Variable tomographic scanning with wavelength scanning digital interference holography

We present a new method for variable tomographic scanning based on the wavelength scanning digital interference holography (WSDIH). A series of holograms are generated with a range of scanned wavelengths. The object field is reconstructed in a number of selected tilted planes from each hologram, and the numerical superposition of all the tilted object fields results in a variable tomographic scanning. The scanning direction can be arbitrary angles in 3D space but not limited in a 2D plane, thus the proposed algorithm offers more flexibility for acquiring and observing randomly orientated features of a specimen in a WSDIH system. Experiments are performed to demonstrate the effectiveness of the method.     

Three-dimensional tomographic reconstruction of unstable ejection phenomena of droplets for electrohydrodynamic jet

The electrohydrodynamic (EHD) jet is becoming increasingly popular within industrial printing areas based on phenomena induced by electrical potentials. Regardless of the physical observations of unstable ejection phenomena in regions possessing high electric potential, quantitative visualization is still necessary; no report exists exemplifying quantitative visualization. Thus, the size, shape and position of EHD droplets were reconstructed in this study using developed three-dimensional tomography methods. Two computer-synthesized phantoms for the liquid meniscus containing small satellite droplets were generated according to actual images captured by two high-speed cameras. These droplets were made in order to numerically reconstruct droplet behavior. Four three-dimensional tomography methods, such as the algebraic reconstruction technique (ART), the adaptive algebraic reconstruction technique (AART), the simultaneous iterative reconstruction technique (SIRT) and the multiplicative algebraic reconstruction technique (MART), were developed to accurately mimic droplet movement using multiple image views. Four basis functions including the cubic B-spline, cosine, o-Moms and Keys basis functions were adopted in order to improve the performance of the tomographic reconstructions. After completing a comparison of the four tomography results, the MART method in association with the cubic cosine basis function was selected as the means to significantly improve reconstruction accuracy. Additionally, it was the applied method for the reconstruction of the droplet behavior from experimental projections by two cameras.     

颈部低剂量 CT 检查实验及临床应用

目的评价山羊及人体颈部多层螺旋CT的辐射剂量和图像质量,探寻颈部多层螺旋CT的最佳低剂量扫描条件。方法通过 CT机的辐射剂量预测软件并结合文献,选取10组低剂量扫描条件（140kV-50mA、140kV-30mA、120kV-100mA、120kV-50mA、120kV-30mA、90kV-200mA、90kV-150mA、90kV-100mA、90kV-50mA、90kV-30mA）。扫描3只山羊的颈部,采用双盲法对CT图像质量（骨质）进行评分,筛选满足诊断要求的扫描条件。另将180例颈椎CT检查的患者随机分成9组,每组20例,用动物实验筛选出的条件进行扫描,对软组织和骨质CT图像质量进行评分。结果 CT辐射剂量与管电压、管电流变化呈线性正相关;CT辐射剂量变化的斜率随管电压或管电流的增大而增大。除90kV-30mA以外,其他9组扫描条件的骨质图像均能满足诊断要求。人体检查时扫描剂量高者图像质量评分高,各组图像的骨质评分均高于软组织评分。120kV-100mA、90kV-200mA组软组织图像质量良好、骨质图像质量优;140kV-50mA、140kV-30mA、120kV-50mA、90kV-150mA、90kV-100mA组软组织图像基本不影响诊断,骨质图像质量良好;120kV-30mA、90kV-50mA组软组织图像影响诊断,骨质图像基本不影响诊断。结论采用低管电压、相对略高的管电流,能获得满足诊断要求的图像,且辐射剂量更低。颈部CT检查时,满足诊断要求的软组织扫描条件为90kV-100mA,若仅需观察颈部的骨质情况,可选用更低的扫描条件90kV-50mA。     

CT对腹部创伤的临床诊断价值分析

目的 探讨多层螺旋CT 在腹部创伤诊断中的临床价值。方法 对132 例腹部创伤患者的临床资料进行回顾性分析,所有患者入院后均行CT 和彩色超声检查,以手术诊断结果为金标准对检查结果进行分析。结果 CT 检查对腹部创伤诊断的灵敏度、特异度和准确率分别为93.67%、97.06%、94.69%;彩色超声检查对腹部创伤诊断的灵敏度、特异度和准确率分别为86.96%、86.36% 和86.73%;两种检查灵敏度、特异度和准确率比较差异均有统计学意义（均P＜0.05）。结论 CT 对腹部创伤诊断的准确率、灵敏度及特异度都较高,可作为腹部创伤后对实质脏器损伤情况评价的重要影像学检查方法。     

Synthetic approaches towards [18F]fluoro-DOG1, a potential radiotracer for the imaging of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) can currently only be identified by invasive biopsy sampling followed by immunohistochemical analysis. It would however be highly advantageous to have a radioligand able to bind the calcium-activated chloride channel DOG1, which is specific for GIST, and thus enable the sensitive, non-invasive and specific functional imaging of the disease by Positron Emission Tomography (PET). For this purpose, we developed different synthetic strategies towards a 4-phenylthiazole-2-amine-based labeling precursor that can be directly reacted with ¹⁸F-fluoride to yield a radiotracer intended to bind DOG1. Of these, a boronic acid pinacol ester radiolabeling precursor could be efficiently reacted with ¹⁸F in a one-step reaction, and the target radioligand [¹⁸F]fluoro-DOG1 be obtained in radiochemical yields of 34.0?±?11.1% within 85?min overall synthesis time.     

STATIC REGIME IMAGING OF LOCATIONS OF CERTAIN 3D ELECTROMAGNETIC IMPERFECTIONS FROM A BOUNDARY PERTURBATION FORMULA

We are concerned, in a static regime, with a three-dimensional bounded domain of certain an imaging approach of the locations in electromagnetic imperfections. This approach is related to Electrical Impedance Tomography and makes use of a new perturbation formula in the electric fields. We present two localization procedures, from a Current Pro- jection method that deals with the single imperfection context and an inverse Fourier process that is devoted to multiple imperfections configurations. These procedures extend those that were described in our previous work, since operating for a broader class of settings. Namely, the localization is additionally performed for certain purely electric imperfections, as established from numerical simulations.     

Polygonal estimation of planar convex-set perimeter from its two projections

This paper deals with the problem of extracting qualitative and quantitative information from few tomographic projections of an object without reconstructing this object. It focuses on the extraction of quantitative information, precisely the border perimeter estimation for a convex set from horizontal and vertical projections. In the case of a multiple reconstruction, lower and upper bounds for the perimeter are established. In the case of a unique reconstruction, we give conditions and a method for constructing an inscribed polygon in a convex set only from the convex-set projections. An inequality on border perimeter is proved when a convex set is included in another one. The convergence of the polygon perimeter, when the number of vertices increases, is established for such polygons.     

利用网络理论进行电阻抗层析成像中的多分辨率技术

首先讨论利用网络理论进行电阻抗层析成像的基本原理，并给出了节点导纳知阵所应服从的两个基本约束．为了加速和改进算法，提出了多分辨率的算法．按照这一算法，首先将被测物体离散化为较大的单元，先在粗分辨率下进行求解，利用所得的结果作为估计的初值，再进行下一级较细分辨求解．计算机模拟结果表明，利用多分辨率技术可以加快收敛，减小误差．     

Spatial and temporal resolution in cryo-electron microscopy—A scope for nano-chemistry

Cryo-electron microscopy has evolved in an established approach to study the structure of bio-colloids. Recent developments in instrumentation and automation, often demanded by life sciences, made cryo-EM a general tool in colloid chemistry. Recently improved instrumentation for vitrification has resulted in reliable and reproducible preparation of specimen in water and other solvents. A dynamic approach, following processes in time is gaining importance and a time resolution up to 1 ms is expected to become general available. With improved instrumentation and automation 3D reconstructions by cryo-EM tomography are becoming routinely accessible. Tomography as such or in conjunction with time resolved microscopy is expected to give new insights in (macro)molecular assembly/disassembly mechanisms and thus become an essential tool in nano-chemistry.     

Optical tomography of the laser's Gaussian electric field

A method for the measurement of the spatial distribution of birefringence, caused by intense femtosecond laser pulses in condensed plasma, is presented for the case of a Gaussian laser beam. For that only two light intensities are to be measured on the probe beam in a polariscope.