Xiangyang Tang PhD, Presenter: Research Grant, Ningbo Xingaoyi Magnetism Co Ltd

Yi Yang PhD, Abstract Co-Author: Nothing to Disclose

We propose to utilize microbubbles as the contrast agent in grating-based x-ray phase contrast CT. Via a phantom study, we investigate the bipolar contrasts generated by microbubbles in grating-based x-ray phase contrast CT and its variation over the size of microbubble targets and detector cells.

The phantom consists of seven targets that are clusters of microbubbles at diameters 2.5 μm. To simulate the small lesions in advanced clinical and preclinical applications, microbubbles are deployed along a spiral locus in each cluster with its outer dimension from the smallest to largest equal to 50, 75, 100, 250, 500, 1,000 and 2,500 μm. To assure a random deployment that mimics a chaotic distribution, half of the microbubbles in each cluster are randomly removed. The projection data are acquired at a 1º angular interval over 360º range. In data acquisition, a 31.6 keV monochromatic x-ray source with infinitesimal focal spot is assumed. At each angular position, grating G1 shifts 8 steps, and the x-ray exposure is gauged as a summation over all the 8 steps of grating shifting and equal to 5.0x107 photon/cm2. To investigate the contrast generated by microbubbles over spatial resolution, we conduct the study at detector cell sizes 48, 96, 128 and 256 μm, respectively.

The preliminary data show that the contrast generated by microbubbles in grating-based x-ray phase contrast CT is bipolar: the one generated by the differential phase contrast mechanism is negative, while that by the dark-field mechanism is positive. Moreover, the microbubbles’ bipolar contrasts in x-ray phase contrast CT are significantly larger than its counterpart in the conventional attenuation CT.

Using microbubbles as the contrast agent, the grating-based x-ray phase contrast CT may outperform the conventional attenuation CT significantly, especially in the scenarios where small lesions are to be detected at high spatial resolution.

The preliminary results reported in this study may be of relevance to the preclinical and eventually clinical applications of grating-based x-ray phase contrast CT.

Tang, X, Yang, Y, Bipolar Contrasts Generated by Microbubbles in Grating-based X-ray Phase Contrast CT.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13028701.html