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Dynamic bowtie attenuator for CT dose reduction and dynamic range control

用于减少 CT 剂量和动态范围控制的动态领结衰减器

基本信息

批准号：
8707834
负责人：
NORBERT J. PELC
金额：
$ 19.04万
依托单位：
STANFORD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-08-01 至 2016-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Computed Tomography (CT) has become a mainstay in diagnostic imaging. The high utility of CT has led to increased use and, as a result, to concerns about the radiation burden to individuals and the population. Although many technologies have been developed to reduce the dose from CT, further reductions are both possible and prudent, and the ALARA principle dictates that any reduction that is reasonably achievable should be adopted. Control of the incident radiation profile through the use of a pre-patient attenuator ("bowtie" filter) is known to reduce patient dose for a given level of image quality and also to reduce the dynamic range requirements and the effects of scatter. However, systems have at most a few attenuator shape choices and the filter is fixed during the scan. At best, they are optimal for circularly symmetric cylindrical objects. By contrast, patients' attenuation properties are rather irregular. In previous research we showed that dynamic control of the illumination profile can lead to significant dose reduction, but that work assumed the use of complex and expensive source arrays. By contrast, a dynamic attenuator would be a cost effective solution for achieving similar control in the illumination profile. Such a dynamic attenuator would tailor the radiation distribution for each patient, slice location, viewing directon, and clinical application. This is aligned with efforts toward personalized medicine. The key requirement is that the attenuator needs to be very adaptive and also provide smooth variation in flux. Prior designs fall short. We have developed a design concept that meets the modulation requirements by using movable wedge attenuators with triangular cross-sections that vary in the axial direction to produce piece-wise linear, dynamic profiles. Initial computer simulations predic large reductions in dose and in the dynamic range of the x-ray signal at the detector. The dose reduction would be of immediate benefit while the reduction in dynamic range would enable the earlier adoption of photon-counting detectors that would have additional benefits. In contrast to the source array approach, the dynamic bowtie is compatible with conventional CT system designs, so if viable it could be readily translated into clinical use. In the proposed research, w will conduct thorough computer simulations to optimize the design and predict performance benefits, build a portion of a dynamic attenuator array, and conduct experiments to validate the concept. Once this research is complete, the dynamic bowtie concept would be ready for adoption into commercial systems.

描述（由申请人提供）：计算机断层扫描（CT）已成为诊断成像的支柱。 CT 的高实用性导致其使用量的增加，从而引发了人们对个人和人群辐射负担的担忧。尽管已经开发了许多技术来减少 CT 剂量，但进一步减少既是可能的也是谨慎的，并且 ALARA 原则规定应采用任何合理可实现的减少。众所周知，通过使用患者前衰减器（“蝴蝶结”滤波器）来控制入射辐射轮廓可以在给定的图像质量水平下减少患者剂量，并且还可以减少动态范围要求和散射影响。然而，系统最多有几种衰减器形状选择，并且滤波器在扫描期间是固定的。充其量，它们最适合圆形对称的圆柱形物体。相比之下，患者的衰减特性相当不规则。在之前的研究中，我们表明，动态控制照明轮廓可以显着减少剂量，但这项工作假设使用复杂且昂贵的光源阵列。相比之下，动态衰减器将是实现照明轮廓中类似控制的具有成本效益的解决方案。这种动态衰减器将为每个患者、切片位置、观察方向和临床应用定制辐射分布。这与个性化医疗的努力是一致的。关键要求是衰减器需要具有很强的适应性，并且还需要提供平滑的通量变化。先前的设计存在不足。我们开发了一种设计理念，通过使用具有三角形横截面的可移动楔形衰减器来满足调制要求，该衰减器在轴向方向上变化，以产生分段线性动态轮廓。最初的计算机模拟预测探测器处 X 射线信号的剂量和动态范围将大幅减少。剂量的减少将带来立竿见影的好处，而动态范围的减少将使光子计数探测器能够更早地采用，从而带来额外的好处。与源阵列方法相比，动态领结与传统 CT 系统设计兼容，因此如果可行，它可以很容易地转化为临床应用。在拟议的研究中，我们将进行彻底的计算机模拟来优化设计并预测性能优势，构建动态衰减器阵列的一部分，并进行实验来验证这一概念。一旦这项研究完成，动态领结概念就可以采用到商业系统中。