Lamb波CT成像的实验研究

根据Ｘ射线ＣＴ成像原理和方法，利用Ｌａｍｂ波对薄层铝板的人工伤进行了ＣＴ成像的实验研究，得到较好的成像结果。     

螺旋CT泌尿系统成像的扫描技术探讨及临床应用

本文阐述了应用螺旋ＣＴ成像技术于泌尿器官的研究，包括贤脏，膀胱，输尿道等。结果表明这种新技术对于精确诊断这些器官的病变能提供可靠的影像数据而不会对病人产生创伤。     

数字图像的基础特性

７０年代初，随着计算机和微电子技术的飞速发展，一大批全新的成像技术进入医学领域。如ＣＴ、ＤＳＡ、ＭＲＩ、ＣＲ、ＤＲ、ＥＣＴ、核素和超声等。这些数字成像技术，不仅极大地丰富了形态诊断信息领域和图像层次，提高了形态学的诊断水平，同时实现了诊断信息的数字化。图像信息的数字化，不仅在医学领域，而且在大众的生活摄影中均成为当今的发展趋势和需要。因为只有数字化，才能进行图像的各种后处理、贮存和传输。为适应科技发展的需要，做为从事医学影像的技术工作者或摄影爱好者来讲，学习、普及和掌握数字图像的基础知识是非常必…     

电容成像技术及其应用

过程成像技术是近十多年来发展起来的一种新型过程检测技术，可以广泛应用于石油、化工、电力及冶金等行业中的两相流测量。本文结合清华大学自动化系过程成像小组研制的电容成像系统，介绍了电容成像技术的发展和现状，包括电容成像基本原理、微电容测量电路和图像重建算法等。论文给出了现有系统在小型流化床模拟装置上进行测量和连续图像重建的实验结果，并进行了分析。此外，论义对电容成像技术今后的发展作出了展望。     

脑部螺旋CT血管造影的技术探讨和临床应用

５１例病人均采用ＰＩＣＫＥＲ６０００ＣＴ常规轴位及注射对比剂延时增强,并螺旋ＣＴＡ原始图像数据采集,病人分Ａ、Ｂ、Ｃ三组进行研究,表明脑部ＳＣＴＡ采用层厚３ｍｍ,层距３ｍｍ,加薄ＩＮＤＥＸ１．５ｍｍ,ＭＩＰ重建,图像质量均达到１级,大脑中动脉可显示至４级,认为脑部ＣＴＡ扫描参数及造影时间的选择很重要,它是一种无创伤性检查方法,值得推广应用。     

三维磁场的快速测量

本文介绍采用ＣＴ技术重建三维磁场图像的圆扫描数据采集方法。与线性扫描方式相比较，提高了数据采集速度。通过对一对Ａ１ＮｉＣｏ５圆柱体任一断面上磁场的测量与成像，表明该系统具有成像速度快、清晰精确等优点。     

卫星层析扫描(CT)遥感大气的通道优化

从ＨＩＴＲＡＮ光谱数据库中以７条具有良好空间分布权孙数，适合于卫星ＣＴ反演大气温度的通道，采用特征值方法，分析了各通这独立性，讨论了扫描角度对ＣＴ反演大气温度廓线权函数的影响。     

X射线同轴相衬成像实验

X射线相衬成像技术对软组织成像时比基于衰减的传统X射线成像技术优势明显,现在亟待发展一套广泛适用的相衬成像理论来指导其发展和临床应用．首先介绍了同轴相衬成像及相位成像的原理,随后根据菲涅耳．基尔霍夫衍射理论,利用数值模拟的方法研究微焦点源的尺寸对图像可见度的影响,最后在数值模拟结果指导下通过实验室直径为50μm的微焦点源X射线成像系统获得了厚度为150μm左右塑料气泡膜的相衬图像．     

SRS 3D家庭音效处理器

ＳＲＳ３Ｄ家庭音效处理器田卫ＳＲＳ３Ｄ系统原理本文向大家介绍一款新颖的ＳＵＰＥＲＨＳＥＰ－Ａ型ＳＲＳ３Ｄ家庭音效处理器。ＨＳＥＰ是英文ＨＯＭＥＳＯＵＮＤＥＦＴＴＥＣＴＰＲＯＣＥＳＳＯＲ（家庭音效处理器）的缩写。ＨＳＥＰ具有系统成本低、环绕效果明显、功...     

调音台操作术语英汉对照（三）

调音台操作术语英汉对照（三）冯杰ＳＩＧＮＡＬＰＲＯＣＥＳＳＯＲ：信号处理器ＥＱＵＡＬＩＺＥＲ：均衡器ＳＵＭ：总输出编组开关ＬＯＷＣＵＴ：低频切除开关ＨＩＧＨＣＵＴ：高频切除开关ＰＨＯＮＯＩＮＰＵＴ：唱机输入ＳＴＥＲＥＯＯＵＴ：立体声输出ＡＣＴＩＶＩＴ...     

超声反射CT在水下物体成像中的应用

本文重点介绍了沿平面扫描成像，提出了修正扫描起始点位置以及换能器孔径影响的一种方法，得到较好的实验结果。     

超声弹性显微镜成像系统开发与应用的初步研究

传统的超声弹性成像技术一般使用1MHz～10MHz的超声波,这一频段超声波的空间分辨率在毫米量级,它不能满足对生物组织中微细结构(如皮肤层,关节软骨等)的研究。文中介绍一套新开发的超声弹性显微镜成像系统,并将其初步应用于对关节软骨和老鼠表皮的成像研究中。该系统由加压系统和背向散射超声显微镜系统两部分组成,其中超声探头频率为50MHz。通过对关节软骨和老鼠表皮的成像实验表明,该系统可以清晰的对生物组织中微细结构成像,研究它们的机械特性。     

Theoretical analysis of three-dimensional imaging and recognition of micro-organisms with a single-exposure on-line holographic microscope

Single-exposure on-line (SEOL) digital holography is a recently proposed technique for monitoring, visualization, and recognition of three-dimensional (3D) objects. In contrast to traditional multi-exposure on-line digital holography, it uses only one exposure, which makes it particularly suitable for imaging and recognizing moving micro-organisms. However, the cost of using only one exposure is the superposition of a conjugate image on the desired reconstructed image. The influence of the conjugate image on the visualization and recognition performance is investigated. The conditions for which the cross-talk noise induced by the conjugate image is negligible are derived. It is demonstrated that with conditions common in imaging of microscopic 3D biological objects, SEOL digital holography is highly tolerant of cross-talk noise induced by the conjugate image.     

Application of Scanning Electron-Acoustic Microscopy to Biological Materials

The imaging methods and results for biological materials by scanning electron acoustic microscopy (SEAM) have been introduced in this paper. The images of the amplitude and phase of a plant leaf by SEAM show that the amplitude image involves more surface features but the phase image displays more subsurface structures. The laminated imaging experiments, which use the x- and y-components of SEAM signals with different reference phases, show the subsurface structures in different depths of biological materials, such as, plant leafs, biological tissues, etc. Using a photothermal technique, the thermal diffusion lengths of the samples of biological materials can be evaluated, by which the depths of the subsurface structures in the laminated images can be estimated. In addition, the damage areas of the leaf and muscles are also imaged by SEAM. For comparison, the second electron images of the same areas of the samples studied by SEAM are also obtained. The images show that SEAM is sensitive to micro-structures of surface, and also subsurface, structures of biological materials.     

Digital holographic microscopy with dual-wavelength phase unwrapping

We apply the techniques of digital holography to obtain microscopic three-dimensional images of biological cells. The optical system is capable of microscopic holography with diffraction-limited resolution by projecting a magnified image of a microscopic hologram plane onto a CCD plane. Two-wavelength phase-imaging digital holography is applied to produce unwrapped phase images of biological cells. The method of three-wavelength phase imaging is proposed to extend the axial range and reduce the effect of phase noise. These results demonstrate the effectiveness of digital holography in high-resolution biological microscopy.     

X-ray phase-contrast imaging: transmission functions separable in Cartesian coordinates

In-line, x-ray phase-contrast imaging is responsive to both phase changes and absorption as the x radiation traverses a body. Expressions are derived for phase-contrast imaging of objects having transmission functions separable in Cartesian coordinates. Starting from the Fresnel-Kirchhoff integral formula for image formation, an expression is found for the phase-contrast image produced by an x-ray source with nonvanishing dimensions. This expression is evaluated in limiting cases where the source-to-object distance is large, where the source acts as a point source, and where the weak phase approximation is valid. The integral expression for the image is evaluated for objects with simple geometrical shapes, showing the influence of the source dimensions on the visibility of phase-contrast features. The expressions derived here are evaluated for cases where the magnification is substantially greater than one as would be employed in biological imaging. Experiments are reported using the in-line phase-contrast imaging method with a microfocus x-ray source and a CCD camera.     

Mathematical model of fluorescence endoscopic image formation

We present a mathematical model that describes the spatial distribution of photons in fluorescence endoscopic images, resulting in expressions for image signal-to-noise ratio and resolution. This model was applied to quantitative analysis of fluorescence images collected from human colonic mucosa with a fiber-optic and an electronic endoscope. It provides a tool for the design of fluorescence endoscopic imaging systems and for extraction of quantitative information about image features. The results apply generally to endoscopic imaging of remote structures in biological and industrial settings, in which light of weak intensity such as fluorescence as well as reflected white light is used.     

Magnetoacoustic imaging of human liver tumor with magnetic induction

Magnetoacoustic tomography with magnetic induction (MAT-MI) is an imaging technique under development to achieve imaging of electrical impedance contrast in biological tissues with spatial resolution close to ultrasound imaging. However, previously reported MAT-MI experimental results are obtained either from low salinity gel phantoms, or from normal animal tissue samples. In this study, we report the experimental study on the performance of the MAT-MI imaging method for imaging in vitro human liver tumor tissue. The present promising experimental results suggest the feasibility of MAT-MI to image electrical impedance contrast between the cancerous tissue and its surrounding normal tissues.     

Indirect Susceptibility Mapping of Thin-Layer Samples Using Nuclear Magnetic Resonance Imaging

We measured and imaged magnetic field distributions of thin layers (2-D objects with negligible thickness) of biological and physical samples, by using nuclear magnetic resonance (NMR). The image represents the magnetic susceptibility distribution in the sample. We used a standard gradient echo imaging method, susceptible to magnetic field homogeneity, for detection. Since the physical and biological samples we investigated do not generate any NMR signal, we used a homogeneous phantom reference - a container filled with water - as a medium. The image acquired by this method is actually a projection of the sample properties onto the homogeneous phantom. The method can be applied in nanotechnology, microelectronics, and especially in the biological and medical sciences.     

生物声学成像中声速不均匀性解决方法的研究进展

对于以超声波为载体的生物医学声学成像(如超声、光声和磁声成像等)技术,为了简化问题,常在假设待测组织内声速恒定的前提下,重建组织内的声阻抗、光吸收分布、光学特性参数分布或者电导率分布等。但是,实际生物组织内部的声速是存在差异的(最大可达10%),因而在此假设前提下重建出的图像通常是不准确的。在介绍声速不均匀性对声学图像重建影响的基础上,对超声、光声和磁声成像中解决声速不均匀问题的主要方法,特别是光声层析成像中重建组织内声速分布的主要方法进行总结和归纳,讨论各自的优点和不足,并展望未来的可能发展方向。