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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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Interfacial structure, bonding and composition of InAs and GaSb thin films determined using coherent Bragg rod analysis

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Physical Review B 2007年第11期75卷 115306-115306页

作者： C. N. Cionca D. A. Walko Y. Yacoby C. Dorin J. Mirecki Millunchick R. Clarke Applied Physics Program Physics Department University of Michigan Ann Arbor Michigan 48109 USA Advanced Photon Source Argonne National Laboratory Argonne Illinois 60439 USA Racah Institute of Physics Hebrew University Jerusalem 91904 Israel Materials Science and Engineering Department University of Michigan Ann Arbor Michigan 48109 USA

We have used Bragg rod x-ray diffraction combined with a direct method of phase retrieval to extract atomic resolution electron-density maps of a complementary series of heteroepitaxial III-V semiconductor samples. From the three-dimensional electron-density maps we derive the monolayer spacings, the chemical compositions, and the characteristics of the bonding for all atomic planes in the film and across the film-substrate interface. InAs films grown on GaSb(001) under two different As conditions (using dimer or tetramer forms) both showed conformal roughness and mixed GaAs∕InSb interfacial bonding character. The As tetramer conditions favored InSb bonding at the interface while, in the case of the dimer, the percentages corresponding to GaAs and InSb bonding were equal within the experimental error. The GaSb film grown on InAs(001) displayed significant In and As interdiffusion and had a relatively large fraction of GaAs-like bonds at the interface.

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3B-3 Calibration of PVDF Hydrophones Using a Broad Focus Electromagnetic Lithotripter

3B-3 Calibration of PVDF Hydrophones Using a Broad Focus Ele...

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IEEE Symposium (IUS) Ultrasonics

作者： O. A. Sapozhnikov Y. A. Pishchalnikov A. D. Maxwell M. R. Bailey Center for Industrial and Medical Ultrasound Applied Physics Laboratory University of Washington Seattle WA USA Department of Acoustics Physics Faculty Moscow State University Moscow Russia Department of Anatomy and Cell Biology Indiana University School of Medicine Indianapolis IN USA Department of Biomedical Engineering University of Michigan MI USA

Correct measurement of acoustic pressure is crucial in many applications, e.g. medical diagnostics and therapy, where the physical effect of ultrasound on tissue depends on specific parameters of the wave, such as positive and negative pressure, shock front thickness, and pulse duration. In our previous paper, we reported building a new low-cost PVDF hydrophone to detect broadband signals from lithotripters and high intensity focused ultrasound (HIFU) sources. The hydrophone was built to complement the fiber optic probe hydrophone (FOPH), which has become the de facto standard broadband hydrophone for high amplitude medical devices. Our PVDF membrane hydrophone is more sensitive than the FOPH, thereby making measurement possible when averaging is not an option. The goal of this research was to develop a reliable method of calibration by comparing the PVDF hydrophone to the FOPH in a repeatable broadband pressure field. The results showed that the PVDF membranes had similar, though not identical responses.

关键词： Calibration Sonar equipment Lithotripsy Pulse measurements Ultrasonic variables measurement Acoustic pulses Ultrasonic imaging Biomembranes Acoustic measurements Thickness measurement

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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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Drug Delivery to Extravascular Tissue by Ultrasound‐activated Microbubbles

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AIP Conference Proceedings 2007年第1期911卷 462-466页

作者： Klazina Kooiman Miranda Harteveld Nico de Jong Annemieke van Wamel *Department of Biomedical Engineering Thoraxcenter Erasmus MC P.O. Box 1738 3000 DR Rotterdam the Netherlands †Interuniversity Cardiology Institute of the Netherlands P.O. Box 19258 3501 DG Utrecht the Netherlands ¶Department of Applied Physics Physics of Fluids University of Twente P.O. Box 217 7500 AE Enschede the Netherlands

Drugs will be delivered to tissue more efficiently if the vascular endothelial permeability is increased. Although recent studies have established that the permeability of single‐cell membranes is increased by ultrasound in combination with contrast agents, it is not known whether this combination can also increase the permeability of an endothelial layer. To investigate endothelial layer permeability, we treated monolayers of human umbilical vein endothelial cells with ultrasound and the contrast agent BR14. Endothelial layer permeability was assessed by measuring the transendothelial electrical resistance (TEER) and the transendothelial transport of fluorescein. Ultrasound in combination with BR14 significantly decreased TEER to 68.0 ± 3.1% of initial values and temporally increased endothelial permeability for fluorescein by 38.1 ± 16.4 %. After treatment, no cell loss or damage was observed. In conclusion, ultrasound in combination with BR14 increased the endothelial layer permeability. This feature may be used for future ultrasound‐guided drug delivery systems.

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Comparison of Reduced Angle and Fully 3D Acquisition Sequencing and Trajectories for Dual-Modality Mammotomography

Comparison of Reduced Angle and Fully 3D Acquisition Sequenc...

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2007 IEEE Nuclear Science Symposium Conference, vol.10

作者： Spencer J. Cutler Priti Madhav Kristy L. Perez Dominic J. Crotty Martin P. Tornai Department of Biomedical Engineering Duke University Durham NC USA Department of Radiology Duke University Medical Center Durham NC USA Medical Physics Graduate program Duke University Medical Center Durham NC USA Duke University Durham NC US

A dual-modality SPECT-CT system for dedicated 3D breast cancer imaging is under development. Independent dedicated SPECT and CT imaging systems have been integrated onto a single gantry for uncompressed breast imaging. This study examines challenges and tradeoffs involved in integrating the acquisition procedures of two independent imaging systems into a single imaging protocol. The physical limitation of the rotating CT tube beneath the custom patient bed currently provides only a 294 degree scan with the bed low enough for the breast to be in the cone-beam CT field-of-view. The directly coupled SPECT system is therefore also limited if the scans are to be taken simultaneously or in an interleaved fashion. Thus, geometric phantoms are imaged to characterize image degradations due to reduced projection angles for both modalities. Two different acquisitions were performed: one with the central ray of the CT cone-beam aligned with the system's center of rotation and one offset from the center of rotation by 5cm. Various sized activity-filled lesions in an anthropomorphic breast phantom were imaged, first with uniform aqueous background activity and then with added acrylic pieces to simulate a non-uniform background. Interleaving the SPECT and CT acquisitions into a single scan was also investigated. Iterative reconstruction algorithms are used to reconstruct the data, and the SPECT and CT images are co-registered. Both the cold rod and breast data indicate that removing 75° of SPECT azimuthal data does not significantly reduce image quality. CT images were also minimally affected if the cone-beam is centrally aligned with the center of rotation, but degraded with the laterally offset cone-beam setup. In the course of these experiments, the patient bed was reconfigured with a larger central hole covered with flexible neoprene, gaining the ability to rotate completely around the breast and dramatically improving CT projection views through the chest wall.

关键词： Computed tomography Imaging phantoms Degradation Breast cancer Protocols Lesions Anthropomorphism Interleaved codes Reconstruction algorithms Image reconstruction

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Monitoring the Dehydration of Collagen by Time-Domain Terahertz Transmission Measurements

Monitoring the Dehydration of Collagen by Time-Domain Terahe...

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32nd International Conference on Infrared and Millimeter Waves, and 15th International Conference on Terahertz Electronics (IRMMW-THz 2007), part 1

作者： Peter M. Corridon Ingrid Wilke Department of Biomedical Engineering Rensselaer Polytechnic Institute Troy NY USA Department of Physics Applied Physics & Astronomy Rensselaer Polytechnic Institute Troy NY USA

We measured the change of the terahertz-frequency dielectric properties in collagen hydrated in saline spanning hypo-normal, normal and hyper-normal physiological conditions, during a 24-hour dehydration period in-vitro.

关键词： Submillimeter wave imaging Biological tissues biomedical applications of electromagnetic radiation biomedical imaging

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Effect of energetic ions on the stability of bond-center hydrogen in silicon

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Physical Review B 2007年第23期75卷 235202-235202页

作者： S. V. S. Nageswara Rao S. K. Dixit G. Lüpke N. H. Tolk L. C. Feldman Department of Physics and Astronomy Vanderbilt University Nashville Tennessee 37235 USA Interdisciplinary Materials Science Program Vanderbilt University Nashville Tennessee 37235 USA Vanderbilt Institute of Nanoscale Science and Engineering Vanderbilt University Nashville Tennessee 37235 USA Department of Applied Science College of William and Mary Williamsburg Virginia 23187 USA

We report an observation of low-temperature, athermal, ion-induced decay of infrared-active bond-center hydrogen (BCH) in silicon. Specifically, the infrared intensity of BCH is found to decay monotonically as a function of ion dose with a decay constant determined by the electronic energy deposited by each ion. Our data indicate that ion-induced decay of BCH results in a different final configuration when compared to the thermal decay process. These findings provide insight into the structure and stability of hydrogen related defects in silicon, and thus have implications for the reliability of state-of-the-art semiconductor devices, radiation damage, and ion-beam characterization studies of hydrogen containing solids.

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Estimation of the Blood Pressure using Arterial Pressure-Volume Model

Estimation of the Blood Pressure using Arterial Pressure-Vol...

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IEEE EMBS International Conference on Information Technology Applications in Biomedicine (ITAB)

作者： J. H. Jung S. H. Yoon J. H. Kim I. C. Kim A. Y. Jeon S. Y. Ye B. C. Kim B. J. Shin J. H. Ro K. G. Nam Y. J. Kim G. R. Jeon Department of Interdisciplinary program in Biomedical Engineering Pusan National University Busan Korea PhysioLab Corp. Busan Korea Department of Physics Inje University Kyungnam Korea BK21 Medical Science Education Center School of medicine Pusan National Universiry Busan Korea Department of BioSystems Engineering Pusan National University Kyungnam Korea Department of Biomedical Engineering College of Medicine Pusan National University Busan Korea Department Electronics Engineering Pusan National University Busan Korea Department of Family Medicine Pusan National University Busan Korea PhysioLab Corporation Busan South Korea

An analysis of the conventional blood pressure estimation method of the oscillometric sphygmomanometer was performed through a computer simulation using an arterial pressure-volume(APV) model. A more accurate blood pressure estimation method was proposed from the analysis. Traditionally, the maximum amplitude algorithm was applied on the oscillation waveforms of the APV model to get the mean arterial pressure and the characteristic ratio. In doing so, the shape of pressure waveforms and the cutoff frequency of high-pass filter circuitry strongly affected the estimation of mean arterial pressure and characteristic ratio. This resulted in errors when estimating blood pressure. To find an algorithm independent from the influence of waveform shapes and filter parameters, the volume oscillation of the APV model and the phase shift of the oscillation with FFT were identified by increasing the cuff pressure from 1 mmHg to 200 mmHg (1 mmHg per second). The phase shift between the ranges of volume oscillation was then only observed between the systolic and diastolic blood pressures. The same results were obtained from simulations performed on two different arterial blood pressure waveforms and one hyperthermia waveform.

关键词： Blood pressure Shape Filters Performance analysis Computer simulation Cutoff frequency Circuits Frequency estimation Arterial blood pressure Hyperthermia

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Pancreatic tissue assessment using fluorescence and reflectance spectroscopy

Pancreatic tissue assessment using fluorescence and reflecta...

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European Conference on biomedical Optics, ECBO 2007

作者： Chandra, Malavika Heidt, David Simeone, Diane McKenna, Barbara Scheiman, James Mycek, Mary-Ann Applied Physics Program University of Michigan Ann Arbor MI 48109 United States Dept. of Surgery University of Michigan Medical School Ann Arbor MI 48109 United States Dept. of Pathology University of Michigan Medical School Ann Arbor MI 48109 United States Division of Gastroenterology University of Michigan Medical School Ann Arbor MI 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

The ability of multi-modal optical spectroscopy to detect signals from pancreatic tissue was demonstrated by studying human pancreatic cancer xenografts in mice and freshly excised human pancreatic tumor tissue. Measured optical spectra and fluorescence decays were correlated with tissue morphological and biochemical properties. The measured spectral features and decay times correlated well with expected pathological differences in normal, pancreatitis and adenocarcinoma tissue states. The observed differences between the fluorescence and reflectance properties of normal, pancreatitis and adenocarcinoma tissue indicate a possible application of multi-modal optical spectroscopy to differentiating between the three tissue classifications. © 2007 SPIE-OSA.

关键词： Tissue

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