X-ray equivalent energy can be used to measure mass thicknesses of materials. Based on this
a method of mass thickness measurement of dual-sample was discussed. It was found that in the range of sample mass thickness under investigation
the equivalent mass attenuation coefficient of a component could be used to compute mass thicknesses of a dual-sample
with relative errors of less than 5%. Mass thickness measurement of a fish sample was performed
and the fish bone and flesh could be displayed separately and clearly by their own mass thicknesses. This indicates that the method is effective in mass thickness measurement of dual-sample of suitable thicknesses.