TY  - THES
AB  - Materials which multiply scatter X-rays and consisting of weakly absorbing microstructures, such as lung tissue, deliver significant signals and remarkable contrast using the diffraction enhanced imaging (DEI) technique. The DEI technique is investigated with respect to multiple scattering properties and its applicability to soft tissue in order to improve medical diagnostics using phase contrast imaging as a new generation of radiography. Methods and calculation algorithms for extracting multiple scattering information by applying the DEI technique were recently developed considering ultra-small angle X-ray scattering. Algorithms and techniques developed in this work allow (i) extending the DEI technique to small-angle scattering of spherical and cylindrical micro-scattering particles, and (ii) computationally efficient analytical calculation of the scattering power by using the properties of a single scattering microparticle. This method was verified during several experiments at the large-scale facilities ELETTRA and ESRF using (i) synthetic specimens, and (ii) applying the calculations to a cow lung tissue specimen assuming alveolar air. While specimen preparation and deflation of the specimen led to uncertainties, the method was verified in this case by comparing the predicted scattering power of mouse lung tissue with Monte-Carlo simulations of the DEI group of Monash University, Melbourne (AUS).
The influence of specimen substructure on multiple scattering is investigated and can be qualitatively reconstructed using the model of scattering elaborated in this work. Calculated scattering angle distributions predict strong influence of substructures on the scattering power.
The instrumental effects of the analyser crystal, acting as an angular band-pass filter, on the multiple scattering power are analysed and simulated by calculation. Similar cut-offs by the analyser crystal are expected for soft tissue as for the synthetic specimens: The calculated scattering power of the cow lung tissue specimen as well as an exemplary calculation of the scattering power of a human lung for a frontal thorax exposure demonstrate a similar scattering power as the synthetic specimens.
AU  - Heitner, Gabriele Heike
DA  - 2005
KW  - Vielfachstreuung
KW  - Radiographie
KW  - Phasenkontrast
LA  - eng
PY  - 2005
TI  - Multiple scattering for diffraction enhanced X-ray imaging
UR  - https://nbn-resolving.org/urn:nbn:de:hbz:467-1062
Y2  - 2024-11-22T01:28:19
ER  -