Biophysical Studies with High-Energy Argon Ions: 1. Depth Dose Measurements in Tissue-Equivalent Liquid and in Water

The beam of high-energy argon ions available at the Lawrence Berkeley Laboratory BEVALAC was employed for biophysical experimentation. In preparation for radiobiological studies, depth doses were measured with a homogeneous tissue-equivalent ionization chamber which traversed the central axis of a tissue-equivalent liquid phantom irradiated by a large, uniform beam of ions. Ancillary measurements showed that for this beam: (1) the depth dose profiles measured in a water phantom and in a tissue-equivalent liquid phantom are essentially the same, provided that the difference in the electron densities of the liquids is taken into account; (2) the depth dose profile measured behind a water absorber is essentially the same as that measured within a water phantom; and (3) reliable dosimetry for tissue can be performed using air instead of tissue-equivalent gas in the cavity of a tissue-equivalent plastic ionization chamber. Biological results are reported in succeeding papers.