Comparison of percent depth doses for various linear accelerators

The aim of this study was to present the method of comparing Percent Depth Dose values (PDDs) for various electron energy beams produced by a linear accelerator in one mode of obtaining an electron beam as well as for electron beams generated in different modes. Four linear accelerators: Neptun 10p, Saturne II+, Philips SL20, Clinac 2300 C/D were employed. Normalization procedures were established as an appropriate method of comparing several PDD obtained in each accelerator. The normalization procedure when the dose is normalized to the depth selected by a physicist makes it possible to compare dose distributions for various energies obtained in linear accelerators both in the scattering and scanning modes. It is a convenient way to compare dose distributions as permits checking and controlling of the beam energy generated by a linear accelerator (during routine measurements). (author)