A QUASIMONOCHROMATIC X-RAY SOURCE FOR MAMMOGRAPHY

该计划的目的是调查使用 作为可调准单色X射线的参数X射线辐射（PXR） 乳腺X线摄影的来源。 PXR是通过将天然或合成的 晶体，或多层结构进入相对论的路径， 电子束 与光场相关的虚光子 电子被周期性晶格布拉格反射，并且真实的 X射线以布拉格角出现。 因此，生产过程 类似于晶体的X射线衍射，除了X射线束 以布拉格角入射的电子束被相对论性电子束代替。 这种类激光源是准单色的，定向的，容易 可调谐和可极化。 这样的来源将允许确定 使剂量最小化， 肿瘤和正常乳腺组织之间的对比。 我们建议发展 乳腺X射线摄影的蒙特卡罗模拟，将计算图像 质量和剂量作为光子能量和带宽的函数， 我们的PXR线人 我们将确定乳房X光检查所需的光子通量 可以从PXR源获得。 为了让源头更 实际上，我们将研究减少所需电子的方法。 能量低于20 MeV。 PXR生成的实验确认 在低到中等的电子束能量下，将尝试使用 现有的实验装置。

The objective of the proposed program is to investigate the use of parametric x-ray radiation (PXR) as a tunable, quasimonochromatic x-ray source for mammography. PXR is generated by placing natural or synthetic crystals, or multilayer structures into the path of a relativistic electron beam. The virtual photons associated with the fields of the electrons are Bragg reflected by the periodic crystal lattice and real x-rays appear at the Bragg angle. The production process is thus analogous to x-ray diffraction by crystals, except that the x-ray beam incident at the Bragg angle is replaced by a relativistic electron beam. This laser-like source is quasi-monochromatic, directional, easily tunable, and polarizable. Such a source would permit the determination of the optimum photon energy which minimizes dosage and maximizes contrast between tumors and normal breast tissue. We propose to develop a Monte Carlo simulation of mammography, which will calculate image quality and dosage as a function of the photon energy and bandwidth of our PXR source. We will determine the needed photon flux for mammography that can be obtained from a PXR source. To make the source more practical, we will investigate methods for reducing the needed electron beam energy to below 20 MeV. Experimental confirmation of PXR generation at low to moderate electron beam energies will be attempted using an existing experimental setup.