Offset Astigmatic and Variable Focusing Collimation for Helical SPECT Brain Scans

该项目的总体目标是利用创新的融合技术开发增强的成像技术- 用于定量单光子发射计算机层析成像的三维螺旋光路准直 (SPECT)。用于脑部疾病诊断的SPECT分子显像剂前景看好 比如帕金森氏症。全锥束(FCB)SPECT有可能成为一种极好的诊断方法 用于小脑结构的成像工具，特别是那些因其放大而位于大脑深处的结构 以及它的高检测效率，随着距离焦点的增加而增加。然而， 当SPECT应用于脑成像时，使用FCB型准直器跟踪圆形轨道的SPECT有两个局限性： I)源分布未完全采样，导致轴向源出现图像伪影 不在准直器中心、横轴(垂直)焦面附近的位置；以及ii)尾部 由于患者的肩膀与脑部的干扰，无法有效地对大脑区域进行成像 准直器的位置。即使是在惠普之后使用FCB准直器的SPECT也存在后一种问题。两者都有 通过将偏置像散波束(OAB)和 遵循HPS的空间可变聚焦(SVF)准直器：i)完全空间采样可以通过以下方式获得 使用3D HPS，从在以下位置获取的投影数据生成高质量、无伪影的重建图像 更高的灵敏度和放大倍率；以及ii)消除了肩部干扰。OAB准直器可以保持 靠近大脑，但其偏移量的横轴焦线位于大脑尾部附近 区域。拟议的研究将涉及实验扫描，以及计算机模拟和分析 计算。现有的三相机SPECT系统和新型会聚光束准直器，与 床平移，将被用来展示创新的成像技术。迭代重建 将开发用于螺旋路径OAB和SVF投影数据的软件。一种激光对准系统和 点源的SPECT采集将用于确定描述系统校准的参数 以及SPECT扫描仪的机械和电气失调。最初，空间抽样的一致性 将使用采集来模拟两个或三个会聚光束准直器与使用 单个会聚光束准直器。最先进的重建计划将考虑到影响 系统失调、点扩散响应、衰减和散射的影响。这些因素对经济增长的影响 图像分辨率、量化和伪影将使用选择的几何和 拟人化的幻影。一项试验性的临床研究将涉及一小部分人类受试者。这 提案支持新成像技术的研究和开发，其结果将提供 这些数据可以作为重大翻译研究的基础。从长远来看，新技术将 通过改进对大脑疾病的诊断，有可能提供更好的医疗保健。

The overall goal of this project is to develop an enhanced imaging technology using innovative convergent- beam collimation with 3D helical paths (HPs) for quantitative single photon emission computedtomography (SPECT). Promising SPECT molecular imaging agents are being developed for diagnosis of brain diseases such as Parkinson's disease. Full-cone-beam (FCB) SPECT has the potential to be an excellent diagnostic imaging tool for small brain structures, particularly those deep within the brain because of its magnification and its high detection efficiency, which increases with increasing proximity to the focal point. However, SPECT using a FCBcollimator following a circular orbit has two limitations when applied to brain imaging: i) The source distribution is not completely sampled, which results in image artifacts for axial source locations that are not near the collimator's central, transaxial (perpendicular) focal plane; and ii) The caudal region of the brain cannot be imaged effectively because of interferenceof the patient's shoulders with the placement of the collimator. Even SPECT using a FCB collimator following a HP has the latter problem. Both problems are effectively addressed by the innovative combination of offset-astigmatic-beam (OAB) and spatially-variable-focusing (SVF) collimators following HPs: i) Complete spatial sampling can be obtained by using 3D HPs, resulting in high quality, artifact-free reconstructed images from projection data acquired at higher sensitivity and magnification; and ii) Shoulder interference is eliminated. OAB collimators can maintain close proximity to the brain and yet have their offset transaxial focal line positioned near the brain's caudal region. The proposed research will involve experimental scans, as well as computer simulations and analytic calculations. An existing triple-camera SPECT systemand novel convergent-beam collimators, coupled with bed translation, will be used to demonstrate the innovative imaging technique. Iterative reconstruction software will be developed for helical-path OAB and SVF projection data. A laser alignment system and SPECT acquisitions of point sources will be used to determine parametersthat describe system calibrations and mechanical and electrical misalignments of the SPECT scanner. Initially, uniformity of spatial sampling will be investigated using acquisitions that simulate two or three convergent-beam collimators versus the use of a single convergent-beam collimator. State-of-the-art reconstruction programs will account for the effects of system misalignments, point-spread-response, attenuation and scatter. The effects of these factors on image resolution, quantification and artifactswill be evaluated using a selection of geometric and anthropomorphic phantoms. A pilot clinical study will involve a small number of human subjects. This proposal supports the research and development of new imaging techniques, and the results will provide data upon which significant translational research can be built. In the long term, the new techniques will potentially provide better health care through improved diagnosis of brain disease.