Effects of the energy-separation filter on the performance of each detector layer in the sandwich detector for single-shot dual-energy imaging

Kim, J.; Kim, D.W.; Kam, Soohwa; Park, E.; Youn, Hanbean; Kim, H.K.

doi:10.1088/1748-0221/11/02/c02065

Cited by 7 publications

(10 citation statements)

References 22 publications

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“…Therefore, quantum noise in DE images in this work is most sensitive to the quantum noise arising from the high-energy projection [18]. Kim et al [19] experimentally showed the trade-offs between contrast and quantum noise in the single-shot DE images. All the results that are shown below are obtained using a sandwich detector without an intermediate filter.…”

Section: Working Principle Of the Sandwich Detectormentioning

confidence: 83%

Microtomography with sandwich detectors for small-animal bone imaging

Kim

et al. 2016

J. Inst.

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An x-ray radiographic system consisting of two detectors in tandem, or a sandwich detector, can produce dual-energy image from a single-shot exposure. Subtraction of two images obtained from the two detectors can produce a sharper image through an unsharp masking effect if the two images are formed at different spatial resolutions. This is indeed possible by incorporating different thicknesses of x-ray conversion layers in the detectors. In this study, we have developed a microtomography system with a sandwich detector in pursuit of high-resolution bone-enhanced small-animal imaging. The results show that the bone-enhanced images reconstructed from the dualenergy projection data provide higher visibility of bone details than the conventionally reconstructed images. The microtomography with the single-shot dual-energy sandwich detector will be useful for the high-resolution bone-enhanced small-animal imaging. K : Computerized Tomography (CT) and Computed Radiography (CR); Medical-image reconstruction methods and algorithms, computer-aided diagnosis 1Corresponding author.

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Section: Working Principle Of the Sandwich Detectormentioning

confidence: 83%

Microtomography with sandwich detectors for small-animal bone imaging

Kim

et al. 2016

J. Inst.

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“…Therefore, there would exist an optimal material (e.g. atomic number and composition) and thickness for an intermediate filter [13], but those optimal figures will be dependent upon detector materials/thickness as well as application-specific tasks (including energies). Theoretical cascadedmodel analysis approach may be helpful for a better design of sandwich detector [10,14,15].…”

Section: Jinst 14 C01021mentioning

confidence: 99%

Noise-reduction approaches to single-shot dual-energy imaging with a multilayer detector

et al. 2019

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The single-shot dual-energy (DE) method using a sandwich-like multilayer detector generally suffers from noise in the resultant DE images due to the poor quantum noise in images obtained from the rear detector layer and its amplification due to the subtraction operation in DE reconstruction. The use of interlayer metal filter can further increase noise in DE images by increasing the rear-detector quantum noise. We have adopted several noise-reduction algorithms to the singleshot DE reconstruction, which included the Gaussian-filtering noise reduction (GNR), the medianfiltering noise reduction (MNR), and the anti-correlated noise reduction (ANR). We assessed the effectiveness of noise-reduction methods by investigating noise and dose-normalized contrast-tonoise ratio for a mouse-mimicking phantom consisting of aluminum bone and polyurethane soft tissues. Noise-power spectrum was also measured to investigate correlation noise. Overall, the ANR showed the best performance. At some extreme imaging technique conditions, such as a lower tube voltages and a larger spectral energy separation using thick copper sheets between the front and rear detector layers, the MNR outperformed the ANR. The performance of GNR was nearly similar to that of MNR. The results were well reflected into demonstration bone images obtained for a postmortem mouse. Although the ANR was effective to reduce noise in the single-shot DE imaging using the sandwich detector, multivariate optimization of ANR parameters with respect to imaging tasks and imaging techniques is remained as a future study. K: Medical-image reconstruction methods and algorithms, computer-aided diagnosis; X-ray radiography and digital radiography (DR)

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“…The only difference between two detector layers is thickness of phosphor layers: ∼ 34 mg cm −2 and ∼ 67 mg cm −2 for the front and rear detectors, respectively. The MTF, NPS, and DQE of each detector layer of the sandwich detector have recently been measured for various applied tube voltages (50 − 90 kVp) and thicknesses of an intermediate copper (Cu) filter (t IF = 0 − 0.5 mm) [6]. Those measured data are used in this study.…”

Section: Measurementsmentioning

confidence: 99%

“…The energy separation can be further controlled by placing a filter layer between the two detector layers, and in this case filter material and its thickness are additional variables for determining the extent of energy separation. Unfortunately, it is hard to obtain high contrast DE images from a sandwich detector without sacrificing image noise because a large energy separation (i.e., low transmittance) reduces the number of x-ray photons reaching the rear detector, increasing image quantum noise [3,5,6]. Subtractive DE reconstruction further increases DE image noise [4].…”

Section: Introductionmentioning

confidence: 99%

Cascaded-systems analysis of sandwich x-ray detectors

Kim

Yun

et al. 2016

J. Inst.

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Active sandwich-like multilayer detectors have been developed, and their potential for motion-artifact-free dual-energy x-ray imaging at a single exposure has been demonstrated in the material decomposition context. Since the sandwich detector uses the x-ray beam transmittance through the front layer, direct x-ray interaction within photodiodes in the front layer is unavoidable, and which can increase noise in the front detector images. Similar direct x-ray interaction can also occur in the rear detector layer. To obtain a better contrast performance, an additional filter layer can be placed between the two detector layers. However, this filter layer can increase adversely noise in images obtained from the rear detector layer by reducing the number of x-ray photons reaching it. A theoretical model, which can describe the signal-to-noise performance of the sandwich detector as functions of various design parameters, has been developed by using a linear cascaded-systems theory. From the cascaded-systems analysis, the direct x-ray interaction increases noise at the high spatial frequencies where the number of secondary quanta lessens. The intermediate filter layer enhances the contribution of additive electronic noise in the overall noise performance of the rear detector layer. The detailed cascaded-systems analysis on the x-ray sandwich detectors are reported in comparisons with the measured noise-power spectra and detective quantum efficiencies. The developed model will be useful for a better design and practical use of a sandwich detector for single-shot dual-energy imaging. K: Detector design and construction technologies and materials; Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); X-ray radiography and digital radiography (DR)1He is now affiliated with the Samsung Electronics Co.

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Effects of the energy-separation filter on the performance of each detector layer in the sandwich detector for single-shot dual-energy imaging

Cited by 7 publications

References 22 publications

Microtomography with sandwich detectors for small-animal bone imaging

Microtomography with sandwich detectors for small-animal bone imaging

Noise-reduction approaches to single-shot dual-energy imaging with a multilayer detector

Cascaded-systems analysis of sandwich x-ray detectors

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