A liquid cathode for medical imaging X-ray sources

项目摘要 人们普遍认为，分布式X射线源（即，具有多个X射线的系统 包含在单个真空外壳内的源）可以从根本上改善断层医学X射线成像 通过消除对X射线源的机械运动的需要来实现成像技术。删除此类动议 提供了开发更紧凑、更高速和更低成本的X射线成像系统的潜力， 更好的图像质量、新的成像模式和更广泛的系统可用性。最终结果将是 使成像系统具有更大的能力，更广泛地提供给更多的人。一 实现这一结果的重大障碍是缺乏合适的阴极（电子发射体）， 分布式X射线源技术。 这项拨款申请旨在探索一种非常不同的方法，用于医疗X射线成像的阴极 来源：液体阴极。这种独特的阴极利用电流体动力学不稳定性来形成场电子 发射点的表面上的液体金属与法拉第波，引起轻微的机械振动， 流体通过压电换能器。因为阴极是液体，它是自我修复，这将减轻故障 与迄今为止使用的场发射阴极相关联的机制，从而导致高可靠性和长寿命。 生活通过在空间中分布所得到的紧凑型电子源元件， 可以改变，即，以电子方式重新配置，在真实的时间。这种方法有可能改变 通过将可靠、长寿命和鲁棒的源与 电子可重构X射线焦斑分布。 该提案的具体目标集中在实验上，以确定液体阴极方法是否具有 医疗成像应用所需的性能特性。其目标是： 目标1.液体阴极实验台的制作 目标2.量化液体阴极的电子发射特性 目标3。量化基于液体阴极的源的X射线发射特性 目标4。为几种广泛使用的医学成像应用开发基于液体阴极的初步设计

PROJECT SUMMARY It is generally agreed that the development of distributed X-ray sources (i.e., systems having multiple X-ray sources contained within a single vacuum envelope) could fundamentally improve tomographic medical X-ray imaging technology by removing the need for mechanical motion of the X-ray source. Removing such motion provides the potential to develop more compact, higher-speed, and lower-cost X-ray imaging systems with better image quality, new imaging modalities, and more widespread system availability. The net result would be to make imaging systems with greater capabilities more widely available to a larger number of people. A significant impediment to achieving this result has been the lack of an appropriate cathode (electron emitter) technology for the distributed X-ray source. This grant application proposes to explore a very different approach to cathodes for medical X-ray imaging sources: a liquid cathode. This unique cathode uses an electrohydrodynamic instability to form field electron emitting sites on the surface of a liquid metal with Faraday waves, induced by slight mechanical vibration of the fluid by a piezoelectric transducer. Because the cathode is a liquid, it is self-healing, which will mitigate failure mechanisms associated with field emission cathodes used to date, thereby resulting in high reliability and long life. By distributing the resulting compact electron source elements in space, the X-ray focal spot distribution can be changed, i.e., reconfigured electronically, in real time. This approach has the potential to shift the paradigm of medical X-ray imaging systems by combining a reliable, long-lived, and robust source with an electronically reconfigurable X-ray focal spot distribution. The specific aims of this proposal focus on experiments to determine whether the liquid cathode approach has the performance characteristics required for medical imaging applications. The aims are: Aim 1. Fabricate liquid cathode testbed Aim 2. Quantify electron emission characteristics of liquid cathode Aim 3. Quantify X-ray emission characteristics of liquid cathode-based source Aim 4. Develop preliminary liquid cathode-based designs for several widely used medical imaging applications