Patent ID: 7496172

Claim:
A method for examining a defect in a steel bar, comprising steps of: (a) obtaining a reinforced concrete having a steel bar; (b) obtaining position of said steel bar; (c) locating a comparing object outside of said reinforced concrete; (d) locating a radiation source outside of said reinforced concrete; (e) radiating a ray penetrating through said reinforced concrete to project said reinforced concrete and said comparing object on an imaging device; and (f) obtaining defect size of said steel bar with images of said reinforced concrete and said comparing object obtained from said radiating step, wherein said radiation source radiates a ray selected from a group consisting of Ir(Iridium)-192, Co(Cobalt)-60 and Cs(Cesium)-137; and wherein said ray has a radiation intensity between 68Ci(Curie) and 82Ci wherein said comparing object is a spherical object.