Central axis depth dose for a 2.5 MV Van de Graaff generator.

ABSTRACT

Central axis percentage depth dose values and isodose curves for the bremsstrahlung beam from a 2.5 MV Van de Graaff generator were measured with a water phantom at 100 cm target-to-surface distance. Tissue-air ratios were calculated from the central axis depth dose data. Use of the 2.5 MV percentage depth dose values are necessary for treatment planning since they are substantially larger than the values given in compilations for 2.0 MV beams.