多层平板探测的X射线多能成像方法

提出一种使用多层平板探测器获取X射线多能图像的成像方法。分别给出单层、多层平板探测器结构,并介绍多层平板探测成像系统工作原理。阐明X射线成像原理,并通过仿真探究单能射线切换下的双能成像、双能减影原理。进一步分析不同kVp,滤过下X射线源的频谱变化,在kVp切换成像试验中多次曝光采集胸部体模低、中、高三能图像,发现胸模多能图像中肋骨、肺部区域存在差异,且对多能图像双能减影可实现骨骼增强、抑制。类似地仿真探究单次曝光下双能射线在双层平板中双能成像、减影原理。给出射线源在不同滤过下的能谱变化,在多层平板成像试验单次曝光中分别使第一层、第三层平板采集胸部体模低、高能图像。发现多层平板采集的低、高能图像中肋骨、肺部区域亦存在差异,对其双能减影亦可实现骨骼增强、抑制。试验表明使用多层平板探测可实现X射线多能成像。     

射线平板探测器成像系统的数理模型

非晶硅X射线数字平板探测器是目前唯一可取代胶片照相的新型技术,对其成像特性的研究已成为高像质的DR和三维CT检测技术的基础。目前X射线成像系统均是以线性时不变理论作为分析基础的。基于X射线平板探测器成像系统、成像机理和几何参数建立了成像系统的点扩展函数(PSF)。用圆柱体等效二维PSF模型,使成像系统退化为比例系统,从而把复杂的反卷积运算转化成用代数方程来求解,能够快速实现通过探测器输出图像来估计透照工件的二维输入图像。此模型的建立为在实际检测中利用输出的图像通过线性变换得到输入估计。在DR系统中,基于上述数理模型建立了灵敏度模型,利用输出场强可以很好的再现输入场强。     

塑料闪烁光纤阵列成像探测器在高能X射线辐照下的串扰分析

采用蒙特卡罗方法对闪烁光纤阵列探测器在高能X射线入射下的串扰进行了模拟研究,并且分析比较了加铅层对串扰的影响.研究中采用对表征成像系统空间分辨率参量--调制传递函数进行模拟分析和比较,得到在光纤阵列之间加入不同铅层厚度后对系统调制传递函数参量曲线的影响.研究结果表明:在高能射线下,采用闪烁光纤阵列作为成像探测器存在严重...     

光学仪器 X射线、紫外线及其仪器

O434.12006032772基于平板模型的X射线散射特性研究=Scatter law of flatmodel[刊,中]/刘进(中物院流体物理研究所.四川,绵阳(621900)),刘军…∥强激光与粒子束.—2006,18(1).—173-176为了进一步研究高能X光散射的特性,以平板为模型,通过解析方法和蒙特卡罗(MC)数值模拟研究了X光散射的规律。研究结果表明,高能X光的散射以康普顿散射为主,当平板厚度相应的X光光程小于2.0时,平板散射中的一次康普顿散射超过75%;当达到探测器的散射照射量最大时,平板厚度相应的X光光程介于1.0与2.0之间。图3表2参5(严寒)光学仪器 X射线、紫外线及其仪…     

9MeV电子直线加速器X射线测量

 高能工业CT采用9MeV电子加速器产生轫致辐射，利用高能X射线能够有效地穿透物质以及同物质对射线吸收和散射不同这一原理来检查物体内部缺陷或内部结构。加速器电子束的焦点、X射线的最高能量、X射线剂量及均匀性与工业CT成像的质量和速度密切相关；对探测器的电子线路部分进行的X射线屏蔽关系到探测器的使用寿命。X射线测量结果表明，所用9MeV电子直线加速器满足高能工业CT检测的要求。     

GEM探测器与X射线成像实验

使用2个GEM探测器系统,分别用作增益测量和位置分辨测量.用GEM探测器测量铜靶X射线能谱,能量分辨率为21.5%.8keV的X射线入射双层GEM探测器,实验测量x方向位置分辨为64μm,y方向位置分辨为68μm.将科研成果经过精炼、核心提取,为核与粒子物理学科的本科生开设GEM探测器和X射线成像实验,使学生对高能粒子探测技术、数据获取和处理等有整体的理解.     

基于平板模型的X射线散射特性研究

 为了进一步研究高能X光散射的特性，以平板为模型，通过解析方法和蒙特卡罗（MC）数值模拟研究了X光散射的规律。研究结果表明：高能X光的散射以康普顿散射为主，当平板厚度相应的X光光程小于2.0时，平板散射中的一次康普顿散射超过75%；当到达探测器的散射照射量最大时，平板厚度相应的X光光程介于1.0与2.0之间。     

“嫦娥一号”上的科学探测仪器

“嫦娥一号”上搭载了8种24台件科学探测仪器，重130kg，即微波探测仪系统、γ射线谱仪、X射线谱仪、激光高度计、太阳高能粒子探测器、太阳风离子探测器、CCD立体相机、干涉成像光谱仪．     

X射线相衬成像法检测内爆靶参数

理论分析了利用X射线同轴离焦相衬成像法测量金黑腔内塑料中心微球位置的可行性,在此基础上进行了实验研究。实验结果证明,由于低Z低密度材料对高能X射线有相位调制作用,因此仍能够形成一定的图像反差,这种效应并不依赖X射线的能量,因此在一定的尺度范围内,可以实现高Z高密度材料与低Z低密度材料在高能X射线下同时成像,克服了传统吸收成像的不足,最终实现了内爆靶装配参数的精密检测。     

塑料闪烁光纤阵列成像探测器在高能X射线辐照下的串扰分析

采用蒙特卡罗方法对闪烁光纤阵列探测器在高能X射线入射下的串扰进行了模拟研究,并且分析比较了加铅层对串扰的影响.研究中采用对表征成像系统空间分辨率参量——调制传递函数进行模拟分析和比较,得到在光纤阵列之间加入不同铅层厚度后对系统调制传递函数参量曲线的影响.研究结果表明:在高能射线下,采用闪烁光纤阵列作为成像探测器存在严重的次级粒子相互串扰的现象,而在阵列之间加入铅介质能够减少这种效应;但另一方面,若所加铅层太厚又会导致成像探测器像素过大而使得空间分辨率下降.通过模拟计算得出:只要在阵列之间加入适当厚度的铅介质,既可以有效抑止阵列之间次级粒子的串扰,同时又能提高闪烁光纤阵列探测器系统的空间分辨率.     

High‐energy X‐ray diffraction using the Pixium 4700 flat‐panel detector

The Pixium 4700 detector represents a significant step forward in detector technology for high‐energy X‐ray diffraction. The detector design is based on digital flat‐panel technology, combining an amorphous Si panel with a CsI scintillator. The detector has a useful pixel array of 1910 × 2480 pixels with a pixel size of 154 µm × 154 µm, and thus it covers an effective area of 294 mm × 379 mm. Designed for medical imaging, the detector has good efficiency at high X‐ray energies. Furthermore, it is capable of acquiring sequences of images at 7.5 frames per second in full image mode, and up to 60 frames per second in binned region of interest modes. Here, the basic properties of this detector applied to high‐energy X‐ray diffraction are presented. Quantitative comparisons with a widespread high‐energy detector, the MAR345 image plate scanner, are shown. Other properties of the Pixium 4700 detector, including a narrow point‐spread function and distortion‐free image, allows for the acquisition of high‐quality diffraction data at high X‐ray energies. In addition, high frame rates and shutterless operation open new experimental possibilities. Also provided are the necessary data for the correction of images collected using the Pixium 4700 for diffraction purposes.     

射线检测数字实时成像的不一致性研究

在基于PaxScan4030平板探测器技术的射线检测中,输出图像的像质除受系统噪声的影响外,同时还受探测器固有的光电响应不一致性的影响。通过对影响平板探测器输出图像质量的分析,建立了探测器响应不一致性校正模型。在用常规叠加方法去除噪声的同时,利用校正因子对采集图像进行实时校正,以改善系统性能,提高成像质量。通过实验数据分析和对校正前后输出图像的比较,验证了此方法的可行性,从而为射线检测提供了一种有效的校正方法。     

发光玻璃在X射线实时成像系统中的应用

 介绍了以铽(Tb)激活的高密度发光玻璃和光导纤维发光玻璃的特性。它应用在X 射线实时成像系统中,可大大改善空间分辨能力。用它做的转换屏比一般晶粒状荧光物质做的厚得多,特别适合用于高能X射线实时成像系统。     

发光玻璃在X射线实时成像系统中的应用

介绍了以铽（Ｔｂ）激活的高密度发光玻璃和光导纤维发光玻璃的特性。它应用在Ｘ射线实时成像系统中,可大大改善空间分辨能力。用它做的转换屏比一般晶粒状荧光物质做的厚得多,特别适合用于高能Ｘ射线实时成像系统     

A multiplexed high‐resolution imaging spectrometer for resonant inelastic soft X‐ray scattering spectroscopy

The optical design of a two‐dimensional imaging soft X‐ray spectrometer is described. A monochromator will produce a dispersed spectrum in a narrow vertical illuminated stripe (～2 µm wide by ～2 mm tall) on a sample. The spectrometer will use inelastically scattered X‐rays to image the extended field on the sample in the incident photon energy direction (vertical), resolving the incident photon energy. At the same time it will image and disperse the scattered photons in the orthogonal (horizontal) direction, resolving the scattered photon energy. The principal challenge is to design a system that images from the flat‐field illumination of the sample to the flat field of the detector and to achieve sufficiently high spectral resolution. This spectrometer provides a completely parallel resonant inelastic X‐ray scattering measurement at high spectral resolution (～30000) over the energy bandwidth (～5 eV) of a soft X‐ray absorption resonance.     

An estimation of EDXRF spectrometer properties,based on a two‐layer composite Si‐Ge detector

A mathematical model for the two‐layer composite Si‐Ge energy dispersive X‐ray detector is proposed, based on analyses of radiation and electron transport in the detector, and a mathematical model of an energy dispersive X‐ray fluorescent spectrometer with the detector is considered. The Monte Carlo method is applied to calculate probabilities of photon detection in different parts of the detector's response function. The composite detector with the time anti‐coincidence scheme is proposed; its first layer is Si detector, and the second layer is Ge detector. It is shown that this composite detector has some advantages, such as reduced Ge photo escape peaks intensities and efficiency of detection of high energy photons similar to efficiency of Ge detector. Applying the X‐ray detector for the energy dispersive X‐ray fluorescent spectrometer provides for a lower background level. Copyright © 2012 John Wiley & Sons, Ltd.     

A sagittally focusing double‐multilayer monochromator for ultrafast X‐ray imaging applications

The development of a sagittally focusing double‐multilayer monochromator is reported, which produces a spatially extended wide‐bandpass X‐ray beam from an intense synchrotron bending‐magnet source at the Advanced Photon Source, for ultrafast X‐ray radiography and tomography applications. This monochromator consists of two W/B₄C multilayers with a 25 Å period coated on Si single‐crystal substrates. The second multilayer is mounted on a sagittally focusing bender, which can dynamically change the bending radius of the multilayer in order to condense and focus the beam to various points along the beamline. With this new apparatus, it becomes possible to adjust the X‐ray beam size to best match the area detector size and the object size to facilitate more efficient data collection using ultrafast X‐ray radiography and tomography.     

Energy resolution of the CdTe‐XPAD detector: calibration and potential for Laue diffraction measurements on protein crystals

The XPAD3S‐CdTe, a CdTe photon‐counting pixel array detector, has been used to measure the energy and the intensity of the white‐beam diffraction from a lysozyme crystal. A method was developed to calibrate the detector in terms of energy, allowing incident photon energy measurement to high resolution (approximately 140 eV), opening up new possibilities in energy‐resolved X‐ray diffraction. In order to demonstrate this, Laue diffraction experiments were performed on the bending‐magnet beamline METROLOGIE at Synchrotron SOLEIL. The X‐ray energy spectra of diffracted spots were deduced from the indexed Laue patterns collected with an imaging‐plate detector and then measured with both the XPAD3S‐CdTe and the XPAD3S‐Si, a silicon photon‐counting pixel array detector. The predicted and measured energy of selected diffraction spots are in good agreement, demonstrating the reliability of the calibration method. These results open up the way to direct unit‐cell parameter determination and the measurement of high‐quality Laue data even at low resolution. Based on the success of these measurements, potential applications in X‐ray diffraction opened up by this type of technology are discussed.     

X光高分辨探测用CsI(Tl)晶体的蒙特卡罗模拟研究

提出了一种基于CsI(Tl)闪烁晶体和面阵CCD器件、采用光纤和光纤面板进行光耦合及传输、以扇形束线阵扫描方式实现对X光高分辨探测的方案。CsI(Tl)晶体的尺寸大小将直接影响到晶体的发光效率及X光的高分辨探测,据此开展了蒙特卡罗模拟研究。模拟研究了X射线能量、X射线源到探测晶体的距离(源距)、CsI(Tl)晶体的厚度与X射线能量分布、全能峰效率与CsI(Tl)闪烁晶体转换效率之间的关系。结果表明,当X射线能量为120~450 keV,CsI(Tl)晶体尺寸厚度为0~1.5 cm变化时,全能峰效率的变化范围为31.34~96.74%,CsI(Tl)闪烁晶体的转换效率的变化范围为12.8~97.43%。可见,X射线的能量及CsI(Tl)闪烁晶体尺寸的厚度,是决定X光高分辨探测的重要参量,这对优化X光高分辨探测用CsI(Tl)晶体的尺寸设计具有一定的参考价值。     

A curved image‐plate detector system for high‐resolution synchrotron X‐ray diffraction

The developed curved image plate (CIP) is a one‐dimensional detector which simultaneously records high‐resolution X‐ray diffraction (XRD) patterns over a 38.7° 2θ range. In addition, an on‐site reader enables rapid extraction, transfer and storage of X‐ray intensity information in ≤30 s, and further qualifies this detector to study kinetic processes in materials science. The CIP detector can detect and store X‐ray intensity information linearly proportional to the incident photon flux over a dynamical range of about five orders of magnitude. The linearity and uniformity of the CIP detector response is not compromised in the unsaturated regions of the image plate, regardless of saturation in another region. The speed of XRD data acquisition together with excellent resolution afforded by the CIP detector is unique and opens up wide possibilities in materials research accessible through X‐ray diffraction. This article presents details of the basic features, operation and performance of the CIP detector along with some examples of applications, including high‐temperature XRD.