Identification of elemental weight fraction and mass density of humanoid tissue-equivalent materials using dual...

The purpose of this study was to obtain the fraction by weight of the elemental composition and mass density of a humanoid tissue phantom that includes lung tissue, soft tissue, and bone tissue, by using dual energy computed tomography (DECT). The fraction by weight and the mass density for tissue-equivalent materials were calculated by means of a least-squares method with a linear attenuation coefficient, using monochromatic photon energies of 10-140keV, as obtained from DECT. The accuracy of calculated values for the fractions by weight of H (hydrogen), C (carbon), N (nitrogen), and O (oxygen) as verified by comparing the values with those that were analyzed using the combustion technique. The fraction by weight for other elements was confirmed by comparing with the analyzed values by means of energy dispersive photon spectroscopy. The calculated mass densities for each tissue were compared with those that were obtained by dividing the weight by volume. The calculated values of the fraction by weight that were obtained by means of DECT had differences of 1.9%, 9.2%, 6.6%, 7.8%, 0.8%, and 0.2% at a maximum for H, C, N, O, P (phosphorus), and Ca (calcium), respectively, from the reference values analyzed by the combustion technique and energy dispersive photon spectroscopy. The difference in the mass density for tissue was 0.011g/cm³ at a maximum. This study demonstrated the fraction by weight and the mass density of the humanoid tissue-equivalent materials that were calculated by means of DECT were expected high accuracy.