Theoretical optimization of a split septaless xenon ionization detector for dual‐energy chest radiography

Cardinal, Héloïse; Fenster, Aaron

doi:10.1118/1.596248

Cited by 26 publications

(11 citation statements)

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“…Methods to estimate the fluctuations in g r and t c by considering the measured fluctuations in the log-signals have been previously described. 18,21,33 Briefly, the differentials of the log-signal functions can be expressed as the linear combination of the differentials of g r and t c to give…”

Section: Coefficients Of the Inverse-mapping Functionsmentioning

confidence: 99%

Dual‐energy digital mammography: Calibration and inverse‐mapping techniques to estimate calcification thickness and glandular‐tissue ratio

Kappadath

Shaw

2003

Medical Physics

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Breast cancer may manifest as microcalcifications in x-ray mammography. Small microcalcifications, essential to the early detection of breast cancer, are often obscured by overlapping tissue structures. Dual-energy imaging, where separate low- and high-energy images are acquired and synthesized to cancel the tissue structures, may improve the ability to detect and visualize microcalcifications. Transmission measurements at two different kVp values were made on breast-tissue-equivalent materials under narrow-beam geometry using an indirect flat-panel mammographic imager. The imaging scenario consisted of variable aluminum thickness (to simulate calcifications) and variable glandular ratio (defined as the ratio of the glandular-tissue thickness to the total tissue thickness) for a fixed total tissue thickness--the clinical situation of microcalcification imaging with varying tissue composition under breast compression. The coefficients of the inverse-mapping functions used to determine material composition from dual-energy measurements were calculated by a least-squares analysis. The linear function poorly modeled both the aluminum thickness and the glandular ratio. The inverse-mapping functions were found to vary as analytic functions of second (conic) or third (cubic) order. By comparing the model predictions with the calibration values, the root-mean-square residuals for both the cubic and the conic functions were approximately 50 microm for the aluminum thickness and approximately 0.05 for the glandular ratio.

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Section: Coefficients Of the Inverse-mapping Functionsmentioning

confidence: 99%

Dual‐energy digital mammography: Calibration and inverse‐mapping techniques to estimate calcification thickness and glandular‐tissue ratio

Kappadath

Shaw

2003

Medical Physics

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“…For the front-back with a filter, the filter material was assumed to also be NaI, as in Cardinal and Fenster where the filter layer was composed of the same material as the detector. 10 Part of the total 5 g/cm 2 of the detector was assigned to be the filter ͑i.e., the filter is essentially an inactive NaI cell͒. The optimal apportionment of the total thickness was 0.08 g/cm 2 for the front cell, 0.11 g/cm 2 for the filter, and 4.81 g/cm 2 for the back cell.…”

Section: Simulationsmentioning

confidence: 99%

“…A single x-ray exposure can be used with a frontback detector, and its performance can be improved with the incorporation of a filter layer between the two cells. [9][10][11][12][13][14] While this method is simpler to implement, its precision is inferior to that of the dual kVp approach for the same dose. 15 Alternatively, consider a detector in which the energy deposited could be measured as a function of depth in the detector.…”

Section: Introductionmentioning

confidence: 99%

Depth‐segmented detector for x‐ray absorptiometry

Stevens

Pelc

2000

Medical Physics

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A new energy-dependent multi-cell detector, which is a generalization of the conventional front-back detector, was studied using computer simulations. The noise performance of the detector for bone quantitation was examined in comparison to an ideal energy discriminating detector, and front-back detectors with and without inter-detector filters. The front-back detectors were optimized for a reference object composed of water and bone, and then compared to the new detector over a range of object compositions. In this paper, precision in calculated bone thickness is used as the criterion for evaluating detector performance. Simulations show that the segmented detector always performs better than the front-back detector without an inter-detector filter. It outperforms the detector incorporating a filter by an amount that depends on the heterogeneity of the x-ray spectrum. In addition, for single component radiographic images, this multi-cell detector retains information which is lost in the front-back detector with a filter layer.

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“…Thus the signal-to-noise ratio (SNR) is given by SNR== (6) The log-normalized signal strengths will be given [27] by the ratio of the moments -in Thus the signal-to-noise ratio (SNR) is given by SNR== (6) The log-normalized signal strengths will be given [27] by the ratio of the moments -in…”

Section: Dual-energy Radiographymentioning

confidence: 99%

Dual-energy decomposition using a kinestatic charge detector

et al. 1998

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The Kinestatic Charge Detector (KCD) is an electronic digital strip beam x-ray detector which has been shown to possess a high detective quantum efficiency, good spatial resolution, and good scatter rejection. We have investigated its use as a dual-energy x-ray detector detector, which involves the acquisition of two images with different mean x-ray energies that can be reconstructed using a suitable algorithm to form images of two basis materials such as bone and soft tissue.Dual-energy imaging with a single exposure may be performed with a KCD by segmenting its x-ray collection region into front and back regions. The lower x-ray photons will then be preferentially abosrbed in the front region. Computer simulations were performed to evaluate a segmented KCD's ability to reconstruct various combinations of Plexiglas and aluminum. Actual experimental data were also taken for various Plexiglas and aluminum combinations with a non-i:maging research KCD. The suitability of using analytic calibration functions as decomposition algorithms for aluminum and Plexiglas basis material images was investigated. Fits were performed for the computer simulations using the high-energy and low-energy data, with and without the addition of noise. Similar fitting techniques were used with the experimental KCD data.A true rms accuracy of 150 pm for aluminum and 500 pm for Plexiglas was obtainable from fits for the computer simulated data, even with the addition ofnoise. The experimental data taken with the non-imaging KCD yielded rms errors of approximately 250 pm for aluminum and 1000 m for Plexiglas, comparable to simulated noisy data.We conclude that suitable decomposition algorithms exist for a segmented dual-energy KCD to be able to reconstruct aluminum and Plexiglas material thicknesses to an accuracy sufficient for clinical diagnosis in chest radiography. /981$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/21/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Performance parameters of the KCD have been discussed in depth elsewhere [22,23,24,25]. An imaging KCD installed at the University of Tennessee-Memphis Biomedical Engineering Department (UTMEM) has been shown to be capable of providing spatial resolution of about 5 lp/mm, and QDE in the krypton gas utilized of approximately 80% [26]. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/21/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Theoretical optimization of a split septaless xenon ionization detector for dual‐energy chest radiography

Cited by 26 publications

References 0 publications

Dual‐energy digital mammography: Calibration and inverse‐mapping techniques to estimate calcification thickness and glandular‐tissue ratio

Dual‐energy digital mammography: Calibration and inverse‐mapping techniques to estimate calcification thickness and glandular‐tissue ratio

Depth‐segmented detector for x‐ray absorptiometry

Dual-energy decomposition using a kinestatic charge detector

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