Conversion factor f for X-ray beam qualities, specified by peak tube potential and HVL value.

Conversion factors of exposure to absorbed dose f in compact bone, muscle, water and adipose tissue are deduced from the measured photon fluence spectra of x-ray beams with potentials from 50 to 250 kV. The results show that accurate determination of f requires beam quality specification not only by the HVL value but also by a second parameter, e.g. the peak tube potential. The differences between the conversion factors f obtained in this work and those deduced from the monoenergetic equivalent energy are evaluated.