专利

美国纽约州的QEL公司的M.J.Bardash提出一种三维激光成像系统设计方案,它是由超短X射线脉冲发生器产生激光作光源、探测器阵列、信号处理器组成的成像系统。第一次发出平行的X射线光脉冲有预先确定的能谱和通过视场的方向。由很多X射线探测器组成的探测器阵列,每个探测器可定时地探测由目标产生的康普顿散射的X射线脉冲强度。信号处理器处理散射辐射中心位置和能量密度数据。     

用于数字式透视和摄片的硒基平板X射线探测器

我们已经成功地开发出第一块用于数字式透视和摄片的硒基平板X射线探测器，此平板X射线探测器能够有效地捕获通过病人身体的X射线。并直接将它转换成为动态或静态的图像。已经证实，它能获得高对比度和高空间分辨率的图像。用作透视能达到每秒30幅图像的性能，使得它具有探测到早期癌症或脉管狭窄的性能。还有许多其它的优点，包括延伸诊断的能力和减少病人X线曝光剂量。我们还将开发从通常的X射线照相到血管照相的各种类型的探测器。本文论述新近开发成功的平板探测器结构和性能并展望下一代诊断用X射线系统。     

螺旋埋弧焊钢管管端焊缝线扫描DR成像系统的应用

随着全球石油天然气长输管线设计钢级越来越高,输送用钢管管径、壁厚越来越大,对焊接钢管焊缝质量和表观质量要求的不断提高,急需一种新型、高效的检测方法来代替传统的X射线拍片技术。基于探测器阵列的DR直接数字成像技术的新型螺旋焊管管端焊缝无损检测X射线数字成像系统,采用新型线阵探测器,使系统具有较高检测灵敏度和空间分辨率,可以对焊管进行实时动态检测;可以通过软件对检测图像进行正/负片转换、图像放大或缩小、伪彩色增强等一系列变换,便于检测人员对缺陷的识别;检测过程操作简单,缺陷定位准确,提高了检测效率,降低了检测成本,完全可以替代传统胶片法和图像增强器检测法给企业带来了显著的经济和社会效益,具有广阔的推广应用前景。     

X射线平板探测器背板工艺研究进展

从高像素填充因子、低噪声、高帧频、高空间分辨率及柔性五个方面对近些年X射线平板探测器背板工艺的研究进展进行了综述.通过对研究过程中的材料选择、像素结构和读出电路优化的详细阐述,分析了X射线平板探测器背板工艺的研究现状及改善方向.文章同时从新结构、新材料、电路设计及三维探测设计四个方面给出了X射线平板探测背板技术未来的发展趋势.     

X射线探测技术

1 引言X射线探测器是用来接收X射线，并把它转化成为可测量或可观察的量的仪器。所有X射线探测器都是基于X射线和物质相互作用的各种特性制成的。根据测量原理，可把X射线探测器分成三类，即：1）零维探测器，包括各种类型的正比计数器和半导体探测器等；2）二维探测器，包括X射线底片、电荷耦合器件（CCD）、X射线成像板、电子变焦管等；3）三维探测器，目前主要是光刻胶。2 X射线零维探测技术所谓零维探测，是指只能探测X射线光子数或X射线强度的技术。零维探测器包含各种计数器，如正比计数器、盖革计数器、闪烁体及半导体探测器等…     

直接数字X射线摄影技术与平板数字X射线探测器

数字化技术与平板薄膜技术的结合正在改变传统的胶片摄影术，直接数字X射线摄影技术已成为当今信息时代的必然发展趋势。本文简要介绍直接数字X射线摄影技术与关健器件——平板数字X射线探测器的工怍原理和技术进展。     

基于凝视成像探测器的平板调制式微扫描器设计

光学微扫描技术是微扫描亚像元成像系统中的核心技术之一。研究了基于凝视成像探测器的平板调制式微扫描器的原理和设计方法,分析了微扫描平板的误差对亚像元成像的影响,设计了一种基于凝视型面阵CCD探测器的光学平板调制式微扫描器,并实现了与亚像元成像实验系统的联调成像。设计方法不仅适于可见光成像,也适于基于凝视焦平面探测器的亚像元热成像。     

高分辨率实时数字X射线成像系统

1.导言1991年首次开发了实时四百万像素的数字X射线成像系统“DR—2000”。该系统由高分辨率12in X射线图像增强器和一具有2100扫描线的1in SATIOON摄像管的摄像机组成。以前,图像增强数字X射线系统已被广泛用作数字减法系统,其优点是实时的图像获取     

乳房X射线成像的CCD探测器

1.引言本文介绍了一种用于乳房X射线成像的多模块组合式CCD探测器。作力一种实用的医疗设备,用于乳房X射线成像的探测器必须满足一系列性能指标,如:成像面积大(18×24cm)、高DQE、高空间分辨率高、信号输出快、     

新型塑料闪烁体探测器对脉冲X射线响应的研究

射线装置产生的X射线脉冲周期长短不一,很多装置会产生短周期脉冲X射线,特别是医院X射线诊断机等。这些装置的最小脉冲宽度为ns级,能量从几到几百KeV。现有的辐射剂量计无法准确测量这种短周期脉冲X射线。因此,文章研究提出一种新的快速响应和更大探测能量的塑料闪烁体探测器针对医院X射线诊断机的检测需求,并与实际应用情况相结合,在对各种探测器进行性能分析的基础上,选用新型塑料闪烁体探测器进行脉冲X射线响应的研究。经过试验,该研究所设计的新型塑料闪烁体探测器检测系统可以较准确地测量医院X射线诊断机的短周期脉冲X射线。     

Thin-film, flat-panel, composite imagers for projection and tomographic imaging

The recent development of large-area, flat-panel a-Si:H imaging arrays is generally expected to lead to real-time diagnostic and megavoltage X-ray projection imagers with film-cassette-like profiles. While such flat-panel imagers offer numerous advantages over existing fluoroscopic and radiographic imaging devices, the unique properties of the arrays also offer the prospect of detector configurations not previously possible with other real-time technologies. The thin, highly uniform profile of the arrays allows the creation of composite imaging devices in which a flat-panel detector overlies a second imaging detector. A dual-energy (diagnostic and megavoltage) composite imager consisting of a pair of stacked, flat-panel imagers would provide unique information helping to resolve the patient localization and verification problem in megavoltage radiotherapy. In PET or SPECT, attenuation corrections could be obtained by placing a flat-panel array for transmission measurements directly in front of the main emission detector. In this article, the concept of such real-time flat-panel composite imagers is proposed. Specific embodiments of this concept applied toward the resolution of outstanding problems in radiotherapy, PET and SPECT are outlined and calculations and data supporting the feasibility of the concept are presented.     

Design, Performance, and Applications of a Hybrid X-Ray/MR System for Interventional Guidance

Image-guided minimally invasive procedures have made a substantial impact in improving patient management, reducing the cost, morbidity, and mortality of treatments and making therapies available to patients who would otherwise have no option. X-ray fluoroscopy and magnetic resonance imaging (MRI) are two powerful tools for guiding interventional procedures but with very different strengths and weaknesses. X-ray fluoroscopy offers very high spatial and temporal resolution and is excellent for guiding and deploying devices. MRI offers tomographic imaging with complete freedom of plane orientation, outstanding soft tissue discrimination, and the ability to portray physiological responses during treatment. We have shown that it is feasible to fully integrate an X-ray fluoroscopy system into the bore of an interventional MR scanner to provide a single congruent field of view, with integration requiring minor modifications to the flat-panel digital detector, and using a static-anode X-ray tube. Given the limited availability of the MR scanner platform (0.5T GE Signa SP magnet), and the X-ray fluence limitations of the static-anode X-ray tube, we are now investigating the technology developments required to place a rotating-anode digital flat-panel X-ray system immediately adjacent to a closed-bore MRI system. These types of hybrid systems could have enormous impact in the diagnosis and treatment of oncologic, cardiovascular, and other disorders.     

Effect of Oblique X-ray Incidence in Flat-Panel Computed Tomography of the Breast

We quantify the variation in resolution due to anisotropy caused by oblique X-ray incidence in indirect flat-panel detectors for computed tomography breast imaging systems. We consider a geometry and detector type utilized in breast computed tomography (CT) systems currently being developed. Our methods rely on MANTIS, a combined X-ray, electron, and optical Monte Carlo transport open source code. The physics models are the most accurate available in general-purpose Monte Carlo packages in the diagnostic energy range. We consider maximum-obliquity angles of 10deg and 13deg at the centers of the 30 and 40 cm detector edges, respectively, and 16deg at the corner of the detector. Our results indicate that blur is asymmetric and that the resolution properties vary significantly with the angle (or location) of incidence. Our results suggest that the asymmetry can be as high as a factor of 2.6 between orthogonal directions. Anisotropy maps predicted by MANTIS provide an understanding of the effect that such variations have on the imaging system and allow more accurate modeling and optimization of breast CT systems. These maps of anisotropy across the detector could lead to improved reconstruction and help motivate physics-based strategies for computer detection of breast lesions.     

An alternate line erasure and readout (ALER) method for implementing slot-scan imaging technique with a flat-panel detector--initial experiences

This paper describes and demonstrates an electronic collimation method, referred to as the alternate line erasure and readout (ALER) technique, for implementing slot-scan digital radiography technique with an amorphous silicon (a-Si) thin-film transistor (TFT) array based flat-panel detector. An amorphus selenium (a-Se) flat-panel detector was modified to implement the ALER technique for slot-scan imaging. A stepping-motor driven fore-collimator was mounted in front of an X-ray tube to generate a scanning X-ray fan beam. The scanning speed and magnification were adjusted to synchronize the fan beam motion with the image line readout rate. The image lines on the leading and trailing edges of the fan beam were tracked and alternately reset and read out, respectively. The former operation resulted in the erasure of the scatter signals accumulated in the leading edge image line prior to the arrival of the fan beam. The latter operation resulted in the acquisition of fan beam exposure data integrated in the trailing edge image line right after the fan beam passed. To demonstrate the scatter rejection capability of this technique, an anthropomorphic chest phantom was placed in PA position and scanned at a speed of 576 lines (8.0 cm)/s at 117 kVp and 32 mA. A tungsten bar is placed at the entrance side of the chest phantom to measure the scatter-to-primary ratio (SPR), scatter reduction factor (SRF), and contrast-to-noise ratio degradation factor (CNRDF) in the slot-scan images to evaluate the effectiveness of scatter rejection and the resultant improvement of image quality. SPR and CNRDF in the open-field images were also measured and used as the reference for comparison. A scatter reduction by 86.4 to 95.4% across lower lung and heart regions has been observed with slot-scan imaging. The CNRs have been found to be improved by a factor of 2 in the mediastinum areas over the open-field image as well.     

A graphical method for determining the in-plane rotation angle in geometric calibration of circular cone-beam CT systems

It is well known that seven parameters completely describe a circular cone-beam geometry in either flat-panel X-ray computed tomography (CT) or single pinhole SPECT imaging. This paper considers the problem of determining one of the seven parameters only, the detector in-plane rotation or twist angle η. We describe a graphical procedure that can determine η independently of all other six parameters from a geometric calibration scan of point objects. Our method is exact in the ideal noise-free case and is general in that the other two out-of-plane detector rotation angles θ and φ can be nonzero. The calibration scan typically needs at least two point objects and an even number of projection views over a full 360° data acquisition. Under certain conditions, projection data truncation or a short scan acquisition of 180° + fan angle can be accommodated without affecting the accuracy of the calibration result. The graphical method is equally applicable to rotational multipinhole SPECT geometry. In this case, the final result is averaged from the individual estimates considering each pinhole separately. We use computer simulations and a multipinhole SPECT experiment to demonstrate the accuracy and precision of the proposed method.     

星载红外探测器快速反射镜控制系统设计

像移补偿是保证星载红外探测器成像质量的关键技术之一,针对某星载红外探测器光学系统的设计特点和成像工作模式,为补偿红外探测器在轨运行方向产生的像移和摆扫方向产生的像移,提出分别对俯仰方向快速反射镜和方位方向快速反射镜实施控制的方案。首先介绍红外遥感原理及像移现象;其次详细分析红外探测器光学系统的设计特点和光学系统组成;然后重点分析了红外探测器在轨工作中的像移产生的原因,并计算出在轨运行方向产生的像移量和摆扫方向产生的像移量;最后提出像移补偿方案,阐明其工作原理,并对像移控制系统硬件设计进行了详细分析。计算结果表明所设计的像移补偿系统的运动范围和运动加速度满足红外探测器技术指标的要求。     

Direct-conversion flat-panel X-ray image sensors for digitalradiography

Advances in active-matrix array flat panels for displays over the last decade have led to the development of flat-panel X-ray image detectors. Recent flat-panel detectors have shown image quality exceeding that of X-ray film/screen cassettes. They can also permit the instantaneous capture, readout, and display of digital X-ray images and, hence, enable the clinical transition to digital radiography. There are two general approaches to flat panel detector technology: 1) direct and 2) indirect conversion. The present paper outlines the operating principles for direct-conversion detectors based on the use of photoconductors. It formulates and reviews the required X-ray photoconductor properties for such applications and examines to what extent potential materials fulfill these requirements. The quantum efficiency, X-ray sensitivity, noise, and detective quantum efficiency factors are discussed with reference to current and potential large area X-ray photoconductors     

采用CMOS太赫兹波探测器的成像系统

太赫兹波成像技术在生物医疗和安全检测等领域具有广阔的应用前景。针对新一代信息技术对便携式太赫兹波成像设备的需求，设计了基于CMOS太赫兹波探测器的成像系统。该系统包括一款CMOS太赫兹波探测器、片外模数转换器（ADC）、FPGA数字信号处理器、二位步进机、四个抛物面镜和太赫兹波辐射源等。CMOS太赫兹波探测器集成了片上贴片天线以及作为检波元件的NMOS晶体管，探测器由180 nm标准CMOS工艺制成。太赫兹波探测器的输出被片外模数转换器（ADC）采集并转换为数字信号，该数字信号被FPGA采集并传输到电脑上成像。所有上述元件均被装备在印刷线路板（PCB）上以减小系统体积。该系统实现了透射式太赫兹波扫描成像而无需斩波-锁相技术，并给出在860 GHz的太赫兹波照射下隐藏在信封内部金属的成像结果。     

圆周阵列太赫兹干涉成像仿真

太赫兹干涉成像原理简单,需要的探测单元少,数据获取效率高,在太赫兹成像应用中有很大发展潜力。研究了太赫兹干涉成像的原理,并设计了用于仿真成像的原理性方案。通过仿真实验分析了成像频率、圆周阵列半径、阵元数目对成像质量的影响以及成像系统的频率带宽。结果表明:在其他条件不变的情况下,成像频率越高,可有效成像要求的阵列半径越小;增加阵元数目可提高成像质量,但增加到一定数量后,提高不明显;均匀圆形阵列的有效成像带宽较宽。仿真结果所得到的结论为太赫兹干涉成像系统设计和实际应用提供了理论依据和技术支持。