A novel approach to separate absorption, refraction and scattering in analyzer based lung imaging

Abstract

In analyzer based imaging (ABI) scattering can be efficiently separated from refraction and absorption effects by acquiring three images of the sample. In the scattering image the lungs appear as areas of high intensity signal (area contrast), which is modulated by the local thickness of the scattering tissue intersecting the X-ray path. The scattering signal is also included in the so-called apparent absorption image, where it adds to the absorption contrast thanks to the extinction of rays which are deviated outside the analyzer crystal's acceptance window. The presence of scattering can be emphasized in the ratio between two images acquired with a strongly detuned and a perfectly tuned analyzer crystal, respectively: we name this ratio as the amplified scatter image. In this paper we present ABI scattering methods applied to postmortem mouse lung imaging to assess their diagnostic value. For this purpose images have been acquired at the SYRMEP beamline of the ELETTRA synchrotron in Trieste (Italy) with the Argus time delay integration CCD detector at a photon energy of 25 keV . Subsequently the parametric images, including the amplified scatter image have been obtained, and contrast and signal-to-noise ratio have been evaluated. It is noteworthy that images have been acquired with a radiation dose of some mGy, thus are compatible with dose restricted medical imaging settings such as mammography.