Volume 21, Issue 2

This paper describes a statistical image reconstruction method for X-ray computed tomography (CT) that is based on a physical model that accounts for the polyenergetic X-ray source spectrum and the measurement nonlinearities caused by energy-dependent attenuation. We assume that the object consists of a given number of nonoverlapping materials, such as soft tissue and bone. The attenuation coefficient of each voxel is the product of its unknown density and a known energy-dependent mass attenuation coefficient. We formulate a penalized-likelihood function for this polyenergetic model and develop an ordered-subsets iterative algorithm for estimating the unknown densities in each voxel. The algorithm monotonically decreases the cost function at each iteration when one subset is used. Applying this method to simulated X-ray CT measurements of objects containing both bone and soft tissue yields images with significantly reduced beam hardening artifacts.

本文描述了一种针对X射线计算机断层扫描（CT）的统计图像重建方法，该方法基于物理模型，考虑了多能X射线源光谱以及由能量依赖衰减引起的测量非线性。我们假设物体由给定数量的非重叠材料组成，例如软组织和骨骼。每个体素的衰减系数是其未知密度与已知能量依赖质量衰减系数的乘积。我们为此多能模型制定了惩罚似然函数，并开发了一种有序子集迭代算法来估计每个体素中的未知密度。当使用一个子集时，该算法在每次迭代中单调地降低成本函数。将此方法应用于包含骨骼和软组织的物体的模拟X射线CT测量，生成的图像显著减少了射束硬化伪影。

The extraction of the centerlines of tubular objects in two and three-dimensional images is a part of many clinical image analysis tasks. One common approach to tubular object centerline extraction is based on intensity ridge traversal. In this paper, we evaluate the effects of initialization, noise, and singularities on intensity ridge traversal and present multiscale heuristics and optimal-scale...

在二维和三维图像中提取管状物体的中心线是许多临床图像分析任务的一部分。一种常用的管状物体中心线提取方法基于强度脊线追踪。本文评估了初始化、噪声和奇异性对强度脊线追踪的影响，并提出了多尺度启发式和最优尺度...

A fully automatic method is presented to detect abnormalities in frontal chest radiographs which are aggregated into an overall abnormality score. The method is aimed at finding abnormal signs of a diffuse textural nature, such as they are encountered in mass chest screening against tuberculosis (TB). The scheme starts with automatic segmentation of the lung fields, using active shape models. The ...

提出了一种全自动方法，用于检测正面胸部X光片中的异常，并将这些异常汇总成整体异常评分。该方法旨在发现弥漫性纹理性质的异常迹象，例如在针对结核病（TB）的大规模胸部筛查中遇到的异常。该方案首先使用主动形状模型自动分割肺野。...

Tomographic image reconstruction using statistical methods can provide more accurate system modeling, statistical models, and physical constraints than the conventional filtered backprojection (FBP) method. Because of the ill posedness of the reconstruction problem, a roughness penalty is often imposed on the solution to control noise. To avoid smoothing of edges, which are important image attribu...

使用统计方法的断层图像重建可以提供比传统滤波反投影（FBP）方法更准确的系统建模、统计模型和物理约束。由于重建问题的不适定性，通常对解施加粗糙度惩罚以控制噪声。为了避免对重要的图像属性——边缘进行平滑，

We present a new method to automatically compute, reorient, and recenter the mid-sagittal plane in anatomical and functional three-dimensional (3-D) brain images. This iterative approach is composed of two steps. At first, given an initial guess of the mid-sagittal plane (generally, the central plane of the image grid), the computation of local similarity measures between the two sides of the head...

我们提出了一种新方法，用于自动计算、重定向和重新居中解剖和功能三维脑图像中的中矢状面。这种迭代方法由两步组成。首先，给定中矢状面的初始猜测（通常是图像网格的中心平面），计算头部两侧之间的局部相似性度量...

Reconstructing an accurate and topologically correct representation of the cortical surface of the brain is an important objective in various neuroscience applications. Most cortical surface reconstruction methods either ignore topology or correct it using manual editing or methods that lead to inaccurate reconstructions. Shattuck and Leahy (1999, 2000) recently reported a fully automatic method t...

在各种神经科学应用中，重建准确且拓扑正确的脑皮层表面是一个重要目标。大多数皮层表面重建方法要么忽略拓扑，要么使用手动编辑或导致重建不准确的方法进行校正。Shattuck和Leahy（1999, 2000）最近报告了一种全自动方法，用于...

A multiple circular path convolution neural network (MCPCNN) architecture specifically designed for the analysis of tumor and tumor-like structures has been constructed. We first divided each suspected tumor area into sectors and computed the defined mass features for each sector independently. These sector features were used on the input layer and were coordinated by convolution kernels of differ...

构建了一种专门用于分析和肿瘤及肿瘤样结构的多圆路径卷积神经网络（MCPCNN）架构。我们首先将每个疑似肿瘤区域划分为扇区，并独立计算每个扇区定义的肿块特征。这些扇区特征用于输入层，并通过不同卷积核进行协调...

In this paper, we propose an interpolation algorithm using a mathematical morphology morphing approach. The aim of this algorithm is to reconstruct the n-dimensional object from a group of (n-1)-dimensional sets representing sections of that object. The morphing transformation modifies pairs of consecutive sets such that they approach in shape and size. The interpolated set is achieved when the tw...

本文提出了一种基于数学形态学变形方法的插值算法。该算法的目标是从一组表示物体切面的(n-1)维集合中重建n维物体。变形变换修改连续集合对，使其在形状和大小上接近。当两个...

Cross-entropy (CE), an information-theoretic measure, quantifies the difference between two probability density functions. This measure is applied to volume image registration. When a good prior estimation of the joint distribution of the voxel values of two images in registration is available, the CE can be minimized to find an optimal registration. If such a prior estimation is not available, on...

交叉熵(CE)是一种信息论度量，用于量化两个概率密度函数之间的差异。该度量被应用于体积图像配准。当配准中两幅图像体素值的联合分布有良好的先验估计时，可以最小化交叉熵以找到最优配准。如果没有这样的先验估计，则...

Finite difference time domain (FDTD) analysis has been successfully formulated for solving diffusion equation in biological tissues. Time-dependent diffusion equations are approximated by FDTD equations by assigning diffuse photon fluence rates and radiant flux defined in the diffusion equations to Yee meshes. At the boundary between scattering and no scattering material, FDTD equation including o...

时域有限差分(FDTD)分析已成功应用于求解生物组织中的扩散方程。通过将扩散方程中定义的漫射光子通量率和辐射通量分配到Yee网格，用FDTD方程近似时间相关扩散方程。在散射和非散射材料之间的边界处，包含...的FDTD方程

We present a novel backprojection algorithm for three-dimensional (3-D) Radon transform data that requires O(N/sup 3/ log/sub 2/ N) operations for reconstruction of an N/spl times/N/spl times/N volume from O(N/sup 2/) plane-integral projections. Our algorithm uses a hierarchical decomposition of the 3-D Radon transform to recursively decompose the backprojection operation. Simulations are presente...

我们提出了一种新颖的三维Radon变换反投影算法，该算法从O(N^2)个平面积分投影重建N×N×N体积，仅需O(N^3 log_2 N)次运算。我们的算法利用三维Radon变换的层次分解，递归地分解反投影操作。仿真结果展示了...