Patent ID: 8325972
Filing Date: 2012-12-04
Classification: G01B

Abstract:
1. A method of carrying out measurements with penetrating radiation on a hollow object having an axial axis, comprising at least one wall surrounding an inner space of the object, said wall comprising an inner surface and an outer surface, said method at least being carried out for determining a position and shape of the inner surface of at least a first portion of the wall and comprising the following steps: a. transmitting radiation through the object such that the radiation is transmitted through at least the at least one first portion of the wall to be examined and through other second portions of the wall of the object by means of at least one radiation source; b. receiving radiation which has travelled through said portions of the wall by means of at least one detector unit for registering at least one radiation image of the object, said at least one radiation image representing the positions where the radiation is received together with the intensity of the received radiation on said positions; c. creating signals by means of at least the at least one detector unit which signals represent the registered at least one radiation image; d. feeding said signals to at least one computer; e. providing the computer at least with (i) information about at least one attenuation coefficient of the wall material or wall materials for the used radiation and/or the function of attenuation of the wall thickness of the wall material or wall materials for the used radiation, (ii) information about the used positions and directions of the transmitted radiation relative to the object and (iii) at least the at least one used position of the radiation detector relative to the object and/or information which can be derived there from (i, ii, iii); f. calculating by means of the computer at least an estimated position and shape of the inner surface of the at least one first portion of the wall on the basis of the registered at least one radiation image on the one hand and on the basis of at least the information provided in step e. on the other hand; g. changing in step a. at least one time the position of the radiation source relative to the object in a direction comprising at least a component in the direction of the axial axis such that in step a. the radiation is first transmitted through the object wherein the radiation is transmitted through at least the at least one first portion of the wall to be examined and through one of the second portions of the wall by means of the at least one radiation source for registering a first radiation image and such that in step a. after the position of the radiation source is changed at least one time the radiation is subsequently transmitted through at least the at least one first portion of the wall to be examined and through a second portion of the wall which differs from a second portion of the wall through which the radiation was previously transmitted, for registering at least one further radiation image which differs from the previously obtained radiation image, wherein the directions of the transmitted radiation relative to the first portion of the wall changes if the radiation source is moved in the direction having a component in the direction of the axial axis, said first registered radiation image and said at least one further registered radiation image being used in step f. for carrying out said calculations.