Development of x-ray backscatter imaging system for inspection of concrete structure

With a goal of establishing a method to visualize, in detail on the spot, the interior of a road floor slab under asphalt having a thickness of several centimeters, or the interior of reinforced concrete or prestressed concrete structure, which has been impossible so far, the authors developed a backscatter X-ray imaging system. In this method, it was necessary to newly establish high-energy X-rays with high penetrating power and X-ray measurement technology simultaneously. The authors used C-band (5.3 GHz) acceleration cavity electron accelerator as a high-energy X-ray source, and demonstrated the possibility of practical realization of a small and stable X-ray generator. In addition, the authors used fan beam X-rays and a cadmium tungstate (CdWO₄: CWO) scintillator X-ray detection element, and newly developed a one-dimensional multi-slit X-ray detector suitable for the backscatter X-ray imaging system. The authors studied its characteristics and showed that it is applicable to the X-ray photography of concrete structures. This study has proven the effectiveness of applying the backscatter X-ray imaging system using high-energy energy X-rays with high penetration power to the nondestructive imaging of concrete structures and the like. (A.O.)