SU‐C‐211‐01: First Results from a Preclinical X‐Ray Phase‐Contrast CT Scanner

Purpose: One of the main limitations of absorption‐based x‐ray imaging of biomedical specimen is the weak soft‐tissue contrast. This limitation can be addressed by phase‐sensitive imaging methods facilitating considerably improved density resolution. During the last decades various approaches have been investigated ‐ amongst them grating‐based interferometric methods with laboratory x‐ray sources. As a first step towards clinical applications, we have developed a grating‐based compact preclinical phase‐contrast CT scanner, from which we present the first commissioning results. Methods: The grating interferometer translates a small local refraction signal of x‐rays in the sample to intensity modulations that can be detected with a conventional x‐ray detector. Using a generalized filtered backprojection based reconstruction algorithm to account for the cone‐beam geometry, phase‐sensitive tomographic imaging of whole rodents is possible. A first phantom study was performed to investigate the performance, quantitativeness and accuracy of phase‐contrast and absorption‐based computed tomography scans. These scans yield the three‐dimensional distribution of attenuation coefficient mu and refractive index decrement delta of the different liquids contained in the phantom. Further performance experiments were conducted to assess the rotation stability and to optimize the phase‐contrast acquisition protocol of the compact gantry system. Results: The experimental phantom data for mu and delta match accurately with tabulated data, and demonstrate that the compact gantry performs well in both absorption and phase contrast. In addition, first imaging results from small‐animal models will be presented. Conclusions: We show results of the first implementation of phase‐contrast imaging into a compact, rotating x‐ray CT gantry system. We believe that this work represents an important milestone in translating phase‐contrast from bench to bedside.