X-Ray CT (Computed Tomography) was developed as a non-distractive inspection tool, and the system spread firstly in the medical field. Since the advantage as a non-distractive inspection tool is recognized in the engineering field, X-ray CT system has been applied in the various kinds of research field including rock engineering. In the case of rock engineering, rocks inevitably contain a lot of hetelogeneity, such as cracks, pores and different kinds of grains. Therefore, the understanding of these characteristics is the first step to develop the research, and X-ray CT has been expected as one of the most useful and effective tools. In this paper, fundamental knowledge of X-ray CT system, types of X-ray CT scanners and their applicability to the rock engineering were introduced. Here, the subjects were focused on the geomaterials such as rocks, stones and closely related materials, and histories of the X-ray CT applications for each research topic, way of analysis and merit/demerit of X-ray CT applications were introduced. The prospective of X-ray CT and its application were also discussed.
