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2012 International Conference on Biomaterial and Bioengineering(ICBB 2012)

作者： Qiang Du Baodong Bai Li Ke Institute of Biomedical and Electromagnetic Engineering Shenyang University of Technology

Magnetic induction tomography(MIT) is a biologic tomography technology, which is to obtain the conductivity distribution by detecting the data on the boundary of the imaging area based on the eddy current principle. The small impedance difference between biological tissues makes the eddy current weak, and it leads to a direct effect on the biological impedance measurement and imaging sensitivity. A measured data standardization method is presented in this paper for enhancing the measured data sensitivity, and combined with the back-projection reconstruction algorithm to get reconstruction image. It is applied to a variety of measurement and the simulation experiment based on the calculation results of finite-element methods. The reconstructed images indicate that the method can improve the image resolution and sensitivity, and which provides an effective data standardization and reconstruction algorithm for the magnetic induction tomography.

关键词： Magnetic Induction Tomography(MIT) Reconstruction algorithm back-projection algorithm Standardization Method

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3D Contour Reconstruction of Convex Object Based on Fluorescence Molecular Tomography

3D Contour Reconstruction of Convex Object Based on Fluoresc...

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第23届过程控制会议

作者： Li Qi-An Zhou Yun Li Yue School of Information and Control Engineering Liaoning Shihua University Fushun 113001

Fluorescence molecular tomography (FMT) based on CCD is developing rapidly these years. In order to get the density of forward model of fluorophore, we need to reconstruct the contour of target object. A new three-dimensional modeling method based on CT back-projection algorithm with few-views is proposed in this paper. Binary pictures is captured by 180° scanning with the help of CCD camera, and then filtering and fitting is operated. Ultimately, surface fitting in three-dimensional modeling is completed by least-squares method. Traditional method of 3D contour reconstruction needs to scan for 360° while this new method needs only 180°, and modeling could be completed even if the projection angle is fewer. Moreover, this method provide a reference to combine FMT and CT into one system.

关键词： FMT back-projection algorithm Least-squares method Three-dimensional modeling

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Statistical Approach for Optoacoustic Image Reconstruction in the Presence of Strong Acoustic Heterogeneities

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IEEE TRANSACTIONS ON MEDICAL IMAGING 2011年第2期30卷 401-408页

作者： Dean-Ben, X. Luis Ma, Rui Razansky, Daniel Ntziachristos, Vasilis Tech Univ Munich Inst Biol & Med Imaging D-85764 Neuherberg Germany Helmholtz Ctr Munich D-85764 Neuherberg Germany

A method is presented to reduce artefacts produced in optoacoustic tomography images due to internal reflection or scattering of the acoustic waves. It is based on weighting the tomographic contribution of each detector with the probability that a signal affected by acoustic mismatches is measured at that position. The correction method does not require a priori knowledge of the acoustic or optical properties of the imaged sample. Performance tests were made with agar phantoms that included air gaps for mimicking strong acoustic reflections as well as with an acoustically heterogeneous adult Zebrafish. The results obtained with the method proposed show a clear reduction of the artefacts with respect to the original images reconstructed with filtered back-projection algorithm. This performance is directly related to in vivo small animal imaging applications involving imaging in the presence of bones, lungs, and other highly mismatched organs.

关键词： Acoustic mismatch back-projection algorithm optoacoustic tomography statistical correction

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The Millimeter-wave Imaging of Concealed Objects

The Millimeter-wave Imaging of Concealed Objects

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IEEE International Symposium on Antennas and Propagation (APSURSI)/USNC/URSI National Radio Science Meeting

作者： Cetinkaya, Harun Kizilhan, Ahmet Vertii, Alexey Demirci, Sevket Yigit, Enes Ozdemir, Caner TUBITAK Marmara Res Ctr Mat Inst Kocaeli Turkey Mersin Univ Dept Elect Elect Engn Mersin Turkey

ISBN: (纸本)9781424495610

In this study, two different applications are performed. An application of concealed object detection is firstly studied through millimeter-wave inverse synthetic aperture radar (ISAR) imaging. For this purpose, near-field W-band ISAR measurements of one centimeter metallic and dielectric cube targets covered by distinct textile materials are carried out in an anechoic chamber room. Then, the images are reconstructed by using back-projection ISAR imaging technique. Then, the performance of the technique is quantified from the resulted images by using the accuracy and quality metrics. An application of a concealed weapon is also handled using millimeter-wave tomography imaging. The tomography imaging of concealed weapon located behind styropor foam wall is performed. Then, the images are reconstructed by using a method which calculates polarization currents on the object surface. The results obtained are finally shown.

关键词： component Millimeter-wave imaging ISAR concealed object imaging back-projection algorithm tomography imaging

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Time-shifting correction in optoacoustic tomographic imaging for media with non-uniform speed of sound

Time-shifting correction in optoacoustic tomographic imaging...

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Conference on Novel Biophotonic Techniques and Applications

作者： Dean-Ben, X. Luis Ntziachristos, Vasilis Razansky, Daniel Tech Univ Munich Inst Biol & Med Imaging Ingolstadter Landstr 1 D-85764 Neuherberg Germany Helmholtz Ctr Munich D-85764 Neuherberg Germany

ISBN: (纸本)9780819486875

An analysis of the time-shifting correction in optoacoustic tomographic reconstructions for media with an a priori known speed of sound distribution is presented. We describe a modification of the filtered back-projection algorithm, for which the absorbed optical energy at a given point is estimated from the value of the measured signals at the instant corresponding to the time-of-flight between such point and the measuring points. In the case that a non-uniform speed of sound distribution does exist, we estimate the time-of-flight with the straight acoustic rays model, for which acoustic waves are assumed not to change direction as they propagate. The validity of this model is analysed for small speed of sound variations by comparing the predicted values of the time-of-flight with the ones estimated considering the refraction of the waves. Experimental results with tissue-mimicking agar phantoms with a higher speed of sound than water showcase the effects of the time-shifting of the optoacoustic signals caused by the acoustic mismatch. The performance of the time-shifting correction relates to the optoacoustic imaging of biological tissues, for which the speed of sound variations are usually lower than 10%.

关键词： Optoacoustic tomography back-projection algorithm heterogeneous speed of sound

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A back-projection algorithm to Stepped-Frequency Synthetic Aperture Through-the-Wall Radar Imaging

A Back-Projection Algorithm to Stepped-Frequency Synthetic A...

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2007 Asian and Pacific Conference on Synthetic Aperture Radar(APSAR 2007)

作者： Guolong Cui,Lingjiang Kong,Jianyu Yang University of Electronic Science and Technology of China(UESTC)

back-projection imaging algorithm is widely used in through-the-wall and GPR imaging because of the high image quality and being compensated *** this paper,the author will introduce the back-projection algorithm to the stepped-frequency through-the-wall radar and put forward the time-minimization method to eliminate the wall's effects,such as refraction,changing in speed and *** of concept is provided using real data collected in a laboratory *** results show that the BP algorithm can outputs a high quality image and the time-minimization method can eliminate the wall's effect very well.

关键词： stepped-frequency through-the-wall radar back-projection algorithm the time-minimization method

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Characterization of changes in therapeutic ultrasound transducer performance over time using the angular spectrum method

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2007年第5期54卷 1028-1035页

作者： Wu, Xia Worthington, Arthur E. Gertner, Mark R. Hunt, John W. Sherar, Michael D. Princess Margaret Hosp Dept Radiat Phys Toronto ON M4X 1K9 Canada Ryerson Univ Dept Phys Toronto ON Canada Princess Margaret Hosp Div Biophys & Bioimaging Toronto ON M4X 1K9 Canada Univ Toronto Dept Med Biophys Toronto ON Canada Princess Margaret Hosp Dept Med Phys Ontario Canc Inst Univ Hlth Network Toronto ON M4X 1K9 Canada Canc Care Ontario Toronto ON Canada

Strongly focused large aperture transducers used in high-intensity focused ultrasound treatments are prone to manufacturing defects and degradation. Current methods for evaluating transducer quality measure only bulk physical changes of transducers. We have determined the pressure distribution at the transducer surface, using the angular spectrum method, to detect defects of the transducer. Three therapeutic transducers were investigated. The pressure distribution at the focal plane of each transducer was measured and input into a back-projection algorithm to calculate the pressure distribution at the transducer surface. A number of scan window sizes were used for the pressure distribution measurement at the focal plane to determine the effect on the resolution of the calculated pressure distribution at the transducer surface. Results showed that one transducer might have suffered manufacturing defects. The second transducer degraded over 1 year of use with one half of the transducer suffering a partial loss of efficiency. The third transducer remained unchanged over 1 year. The scan window of 40 mm x 40 mm at the focal plane was required to identify defects 6 mm in diameter on the transducer surface. The results demonstrate that the angular spectrum method could be a useful tool for evaluating transducer quality.

关键词： biomedical transducers biomedical ultrasonics patient treatment ultrasonic transducers angular spectrum back-projection algorithm large aperture transducers pressure distribution therapeutic ultrasound transducer Transducers ultrasonic transducers biomedical transducers patient treatment Pressure Distribution biomedical ultrasonics response spectrum method

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Aperture weighted cardiac reconstruction for cone-beam CT

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PHYSICS IN MEDICINE AND BIOLOGY 2006年第14期51卷 3433-3448页

作者： Koken, P. Grass, M. Philips Res Labs Sector Tech Syst D-22335 Hamburg Germany

Multi-row detectors together with fast rotating gantries made cardiac imaging possible for CT. Due to the cardiac motion, ECG gating has to be integrated into the reconstruction of the data measured on a low pitch helical trajectory. Since the first multi-row scanners were introduced, it has been shown that approximative true cone-beam reconstruction methods are most suitable for the task of retrospectively gated cardiac volume CT. In this paper, we present the aperture weighted cardiac reconstruction (AWCR), which is a three-dimensional reconstruction algorithm of the filtered back-projection type. It is capable of handling all illumination intervals of an object point, which occur as a consequence of a low pitch helical cone-beam acquisition. Therefore, this method is able to use as much redundant data as possible, resulting in an improvement of the image homogeneity, the signal to noise ratio and the temporal resolution. Different optimization techniques like the heart rate adaptive cardiac weighting or the automatic phase determination can be adopted to AWCR. The excellent image quality achieved by AWCR is presented for medical datasets acquired with both a 40-slice and a 64-slice cone-beam CT scanner.

关键词： back-projection algorithm COMPUTED-TOMOGRAPHY IMAGE-RECONSTRUCTION SPIRALCT PERFORMANCE EVALUATION TEMPORAL RESOLUTION ARBITRARY PITCH DOSE USAGE backprojection ACQUISITION

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A special operation mode of BoomSAR in application to foliage penetration imaging

A special operation mode of BoomSAR in application to foliag...

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CIE International Conference on Radar

作者： Sun, Hongbo Liu, Weixian Lu, Yilong Borderies, Pierre Lemaitre, Francois Tai, Ling Chiat Seah, Heong Wann Chan, Hian Lim Nanyang Technol Univ Temasek Labs Singapore Singapore Off Natl Etudes & Recherches Aerosp Lannion France Def Sci & Technol Agcy Singapore Singapore

ISBN: (纸本)9780780395824

BoomSAR system is a SAR device embarked in the basket of a boomlift, which provides a cheap and flexible platform to evaluate the performance of radar system and signal processing algorithm, especially for foliage penetration imaging. The common BoomSAR system moves along a straight fine to produce the synthetic aperture effect. This paper introduces a special operation mode of BoomSAR, where the rotation of boomlift arm is adopted to form a curving synthetic aperture trajectory. The experimental results show the feasibility and effectiveness of this special operation mode in application to foliage penetration imaging and the theoretical resolution performance is achieved.

关键词： foliage penetration radar BoomSAR back-projection algorithm

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ABOUT FOURIER TECHNIQUES IN SPOTLIGHT SAR PROCESSING

ABOUT FOURIER TECHNIQUES IN SPOTLIGHT SAR PROCESSING

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1991 INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMP - REMOTE SENSING : GLOBAL MONITORING FOR EARTH MANAGEMENT ( IGARSS 91 )

作者： DENDAL, D Electronic Department of Montefiore Institute of Electricity University of Liège Liege Belgium

ISBN: (纸本)0879426756

A description is given of Fourier reconstruction techniques in the Spotlight synthetic aperture radar (SAR) domain. The particular disposition of the Fourier data in this scanning mode does not make straightforward the fast Fourier processing and raises some fundamental interrogations. Other specific aspects are also treated, such as the consequences of a frequency shift or mixing in the Fourier plane. A Fourier data extrapolation attempt is discussed. Besides the processing descriptions and theoretic discussions, Spotlight scanning properties are emphasized by the many simulation results obtained from the convolution back-projection algorithm, adapted to the Spotlight context in harmony with the tomographic analogy of radar principles.

关键词： FOURIER TECHNIQUES SPOTLIGHT SAR TOMOGRAPHIC FORMULATION back-projection algorithm

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