Corrections for beam‐hardening artifacts in computed tomography can be made by using a model which assumes that water and bone mineral are the only constituents of tissue. With this model, a correction factor for the measured transmission values can be calculated such that the reconstructed attenuation coefficients have values corresponding to a monoenergetic source of known energy. Systematic errors in the uncorrected attenuation coefficients, which may be 5%, can be reduced to less than 1% if corrected transmission values are used.