Figure 4.

The absorbed-dose energy dependence of EBT film calculated for monoenergetic photons and for spectra versus either the photon fluence weighted mean energy or the effective energy based on HVL calculations (uncertainties for spectral calculations smaller than symbols). For comparison, the inverse of the relative absorbed-dose sensitivities relative to 6 MV beams from Butson et al. (Ref. ⁴), Rink et al. (Ref. ⁵), and Richter et al. (Ref. ⁷) are shown where the effective energies of their spectra were determined using HVL measurements [or with an equation in the case of the two high photon energy data points from Richter et al. (Ref. ⁷)]. The uncertainties for the spectral calculation data points are smaller than the symbols.