A Fast Experimental Beam Hardening Correction Method For Accurate Bone Mineral Measurements In 3d Ct Imaging System

Bone mineral density plays an important role in the determination of bone strength and fracture risks. Consequently, it is very important to obtain accurate bone mineral density measurements. The microcomputerized tomography system provides 3D information about the architectural properties of bone. Quantitative analysis accuracy is decreased by the presence of artefacts in the reconstructed images, mainly due to beam hardening artefacts (such as cupping artefacts). In this paper, we introduced a new beam hardening correction method based on a postreconstruction technique performed with the use of off-line water and bone linearization curves experimentally calculated aiming to take into account the nonhomogeneity in the scanned animal. In order to evaluate the mass correction rate, calibration line has been carried out to convert the reconstructed linear attenuation coefficient into bone masses. The presented correction method was then applied on a multimaterial cylindrical phantom and on mouse skeleton images. Mass correction rate up to 18% between uncorrected and corrected images were obtained as well as a remarkable improvement of a calculated mouse femur mass has been noticed. Results were also compared to those obtained when using the simple water linearization technique which does not take into account the nonhomogeneity in the object.Lay description The determination of bone mass in mice longitudinal experiments allow to study pathologies like osteoporosis or bone mass loss in cystic fibrosis patients. Computerized tomography is a very good method to perform this kind of bone mass measurements compared to ultrasound, .... computerized tomography consists in a X-ray tube and a detector. Due to the polychromatic nature of the X-rays produced by the tube, there are artefacts in the recorded images (compared to monochromatic source like X-rays from synchrotron). In this paper we propose a method to decrease these artefacts. It allows to obtain more accurate bone mass measurements. We validated our method on real mouse bones (femora and skull). The error was decrease from 5% to almost 0% in the case of femora (from 7% to 3% in the case of the skull).