Phase-Contrast X-Ray Imaging

Conventional x-ray imaging is based on partial absorption of the radiation in the object (absorption-contrast x-ray imaging). It may therefore be difficult to examine very thin samples, or objects of light and weakly absorbing materials.

Phase-contrast x-ray imaging may, however, generate images of such objects. Phase contrast occurs because the phase of the x-rays is changed as the radiation passes through an object. Letting the x-rays propagate some distance past the object before being recorded by a detector will result in interference patterns in the image. These patterns are the result of high refractive index gradients in the object, which occur at e.g. edges and material boundaries in the object.

Due to the distance from the sample to the detector this imaging technique needs very long exposure times. Acquisition of images with a high signal-to-noise level may require several minutes of exposure with a conventional solid anode x-ray source. Using a metal-jet anode microfocus x-ray source instead immediately reduces the exposure time by a factor of ten.