六边形多源CT结构及混合投影分离算法研究

项目名称： 六边形多源CT结构及混合投影分离算法研究

项目编号： No.61300142

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 自动化技术、计算机技术

项目作者： 叶人珍

作者单位： 华中农业大学

项目金额： 25万元

中文摘要： 在常规CT系统中，每次只能允许一个X射线源照射待重建物体，由探测器采集投影数据，然后X射线源再转到下个位置再重复原来的方式采集投影数据，在这种情况下存在几个问题，首先:CT投影数据的采集需要极快的机架旋转速度和极高的X射线峰值功率;其次：投影数据的采集速度受限于X射线源的机械转动速度,而且X射线源的机械转动的到达的位置并不十分精确，容易造成重建过程中出现伪像。鉴于此，本文拟提出一个基于碳纳米管新的数据并行采集结构，即"六边形多源CT成像结构"，加快数据采集速度，来避免机械转动所带来伪影问题。在新的模式下，采用本文拟提出的基于MSE准则的编码矩阵算法来控制多个射线源的通断，之后同时照射待重建物体来采集混合投影数据，并依据所采用的编码矩阵对混合投影进行分离，从而可以保证每个射线源都有对应的投影值。在保证投影数据质量前提下，提高了数据采集速度和降低X射线峰值功率，并避免了X射线管和探测器的转动。

中文关键词： 多源CT；稀疏编码；去模糊分离算法；图像检测；图像检索

英文摘要： In a conventional CT system, the reconstructed object is often traversed by single X-ray source at each time. However, the conventional CT system exists some drawbacks. Firstly, almost all CT scanners collect the projection sequentially by adopting a step-and-shoot process, which demands high x-ray power and high speed of gantry rotation. Secondly, the speed of the collcted projction data depends on the mechanical rotation speed of CT rotation gantry. Finally, the "bad" projection data often arise from the mechanical rotation of the gantry, which will result in the artifacts of the reconstructed object. To overcome the aforementioned drawbacks, the simultaneous collection structure of projection named "Hexagonal Imaging Structure of the Multi-Source CT" is proposed in this project, which is based on the carbon nanotube x-ray array. Based on the proposed hexagonal imaging structure, the coding matrix generated from the mean square error criterion indicates that the sources are off or on at a given time. In this case,the coding matrix is exploited to decompose the mixing projection data, which are collected from the multisource CT detector. By using the proposed method, a drastic increase of the speed and reduction of the x-ray peak power can be achieved without compromising the imaging quality.

英文关键词： multi-source computed tomography；sparse coding；deblurring；image detection；image retrieval