Patent ID: 6574302
Filing Date: 2003-06-03
Classification: A61B

Abstract:
A method of determining a density of a volume in an image data set of an object (114) to be examined, which volume can be distinguished from its environment in that the volume contains a material having a characteristic parameter (&mgr;) which can be dedicated, which method includes the step of:exposing the volume with the environment to X-rays (101) in different exposure positions, in each exposure position there being performed an exposure with a first energy and with a second energy of the X-rays (101) so as to obtain on an X-ray detector a first set (1, 3) of transmission images of the object which corresponds to these energies, characterized in that the method also includes: the use of a two-dimensional detector (112) as the X-ray detector; performing a first calibration (7) in conformity with a dual-energy method so as to obtain a first set of parameters (xp1) and a second set (xa1) of parameters; performing a second calibration (9) in conformity with a dual-energy method so as to obtain a third parameter (&phgr;) and a fourth parameter (f), the third parameter being characteristic of the environment and the fourth parameter being characteristic of the material, performing a first operation (5) on the first set (1, 3) of transmission images while using the first set of parameters (xp1) and the second set of parameters (xa1) so as to obtain a set of density images (11, 13); applying the third parameter (&phgr;) to the set of the density images (11, 13) so as to eliminate the environment from the set of density images (15); carrying out a 3D reconstruction algorithm (20) with information of the set of density images so as to obtain an image of the volume (30); applying the fourth parameter (f) to the image of the volume so as to calculate the density of the material in the volume (50).