Advanced CT Strategies for Image Quality Improvement and Dose Reduction

X射线计算机断层扫描(CT)产生详细的身体图像，是医疗保健的重要工具。这些系统应用于医学的方方面面，从癌症筛查到评估伤害，再到指导治疗，如放射治疗和手术。*然而，通过更好地利用潜在的物理来提高图像质量并将对患者的辐射剂量降至最低，来增强CT技术的机会是巨大的。这一研究计划建立在X射线成像方法和系统开发方面20多年的经验基础上，以开发利用计算方法、机电一体化和纳米技术进步的下一代CT方法。研究集中在两个主要主题上：*1.使用基于物理的模型来校正不需要的X射线散射来改善图像质量*2.使用一种称为通量场调制CT(FFMCT)的新方法来降低与CT成像相关的风险。简而言之，CT的工作原理是将一束X射线从发射器通过患者发送到探测器。信号的变化取决于两者之间的相互作用，例如，骨骼比肌肉阻挡更多的X射线。然而，一些X光是分散的，并没有沿着一条直线穿过患者。这些散射X射线对图像质量有很大的影响，在锥束CT(CBCT)中，由于照射的组织体积和缺乏排斥方法，这一点变得更加严重。使用蒙特卡罗(MC)模拟对散射背后的物理模型进行精确建模，使我们能够更好地理解和纠正散射，从而改进图像和患者剂量管理。我们最近让模拟变得更高效、更快，这是将它们整合到临床成像系统中所需的第一步。该项目将改进模拟的建模和准确性，并将工作扩展到具有类似挑战的其他成像方式，如正电子发射断层扫描(PET)。*FFMCT是在我的实验室开发的，它有可能通过根据成像任务的目标改变CT扫描仪的操作来改变CT技术。它涉及在图像采集过程中动态调整X射线通量模式，以便针对特定感兴趣区域调整图像质量和剂量。FFMCT可以减少对不感兴趣的敏感组织(如肺部筛查中的乳腺组织)的剂量，从而在保证或改善现有CT图像质量的同时降低暴露风险。新的基于纳米技术的X射线发射器将使我们能够开发具有多个可编程源的新型FFMCT原型；这种方法还将利用我实验室中先进的基于物理的模型。

X-ray computed tomography (CT) produces detailed images of the body and is a critical tool in health care. These systems are employed in every facet of medicine from cancer screening to assessing injuries to guiding treatments such as radiotherapy and surgery. ******However, there is significant opportunity enhance CT technology by better exploiting the underlying physics to improve image quality and minimize the radiation dose to patients. This program of research builds upon over 20 years of experience in X-ray imaging methods and system development to develop next-generation CT methods that leverage advances in computational methods, mechatronics, and nanotechnology. The research focuses on two major topics:***1. Improving image quality by using physics-based models to correct for unwanted X-ray scatter***2. Lowering the risk associated with CT imaging using a novel approach called fluence-field modulated CT (FFMCT). ******In brief, CT works by sending a beam of X-rays from an emitter through the patient to a detector. The signal changes depending on what's in-between the two, e.g. with bone blocking more X-rays than muscle. However, some X-rays are scattered and didn't follow a straight line through the patient. These scattered X-rays have a significant effect on image quality, which is exacerbated in cone beam CT (CBCT) due to the volume of tissue irradiated and lack of a rejection method. Accurate modeling of the physics underlying scatter with Monte Carlo (MC) simulations allows us to better understand and correct for scatter, leading to improved images and patient dose management. We recently made the simulations more efficient and faster, a first step needed to incorporate them in clinical imaging systems. This project will improve the modelling and accuracy of the simulations, and extend the work to other imaging modalities with similar challenges such as positron emission tomography (PET). ******FFMCT was developed in my laboratory and has the potential to transform CT technology by changing the operation of the CT scanner depending on the objective of the imaging task. It involves dynamically adjusting the X-ray fluence pattern during image acquisition so that the image quality and dose are adjusted for specific regions-of-interest. FFMCT can reduce dose to sensitive tissues not of interest (e.g. breast tissue in lung screening)and as a result lower the exposure risk while assuring or improving upon existing CT image quality. New nanotechnology-based X-ray emitters will let us develop a novel FFMCT prototype with multiple programmable sources; this approach will also leverage the physics-based models being advanced in my lab.