LASER BASED MONOENERGETIC AND TUNABLE X RAY SYSTEM

描述(改编自申请人摘要)：常规X光片 显像管的特点是输出低、亮度低、焦斑大和 一种多色光子能量分布。大焦点问题是 尤其是在放大工作中有问题。低产出要求 暴露时间过长。多色光谱分布， 平均光子能量控制非常有限，阻碍了有效应用 DSA并使DESA不切实际。申请人提出了一种新的x光检查方法。 通过将高能激光脉冲聚焦到表面而产生的源 固体的。这种以激光为基础的光源非常明亮，在 来自极小焦点区域的极短脉冲(低于1微秒)的形式 (低至10微米)。临床系统的估计成本相当于 旋转的阳极型机组。这一新技术的另一个优势是 基于激光的光源基于这样一个事实，即它具有一次性靶标， 在每个激光脉冲之后被替换。目标的元素组成可以 因此，在随后的激光脉冲之间迅速(几十赫兹)改变。这 允许定制(包括优化的K边滤光片)频谱 特征发射线相对于特定成像任务的位置(例如 放大检查中的患者厚度或造影剂的K边缘 在DSA研究中)。由于基于激光的x射线的高亮度 光源，球状弯曲晶体单色器可以插入在 靶点和患者允许使用近单能X射线治疗 真正的数字能量减影血管造影术研究。多彩的 由电子撞击管产生的x射线束的结构不 允许精确匹配到感兴趣对象的K边，并且始终为 与典型X射线探测器的最佳能量响应不匹配 用于放射学。因此，可以预期 接近单能的x射线源将导致积分剂量降低 根据受试者的成分精确调整X射线能量 厚度，并通过更好地匹配x射线能量与优化 探测器。在这个拟议的项目中，申请者提议学习， 开发、评估和优化基于激光的超微聚焦和非常 基于短脉冲激光的X射线源在放大和测量中的应用 DSA研究和单色X射线系统LAMOX(基于激光的单色 X射线)，用于数字能量减影血管造影术(DESA)。 该项目将在x射线公司的密切合作下实现。 物理学家(单色仪)、激光物理学家(激光X射线源)、医学 物理学家、生理学家和放射学家(评估和优化 该系统通过幻影研究)。这个项目的具体目标是 以优化图像质量和剂量利用率，并演示 基于激光的X射线系统作为一种可行的临床应用的经济可行性， 以医院为基础，替代传统放大、DSA和DESA 系统。

DESCRIPTION (Adapted from Applicant's Abstract): The conventional x-ray tube is characterized by low output, low brightness, a large focal spot and a polychromatic photon energy distribution. The large focal spot problem is especially problematic in magnification work. The low output mandates undersirable long exposure times. The polychromatic spectral distribution, with very limited mean photon energy control, impedes effective application of DSA and makes DESA impractical. The applicants proposed a new x-ray source that is created by focusing a high energy laser pulse on the surface of solids. This laser-based source is very bright and delivers radiation in the form of very short pulses (below 1 us) from a very small focal spot area (as low as 10 um). The estimated cost of a clinical system is comparable to the rotating anode-based units. An additional advantage of this new laser-based source rests on the fact that it has a disposable target which is replaced after each laser pulse. The target's elemental composition can be thus rapidly (tens of Hz) changed between subsequent laser pulses. This allows tailoring (including optimized K-edge filters) of the spectral position of characteristic emission lines to the specific imaging tast (e.g. patient thickness in magnification studies or the K-edge of a contrast agent in DSA studies). Due to the high brightness of the laser-based x-ray source, a spherically bent crystal monochromator can be inserted between the target and the patient allowing utilization of near-monoenergetic x-rays for true digital energy subtraction angiography studies. The polychromatic structure of the x-ray beam generated by an electron-impact tube does not allow precise matching to the K-edge of the object of interest and is always mismatched with the optimal energy response of the typical x-ray detectors used in radiology. Therefore, one could expect that the application of the near-monoenergetic x-ray source will result in lowering the integral dose by precisely tuning the x-ray energy according to the subject's composition and thickness and by better matching the x-ray energy with the optimized detector. In this proposed project, the applicants proposed to study, develop, evaluate, and optimize a laser-based ultra-microfocused and very short pulsed laser-based x-ray source for application in magnification and DSA studies and monochromatic x-ray system LAMOX (LAser-based Monochromatic X-rays) for application in digital energy subtraction angiography (DESA). This project will be realized with close collaboration among x-ray physicists (monochromator), laser physicists (laser x-ray source), medical physicists, a physiologist and radiologists (evaluation and optimization of the system through phantom studies). The specific goals of this project are to optimize image quality and dose utilization and to demonstrate the economic feasibility of the laser-based x-ray systems as a viable clinical, hospital based, alternative to traditional magnification, DSA and DESA systems.