Development of Spectral Phase Contrast Micro-CT

能谱X射线相衬显微CT的研制 项目摘要 体内微CT的挑战性方面涉及所需的有害辐射剂量水平，特别是 对于需要纵向跟踪同一受试者的研究。主要的制约因素是衰减差 软组织中X射线的对比度以及需要长成像时间。研究人员研究了使用 多能量（或光谱）X射线采集，以使用微型CT系统执行材料分解，但 这些方法的通用性再次受到相同的对比度-剂量折衷的限制。相衬成像 (PCI)可以在较高能量下提供显著的相位增强对比度，从而潜在地降低微CT 次给药结束然而，现有的PCI方法仍然需要高剂量和长成像时间以获得准确的相位 检索我们最近开发了一种光谱PCI的算法方法， 与衰减成像相当的时间。我们的假设是，PCI在正常临床条件下进行， 约束可以在比衰减更低的剂量下产生更好的组织定量和小特征描绘 显像我们将开发一种独特的光谱微型CT系统，具有PCI和非PCI功能， 这个假设。一个关键的系统组件将是一个创新的高性能，高分辨率的光子- 计数探测器（PCD）将在休斯顿大学和Advacam的资助下联合开发 s.r.o.将评估两种非干涉式PCI几何结构。第一个具体目标是设计微型 基于诸如源kVp和PCD传感器厚度、像素大小和能量等考虑的CT系统 bin配置。PCI特定标准包括放大率和X射线掩模属性。优化研究 将针对PCI和非PCI模式执行。对于目标2，我们将与Advacam合作开发 用于系统的广域、高帧率和高Z传感器PCD。高性能PCD将 基于Medipix 3RX ASIC技术构建，将具有高分辨率和内置光谱 校正方案和快速读数。根据目标3，将建造微型CT装置， 将制定校准和校正方案，以使系统能够有效运行。第四个具体 目的是比较光谱显微CT的PCI和非PCI模式与物理体模的性能 以及动物研究以评估低对比敏感度的增强。使用脂质体的体内研究 碘纳米颗粒将检查PCI区分治疗中血管分布差异的能力- 在小鼠中的反应性和治疗抵抗性前列腺癌模型。

Development of Spectral X-Ray Phase-Contrast Micro-CT Project Summary A challenging aspect of in vivo micro-CT relates to the required deleterious radiation dose levels - particularly for studies required to follow the same subject longitudinally. The main constraint is the poor attenuation contrast for x-rays in soft tissue and the need for long imaging times. Researchers have studied the use of multi-energy (or spectral) x-ray acquisitions to perform material decomposition with micro-CT systems, but the versatility of these methods is again constrained by the same contrast-dose trade-off. Phase-contrast imaging (PCI) can provide significant phase-enhanced contrast at higher energies, thus potentially reducing micro-CT dose. However, existing PCI methods still require high dose and long imaging times for accurate phase retrieval. We have recently developed an algorithmic approach to spectral PCI that enables dose and imaging times commensurate with attenuation imaging. Our hypothesis is that PCI performed under normal clinical constraints can yield better tissue quantitation and small feature delineation at lower dose than attenuation imaging. We shall develop a unique spectral micro-CT system with both PCI and non-PCI capabilities to test this hypothesis. A key system component will be an innovative high-performance, high-resolution photon- counting detector (PCD) to be developed jointly under this grant by the University of Houston and Advacam s.r.o. Two non-interferometric PCI geometries will be evaluated. The first specific aim is to design the micro- CT system based on considerations such as source kVp and the PCD sensor thickness, pixel size, and energy bin configuration. PCI-specific criteria include magnification and the x-ray mask properties. Optimization studies will be carried out for both the PCI and the non-PCI modes. For Aim 2, we will work with Advacam to develop the wide-area, high frame rate and high Z sensor PCD for the system. The high-performance PCD will be constructed based on Medipix3RX ASIC technology and will feature high resolution and built-in spectral correction schemes and fast readouts. Under Aim 3, the micro-CT unit will be constructed and energy calibration and correction schemes will be developed to allow efficient system performance. Our fourth specific aim is to compare the performance of the PCI and non-PCI modes of spectral micro-CT with physical phantoms and animal studies to evaluate the enhancement of low contrast sensitivity. In vivo studies using liposomal iodine nanoparticles will examine the ability of PCI to distinguish differences in blood vascularity for treatment- responsive and treatment-resistive prostate cancer models in mice.