Patent ID: 8517608
Filing Date: 2013-08-27
Classification: A61B,G16H

Abstract:
1. A method to calibrate computerized tomography scanners (CT) to produce image voxels expressed in Hounsfield Units referenced to water without the use of a water phantom by using only voxel intensities of tissues of a patient being scanned, the method comprising: determining at least one volumetric region of a CT scan that is positioned using computed anatomical measures; selecting unwanted sub-regions of the at least one volumetric region that are to be excluded from further analysis; determining the voxel intensity distribution of the at least one volumetric region after exclusion of the unwanted sub-regions; finding a first peak within the voxel intensity distribution; determining if the first peak is likely representative of a first identified tissue type having a first known tissue density; selecting a portion of the intensity distribution that does not include the first peak and finding a second peak; determining if the second peak is likely representative of a second identified tissue type having a second known tissue density; finding two voxel intensity measures representative of the two peaks of the voxel intensity distribution; finding a calculated voxel intensity half way between the representative voxel intensity measures of the two peaks and defining the calculated voxel intensity as a measured calibration reference point; computing a computed theoretical density of the calibration reference point using the known densities of the two identified tissue types; and using the measured calibration reference point and the computed theoretical density of the calibration reference point to compute calibrated voxel intensities in HU values.