X-ray dark field refraction-contrast imaging - a new tool for medical imaging

Refractive contrast, originating from the variation of refractive indices of different parts of studied objects, in many cases, produces much more detailed images than conventional absorption contrast imaging techniques, especially when biological tissues are involved or observed features are on a scale of less than 1 mm. In this paper we describe a new method, referred to as dark-field refraction-contrast (or phase-contrast) imaging, which contrary to many other refraction-contrast imaging techniques can use laboratory X-ray sources rather than coherent synchrotron radiation. The signal-to-noise ratio in the described method is significantly increased due to the suppression of the shot noise produced by the direct (unrefracted) beam, thus leading to substantial reduction of radiation dose compared to standard X-ray radiography.