Polycapillary optics for medical applications

Polycapillary optics can be designed for a wide variety of x-ray applications, including x-ray fluorescence for non-destructive materials analysis and diffraction applications such as protein crystallography. Of particular interest are medical applications, including the removal of Compton scattering with the resultant improvement in contrast and resolution in mammography, the production of monochromatic parallel beams for high-contrast imaging in clinical settings and the localization of radioactive tracers. A recent development is the use of polycapillary optics to improve beam coherence for x-ray phase imaging. Conventional radiographic techniques depend on attenuation, which provides only low contrast between soft tissues. Phase imaging can yield significantly higher contrast but requires spatially coherent beams. Conventional sources small enough to produce high coherence are necessarily low power, requiring long exposures. Polycapillary optics employed to create a small secondary source from high power sources have been shown to yield strong phase effects. Polycapillary optics can also be combined with other x-ray optics. A combination of a toroidally bent crystal with a polycapillary optic has been shown to produce enhanced resolution in a magnified image. Another x-ray imaging technique which does not rely on the small attenuation contrast is the capture of coherently scattered radiation, for which polycapillary optics could be used as angular filters to collect the beam, resulting in a map of tissue or material type.