Varian TrueBeam-STx machine was used to acquire cone-beam CT (CBCT) images. Results: Themore » dose distributions from axial, helical and cone-beam CT were non-uniform over the region-of-interest with strong spatial and angular dependence. In axial CT, a large dose gradient was measured that decreased from lateral sides to the middle of the phantom due to large superficial dose at the side of the phantom in comparison with larger beam attenuation at the center. The dose decreased at the superior and inferior regions in comparison to the center of the phantom in axial CT. An asymmetry was found between the right-left or superior-inferior sides of the phantom which possibly to angular dependence in the dose distributions. The dose level and distribution varied from one imaging technique into another. For the pelvis technique, axial CT deposited a mean dose of 3.67 cGy, helical CT deposited a mean dose of 1.59 cGy, and CBCT deposited a mean dose of 1.62 cGy. Conclusions: MapCheck2 provides a robust tool to measure directly 2D-dose distributions for CT imaging with high spatial resolution detectors in comparison with ionization chamber that provides a single point measurement or an average dose to the phantom. The dose distributions measured with MapCheck2 consider medium heterogeneity and can represent specific patient dose.« less
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