Grating-based X-ray Phase-contrast Tomography Methods

基于光栅的 X 射线相衬断层扫描方法

• 批准号: 8696391
• 负责人: Ge Wang
• 金额: $ 32.42万
• 依托单位: RENSSELAER POLYTECHNIC INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8696391
• 关键词: Algorithms; Animal Model; Animals; Area; Biological; Caliber; Communities; Computer software; Data; Diagnostic; Dose; Elements; Environment; Face; Fracture; Fracture Healing; Goals; Goat; Healed; High Performance Computing; Hospitals; Image; Light; Measures; Mechanics; Methods; Modeling; Pattern; Performance; Phase; Photons; Process; Property; Radiation; Refractive Indices; Relative (related person); Resolution; Resources; Roentgen Rays; Scanning; Signal Transduction; Software Engineering; Source; Structure; System; Techniques; Technology; Testing; Thinking; Tibial Fractures; Time; Tube; Validation; Variant; Weight-Bearing state; attenuation; base; bone; data acquisition; density; detector; flexibility; frontier; healing; image reconstruction; in vivo; innovation; interest; musculoskeletal imaging; novel; prototype; public health relevance; reconstruction; repaired; research study; response; simulation; soft tissue; synchrotron radiation; theories; tibia; tomography; transmission process

DESCRIPTION (provided by applicant): Biological soft tissue consists mainly of light elements, and its composition is nearly uniform with little density variation. Traditional attenuation-based x-ray imaging cannot provide sufficient contrast for this type of materials. The cross-section of x-ray phase shift is three orders of magnitude greater than that of x-ray attenuation in soft tissue over the diagnostic energy range. Hence, x-ray phase-contrast imaging is sensitive to subtle features especially micro-structures of soft tissue and offers superior contrast for analyses of various normal and diseased conditions. X-ray phase-contrast imaging approaches face challenges in biomedical applications. Analyzer-based phase- contrast imaging requires monochromatic x-rays and high-precision crystals, being limited to the synchrotron radiation facility. Propagation-based imaging suffers from a low photon flux of a micro-focus x-ray tube. Grating-based phase-contrast imaging is a recent breakthrough. However, two main obstacles for this paradigm shift are (1) the large-area gratings of small periods and high aspects and (2) the long time needed for data acquisition. Technically, it is rather difficult to make large gratings especially when x-ray energy is high. Theoretically, it is extremely complicated to model the propagation of x-rays through large gratings from a point x-ray source. In this project, we will establish two enabling innovations that are (1) interior phase contrast tomography for accurate region of interest (ROI) reconstruction and (2) few-view phase-contrast reconstruction without phase-stepping for accelerated data acquisition and minimized radiation dose. The synergistic combination of these innovations will define a new frontier of x-ray phase-contrast tomography. Although the conventional wisdom is that grating-based phase-contrast tomography must use sufficiently large gratings to cover an object and capture projections completely, our main innovative thinking is to target theoretically exact reconstruction over an ROI from truncated data collected with relatively small gratings. It is underlined that the grating-based phase-contrast interior reconstruction takes truncated differential projections, while the typical interior reconstruction assumes truncated direct projections. Another new idea for this project is to utilize the reweighted L1 norm for fewer-view image reconstruction. The overall goal of this project is to establish x-ray-grating-based interior tomography theory, develop the associated few-view reconstruction methods and system without phase stepping, and promote its biomedical applications. The proposed technology will be characterized in numerical simulation and phantom experiments, and applied for musculoskeletal imaging in an animal model. Upon the completion of this project, the proposed grating-based system will have achieved 30¿m resolution, shortened scanning time, and reduced radiation dose over a 3cm- diameter ROI, outperforming micro-CT in terms of contrast resolution yet delivering comparable ROI image quality relative to that of conventional grating-based phase-contrast tomography.

描述（由应用提供）：生物软组织主要由光元素组成，其组成几乎均匀，密度变化很小。传统的基于衰减的X射线成像不能为这类材料提供足够的对比度。 X射线相移的横截面是在诊断能量范围内软组织中X射线衰减的三个数量级。因此，X射线相位对比成像对微妙的特征尤其是软组织的微观结构敏感，并为分析各种正常和解散条件的分析提供了卓越的对比度。 X射线相位对比成像方法在生物医学应用中面临挑战。基于分析仪的相比成像需要单色X射线和高精度晶体，仅限于同步加速器辐射设施。基于繁殖的成像受到微焦X射线管的低光子通量。基于光栅的相比成像是最近的突破。但是，这种范式转变的两个主要障碍是（1）小时候和高方面的大部分光栅以及（2）数据获取所需的长时间。从技术上讲，很难制作大型光栅，尤其是当X射线能量很高时。理论上，通过从点X射线源的大光栅进行建模X射线的传播非常复杂。在这个项目中，我们将建立两个启用创新，分别是（1）内部阶段 精确感兴趣区域（ROI）重建和（2）的对比度层析成像和（2）几乎没有相互对比的重建，而无需加速数据采集和最小化辐射剂量。这些创新的协同组合将定义X射线相对比层析成像的新边界。尽管传统的观点是，基于光栅的相对比断层扫描必须使用足够大的光栅来涵盖对象并完全捕获投影，但我们的主要创新思维是针对理论上确切的重建，从收集的截短数据中，收集的带有相对较小的光栅的ROI。强调的是，基于光栅的相对相对比的内部重建需要截断的差分项目，而典型的内部重建则假定截断的直接项目。该项目的另一个新想法是利用重新持续的L1标准进行更少的图像重建。该项目的总体目标是建立基于X射门的内饰 断层扫描理论，开发相关的少量视图重建方法和系统，而无需阶段阶梯，并促进其生物医学应用。所提出的技术将在数值模拟和幻影实验中进行表征，并用于动物模型中的肌肉骨骼成像。该项目完成后，提议的基于光栅的系统将达到30»分辨率，缩短扫描时间并减少在3厘米直径的ROI上的辐射剂量，而与传统基于基于Grating的基于基于Grating的基于基于Grating的基于基于GRATIAL的相关相对对比度术相对于对比度分辨率但可交付的ROI图像质量，则优于Micro-CT。