The Experts below are selected from a list of 90 Experts worldwide ranked by ideXlab platform

Kenneth R Hoffmann - One of the best experts on this subject based on the ideXlab platform.

  • su gg i 12 effect of Geometric Unsharpness on the reconstructed image in region of interest roi μct
    Medical Physics, 2008
    Co-Authors: W Wang, Daniel R Bednarek, V Patel, C Keleshis, Kenneth R Hoffmann, S Rudin
    Abstract:

    Purpose: To demonstrate the effects of variation of focal‐spot size and magnification on the spatial resolution of reconstructed images of a micro‐computed tomography (μCT) system which is attached to a standard angiographic C‐arm gantry to enable Region‐of‐Interest cone‐beam CT (ROI‐CBCT). Method and Materials: High‐resolution ROI projection data of a vascular phantom were acquired using a new high‐sensitivity, microangiographic fluoroscope (HSMAF) detector (35 μm pixels), which was attached to the C‐arm gantry and able to be positioned in front of a standard full field‐of‐view, low‐resolution commercial flat‐panel detector(FPD) (194 μm pixels). The HSMAF consists of a CsI phosphor viewed by a 4‐cm diameter light image‐intensifier with large variable dynamic range whose output is coupled via a fiber‐optic taper to a CCDcamera. The test objects in the vascular phantom were a stent (100 micron struts) inside of a catheter in a cylindrical water bath. The phantom was placed on a portable test platform (PTP) enabling CBCT image acquisition by the HSMAF every 1°. Six μCT runs were performed using two focal‐spot sizes (0.3 and 0.6 mm) and three magnification factors (1.15, 1.29, and 1.48). Profiles were extracted from the reconstructed struts, and the full width half‐maximum (FWHM) were measured. Results: The reconstructed data show that using the optimal configuration (smallest magnification with small focal spot) compared to the worst configuration (largest magnification and the large focal spot) resulted in a 47% reduction in the FWHM in the object plane (175 μm versus 375 μm). Conclusion: Micro‐CBCT can provide more accurate visualization of fine device features; however, Geometric Unsharpness and/or large focal spots can substantially degrade resolution reducing the quality of the μCBCT reconstructions. (Research sponsored by: NIH Grants R01‐NS43924, R01‐EB002873, Toshiba Medical Systems Corporation)

  • generalized performance evaluation of x ray image intensifier compared with a microangiographic system
    Proceedings of SPIE--the International Society for Optical Engineering, 2005
    Co-Authors: G Yadava, Iacovos S Kyprianou, Stephen Rudin, Daniel R Bednarek, Kenneth R Hoffmann
    Abstract:

    Standard objective parameters such as MTF, NPS, NEQ and DQE do not reflect complete system performance, because they do not account for Geometric Unsharpness due to finite focal spot size and scatter due to the patient. The inclusion of these factors led to the generalization of the objective quantities, termed GMTF, GNNPS, GNEQ and GDQE defined at the object plane. In this study, a commercial x-ray image intensifier (II) is evaluated under this generalized approach and compared with a high-resolution, ROI microangiographic system previously developed and evaluated by our group. The study was performed using clinically relevant spectra and simulated conditions for neurovascular angiography specific for each system. A head-equivalent phantom was used, and images were acquired from 60 to 100 kVp. A source to image distance of 100 cm (75 cm for the microangiographic system) and a focal spot of 0.6 mm were used. Effects of varying the irradiation field-size, the air-gaps, and the magnifications (1.1 to 1.3) were compared. A detailed comparison of all of the generalized parameters is presented for the two systems. The detector MTF for the microangiographic system is in general better than that for the II system. For the total x-ray imaging system, the GMTF and GDQE for the II are better at low spatial frequencies, whereas the microangiographic system performs substantially better at higher spatial frequencies. This generalized approach can be used to more realistically evaluate and compare total system performance leading to improved system designs tailored to the imaging task.

  • generalizing the mtf and dqe to include x ray scatter and focal spot Unsharpness application to a new microangiographic system
    Medical Physics, 2005
    Co-Authors: Iacovos S Kyprianou, Stephen Rudin, Daniel R Bednarek, Kenneth R Hoffmann
    Abstract:

    Detector characterization with modulation transfer function(MTF) and detective quantum efficiency (DQE) inadequately predicts image quality when the imagingsystem includes focal spot Unsharpness and patient scatter. The concepts of MTF, noise power spectrum, noise equivalent quanta and DQE were referenced to the object plane and generalized to include the effect of Geometric Unsharpness due to the finite size of the focal spot and the effect of the spatial distribution and magnitude of x-rayscatter due to the patient. The generalized quantities provide performance characteristics that consider the complete imagingsystem, but reduce to a description of the detector properties without magnification or scatter. We have evaluated a new neurovascular angiography imagingsystem based on a region of interest (ROI) microangiographic detector using these generalized quantities. A uniform head-equivalent phantom was used as a filter and x-rayscatter source. This allowed the study of all properties of the detector under clinically relevant x-ray spectra and x-rayscatter conditions. Realistic focal spots ( 0.8 mm nominal), beam energies ( 60 – 100 kVp ) , and detector exposures ( 0.8 – 2.3 mR ) were used, and the effects of different scatter fractions (0–0.62) resulting from changing the beam size ( 0 – 100 cm 2 ) were investigated. The generalized MTF and DQE were found to have very little dependence on the tube voltage and the detector entrance exposure. Magnification, with the focal spot used, results in a large decrease of the generalized DQE at higher frequencies (about 100-fold at 10 cycles ∕ mm ), but a significantly smaller decrease at lower frequencies. Scatter on the other hand, causes a constant drop in the generalized DQE (factor of 3 for scatter fraction 0.3) for all frequencies. Our results show that there are tradeoffs in the choice of the different system parameters; therefore this methodology of studying the imagingsystem as a whole could provide guidance in system design.

Daniel R Bednarek - One of the best experts on this subject based on the ideXlab platform.

  • tu fg 209 05 demonstration of the line focus principle using the generalized measured relative object detectability gm rod metric
    Medical Physics, 2016
    Co-Authors: M Russ, Daniel R Bednarek, Alok Shankar, A Lau, Stephen Rudin
    Abstract:

    Purpose: Demonstrate and quantify the augmented resolution due to focalspot size decrease in images acquired on the anode side of the field, for both small and medium (0.3 and 0.6mm) focal-spot sizes using the experimental task-based GM-ROD metric. Theoretical calculations have shown that a medium focal-spot can achieve the resolution of a small focal-spot if acquired with a tilted anode, effectively providing a higher-output small focal-spot. Methods: The MAF-CMOS (micro-angiographic fluoroscopic complementary-metal-oxide semiconductor) detector (75µm pixel pitch) imaged two copper wire segments of different diameter and a pipeline stent at the central axis and on the anode side of the beam, achieved by tilting the x-ray C-arm (Toshiba Infinix) to 6° and realigning the detector with the perpendicular ray to correct for x-ray obliquity. The relative gain in resolution was determined using the GM-ROD metric, which compares images on the basis of the Fourier transform of the image and the measured NNPS. To emphasize the Geometric Unsharpness, images were acquired at a magnification of two. Results: Images acquired on the anode side were compared to those acquired on the central axis with the same target-area focal-spot to consider the effect of an angled tube, and for all three objects the advantage of the smaller effective focal-spot was clear, showing a maximum improvement of 36% in GM-ROD. The images obtained with the small focal-spot at the central axis were compared to those of the medium focal-spot at the anode side and, for all objects, the relative performance was comparable. Conclusion: For three objects, the GM-ROD demonstrated the advantage of the anode side focal-spot. The comparable performance of the medium focal-spot on the anode side will allow for a high-output small focal-spot; a necessity in endovascular image-guided interventions. Partial support from an NIH grant R01EB002873 and an equipment grant from Toshiba Medical Systems Corp.

  • generalized two dimensional 2d linear system analysis metrics gmtf gdqe for digital radiography systems including the effect of focal spot magnification scatter and detector characteristics
    Proceedings of SPIE, 2010
    Co-Authors: A Jain, Daniel R Bednarek, A Kuhlsgilcrist, Sandesh K Gupta, Stephen Rudin
    Abstract:

    The MTF, NNPS, and DQE are standard linear system metrics used to characterize intrinsic detector performance. To evaluate total system performance for actual clinical conditions, generalized linear system metrics (GMTF, GNNPS and GDQE) that include the effect of the focal spot distribution, scattered radiation, and Geometric Unsharpness are more meaningful and appropriate. In this study, a two-dimensional (2D) generalized linear system analysis was carried out for a standard flat panel detector (FPD) (194-micron pixel pitch and 600-micron thick CsI) and a newly-developed, high-resolution, micro-angiographic fluoroscope (MAF) (35-micron pixel pitch and 300-micron thick CsI). Realistic clinical parameters and x-ray spectra were used. The 2D detector MTFs were calculated using the new Noise Response method and slanted edge method and 2D focal spot distribution measurements were done using a pin-hole assembly. The scatter fraction, generated for a uniform head equivalent phantom, was measured and the scatter MTF was simulated with a theoretical model. Different magnifications and scatter fractions were used to estimate the 2D GMTF, GNNPS and GDQE for both detectors. Results show spatial non-isotropy for the 2D generalized metrics which provide a quantitative description of the performance of the complete imaging system for both detectors. This generalized analysis demonstrated that the MAF and FPD have similar capabilities at lower spatial frequencies, but that the MAF has superior performance over the FPD at higher frequencies even when considering focal spot blurring and scatter. This 2D generalized performance analysis is a valuable tool to evaluate total system capabilities and to enable optimized design for specific imaging tasks.

  • su gg i 12 effect of Geometric Unsharpness on the reconstructed image in region of interest roi μct
    Medical Physics, 2008
    Co-Authors: W Wang, Daniel R Bednarek, V Patel, C Keleshis, Kenneth R Hoffmann, S Rudin
    Abstract:

    Purpose: To demonstrate the effects of variation of focal‐spot size and magnification on the spatial resolution of reconstructed images of a micro‐computed tomography (μCT) system which is attached to a standard angiographic C‐arm gantry to enable Region‐of‐Interest cone‐beam CT (ROI‐CBCT). Method and Materials: High‐resolution ROI projection data of a vascular phantom were acquired using a new high‐sensitivity, microangiographic fluoroscope (HSMAF) detector (35 μm pixels), which was attached to the C‐arm gantry and able to be positioned in front of a standard full field‐of‐view, low‐resolution commercial flat‐panel detector(FPD) (194 μm pixels). The HSMAF consists of a CsI phosphor viewed by a 4‐cm diameter light image‐intensifier with large variable dynamic range whose output is coupled via a fiber‐optic taper to a CCDcamera. The test objects in the vascular phantom were a stent (100 micron struts) inside of a catheter in a cylindrical water bath. The phantom was placed on a portable test platform (PTP) enabling CBCT image acquisition by the HSMAF every 1°. Six μCT runs were performed using two focal‐spot sizes (0.3 and 0.6 mm) and three magnification factors (1.15, 1.29, and 1.48). Profiles were extracted from the reconstructed struts, and the full width half‐maximum (FWHM) were measured. Results: The reconstructed data show that using the optimal configuration (smallest magnification with small focal spot) compared to the worst configuration (largest magnification and the large focal spot) resulted in a 47% reduction in the FWHM in the object plane (175 μm versus 375 μm). Conclusion: Micro‐CBCT can provide more accurate visualization of fine device features; however, Geometric Unsharpness and/or large focal spots can substantially degrade resolution reducing the quality of the μCBCT reconstructions. (Research sponsored by: NIH Grants R01‐NS43924, R01‐EB002873, Toshiba Medical Systems Corporation)

  • generalized performance evaluation of x ray image intensifier compared with a microangiographic system
    Proceedings of SPIE--the International Society for Optical Engineering, 2005
    Co-Authors: G Yadava, Iacovos S Kyprianou, Stephen Rudin, Daniel R Bednarek, Kenneth R Hoffmann
    Abstract:

    Standard objective parameters such as MTF, NPS, NEQ and DQE do not reflect complete system performance, because they do not account for Geometric Unsharpness due to finite focal spot size and scatter due to the patient. The inclusion of these factors led to the generalization of the objective quantities, termed GMTF, GNNPS, GNEQ and GDQE defined at the object plane. In this study, a commercial x-ray image intensifier (II) is evaluated under this generalized approach and compared with a high-resolution, ROI microangiographic system previously developed and evaluated by our group. The study was performed using clinically relevant spectra and simulated conditions for neurovascular angiography specific for each system. A head-equivalent phantom was used, and images were acquired from 60 to 100 kVp. A source to image distance of 100 cm (75 cm for the microangiographic system) and a focal spot of 0.6 mm were used. Effects of varying the irradiation field-size, the air-gaps, and the magnifications (1.1 to 1.3) were compared. A detailed comparison of all of the generalized parameters is presented for the two systems. The detector MTF for the microangiographic system is in general better than that for the II system. For the total x-ray imaging system, the GMTF and GDQE for the II are better at low spatial frequencies, whereas the microangiographic system performs substantially better at higher spatial frequencies. This generalized approach can be used to more realistically evaluate and compare total system performance leading to improved system designs tailored to the imaging task.

  • efficiency of the human observer compared to an ideal observer based on a generalized neq which incorporates scatter and Geometric Unsharpness evaluation with a 2afc experiment
    Medical Imaging 2005: Image Perception Observer Performance and Technology Assessment, 2005
    Co-Authors: Iacovos S Kyprianou, Brandon D Gallas, Arundhuti Ganguly, Stephen Rudin, Daniel R Bednarek, Kyle J. Myers
    Abstract:

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and Geometric Unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 um) filled with iodine contrast (concentrations between 0-120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 um pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and Geometric Unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Stephen Rudin - One of the best experts on this subject based on the ideXlab platform.

  • tu fg 209 05 demonstration of the line focus principle using the generalized measured relative object detectability gm rod metric
    Medical Physics, 2016
    Co-Authors: M Russ, Daniel R Bednarek, Alok Shankar, A Lau, Stephen Rudin
    Abstract:

    Purpose: Demonstrate and quantify the augmented resolution due to focalspot size decrease in images acquired on the anode side of the field, for both small and medium (0.3 and 0.6mm) focal-spot sizes using the experimental task-based GM-ROD metric. Theoretical calculations have shown that a medium focal-spot can achieve the resolution of a small focal-spot if acquired with a tilted anode, effectively providing a higher-output small focal-spot. Methods: The MAF-CMOS (micro-angiographic fluoroscopic complementary-metal-oxide semiconductor) detector (75µm pixel pitch) imaged two copper wire segments of different diameter and a pipeline stent at the central axis and on the anode side of the beam, achieved by tilting the x-ray C-arm (Toshiba Infinix) to 6° and realigning the detector with the perpendicular ray to correct for x-ray obliquity. The relative gain in resolution was determined using the GM-ROD metric, which compares images on the basis of the Fourier transform of the image and the measured NNPS. To emphasize the Geometric Unsharpness, images were acquired at a magnification of two. Results: Images acquired on the anode side were compared to those acquired on the central axis with the same target-area focal-spot to consider the effect of an angled tube, and for all three objects the advantage of the smaller effective focal-spot was clear, showing a maximum improvement of 36% in GM-ROD. The images obtained with the small focal-spot at the central axis were compared to those of the medium focal-spot at the anode side and, for all objects, the relative performance was comparable. Conclusion: For three objects, the GM-ROD demonstrated the advantage of the anode side focal-spot. The comparable performance of the medium focal-spot on the anode side will allow for a high-output small focal-spot; a necessity in endovascular image-guided interventions. Partial support from an NIH grant R01EB002873 and an equipment grant from Toshiba Medical Systems Corp.

  • generalized two dimensional 2d linear system analysis metrics gmtf gdqe for digital radiography systems including the effect of focal spot magnification scatter and detector characteristics
    Proceedings of SPIE, 2010
    Co-Authors: A Jain, Daniel R Bednarek, A Kuhlsgilcrist, Sandesh K Gupta, Stephen Rudin
    Abstract:

    The MTF, NNPS, and DQE are standard linear system metrics used to characterize intrinsic detector performance. To evaluate total system performance for actual clinical conditions, generalized linear system metrics (GMTF, GNNPS and GDQE) that include the effect of the focal spot distribution, scattered radiation, and Geometric Unsharpness are more meaningful and appropriate. In this study, a two-dimensional (2D) generalized linear system analysis was carried out for a standard flat panel detector (FPD) (194-micron pixel pitch and 600-micron thick CsI) and a newly-developed, high-resolution, micro-angiographic fluoroscope (MAF) (35-micron pixel pitch and 300-micron thick CsI). Realistic clinical parameters and x-ray spectra were used. The 2D detector MTFs were calculated using the new Noise Response method and slanted edge method and 2D focal spot distribution measurements were done using a pin-hole assembly. The scatter fraction, generated for a uniform head equivalent phantom, was measured and the scatter MTF was simulated with a theoretical model. Different magnifications and scatter fractions were used to estimate the 2D GMTF, GNNPS and GDQE for both detectors. Results show spatial non-isotropy for the 2D generalized metrics which provide a quantitative description of the performance of the complete imaging system for both detectors. This generalized analysis demonstrated that the MAF and FPD have similar capabilities at lower spatial frequencies, but that the MAF has superior performance over the FPD at higher frequencies even when considering focal spot blurring and scatter. This 2D generalized performance analysis is a valuable tool to evaluate total system capabilities and to enable optimized design for specific imaging tasks.

  • generalized performance evaluation of x ray image intensifier compared with a microangiographic system
    Proceedings of SPIE--the International Society for Optical Engineering, 2005
    Co-Authors: G Yadava, Iacovos S Kyprianou, Stephen Rudin, Daniel R Bednarek, Kenneth R Hoffmann
    Abstract:

    Standard objective parameters such as MTF, NPS, NEQ and DQE do not reflect complete system performance, because they do not account for Geometric Unsharpness due to finite focal spot size and scatter due to the patient. The inclusion of these factors led to the generalization of the objective quantities, termed GMTF, GNNPS, GNEQ and GDQE defined at the object plane. In this study, a commercial x-ray image intensifier (II) is evaluated under this generalized approach and compared with a high-resolution, ROI microangiographic system previously developed and evaluated by our group. The study was performed using clinically relevant spectra and simulated conditions for neurovascular angiography specific for each system. A head-equivalent phantom was used, and images were acquired from 60 to 100 kVp. A source to image distance of 100 cm (75 cm for the microangiographic system) and a focal spot of 0.6 mm were used. Effects of varying the irradiation field-size, the air-gaps, and the magnifications (1.1 to 1.3) were compared. A detailed comparison of all of the generalized parameters is presented for the two systems. The detector MTF for the microangiographic system is in general better than that for the II system. For the total x-ray imaging system, the GMTF and GDQE for the II are better at low spatial frequencies, whereas the microangiographic system performs substantially better at higher spatial frequencies. This generalized approach can be used to more realistically evaluate and compare total system performance leading to improved system designs tailored to the imaging task.

  • efficiency of the human observer compared to an ideal observer based on a generalized neq which incorporates scatter and Geometric Unsharpness evaluation with a 2afc experiment
    Medical Imaging 2005: Image Perception Observer Performance and Technology Assessment, 2005
    Co-Authors: Iacovos S Kyprianou, Brandon D Gallas, Arundhuti Ganguly, Stephen Rudin, Daniel R Bednarek, Kyle J. Myers
    Abstract:

    Under certain assumptions the detectability of the ideal observer can be defined as the integral of the system Noise Equivalent Quanta multiplied by the squared object spatial frequency distribution. Using the detector Noise-Equivalent-Quanta (NEQD) for the calculation of detectability inadequately describes the performance of an x-ray imaging system because it does not take into account the effects of patient scatter and Geometric Unsharpness. As a result, the ideal detectability index is overestimated, and hence the efficiency of the human observer in detecting objects is underestimated. We define a Generalized-NEQ (GNEQ) for an x-ray system referenced at the object plane that incorporates the scatter fraction, the spatial distributions of scatter and focal spot, the detector MTFD, and the detector Normalized-Noise-Power-Spectrum (NNPSD). This GNEQ was used in the definition of the ideal detectability for the evaluation of the human observer efficiency during a two Alternative Forced Choice (2-AFC) experiment, and was compared with the case where only the NEQD was used in the detectability calculations. The 2-AFC experiment involved the detection of images of polyethylene tubes (diameters between 100-300 um) filled with iodine contrast (concentrations between 0-120 mg/cm3) placed onto a uniform head equivalent phantom placed near the surface of a microangiographic detector (43 um pixel size). The resulting efficiency of the human observer without regarding the effects of scatter and Geometric Unsharpness was 30%. When these effects were considered the efficiency was increased to 70%. The ideal observer with the GNEQ can be a simple optimization method of a complete imaging system.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

  • generalizing the mtf and dqe to include x ray scatter and focal spot Unsharpness application to a new microangiographic system
    Medical Physics, 2005
    Co-Authors: Iacovos S Kyprianou, Stephen Rudin, Daniel R Bednarek, Kenneth R Hoffmann
    Abstract:

    Detector characterization with modulation transfer function(MTF) and detective quantum efficiency (DQE) inadequately predicts image quality when the imagingsystem includes focal spot Unsharpness and patient scatter. The concepts of MTF, noise power spectrum, noise equivalent quanta and DQE were referenced to the object plane and generalized to include the effect of Geometric Unsharpness due to the finite size of the focal spot and the effect of the spatial distribution and magnitude of x-rayscatter due to the patient. The generalized quantities provide performance characteristics that consider the complete imagingsystem, but reduce to a description of the detector properties without magnification or scatter. We have evaluated a new neurovascular angiography imagingsystem based on a region of interest (ROI) microangiographic detector using these generalized quantities. A uniform head-equivalent phantom was used as a filter and x-rayscatter source. This allowed the study of all properties of the detector under clinically relevant x-ray spectra and x-rayscatter conditions. Realistic focal spots ( 0.8 mm nominal), beam energies ( 60 – 100 kVp ) , and detector exposures ( 0.8 – 2.3 mR ) were used, and the effects of different scatter fractions (0–0.62) resulting from changing the beam size ( 0 – 100 cm 2 ) were investigated. The generalized MTF and DQE were found to have very little dependence on the tube voltage and the detector entrance exposure. Magnification, with the focal spot used, results in a large decrease of the generalized DQE at higher frequencies (about 100-fold at 10 cycles ∕ mm ), but a significantly smaller decrease at lower frequencies. Scatter on the other hand, causes a constant drop in the generalized DQE (factor of 3 for scatter fraction 0.3) for all frequencies. Our results show that there are tradeoffs in the choice of the different system parameters; therefore this methodology of studying the imagingsystem as a whole could provide guidance in system design.

David Gorsich - One of the best experts on this subject based on the ideXlab platform.

  • neutron imaging of lithium concentration in lfp pouch cell battery
    Journal of The Electrochemical Society, 2011
    Co-Authors: Jason B Siegel, Anna G Stefanopoulou, Daniel S Hussey, David L Jacobson, David Gorsich
    Abstract:

    This paper shows how neutron radiography can be used for in situ quantification of the lithium concentration across battery electrodes, a critical physical system state. The change in lithium concentration between the charged and discharged states of the battery causes a change in number of detected neutrons after passing through the battery. Electrode swelling is also observed during battery charging. The experimental setup and the observations from testing a pouch cell with LFP cathode and graphite anode are reported here. The bulk Li concentration across the electrode and folds of the pouch cell is quantified at various states of charge. To interpret the measurements, the optics of the neutron beam (Geometric Unsharpness) and detector resolution are considered in order to quantify the lithium concentration from the images due to the thinness of the electrode layers. The experimental methodology provides a basis for comprehensive in situ metrology of bulk lithium concentration.

  • Neutron imaging of lithium concentration in battery pouch cells
    Proceedings of the 2011 American Control Conference, 2011
    Co-Authors: Jason B Siegel, Anna G Stefanopoulou, Xinfan Lin, David Gorsich
    Abstract:

    This paper shows how the principle of neutron radiography can be used to quantify the critical physical state of lithium concentration across battery electrodes at steady-state conditions (after a long relaxation time or small load) as a first step in this important effort to measure in-situ battery physical states and validate electrochemical battery models. A model of the expected loss in beam intensity after passing through the different layers of a battery pouch cell is constructed based on the material densities and dimensions. This model is augmented with simulation of the neutron transmission behavior, including optical effects due to the Geometric Unsharpness and the detector response. The resulting model provides the basis for a comprehensive simulation of the in-situ metrology of lithium concentration in Li-ion batteries, and comparison with experimental results. This work was also presented as a poster at the 27th Annual Army Science Conference [1].

Jason B Siegel - One of the best experts on this subject based on the ideXlab platform.

  • neutron imaging of lithium concentration in lfp pouch cell battery
    Journal of The Electrochemical Society, 2011
    Co-Authors: Jason B Siegel, Anna G Stefanopoulou, Daniel S Hussey, David L Jacobson, David Gorsich
    Abstract:

    This paper shows how neutron radiography can be used for in situ quantification of the lithium concentration across battery electrodes, a critical physical system state. The change in lithium concentration between the charged and discharged states of the battery causes a change in number of detected neutrons after passing through the battery. Electrode swelling is also observed during battery charging. The experimental setup and the observations from testing a pouch cell with LFP cathode and graphite anode are reported here. The bulk Li concentration across the electrode and folds of the pouch cell is quantified at various states of charge. To interpret the measurements, the optics of the neutron beam (Geometric Unsharpness) and detector resolution are considered in order to quantify the lithium concentration from the images due to the thinness of the electrode layers. The experimental methodology provides a basis for comprehensive in situ metrology of bulk lithium concentration.

  • Neutron imaging of lithium concentration in battery pouch cells
    Proceedings of the 2011 American Control Conference, 2011
    Co-Authors: Jason B Siegel, Anna G Stefanopoulou, Xinfan Lin, David Gorsich
    Abstract:

    This paper shows how the principle of neutron radiography can be used to quantify the critical physical state of lithium concentration across battery electrodes at steady-state conditions (after a long relaxation time or small load) as a first step in this important effort to measure in-situ battery physical states and validate electrochemical battery models. A model of the expected loss in beam intensity after passing through the different layers of a battery pouch cell is constructed based on the material densities and dimensions. This model is augmented with simulation of the neutron transmission behavior, including optical effects due to the Geometric Unsharpness and the detector response. The resulting model provides the basis for a comprehensive simulation of the in-situ metrology of lithium concentration in Li-ion batteries, and comparison with experimental results. This work was also presented as a poster at the 27th Annual Army Science Conference [1].