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Dual-Energy Technique at Low Tube Voltages for Small Animal Imaging

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Tsinghua Science and Technology 2010年第1期15卷 79-86页

作者： CHO Seungryong sidky emil y Department of Radiology University of ChicagoChicagoIL 60637USA

We investigate the feasibility of dual-energy method for image contrast enhancement in small animal studies using a low kV X-ray radiographic system. A robust method for X-ray spectrum estimation from transmission measurements, based on expectation-maximization （EM） method, is applied to an X-ray specimen radiographic system for dual energy imaging of a mouse. From transmission measurements of two known attenuators at two different X-ray tube voltages, the X-ray energy spectra are reconstructed using the EM-based method. From the spectra information thus obtained, the transmission data for bone and soft tissue in terms of vadous thicknesses are generated. Two polynomial functions of transmission data are then sought for to fit the inverted thicknesses of bone and soft-tissue. Scatters in cone-beam projection data acquired at two X-ray energies were corrected. From the scatter-corrected data, a bone thickness map is separated from a soft-tissue thickness map by use of the polynomial functions.

关键词： dual-energy specimen radiography spectrum estimation

Consistency Conditions for Cone-Beam CT Data Acquired with a Straight-Line Source Trajectory

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Tsinghua Science and Technology 2010年第1期15卷 56-61页

作者： LEVINE Margo S sidky emil y Department of Radiology University of Chicago5841 S.Maryland Ave.ChicagoIL 60637USA

A consistency condition is developed for computed tomography （CT） projection data acquired from a straight-line X-ray source trajectory. The condition states that integrals of normalized projection data along detector lines parallel to the X-ray path must be equal. The projection data is required to be untruncated only along the detector lines parallel to the X-ray path, a less restrictive requirement compared to Fourier conditions that necessitate completely untruncated data. The condition is implemented numerically on simple image functions, a discretization error bound is estimated, and detection of motion inconsistencies is demonstrated. The results show that the consistency condition may be used to quantitatively compare the quality of projection data sets obtained from different scans of the same image object.

关键词： data redundancy John's equation consistency conditions

Investigation of Sparse Data Mouse Imaging Using Micro-CT with a Carbon-Nanotube-Based X-ray Source

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Tsinghua Science and Technology 2010年第1期15卷 74-78页

作者： sidky emil y ZHOU Otto Department of Radiology University of Chicago5841 S.Maryland AvenueChicagoIL 60637USA

There has been a renewed interest in algorithm development for image reconstruction from highly incomplete data in computed tomography （CT）. Such algorithms may lead to reduced imaging dose and time, and to the design of innovative configurations tailored to specific imaging tasks. In recent years, a carbon-nanotube （CNT）-based field-emission x-ray source has been developed, which offers easy electronic control of radiation and thus can be an ideal candidate for gated imaging. We have recently proposed algorithms for image reconstruction from fan- and cone-beam data collected at highly sparse angular views through minimization of the total-variation （TV） of the image subject to the condition that the estimated data are consistent with the measured data, In this work, we investigate and demonstrate the application of the TV-minimization algorithm to reconstructing images from mouse data acquired with a CNT-based CT scanner at a number of views much lower than what is used in conventional CT imaging. The results demon- strate that the TV-minimization algorithm can yield images with quality comparable to those obtained from a large number of views by use of the conventional algorithms. The significance of the work may lie in that the substantial reduction of projection views promised by the TV-minimization algorithm can be exploited for reducing imaging dose and time or for improving temporal resolution in tasks such as dynamic imaging.

关键词： computed tomography image reconstruction compressed sensing TV minimization

Boundary reconstruction on chords in cone-beam tomography

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中国体视学与图像分析 2005年第3期10卷 137-140页

作者： Mark A. Anastasio emil y. sidky Chicago IL 60616 USA5841 S. Maryland Avenue Chicago IL 60637 USA

In this work, we demonstrate that the theory of cone-beam tomography image reconstruction on chords can be modified for use with local tomography problems. Our analysis reveals that discontinuities in the profiles of the object function along chords can be reconstructed readily. By consideration of all possible chords, an image that de-scribes the location of boundaries within an object can be reconstructed. A preliminary numerical study is conducted to validate and demonstrate the reconstruction method.

关键词：锥束CT 弦边缘图像图像重建 CT检查

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另一种基于弦的锥束CT图像重建的推导方法

中国体视学与图像分析 2005年第3期10卷 134-136页

作者： emily.sidky 邹宇潘晓川 5841 S. Maryland Avenue Department of Radiology IL 60637 The University of Chicago USA

Recently, we have developed a new formula for cone-beam CT image reconstruction. From the formula, we have also derived three algorithms. Two of the algorithms, which are referred to as the back-projection filtration (BPF) and minimum-data filtered backprojection (MD-FBP) algorithms, can provide volume images from projection data with a minimal scanning arc and minimal irradiation per view angle. The fact that these reconstruction algorithms allow for minimum irradiation per view is unique to the BPF and MD-FBP algorithms. This article explores the mathematical relationship between the projection data and an intermediate back-projection image necessary for obtaining the actual volume image. An alternative proof of the formula and the BPF algorithm are also provided.

关键词：弦锥束CT 图像重建推导方法 CT检查

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双弧源轨迹锥束CT的三维图像重建

中国体视学与图像分析 2005年第3期10卷 129-133页

作者：邹宇潘晓川 emily.sidky Department of Radiology IL 60637 The Uniersity of Chicago 5841 S. Maryland Avenue USA

In this paper, we review the general theory and algorithms that have proposed for image reconstruction from cone-beam data for general trajectories with kinks. The reconstruction algorithms include the backprojection filtration (BPF) algorithm and the minimum-data filteredbackprojection (MD-FBP) algorithm. One of the unique features of these new algorithms is that they can reconstruct exactly images within regions of interest (ROIs) from data containing truncations. In this work, we also apply these algorithms to reconstructing ROI images from truncated data acquired with a trajectory consisting of two pieces of arcs, which is referred to as the arc-arc trajectory. The numerical results in these studies show that exact ROI images can be reconstructed by use of the BPF and MD-FBP algorithms from truncated data acquired with an arc-arc trajectory.

关键词：双弧源轨迹锥束CT 三维图像图像重建 CT检查