Volume 19, Issue 9

Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (<1%), and excellent linearity (/spl sim/1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-1p/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.

最近开发的大面积平板探测器（FPD）的初步评估表明，FPD具有一些潜在优势：紧凑性、无几何失真和光晕，同时具有高分辨率、高探测量子效率（DQE）、高帧率、高动态范围、小图像滞后（<1%）和优异的线性度（/spl sim/1%）。新型FPD的这些优势使其成为锥束容积计算机断层扫描（CT）血管成像（CBVCTA）的有前景候选。本研究旨在表征一种用于CBVCTA应用的原型FPD成像系统。围绕改进的GE 8800 CT扫描仪设计和构建了一种基于FPD的原型CBVCTA成像系统。使用四个体模和一只冷冻大鼠对该系统在头颈部CBVCTA成像任务中进行评估。首先根据探测器的线性度和动态范围进行表征。然后确定CBVCTA的最佳千伏峰值选择，并评估图像滞后和散射对CBVCTA系统图像质量的影响。接下来测量低对比度分辨率和高对比度空间分辨率。最后展示冷冻大鼠的重建图像示例。结果表明，基于FPD的CBVCT可以在0%调制传递函数（MTF）下达到2.75线对/毫米的空间分辨率，并在临床可接受的入射暴露水平下为头颈部静脉内CBVCTA成像提供足够高的低对比度分辨率。结果还提示，将FPD用于大锥角应用（如体部血管成像）需要进一步研究。

This paper presents the adaptive axial interpolator (AAI), a novel spiral interpolation approach for multislice spiral computed tomography (CT) implemented in a clinical multislice CT scanner, the SOMATOM Volume Zoom (Siemens Medical Systems, Forchheim, Germany). The method works on parallel-beam data generated from the acquired fan-beam data by azimuthal rebinning. Spiral interpolation is perform...

本文介绍了自适应轴向插值器（AAI），这是一种用于多层螺旋计算机断层扫描（CT）的新型螺旋插值方法，已在临床多层螺旋CT扫描仪SOMATOM Volume Zoom（西门子医疗系统，德国福希海姆）中实现。该方法通过对采集的扇形束数据进行方位角重排，生成平行束数据。螺旋插值执行...

The new spiral multislice computed tomography (CT) scanners and the significant increase in rotation speed offer great potential for cardiac imaging with X-ray CT. The authors have therefore developed the dedicated cardiac reconstruction algorithms 180/spl deg/ multislice cardio interpolation (MCI) and 180/spl deg/ multislice cardio delta (MCD) and here offer further details and validation. The al...

新型螺旋多层计算机断层扫描（CT）扫描仪以及旋转速度的显著提高为X射线CT心脏成像提供了巨大潜力。因此，作者开发了专门的心脏重建算法180°多层心脏插值（MCI）和180°多层心脏delta（MCD），并在此提供进一步的细节和验证。该算...

A new class of acquisition schemes for helical cone-beam computed tomography (CB-CT) scanning is introduced, and their effect on the reconstruction methods is analyzed. These acquisition schemes are based on a new detector shape that is bounded by the helix. It will be shown that the data acquired with these schemes are compatible with exact reconstruction methods, and the adaptation of exact reco...

介绍了一类用于螺旋锥束计算机断层扫描（CB-CT）的新型采集方案，并分析了它们对重建方法的影响。这些采集方案基于一种由螺旋线界定的新型探测器形状。将证明这些方案采集的数据与精确重建方法兼容，并且精确重建方法的适应...

Exact reconstruction from axially truncated cone-beam projections acquired with a helical vertex path is a challenging problem for which solutions are currently under investigation by some researchers. This paper deals with a difficult class of this problem called the long-object problem. Its purpose is to reconstruct a central region of interest (ROI) of a long object when the helical path extend...

从螺旋顶点路径获取的轴向截断锥束投影中进行精确重建是一个具有挑战性的问题，目前一些研究人员正在研究解决方案。本文讨论了该问题中的一个困难类别，称为长物体问题。其目的是在螺旋路径延伸时重建长物体的中心感兴趣区域。

High-resolution micro-computed tomography (CT) scanners now exist for imaging small animals. In particular, such a scanner can generate very large three-dimensional (3-D) digital images of the rat's hepatic vasculature. These images provide data on the overall structure and function of such complex vascular trees. Unfortunately, human operators have extreme difficulty in extracting the extensive v...

高分辨率显微计算机断层扫描（CT）扫描仪现已可用于小动物成像。特别是，这种扫描仪可以生成大鼠肝脏血管系统的非常大的三维（3-D）数字图像。这些图像提供了此类复杂血管树的整体结构和功能数据。不幸的是，人类操作员在提取广泛的血管结构时面临极大困难...

At the advent of multislice computed tomography (CT) a variety of approximate cone-beam algorithms have been proposed suited for reconstruction of small cone-angle CT data in a spiral mode of operation. The goal of this study is to identify a practical and efficient approximate cone-beam method, extend its potential for medical use, and demonstrate its performance at medium cone-angles required fo...

随着多层计算机断层扫描（CT）的出现，提出了多种适用于螺旋模式下小锥角CT数据重建的近似锥束算法。本研究旨在确定一种实用且高效的近似锥束方法，扩展其在医学应用中的潜力，并展示其在中等锥角（医学所需）下的性能...

For pt. I see ibid., vol. 19, no. 9, p. 822-34 (2000). The recently introduced multislice data acquisition for computed tomography (CT) is based on multirow detector design, increased rotation speed, and advanced z-interpolation and z-filtering algorithms. The authors evaluated slice sensitivity profiles (SSPs) and noise of a clinical multislice spiral CT (MSCT) scanner with M=4 simultaneously acq...

参见第一部分（同上，卷19，第9期，第822-34页，2000年）。最近引入的用于计算机断层扫描（CT）的多层数据采集基于多排探测器设计、增加的旋转速度以及先进的z插值和z滤波算法。作者评估了具有同时采集M=4排的临床多层螺旋CT（MSCT）扫描仪的切片敏感度轮廓（SSP）和噪声...

Utilization of solid-state detectors for computed tomography (CT) has been the focus of many studies. Previous phantom and clinical experiments have shown that one of the important performance parameters for the solid-state detector is the primary speed and afterglow. In this paper, the authors present a detailed investigation on the signal decay characteristics of the HiLight (GE Medical Systems,...

固态探测器在计算机断层扫描（CT）中的应用一直是许多研究的焦点。先前的体模和临床实验表明，固态探测器的重要性能参数之一是初级速度和余辉。本文中，作者对HiLight（GE Medical Systems,...）的信号衰减特性进行了详细研究。

X-ray computed tomography (CT) is in transition from fan-beam to cone-beam geometry. For cone-beam volumetric imaging, reduction of radiation exposure remains an important issue. Because the wavelet approach was shown to be effective and flexible for two-dimensional (2-D) local region reconstruction, the authors are motivated to perform wavelet local CT in cone-beam geometry. In this paper, they f...

X射线计算机断层成像（CT）正从扇形束向锥束几何过渡。对于锥束体积成像，减少辐射暴露仍然是一个重要问题。由于小波方法在二维局部区域重建中显示出有效性和灵活性，作者有动力在锥束几何中进行小波局部CT。在本文中，他们f...

One of the most recent technical advancements in computed tomography (CT) is the introduction of multislice CT (MCT). Because multiple detector rows are used for data acquisition, MCT offers higher volume coverage, faster scan speed, and reduced X-ray tube loading. Recognizing its unique data-sampling pattern, several image reconstruction algorithms were developed. These algorithms have been shown...

计算机断层扫描（CT）技术的最新进展之一是引入了多层CT（MCT）。由于采用多个探测器行进行数据采集，MCT提供了更高的体积覆盖、更快的扫描速度和更低的X射线管负载。认识到其独特的数据采样模式，开发了几种图像重建算法。这些算法已被证明...

Measurements of various image quality parameters were carried out with two different detector systems in an otherwise unchanged medical computed tomography (CT) scanner. As all other components of the scanner and the image reconstruction system remained identical, the authors were able to quantify the difference in performance between a xenon gas ionization detector and a new solid-state scintilla...

在未改变其他部件的医学计算机断层扫描（CT）扫描仪上，使用两种不同的探测器系统对各种图像质量参数进行了测量。由于扫描仪和图像重建系统的所有其他组件保持相同，作者能够量化氙气电离探测器与新型固态闪烁体探测器之间的性能差异...