SPECT with pinholes separated by slats for high-sensitivity complete imaging

SPECT 具有由板条分隔的针孔，可实现高灵敏度完整成像

• 批准号: 7262743
• 负责人: SCOTT DEAN METZLER
• 金额: $ 36.68万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-24 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7262743
• 关键词: Accounting; Algorithms; Animals; Blur; Brain; Breast; Caliber; Calibration; Characteristics; Childhood; Clinical; Clinical Research; Collimator; Computer Simulation; Computer software; Data; Diagnosis; Discipline of Nuclear Medicine; Disease; Evaluation; Gamma Cameras; Goals; Hand; Human; Image; Imaging Techniques; Joints; Knowledge; Lead; Lesion; Limb structure; Maps; Measurement; Measures; Methods; Modality; Modeling; Morphologic artifacts; Motivation; Ocular orbit; Performance; Positioning Attribute; Production; Property; Radiolabeled; Relative (related person); Research; Research Personnel; Research Project Grants; Resolution; Retinal Cone; Rotation; Sampling; Scanning; Slice; Source; Speed; System; Techniques; Testing; Time; Tracer; Translating; Vendor; attenuation; base; design; detector; image reconstruction; improved; prevent; prototype; radiotracer; radius bone structure; reconstruction; retinal rods; single photon emission computed tomography; size; usability

DESCRIPTION (provided by applicant): The overall goal of this project is to develop a new collimation technique for single photon emission computed tomography (SPECT) in nuclear medicine. This new collimator merges the sensitivity and resolution properties of pinhole collimation in the transaxial direction with the complete-sampling properties of parallel-beam (PB) and fan-beam (FB). SPECT is a commonly used imaging technique that uses radiolabeled tracers for diagnosing disease states. Collimation is used in SPECT in conjunction with a position-sensitive detector (i.e., a gamma camera). Thus, SPECT measures a set of line integrals, which are inverted through reconstruction software into a 3D distribution of the tracer's concentration. PB and FB, which magnifies in the transaxial direction, are commonly used clinical collimators. Pinhole and cone-beam (CB) collimators are also used in research and clinical scenarios. CB's sensitivity increases near the focal point, analogously to FB's, yet CB's and FB's resolutions are better near the detector. Pinhole collimation is different in that sensitivity and resolution are both better near the focal point (i.e., the aperture), whereas CB's and FB's best resolutions occur where their sensitivities are worst (i.e., near the detector). However, a problem with both pinhole and CB is that they do not yield complete data from a circular orbit, leading to axial blurring artifacts. These artifacts do not occur for PB and FB, which yield complete data. The collimation proposed in this project combines the favorable transaxial sensitivity and resolution properties of a pinhole with the complete-sampling properties of FB. The collimation is 2D in that the collimator may be translated axially yet produce the same projection image; this property is beneficial for image reconstruction because slices are independent of each other, except for detector resolution. This contrasts sharply with pinhole and CB which have large mixing of axial slices. In this project, a prototype 2D-pinhole collimator will be designed and fabricated. The imaging properties of sensitivity and resolution will be calculated analytically and numerically. These calculations will be validated through experimental point-source measurements. The sensitivity and resolution will be incorporated into an iterative reconstruction algorithm that is 3D, but considers only nearby slices since there is limited axial overlap, which will aid reconstruction speed. Reconstruction of experimental phantoms will be used to test the system. In the later years of the project, a set of "production" collimators, each of which is likely to incorporate multiple slits for improved sensitivity, will be fabricated based on the knowledge gained from the prototype. This set will be evaluated for potential clinical impact using anthropomorphic phantoms. The new collimator is expected to be advantageous when the object diameter is mid-size (-11-27 cm). Thus, clinical and research scans that are likely to benefit from this new technique include brain, breast, limb, as well as some pediatric and animal applications.

项目描述（由申请人提供）：本项目的总体目标是开发一种新的核医学单光子发射计算机断层扫描（SPECT）准直技术。该准直器将针孔准直在跨轴方向上的灵敏度和分辨率特性与平行光束和扇形光束的完全采样特性相结合。SPECT是一种常用的成像技术，它使用放射性标记示踪剂来诊断疾病状态。在SPECT中，准直与位置敏感检测器（即伽马相机）一起使用。因此，SPECT测量一组线积分，通过重建软件将其倒置成示踪剂浓度的3D分布。PB和FB是临床上常用的准直器，具有跨轴放大功能。针孔和锥束（CB）准直器也用于研究和临床场景。与FB类似，CB的灵敏度在焦点附近增加，但CB和FB的分辨率在探测器附近更好。针孔准直的不同之处在于灵敏度和分辨率在焦点附近（即光圈）都更好，而CB和FB的最佳分辨率发生在灵敏度最差的地方（即探测器附近）。然而，针孔和CB的一个问题是，它们不能从圆形轨道产生完整的数据，导致轴向模糊伪影。PB和FB不会出现这些伪影，它们会产生完整的数据。本项目提出的准直结合了针孔良好的跨轴灵敏度和分辨率特性和FB的完全采样特性。准直是二维的，因为准直器可以轴向平移，但产生相同的投影图像；这一特性有利于图像重建，因为除了检测器分辨率之外，切片是相互独立的。这与具有大量轴向片混合的针孔和CB形成鲜明对比。在这个项目中，将设计和制造一个原型2d针孔准直器。对灵敏度和分辨率的成像特性进行了解析和数值计算。这些计算将通过实验点源测量进行验证。灵敏度和分辨率将被纳入3D的迭代重建算法，但只考虑附近的切片，因为轴向重叠有限，这将有助于重建速度。实验幻影的重建将用于测试系统。在项目的后期，将根据从原型中获得的知识制造一套“生产”准直器，每个准直器都可能包含多个狭缝以提高灵敏度。这一组将被评估潜在的临床影响，使用拟人化的幻影。当目标直径为中等大小（-11-27厘米）时，新的准直器有望发挥优势。因此，临床和研究扫描可能受益于这项新技术，包括脑，乳房，肢体，以及一些儿科和动物应用。