The effects of the stopping power ratios of different protocols on %DD curve were investigated in this study.
METHODS
Percentage ionization curve was measured at SSD=95 cm
using 10x10 standard cone and 6, 8, 10, 12, 15 and 18 MeV
electron energies. Stopping power ratios at each depth were
determined as recommended by the three protocols. %DD
curves were then found and compared. The stopping power
ratios of the different protocols were determined and plotted
against R50.
RESULTS
The stopping power ratios of the different protocols did have
an effect on %DD curves. The clearest difference was seen at
the surface. The maximum difference was 1.45% at 10 MeV,
while the minimum difference was 0.09% at 6 MeV.
CONCLUSION Stopping power ratios as found using realistic electron beams provide more accurate surface doses, as reported in the literature.
Keywords : Stopping power ratios; electron beams; clinical protocols/ standards; IAEA protocols