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Medical Imaging 2007: Computer-Aided Diagnosis

作者： Singh, Swatee Tourassi, Georgia D. Lo, Joseph Y. Department of Biomedical Engineering Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705 Duke Medical Physics Program Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705 Department of Radiology Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705

ISBN: (纸本)0819466328

The purpose of this project is to study Computer Aided Detection (CADe) of breast masses for digital tomosynthesis. It is believed that tomosynthesis will show improvement over conventional mammography in detection and characterization of breast masses by removing overlapping dense fibroglandular tissue. This study used the 60 human subject cases collected as part of on-going clinical trials at Duke University. Raw projections images were used to identify suspicious regions in the algorithm's high-sensitivity, low-specificity stage using a Difference of Gaussian (DoG) filter. The filtered images were thresholded to yield initial CADe hits that were then shifted and added to yield a 3D distribution of suspicious regions. These were further summed in the depth direction to yield a flattened probability map of suspicious hits for ease of scoring. To reduce false positives, we developed an algorithm based on information theory where similarity metrics were calculated using knowledge databases consisting of tomosynthesis regions of interest (ROIs) obtained from projection images. We evaluated 5 similarity metrics to test the false positive reduction performance of our algorithm, specifically joint entropy, mutual information, Jensen difference divergence, symmetric Kullback-Liebler divergence, and conditional entropy. The best performance was achieved using the joint entropy similarity metric, resulting in ROC A2 of 0.87 ±0.01. As a whole, the CADe system can detect breast masses in this data set with 79% sensitivity and 6.8 false positives per scan. In comparison, the original radiologists performed with only 65% sensitivity when using mammography alone, and 91% sensitivity when using tomosynthesis alone.

关键词： Tumors

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A comparison between traditional shift-and-add (SAA) and point-by-point back projection (BP) - Relevance to morphology of microcalcifications for isocentric motion in Digital Breast tomosynthesis (DBT)

A comparison between traditional shift-and-add (SAA) and poi...

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7th IEEE International Conference on Bioinformatics and Bioengineering, BIBE

作者： Chen, Ying Lo, Joseph Y Dobbins III, James T. Department of Electrical and Computer Engineering Southern Illinois University Carbondale Carbondale IL 62901 United States Department of Biomedical Engineering Duke University Duke University Medical Center Durham NC 27710 United States Duke Advanced Imaging Laboratories Duke University Duke University Medical Center Durham NC 27710 United States Medical Physics Graduate Program Duke University Duke University Medical Center Durham NC 27710 United States

ISBN: (纸本)1424415098

Digital breast tomosynthesis (DBT) is a three-dimensional imaging technique providing an arbitrary set of reconstruction planes in the breast with limited series of projection images. This paper describes a comparison between traditional shift-and-add (SAA) and point-by-point back projection (BP) algorithms by impulse response and modulation transfer function (MTF) analysis. Due to the partial isocentric motion of the x-ray tube in DBT, structures such as microcalcifications appear slightly blurred in traditional shift-and-add (SAA) images in the direction perpendicular to the direction of tube 's motion. Point-by-point BP improved rendition of microcalcifications. The sharpness and morphology of calcifications were improved in a human subject images. A Filtered Back Projection (FBP) deblurring approach was used to demonstrate deblurred point-by-point BP tomosynthesis images. The point-by-point BP rather than traditional SAA should be considered as the foundation of further deblurring algorithms for DBT reconstruction. ©2007 IEEE.

关键词： Impulse response

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Student Categorization of Problems—An Extension

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AIP Conference Proceedings 2007年第1期951卷 112-115页

作者： Kathleen A. Harper Zachary D. Hite Richard J. Freuler John T. Demel aDepartment of Physics The Ohio State University 191 W Woodruff Ave Columbus OH 43210 bFirst‐Year Engineering Program The Ohio State University 244 Hitchcock Hall 2070 Neil Ave Columbus OH 43210

As part of gathering baseline data for a study on problem categorization, first‐year engineering honors students who had recently completed a two‐quarter sequence in physics were interviewed. The primary task in this interview was much like the problem categorization study described by Chi et al. There were, however, at least two distinct modifications: 1) in addition to the problem statements, solutions were included on the cards to be sorted 2) the problems were written such that they could also be grouped according to the nature of information presented in the problem statements and/or the number of possible solutions. The students in this baseline study, although similar in background to the novices described by Chi et al., in many ways performed more like experts. Several possibilities for this behavior are discussed.

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Evidence for Viscoelastic Effects in Surface Capillary Waves of Molten Polymer Films

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Physical Review Letters 2007年第22期98卷 227801-227801页

作者： Zhang Jiang Hyunjung Kim X. Jiao H. Lee Y.-J. Lee Y. Byun S. Song D. Eom C. Li M. H. Rafailovich L. B. Lurio S. K. Sinha Department of Physics University of California at San Diego La Jolla California 92093 USA Department of Physics and Interdisciplinary Program of Integrated Biotechnology Sogang University Seoul 121-742 Korea Department of Physics Northern Illinois University DeKalb Illinois 60115 USA Department of Materials Science and Engineering SUNY at Stony Brook New York 11794 USA LANSCE Los Alamos National Laboratory Los Alamos New Mexico 87545 USA

The surface dynamics of supported ultrathin polystyrene films with thickness comparable to the radius of gyration were investigated by surface sensitive x-ray photon correlation spectroscopy. We show for the first time that the conventional model of capillary waves on a viscous liquid has to be modified to include the effects of a shear modulus in order to explain both static and dynamic scattering data from ultrathin molten polymer films.

关键词： Polymer films

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Lattice Boltzmann algorithms for fluid turbulence

Lattice Boltzmann algorithms for fluid turbulence

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Department of Defense - HPCMP Users Group Conference 2007;High Performance Computing Modernization program: A Bridge to Future Defense, DoD HPCMP UGC

作者： Vahala, George Yepez, Jeffrey Soe, Min Vahala, Linda Ziegeler, Sean Department of Physics College of William and Mary Williamsburg VA United States Hanscom Field MA United States Department of Mathematics and Science Rogers State University Claremore OK United States Department of Electrical and Computer Engineering Old Dominion University Norfolk VA United States High Performance Computing Modernization Program Mississippi State University MS United States

ISBN: (纸本)0769530885

Lattice Boltzmann algorihms are a mesoscopic representation of nonlinear continuum physics (like Navier-Stokes, magnetohydrodynamics (MHD), Gross-Pitaevskii equations) which are ideal for parallel supercomputers because they transform the difficult nonlinear convective macroscopic derivatives into purely local moments of distribution functions. The macroscopic nonlinearities are recovered by relaxation distribution functions in the collision operator whose dependence on the macroscopic velocity is algebraically nonlinear and thus purely local. Unlike standard computational fluid dynamics codes, there is no loss in parallelization in handling arbitrary geometric boundaries, e.g., using bounce-back rules from kinetic theory. By encoding detailed balance into the collision operator through the introduction of discrete H-function, the lattice Boltzmann algorithm can be made unconditionally stable for arbitrary high Reynolds numbers. It is shown that this approach is a special case of a quantum lattice Boltzmann algorithm that entangles local qubits through unitary collision operators and which is ideally parallelized on quantum computer architectures. Here we consider turbulence simulations using 2,048 PEs on a 1,6003-spatial grid. A connection is found between the rate of change of enstrophy and the onset of laminar-to-turbulent flows. © 2007 IEEE.

关键词： Magnetohydrodynamics

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Sensing metabolic activity in tissue engineered constructs

Sensing metabolic activity in tissue engineered constructs

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European Conference on Biomedical Optics, ECBO 2007

作者： Chandra, Malavika Wilson, Robert H. Lo, Wen-Liang Vishwanath, Karthik Izumi, Kenji Feinberg, Stephen E. Mycek, Mary-Ann Applied Physics Program University of Michigan Ann Arbor MI 48109 United States Oral and Maxillofacial Surgery University of Michigan Ann Arbor 48109 United States Dept. of Biomedical Engineering University of Michigan Ann Arbor MI 48109 United States Comprehensive Cancer Center University of Michigan Medical School Ann Arbor MI 48109 United States

ISBN: (纸本)9780819467713

Tissue engineered constructs can be employed to graft wounds or replace diseased tissue. Non-invasive methods are required to assess cellular viability in these constructs both pre-and post-implantation into patients. In this study, Monte Carlo simulations and fluorescence experiments were executed on ex vivo produced oral mucosa equivalent (EVPOME) constructs to investigate the fluorescence emitted at 355 nm excitation from these constructs. Both simulations and experiments indicated the need to investigate alternative excitation wavelengths in order to increase the cellular fluorescence from these constructs, while decreasing contributions from extra-cellular fluorophores. © 2007 SPIE-OSA.

关键词： Tissue engineering

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Cultivating Problem Solving Skills via a New Problem Categorization Scheme

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AIP Conference Proceedings 2007年第1期883卷 141-144页

作者： Kathleen A. Harper Richard J. Freuler John T. Demel *Department of Physics The Ohio State University 191 W Woodruff Ave Columbus OH 43210 †First‐Year Engineering Program The Ohio State University Room 244 Hitchcock Hall 2070 Neil Ave Columbus OH 43210

When one looks at STEM disciplines as a whole, the need for effective problem solving skills is a commonality. However, studies indicate that the bulk of students who graduate from problem‐solving intensive programs display little increase in their problem solving abilities. Also, there is little evidence for transfer of general skills from one subject area to another. Furthermore, the types of problems typically encountered in introductory STEM courses do not often cultivate the skills students will need when solving “real‐world” problems. Initial efforts to develop and implement an interdisciplinary problem categorization matrix as a tool for instructional design are described. The matrix, which is independent of content, shows promise as a means for promoting useful problem‐solving discussion among faculty, designing problem‐solving intensive courses, and instructing students in developing real‐world problem solving skills.

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Role of Ge in Bridging Ferromagnetism in the Giant Magnetocaloric Gd5(Ge1−xSix)4 Alloys

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Physical Review Letters 2007年第24期98卷 247205-247205页

作者： D. Haskel Y. B. Lee B. N. Harmon Z. Islam J. C. Lang G. Srajer Ya. Mudryk K. A. Gschneidner, Jr. V. K. Pecharsky Advanced Photon Source Argonne National Laboratory Argonne Illinois 60439 USA Condensed Matter Physics Program Ames Laboratory Iowa State University Ames Iowa 50011-3020 USA Ames Laboratory and Department of Materials Science and Engineering Iowa State University Ames Iowa 50011-3020 USA

X-ray magnetic circular dichroism (XMCD) measurements and density functional theory (DFT) are used to study the electronic conduction states in Gd5(Ge1−xSix)4 materials through the first-order bond-breaking magnetostructural transition responsible for their giant magnetocaloric effect. Spin-dependent hybridization between Ge 4p and Gd 5d conduction states, which XMCD senses through the induced magnetic polarization in Ge ions, enables long-range Ruderman-Kittel-Kasuya-Yosida ferromagnetic interactions between Gd 4f moments in adjacent Gd slabs connected by Ge(Si) bonds. These interactions are strong below but weaken above the Ge(Si) bond-breaking transition that destroys 3D ferromagnetic order.

关键词： Gadolinium alloys

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A Novel Method Improving the Imaging Resolution of a Table-top Compton Camera

A Novel Method Improving the Imaging Resolution of a Table-t...

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2007 IEEE Nuclear Science Symposium Conference (NSS 2007), vol.7

作者： Hee Seo Se Hyung Lee Jong Hwi Jeong Ju Hahn Lee Chun Sik Lee Jae Sung Lee Chan Hyeong Kim Department of Nuclear Engineering Hanyang University Seoul South Korea Department of Physics Chung-Ang University Seoul South Korea Department of Nuclear Medicine and Interdisciplinary Program in Radiation Applied Life Science Seoul National University Seoul South Korea

For a table-top Compton camera, which is currently under development in our group, the interaction position resolution of the absorber detector is a critical or limiting detector parameter that most seriously affects the imaging resolution of the Compton camera. Currently, it is assumed that all the interactions occur at the centers of the detector segments of the absorber detector, which is simple, but obviously not the best choice considering that the interaction depths of the photons in the absorber detector is not distributed uniformly, especially for the low-energy photons. To this end, the present study develops a novel method, called "average interaction depth (AID) method" to improve the imaging resolution of Compton camera by additionally considering the interaction depth of the incident photon in the absorber detector. Our simulation studies with Geant4 show that the imaging resolution of Compton camera can be significantly improved by using the AID method. The imaging resolution of the table-top Compton camera was improved from 9.9mm to 7.6mm in full width at half maximum (FWHM) for a 511keV γ point source. For a 364keV γ point source, the imaging resolution was improved more significantly, i.e., from 11.4mm to 7.2mm.

关键词： Image resolution Cameras

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Spin-wave dispersion in magnetostrictive Fe-Ga alloys: Inelastic neutron scattering measurements

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Physical Review B 2007年第5期75卷 052406-052406页

作者： J. L. Zarestky O. Moze J. W. Lynn Y. Chen T. A. Lograsso D. L. Schlagel Ames Laboratory and Department of Physics and Astronomy Iowa State University Ames Iowa 50011 USA Dipartimento di Fisica Università di Modena e Reggio Emilia Modena 41100 Italy NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg Maryland 20899-8562 USA Department of Materials Science and Engineering University of Maryland College Park Maryland 20742 USA Ames Laboratory Materials and Engineering Physics Program Iowa State University Ames Iowa 50011 USA

Fe-Ga alloys of appropriate Ga concentration and heat treatment show a very large enhancement in the tetragonal magnetostriction over that of pure α−Fe [λ100(Fe−Ga)∼15λ100(Fe)]. In order to gain further understanding of the extraordinary magnetoelastic characteristics of this system, the spin dynamics of two of these alloys, Fe1−xGax (x=0.160 and 0.225), were studied using inelastic neutron scattering techniques. The correlation of the spin-wave dispersion curve with the lattice constant and atomic radii of solute is examined for this and other Fe alloys.

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