Beam Quality of kilovoltage therapy x-ray beams

Beam quality of a kilovoltage beam must be specified with both kVp and HVL.

Two different beams with different kVp may have the same HVL. For example a heavily filtered kV xray beam and a medium filtered kV beam of somewhat higher kV x-rays can have the same HVL, so specifying both kVp and HVL will specify beam quality with much less ambiguity.