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. T...
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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.
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-dim...
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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.
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 detect...
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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.
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-projec...
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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%.
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-...
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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.
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 th...
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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.
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 pen...
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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.
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 th...
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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.
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