用于活体小鼠的微型CT呼吸门控技术研究

发布时间：2018-01-29 02:24

本文关键词： 微型CT 快速扫描呼吸门控活体小动物　出处：《华中科技大学》2012年硕士论文　论文类型：学位论文

【摘要】：微型CT具有高空间分辨率，能够无损地获得小动物的结构信息等优点，为各种疾病模型的研究、新药研发等提供了长时间连续监测的工具，已经在生物医学研究中发挥重要作用。然而，使用微型CT对活体小动物胸部或腹部等成像时，呼吸活动会产生运动伪影，导致图像空间分辨率的降低。为了消除这些影响，出现了微型CT呼吸门控技术。为了在微型CT系统上实现呼吸门控技术，本文在实验室已有的微型CT系统上通过平板探测器图像采集传输的时序信号与旋转台旋转之间的同步实现了快速扫描，缩短了系统的扫描时间，可实现最大30fps的图像采集速度。基于该快速、高空间分辨率的微型CT系统，发展了基于硬件和软件的两种活体小动物回顾性呼吸门控技术。基于硬件的方法是通过固定在麻醉的小动物腹部的空气压力传感器来获取呼吸信号，而基于软件的方法是利用扫描得到的投影图像的特征来获取呼吸信号。得到呼吸信号后，根据每幅投影图像与呼吸信号之间的对应关系，按照呼吸信号的幅度，将投影图像归类于不同的呼吸相位，最后使用FDK算法对处于同一呼吸相位的投影图像进行数据重建。结果表明，呼吸门控的CT图像的质量优于非呼吸门控的CT图像，经呼吸门控的CT图像可以观察到更清楚的肺隔膜边界及肋骨结构，表明呼吸门控技术能够很好的消除运动伪影。通过比较两种呼吸门控方法，发现这两种方法在提高CT图像质量上具有一致性。但是基于软件的方法只有在图像采集帧速到达15fps时才能有效地获得呼吸信号，而基于硬件的方法虽然增加了系统的复杂程度，但是能稳定地获取呼吸信号，，具有更为广泛的应用范围。
[Abstract]:Micro CT has the advantages of high spatial resolution and the ability to obtain structural information of small animals without damage. It provides a long-term continuous monitoring tool for the study of various disease models and the development of new drugs. It has played an important role in biomedical research. However, breathing activities can produce motion artifacts when microCT is used to visualize the chest or abdomen of small living animals. In order to eliminate these effects, micro CT respiratory gating technology has been developed in order to reduce the spatial resolution of images. In order to realize the respiratory gating technology on the micro CT system. In this paper, the scanning time is shortened and the scanning time is shortened by the synchronization between the time sequence signal collected and transmitted by the flat panel detector image and the rotation of the rotating table on the existing miniature CT system in the laboratory. The maximum image acquisition speed of 30 fps can be achieved. Based on the fast and high spatial resolution micro CT system. Two retrospective breathing gating techniques based on hardware and software for small animals in vivo are developed. The hardware based approach is to obtain respiratory signals by means of air pressure sensors fixed in the abdomen of anesthetized small animals. The method based on software is to obtain the respiratory signal by using the features of the scanned projection image. After obtaining the respiratory signal, according to the corresponding relationship between each projection image and the respiratory signal, according to the amplitude of the respiratory signal. The projection images are classified into different breathing phases, and the FDK algorithm is used to reconstruct the projected images with the same breathing phase. The results showed that the quality of respiratory gated CT images was better than that of non-respiratory gated CT images, and the pulmonary septum boundary and rib structure could be observed more clearly by respiratory gated CT images. The results show that the breathing gating technique can eliminate motion artifacts very well. It is found that the two methods are consistent in improving the quality of CT images, but the software-based method can only obtain respiratory signals effectively when the frame rate of image acquisition reaches 15fps. Although the hardware-based method increases the complexity of the system, it can obtain respiratory signals stably and has a wider range of applications.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R814.42

【参考文献】