Electron depth-dose dependence on energy spectral quality.

Electron depth-dose curves and spectra have been measured from an experimental accelerator on which both energy and spectral shape could be varied independently. The measurements were made at nominal energies of 6 and 12 MeV, with the energy spread (FWHM) varied from 1.7% to over 10% of average energy. Changes in depth-dose fall-off characteristics correlated only weakly with the width of the accelerator's spectrum. The use of a single accelerator and experiment set-up eliminated the differences that have complicated previous comparisons of beams of different spectral quality, which have been based upon data from different accelerator designs.