BIOMEDICAL IMAGE PROCESSING

不同断层摄影视图的叠加和配准是一种有效的方法。 研究人员试图将大脑形态 （结构），来自X射线计算机断层扫描（CT）图像， 脑功能（代谢），核医学正电子显示 发射断层扫描（PET）图像。 出于这个原因，正在尝试开发用于 CT结构数据与PET代谢信息的准确相关性， 为了加强我们对这些过程的理解， 生成PET图像。 我们的方法有三个阶段：第一，实践方法必须 发现的准确和可重复的头部放置在 一个断层扫描仪的孔径;第二，监测头的技术 在图像采集过程中的位置必须制定，以纠正 在图像生成之前进行头部运动;第三， 必须找到用于缩放和配准数字化图像的算法， 在数字显示子系统上的不同扫描仪。 在扫描仪的孔径内精确定位受试者的颅骨 使用基于PC的Polhemus位置/方向进行监测和记录 测量子系统，允许同时使用两个独立的 传感器.两种廉价定制成型口腔矫治器的研制 允许Polhemus子系统的传感器固定到受试者的头骨上。 一种新的目标定位算法，推导出提供给系统操作员 与扫描仪成像体积内的头部位置相关的视觉提示。 双传感器软件已完成，广泛的评估工作已开始 在对测试对象进行实验性使用之前。 获得了附加的位置/方向测量子系统 并评价线性和对附近金属的灵敏度 物体，这是基于电磁的跟踪系统的常见问题。 该装置利用准静态场的目的是增加 它对某些金属的免疫力虽然 这种新的位置测量系统的性能是好的，它没有 在有PET扫描仪的情况下性能优于Polhemus系统。

The superposition and registration of differing tomographic views is a difficult problem for investigators attempting to correlate brain form (structure), derived from x-ray computed tomography (CT) images, with brain function (metabolism), revealed by nuclear medicine positron emission tomography (PET) images. For this reason, an attempt is being made to develop techniques for the accurate correlation of CT structural data with PET metabolic information, in order to enhance our understanding of the processes underlying the generation of PET images. Our approach has three stages: firstly, practical methods must he discovered for the accurate and reproducible placement of the head within a tomographic scanner's aperture; secondly, techniques for monitoring head position during the image acquisition process must be developed to correct for head movement before the image is generated; thirdly, simplified algorithms must be found for scaling and registering digitized images from different scanners on a digital display subsystem. Precise orientation of the subject's skull within the scanner's aperture is monitored and recorded with a PC-based Polhemus position/orientation measurement subsystem, allowing simultaneous use of two independent sensors. The development of two inexpensive custom-molded oral appliances allows the Polhemus subsystem's sensor to be fixed to the subject's skull. A novel targeting algorithm was derived to provide to the system operator visual cues related to head position within a scanner's imaging volume. Two-sensor software was completed, and extensive evaluation has begun prior to its experimental use with test subjects. An additional position/orientation measurement subsystem has been obtained and evaluated for linearity and for sensitivity to nearby metallic objects, a problem common to an electromagnetic-based tracking systems. This device's utilization of quasi-static fields was designed to increase its immunity to close proximity of certain types of metal. Although performance of this new position measurement system was good, it did not outperform the Polhemus system in the presence of PET scanners.