Molecular imaging with computed tomography.
Molecular imaging with computed tomography.
复制标题
计算机断层扫描分子成像。
DOI：
10.1002/cmmi.1581
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发表时间：
2014
影响因子：
--
通讯作者：
Pan,Dipanjan
中科院分区：
文献类型：
--
作者：
Lanza,GregoryM;Pan,Dipanjan
第一次临床计算机断层扫描 (CT) 扫描于 1971 年 10 月在英国伦敦的阿特金森莫利医院进行，使用由 Godfrey Hounsfield 及其团队在伦敦西部海斯 EMI 中央研究实验室开发的原型扫描仪来评估疑似额叶肿瘤 (1)。该扫描仪在 5 分钟后生成了 80×80 矩阵的图像，然后需要大约 5 分钟的时间来处理和重建图像。如今，CT 扫描仪可在 0.3 秒内生成 1024×1024 矩阵的图像，已成为医疗诊断和管理的支柱。 CT 成像的发展在 20 世纪 70 年代迅速发展，出现了大量创新 (2-4)。 20 世纪 80 年代见证了这项技术的巩固和增长放缓；然而，20 世纪 90 年代的特点是 CT 的许多发展，包括螺旋 CT 和多源、多行探测器 (2-4)。近 20 年后的今天，沿着这些思路的发展仍在继续。然而，在新千年，能量分辨成像从各种双能 CT 探测器和 X 射线管的快速电压切换开始，已发展成为一种新的 CT 模式，称为光谱 CT (5)。X 射线物质的衰减特性与能量和材料相关，并且允许使用多种不同的 X 射线能量进行成像来导出材料特性 (6)。 CT 扫描仪中的 X 射线管产生宽能谱的 X 射线，可由传统光子积分探测器感知。探测器输出的信号与随时间积分的整个 X 射线能量带宽所赋予的总能量成比例。这种方法的改进是“双能量成像”(7-10)，它是使用不同的入射光谱 (10) 或能量辨别探测器（即“双晶体方法”）(11, 12) 来完成的，以估计体素内材料的平均 Z 数。在实践中，该方法可用于在一定程度上区分钙或碘以及形成身体组织的轻元素。 X 射线光子撞击探测器元件的衰减是光电效应、康普顿效应和 K 边效应的净函数。每个元素都有一个具有独特能量的 K 壳层电子，碘和铋之间的那些元素具有落在可用诊断 X 射线带宽内的 K 边缘能量。 K壳层电子吸附等能量的X射线光子的衰减显着增加。这种衰减不连续性的谱带位置和高度称为其 K 边缘。不同的材料可以根据其独特的 K 边缘来区分，而通常用于量化标准 CT 对比度的亨斯菲尔德数可能非常相似。
The first clinical computed tomography (CT) scan was performed in October 1971 at Atkinson Morley’s Hospital, in London, UK, using a prototype scanner, developed by Godfrey Hounsfield and his team at EMI Central Research Laboratories in Hayes, West London, to assess a suspected frontal lobe tumor (1). That scanner produced an image with an 80× 80 matrix after 5 min, which then required~ 5min more to process and reconstruct into an image. Today CT scanners produce images with a 1024× 1024 matrix in< 0.3 s, and they have become a pillar for medical diagnosis and management. The evolution in CT imaging progressed rapidly in the 1970s with numerous innovations (2–4). The 1980s saw a consolidation of this technology and slower growth period; however, the 1990s were characterized by many developments in CT, including spiral CT and multisource, multirow detectors (2–4). Developments along these lines continue today, nearly 20years later. However, in the new millennium, energy-resolving imaging, begun with various dual-energy CT detectors and rapid voltage switching of the X-ray tube, has evolved into a new CT modality, called Spectral CT (5).The attenuation properties of matter for X-rays are energyand material-dependent, and permit material properties to be derived using a multitude of different X-ray energies for imaging (6). X-ray tubes in CT scanners produce a broad energy spectrum of X-rays that are sensed by a conventional photon-integrating detector. The detector outputs a signal proportional to the total energy imparted by the entire X-ray energy bandwidth integrated over time. A refinement of this approach,‘dualenergy imaging’(7–10) is accomplished using different incident spectra (10) or an energy discriminating detector (ie ‘dual crystal method’)(11, 12), to estimate the average Z-number of the material within a voxel. In practice, this method can be used to differentiate to some extent between calcium or iodine and lighter elements, which form body tissues. The attenuation of an X-ray photon impacting a detector element is the net function of the photoelectric, Compton and K-edge effects. Each element has a K-shell electron with a unique energy, and those elements between iodine and bismuth have K-edge energies that fall within the useable diagnostic X-ray bandwidth. The attenuation of a K-shell electron adsorbing an X-ray photon of equal energy is markedly increased. The spectral band position and height of this attenuation discontinuity is called its K-edge. Different materials can be distinguished according to their unique K-edges, while Hounsfield numbers, commonly used to quantify standard CT contrast, may be very similar.