Figure 2. (a) The energy spectra of the 6 MV and 10 MV beams of an Elekta SL15 linear accelerator (Elekta, Crawley, UK) as generated by Monte Carlo simulation, using energy bins all 0.1 MeV in width. (b) The spectra rebinned for use in Pinnacle³ (Philips Radiation Oncology Systems, Milpitas, CA), with the unequally spaced energy bins depicted along the top of the graph.