In recent years, the X-ray refraction contrast was widely developed and applied in different fields of science which deal with the nondestructive observation methods. As it follows from the name, the refraction contrast is the distribution of the X-ray intensity dependent on the deflection angle of the X-ray beam. This property of the contrast provides certain advantages over other contrasts such as absorption and phase-shift. The refraction contrast can show tiny details of the inner structure which are invisible in other types of the X-ray imaging techniques. Another advantage of the X-ray refraction contrast is the sensitivity to the low Z materials. This property of the refraction contrast may be of great importance in the medical applications of the X-ray. The advantages provided by the refraction contrast allow one to expect the same advantages of the computed tomography (CT) from the refraction contrast. Therefore this report is dedicated to the realization of the refraction-based CT. It describes the theoretical background of the problem, experimental realization of the method and actual results of the reconstruction of the breast cancer sample. The experimental data were acquired using X-ray synchrotron source at Photon Factory (KEK, Japan). The energy of used in the experiment was 11.7keV. The spatial resolution of the reconstructed images is about 20 microns.
We have developed X-ray refraction based computed tomography (CT) which is able to visualize soft tissue in
between hard tissue. The experimental system consists of Si(220) diffraction double-crystals called the DEI (diffraction-enhanced
imaging) method, object locating in between them and a CCD camera to acquire data of 900 x-ray images.
The x-ray energy used was 17.5 keV. The algorithm used to reconstruct CT images has been invented by A.
Maksimenko et al.. We successfully visualized calcification and distribution of breast cancer nest which are the inner
structure. It has much higher contrast which in comparison with the conventional absorption based CT system.