Abstract
Computed tomography system for in situ NDE of degradation bridges is under development, with portable 950 keV/3.95 MeV X-band linac as x-ray source. Collimator is adopted to reduce scattered X-ray noise and 3D model can be built from sectional images so that it becomes possible to evaluate mechanical characters of bridges referring to structural analysis with reduced stiffness. Furthermore, considering limitation of projection angle range during in situ scanning, reconstruction technique with incomplete projection data is studied with experimental data.