Dr. Robert A. Kruger Profile

Dr. Robert A. Kruger

President at OptoSonics Inc

SPIE Involvement:

Author

Publications (39)

Proceedings Article | 24 February 2010 Paper

Evaluation of Her2 status using photoacoustic spectroscopic CT techniques

Michael Shaffer, Robert Kruger, Daniel Reinecke, Helen Chin-Sinex, Marc Mendonca, Keith Stantz

Proceedings Volume 7564, 756435 (2010) https://doi.org/10.1117/12.842639

KEYWORDS: Tumors, Spectroscopy, Photoacoustic spectroscopy, Oxygen, Luminescence, Near infrared, In vivo imaging, Scanners, Data acquisition, Near infrared spectroscopy

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Proceedings Article | 24 February 2010 Paper

Ex vivo hemoglobin status study using photoacoustic computed tomography small animal scanner

Bo Liu, Robert Kruger, Daniel Reinecke, Keith Stantz

Proceedings Volume 7564, 75643A (2010) https://doi.org/10.1117/12.842836

KEYWORDS: Blood, Oxygen, Scanners, Photon transport, Error analysis, Absorption, Monte Carlo methods, Molecules, Acoustics, Imaging systems

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Proceedings Article | 24 February 2010 Paper

Monitor hemoglobin concentration and oxygen saturation in living mouse tail using photoacoustic CT scanner

Bo Liu, Robert Kruger, Daniel Reinecke, Keith Stantz

Proceedings Volume 7564, 756439 (2010) https://doi.org/10.1117/12.842827

KEYWORDS: Oxygen, Scanners, Spectroscopy, Arteries, Photoacoustic spectroscopy, Blood, Acoustics, Veins, Bone, Imaging spectroscopy

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Proceedings Article | 24 February 2010 Paper

Polarization effects in thermoacoustic CT of biologic tissue at 434 MHz

Stephen DelRio, Robert Kruger, Richard Lam, Daniel Reinecke

Proceedings Volume 7564, 75642D (2010) https://doi.org/10.1117/12.841027

KEYWORDS: Tissues, Dielectric polarization, Microwave radiation, Polarization, Transducers, Computed tomography, Ultrasonics, Waveguides, Absorption, Tomography

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Proceedings Article | 24 February 2010 Paper

Co-registered photoacoustic, thermoacoustic, and ultrasound mouse imaging

Daniel Reinecke, Robert Kruger, Richard Lam, Stephen DelRio

Proceedings Volume 7564, 756420 (2010) https://doi.org/10.1117/12.841147

KEYWORDS: Ultrasonography, Photoacoustic spectroscopy, Imaging systems, 3D image processing, Microwave radiation, Sensors, Computed tomography, Tissues, Waveguides, Tissue optics

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Proceedings Article | 23 February 2010 Paper

Dynamic optical angiography of mouse anatomy using radial projections

Richard Lam, Robert Kruger, Daniel Reinecke, Stephen DelRio, Michael Thornton, Paul Picot, Timothy Morgan

Proceedings Volume 7564, 756405 (2010) https://doi.org/10.1117/12.841024

KEYWORDS: Angiography, Sensors, Photoacoustic spectroscopy, Scanners, Spatial resolution, Temporal resolution, Signal detection, Data acquisition, Image processing, Photoacoustic tomography

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Proceedings Article | 25 February 2009 Paper

HYPR-spectral photoacoustic CT for preclinical imaging

Robert Kruger, Daniel Reinecke, Gabe Kruger, Michael Thornton, Paul Picot, Timothy Morgan, Keith Stantz, Charles Mistretta

Proceedings Volume 7177, 71770F (2009) https://doi.org/10.1117/12.810175

KEYWORDS: Spatial resolution, Scanners, Photoacoustic spectroscopy, Signal to noise ratio, Computed tomography, Preclinical imaging, 3D acquisition, Composites, Sensors, 3D image processing

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Proceedings Article | 18 March 2008 Paper

HYPR: constrained reconstruction for enhanced SNR in dynamic medical imaging

C. Mistretta, O. Wieben, J. Velikina, Y. Wu, K. Johnson, F. Korosec, O. Unal, G. Chen, S. Fain, B. Christian, O. Nalcioglu, R. Kruger, W. Block, A. Samsonov, M. Speidel, M. Van Lysel, H. Rowley, M. Supanich, P. Turski, Yan Wu, J. Holmes, S. Kecskemeti, C. Moran, R. O'Halloran, L. Keith, A. Alexander, E. Brodsky, J. Lee, T. Hall, J. Zagzebski

Proceedings Volume 6913, 691305 (2008) https://doi.org/10.1117/12.771413

KEYWORDS: Signal to noise ratio, Composites, Image processing, X-rays, Magnetic resonance imaging, Medical imaging, Lawrencium, Convolution, Angiography, Positron emission tomography

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Proceedings Article | 28 February 2008 Paper

Improving limited-view reconstruction in photoacoustic tomography by incorporating a priori boundary information

Mark Anastasio, Kun Wang, Jin Zhang, Gabe Kruger, Daniel Reinecke, Robert Kruger

Proceedings Volume 6856, 68561B (2008) https://doi.org/10.1117/12.764178

KEYWORDS: Reconstruction algorithms, Transducers, Acquisition tracking and pointing, Photoacoustic spectroscopy, Absorption, Photoacoustic tomography, Biomedical optics, Ultrasonography, Tomography, Tissue optics

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Proceedings Article | 13 February 2007 Paper

Photoacoustic molecular imaging

William Kiser, Daniel Reinecke, Timothy DeGrado, Sibaprasad Bhattacharyya, Robert Kruger

Proceedings Volume 6437, 643721 (2007) https://doi.org/10.1117/12.705136

KEYWORDS: Tissue optics, Breast, Breast cancer, Absorption, Infrared imaging, Photoacoustic spectroscopy, Tissues, Receptors, In vivo imaging, Molecular imaging

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Proceedings Article | 13 February 2007 Paper

Phantom and in-vivo measurements of hemoglobin concentration and oxygen saturation using PCT-S small animal scanner

Bo Liu, Daniel Reinecke, Robert Kruger, Keith Stantz

Proceedings Volume 6437, 64371X (2007) https://doi.org/10.1117/12.701376

KEYWORDS: Blood, Oxygen, Scanners, Absorption, Tumors, In vivo imaging, Veins, Arteries, Hypoxia, Calibration

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Proceedings Article | 13 February 2007 Paper

Using Monte Carlo simulations to understand the influence of photon propagation on photoacoustic spectroscopic imaging

Keith Stantz, Bo Liu, Robert Kruger

Proceedings Volume 6437, 64370Z (2007) https://doi.org/10.1117/12.701395

KEYWORDS: Monte Carlo methods, Tumors, Blood, Photoacoustic spectroscopy, Absorption, Near infrared, Tissue optics, Photon transport, Acoustics, Signal attenuation

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Purpose: The purpose of this study is to evaluate the influence of photon propagation on the NIR spectral features associated with photoacoustic imaging. Introduction: Photoacoustic CT spectroscopy (PCT-S) has the potential to identify molecular properties of tumors while overcoming the limited depth resolution associated with optical imaging modalities (e.g., OCT and DOT). Photoacoustics is based on the fact that biological tissue generates high-frequency acoustic signals due to volume of expansion when irradiated by pulsed light. The amplitude of the acoustic signal is proportional to the optical absorption properties of tissue, which varies with wavelength depending on the molecular makeup of the tissue. To obtain quantifiable information necessitate modeling and correcting for photon and acoustic propagation in tumors. Material and Methods: A Monte Carlo (MC) algorithm based on MCML (Monte Carlo for Multi-Layered edia) has been developed to simulate photon propagation within objects comprised of a series of complex 3D surfaces (Mcml3D). This code has been used to simulate and correct for the optical attenuation of photons in blood, and for subcutaneous tumors with homogenous and radially heterogeneous vascular distributions. Results: The NIR spectra for oxygenated and deoxygenated blood as determined from Monte Carlo simulated photoacoustic data matched measured data, and improving oxygen saturation calculations. Subcutaneous tumors with a homogeneous and radially heterogeneous distribution of blood revealed large variations in photon absorption as a function of the scanner projection angle. For select voxels near the periphery of the tumor, this angular profile between the two different tumors appeared similar. Conclusions: A Monte Carlo code has been successfully developed and used to correct for photon propagation effects in blood phantoms and restoring the integrity of the NIR spectra associated with oxygenated and deoxygenated blood. This code can be used to simulate the influence of intra-tumor heterogeneity on the molecular identification via NIR spectroscopy.

Proceedings Article | 20 March 2006 Paper

Evaluating dynamic contrast-enhanced and photoacoustic CT to assess intra-tumor heterogeneity in xenograft mouse models

Keith Stantz, Bo Liu, Minsong Cao, Dan Reinecke, Mario Dzemidzic, Yun Liang, Robert Kruger

Proceedings Volume 6143, 61431F (2006) https://doi.org/10.1117/12.654056

KEYWORDS: Tumors, Oxygen, Blood, Photoacoustic spectroscopy, Breast, In vivo imaging, Vascular physiology, Calibration, Error analysis, Plasma

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Proceedings Article | 6 March 2006 Paper

Assessment of photoacoustic computed tomography to classify tissue in a polycystic-kidney disease mouse model

Bo Liu, Vincent Gattone, Robert Kruger, Keith Stantz

Proceedings Volume 6086, 608607 (2006) https://doi.org/10.1117/12.646180

KEYWORDS: Kidney, Tissues, Mouse models, Tissue optics, Image segmentation, Photons, Photoacoustic tomography, Photography, Computed tomography, Absorption

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Proceedings Article | 6 March 2006 Paper

Photoacoustic spectroscopic imaging of intra-tumor heterogeneity and molecular identification

Keith Stantz, Bo Liu, Minsong Cao, Daniel Reinecke, Kathy Miller, Robert Kruger

Proceedings Volume 6086, 608605 (2006) https://doi.org/10.1117/12.645106

KEYWORDS: Tumors, Blood, Photoacoustic spectroscopy, In vivo imaging, Spectroscopy, Error analysis, Oxygen, Liver, Tissue optics, Bladder

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Purpose. To evaluate photoacoustic spectroscopy as a potential imaging modality capable of measuring intra-tumor heterogeneity and spectral features associated with hemoglobin and the molecular probe indocyanine green (ICG). Material and Methods. Immune deficient mice were injected with wildtype and VEGF enhanced MCF-7 breast cancer cells or SKOV3x ovarian cancer cells, which were allowed to grow to a size of 6-12 mm in diameter. Two mice were imaged alive and after euthanasia for (oxy/deoxy)-hemoglobin content. A 0.4 mL volume of 1 μg/mL concentration of ICG was injected into the tail veins of two mice prior to imaging using the photoacoustic computed tomography (PCT) spectrometer (Optosonics, Inc., Indianapolis, IN 46202) scanner. Mouse images were acquired for wavelengths spanning 700-920 nm, after which the major organs were excised, and similarly imaged. A histological study was performed by sectioning the organ and optically imaging the fluorescence distribution. Results. Calibration of PCT-spectroscopy with different samples of oxygenated blood reproduced a hemoglobin dissociation curve consistent with empirical formula with an average error of 5.6%. In vivo PCT determination of SaO₂ levels within the tumor vascular was measurably tracked, and spatially correlated to the periphery of the tumor. Statistical and systematic errors associated with hypoxia were estimated to be 10 and 13%, respectively. Measured ICG concentrations determined by contrast-differential PCT images in excised organs (tumor, liver) were approximately 0.8 μg/mL, consistent with fluorescent histological results. Also, the difference in the ratio of ICG concentration in the gall bladder-to-vasculature between the mice was consistent with excretion times between the two mice. Conclusion. PCT spectroscopic imaging has shown to be a noninvasive modality capable of imaging intra-tumor heterogeneity of (oxy/deoxy)-hemoglobin and ICG in vivo, with an estimated error in SaO₂ at 17% and in ICG at 0.8 μg/mL in excised tissue. Ongoing development of spectroscopic analysis techniques, probe development, and calibration techniques are being developed to improve sensitivity to both exogenous molecular probes and (oxy/deoxy)-hemoglobin fraction.

Proceedings Article | 12 July 2004 Paper

Thermoacoustic in vivo determination of blood oxygenation

William Kiser, Robert Kruger, Daniel Reinecke, Gabe Kruger, Kathy Miller

Proceedings Volume 5320, (2004) https://doi.org/10.1117/12.532666

KEYWORDS: Imaging systems, Blood, Tumors, Tissue optics, Absorption, Tissues, Computed tomography, Near infrared, Infrared radiation, Image processing

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Proceedings Article | 3 May 2002 Paper

Thermoacoustic CT of the breast

Robert Kruger, Keith Stantz, William Kiser

Proceedings Volume 4682, (2002) https://doi.org/10.1117/12.465596

KEYWORDS: Scanners, Breast, Transducers, Waveguides, Image quality, Optical spheres, Data acquisition, Computed tomography, 3D image processing, Ultrasonography

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Proceedings Article | 15 June 2001 Paper

Thermoacoustic CT of the breast: pilot study observations

Robert Kruger, William Kiser, A. Romilly, Phyllis Scmidt

Proceedings Volume 4256, (2001) https://doi.org/10.1117/12.429292

KEYWORDS: Breast, Mammography, Image quality, Visualization, Cancer, X-rays, Tissues, Ultrasonography, Absorption, Computed tomography

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Proceedings Article | 19 May 2000 Paper

Thermoacoustic CT: imaging principles

Robert Kruger, William Kiser, Kathy Miller, Handel Reynolds, Daniel Reinecke, Gabe Kruger, Peter Hofacker

Proceedings Volume 3916, (2000) https://doi.org/10.1117/12.386316

KEYWORDS: Transducers, Optical spheres, Tissues, Computed tomography, Spatial resolution, Absorption, Antennas, Point spread functions, 3D image processing, Breast

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Proceedings Article | 12 April 2000 Paper

Thermoacoustic CT scanner for breast imaging: design considerations

Robert Kruger, William Kiser, Kathy Miller, Handel Reynolds, Daniel Reinecke, Gabe Kruger, Peter Hofacker, R. Eisenhart

Proceedings Volume 3982, (2000) https://doi.org/10.1117/12.382244

KEYWORDS: Breast, Scanners, Transducers, Spatial resolution, Point spread functions, Computed tomography, Tissues, Waveguides, Breast imaging, Phased arrays

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Proceedings Article | 28 May 1999 Paper

Thermoacoustic computed tomography: limits to spatial resolution

William Kiser, Robert Kruger

Proceedings Volume 3659, (1999) https://doi.org/10.1117/12.349572

KEYWORDS: Transducers, Imaging systems, Spatial resolution, Acoustics, Microwave radiation, Image resolution, Absorption, Tissues, Computing systems, Photoacoustic spectroscopy

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Proceedings Article | 28 May 1999 Paper

Application of thermoacoustic computed tomography to breast imaging

Robert Kruger, William Kiser, Daniel Reinecke, Gabe Kruger

Proceedings Volume 3659, (1999) https://doi.org/10.1117/12.349519

KEYWORDS: Tissues, Absorption, Breast, Transducers, Spatial resolution, Computed tomography, CT reconstruction, 3D image reconstruction, Scanners, Acoustics

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Proceedings Article | 11 April 1996 Paper

Simulation of photoacoustic signal production in human breast phantoms at 1064 nm

Pingyu Liu, Robert Kruger, C. Robert Appledorn, Yuncai Fang

Proceedings Volume 2708, (1996) https://doi.org/10.1117/12.237792

KEYWORDS: Tumors, Transducers, Photoacoustic spectroscopy, Breast, Absorption, Signal generators, Natural surfaces, Chlorine, Liquids, Scattering

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Proceedings Article | 11 April 1996 Paper

Energy deposition patterns in the breast at 1064 nm for photoacoustic ultrasound

C. Robert Appledorn, Robert Kruger, Pingyu Liu, Yuncai Fang

Proceedings Volume 2708, (1996) https://doi.org/10.1117/12.237829

KEYWORDS: Absorption, Scattering, Breast, Monte Carlo methods, Photoacoustic spectroscopy, Light scattering, Photon transport, Ultrasonography, Ultrasonics, Acoustics

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Proceedings Article | 11 April 1996 Paper

Microwave applicators for photoacoustic ultrasonagraphy

Yuncai Fang, Robert Kruger, Pingyu Liu, C. Robert Appledorn

Proceedings Volume 2708, (1996) https://doi.org/10.1117/12.237828

KEYWORDS: Microwave radiation, Waveguides, Photoacoustic spectroscopy, Tissues, Polarization, Absorption, Ultrasonography, Temperature metrology, Optical fibers, Transducers

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Proceedings Article | 17 August 1994 Paper

Photoacoustic ultrasound: experimental results

Robert Kruger, Pingyu Liu

Proceedings Volume 2134, (1994) https://doi.org/10.1117/12.182926

KEYWORDS: Tissue optics, Absorption, Ultrasonography, Biomedical optics, Photoacoustic spectroscopy, Transducers, Scattering media, Ultrasonics, Laser scattering, Scattering

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Proceedings Article | 17 August 1994 Paper

Photoacoustic ultrasound: theory

Robert Kruger, Pingyu Liu

Proceedings Volume 2134, (1994) https://doi.org/10.1117/12.182925

KEYWORDS: Tissue optics, Absorption, Acoustics, Biomedical optics, Tissues, Ultrasonography, Light scattering, Scattering, Photoacoustic spectroscopy, Ultrasonics

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SPIE Journal Paper | 1 August 1994

Semianalytical approach to pulsed light propagation in scattering and absorbing media

Pingyu Liu, Robert Kruger

OE, Vol. 33, Issue 08, (August 1994) https://doi.org/10.1117/12.10.1117/12.173572

KEYWORDS: Scattering, Light scattering, Mie scattering, Biomedical optics, Signal attenuation, Photons, Picosecond phenomena, Laser scattering, Sensors, Radiative transfer

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Proceedings Article | 8 July 1994 Paper

Computerized tomographic angiography image segmentation for 3D-volume reconstruction

Yun Liang, Robert Kruger

Proceedings Volume 2299, (1994) https://doi.org/10.1117/12.179256

KEYWORDS: Image segmentation, Arteries, Angiography, Image processing, Tissues, Bone, X-ray computed tomography, 3D image processing, 3D image reconstruction, Computed tomography

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Proceedings Article | 19 May 1994 Paper

New approach to the "forward problem" of optical diffusion tomography of turbid media

Pingyu Liu, Robert Kruger

Proceedings Volume 2135, (1994) https://doi.org/10.1117/12.175997

KEYWORDS: Diffusion, Biomedical optics, Optical tomography, Tomography, Scattering, Inverse optics, Monte Carlo methods, Computer simulations, Maxwell's equations, Radiative transfer

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Proceedings Article | 19 May 1994 Paper

Simulation of photon paths through isotropically scattering media

C. Robert Appledorn, Robert Kruger

Proceedings Volume 2135, (1994) https://doi.org/10.1117/12.175993

KEYWORDS: Scattering, Photon transport, Monte Carlo methods, Diffusion, Tissue optics, Particles, Tissues, Scattering media, Absorption, Light scattering

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Proceedings Article | 19 May 1994 Paper

Time-resolved optical diffusion tomography

C. Robert Appledorn, Robert Kruger, Pingyu Liu

Proceedings Volume 2135, (1994) https://doi.org/10.1117/12.175996

KEYWORDS: Absorption, Reconstruction algorithms, Photons, Scattering, Algorithm development, Tissues, Light scattering, Tomography, Laser scattering, Diffusion

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Proceedings Article | 1 February 1994 Paper

Solution to the time-dependent photon transport equation

Pingyu Liu, Robert Kruger

Proceedings Volume 2077, (1994) https://doi.org/10.1117/12.168023

KEYWORDS: Photon transport, Biomedical optics, Diffusion, Geometrical optics, Optical tomography, Tomography, Picosecond phenomena, Scattering, Monte Carlo methods, Image restoration

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Proceedings Article | 1 July 1991 Paper

Tomographic imaging using picosecond pulses of light

Jeremy Hebden, Robert Kruger, Kam Sing Wong

Proceedings Volume 1443, (1991) https://doi.org/10.1117/12.43448

KEYWORDS: Picosecond phenomena, Photons, Streak cameras, Scattering, Signal attenuation, Diagnostics, Light scattering, Medical imaging, Tissue optics, Tomography

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Proceedings Article | 1 July 1991 Paper

Clinical image-intensifier-based volume CT imager for angiography

Ruola Ning, John Barsotti, Daniel Kido, Robert Kruger

Proceedings Volume 1443, (1991) https://doi.org/10.1117/12.43446

KEYWORDS: Distortion, Image intensifiers, Imaging systems, Reconstruction algorithms, 3D image processing, X-ray computed tomography, Angiography, 3D image reconstruction, Image quality, Medical imaging

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Proceedings Article | 1 May 1991 Paper

Time-of-flight breast imaging system: spatial resolution performance

Jeremy Hebden, Robert Kruger

Proceedings Volume 1431, (1991) https://doi.org/10.1117/12.44193

KEYWORDS: Spatial resolution, Photons, Picosecond phenomena, Imaging systems, Modulation transfer functions, Tissue optics, Streak cameras, Imaging spectroscopy, Tissues, Diagnostics

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Proceedings Article | 1 August 1990 Paper

Simulating the performance of a time-of-flight transillumination imaging system

Jeremy Hebden, Robert Kruger

Proceedings Volume 1205, (1990) https://doi.org/10.1117/12.17789

KEYWORDS: Photons, Breast, Scattering, Tissues, Spatial resolution, Imaging systems, Tissue optics, Signal attenuation, Absorption, Picosecond phenomena

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Proceedings Article | 1 July 1990 Paper

Image-intensifier-based volume CT imager: angiographic application

Ruola Ning, Robert Kruger

Proceedings Volume 1233, (1990) https://doi.org/10.1117/12.18929

KEYWORDS: Imaging systems, Angiography, 3D image reconstruction, Reconstruction algorithms, 3D image processing, X-ray computed tomography, Image intensifiers, CCD cameras, Signal to noise ratio, Prototyping

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