A method for improving tomographic determinations for the inspection of steel reinforcements in concrete structures, said method comprising the steps of: i. defining and fixing a main coordinate system to the structure under study, to which the results of the analysis will be referred; ii. providing a reference system with a plurality of independently identified and individualized reference elements (104,207) made of a high density radiation-absorbent material and contained in a rack (101, 205), such reference elements being arranged in accurately known positions on a radiation source (201,202) side and/or a recording means side of said structure in order to record fiducial marks on the recording means; iii. determining irradiation times; iv. irradiating said structure with penetrating radiation from different positions (201,202) by means of a radiation source (201,202) and v. recording, in recording means, said radiation transmitted through said structure for the different positions of the radiation source (201,202); vi. providing each successive measurement with an identifier; and vii. determining the position of the fiducial marks resulting from the reference elements (104,207) in the racks (101,205), and then determining the position of both the radiation source (201,202) and the recording means with respect to the structure under study, based on the position of such fiducial marks; viii. determining the position and size of reinforcements within a structure based on information recorded on each of the recording means used for measurement by means of combining the data resulting from the different coordinate systems for each of the recording means in the single main coordinate system fixed to the structure under study. i. defining and fixing a main coordinate system to the structure under study, to which the results of the analysis will be referred; ii. providing a reference system with a plurality of independently identified and individualized reference elements (104,207) made of a high density radiation-absorbent material and contained in a rack (101, 205), such reference elements being arranged in accurately known positions on a radiation source (201,202) side and/or a recording means side of said structure in order to record fiducial marks on the recording means; iii. determining irradiation times; iv. irradiating said structure with penetrating radiation from different positions (201,202) by means of a radiation source (201,202) and v. recording, in recording means, said radiation transmitted through said structure for the different positions of the radiation source (201,202); vi. providing each successive measurement with an identifier; and vii. determining the position of the fiducial marks resulting from the reference elements (104,207) in the racks (101,205), and then determining the position of both the radiation source (201,202) and the recording means with respect to the structure under study, based on the position of such fiducial marks; viii. determining the position and size of reinforcements within a structure based on information recorded on each of the recording means used for measurement by means of combining the data resulting from the different coordinate systems for each of the recording means in the single main coordinate system fixed to the structure under study.