Accurate quantification of width and density of bone structures by computed tomography
Accurate quantification of width and density of bone structures by computed tomography
复制标题
DOI：
10.1118/1.2769102
复制
发表时间：
2007-10-01
期刊：
影响因子：
3.8
通讯作者：
Short, David F.
中科院分区：
文献类型：
--
作者：
Hangartner, Thomas N.;Short, David F.
在计算机断层摄影（CT）中，不同密度的对象之间的边缘的表示受到扫描器的有限空间分辨率的影响。这导致窄物体密度的错误表示，导致高达70%或更多的误差。我们感兴趣的是狭窄骨结构的成像和测量，对于临床CT扫描仪、外周定量CT扫描仪或微型CT扫描仪的成像，问题是相同的。数学模型、体模和患者数据的测试导致了以下过程：（i）从与骨边界成直角的CT图像中以一度增量提取密度轮廓;（ii）由于不同的相邻软组织，分别考虑每个轮廓的外边缘和内边缘;（iii）基于软组织值和第一近似骨值之间的差的固定百分比处的阈值来测量每个轮廓的宽度;（iv）借助于从计算机模拟和体模测量获得的密度-宽度曲线，基于测量的宽度校正每个轮廓的骨的底层材料密度。后一曲线是特定于某个扫描仪的，并且不依赖于患者中所见范围内的组织密度。该程序允许计算骨的材料密度。基于体模测量，我们估计密度误差相对于正常骨密度低于2%，骨宽度误差约为像素大小的十分之一。(C)2007年美国医学物理学家协会。
In computed tomography (CT), the representation of edges between objects of different densities is influenced by the limited spatial resolution of the scanner. This results in the misrepresentation of density of narrow objects, leading to, errors of up to 70% and more. Our interest is in the imaging and measurement of narrow bone structures, and the issues are the same for imaging with clinical CT scanners, peripheral quantitative CT scanners or micro CT scanners. Mathematical models, phantoms and tests with patient data led to the following procedures: (i) extract density profiles at one-degree increments from the CT images at right angles to the bone boundary; (ii) consider the outer and inner edge of each profile separately due to different adjacent soft tissues; (iii) measure the width of each profile based on a threshold at fixed percentage of the difference between the soft-tissue value and a first approximated bone value; (iv) correct the underlying material density of bone for each profile based on the measured width with the help of the density-versus-width curve obtained from computer simulations and phantom measurements. This latter curve is specific to a certain scanner and is not dependent on the densities of the tissues within the range seen in patients. This procedure allows the calculation of the material density of bone. Based on phantom measurements, we estimate the density error to be below 2% relative to the density of normal bone and the bone-width error about one tenth of a pixel size. (C) 2007 American Association of Physicists in Medicine.