Physics Bucharest 2017

PENCIL BEAM STEPS • Beforehand – Calculate pencil beam kernels from Monte Carlo • Kernel for each energy – Fit energy spectrum to measured depth dose curves using Monte Carlo – Generate polyenergetic pencil beam kernel • At time of calculation – Ray trace through accelerator head components and patient • Take into account energy spectrum and off-axis spectral changes – Convolve with source distribution

– Convolve with polyenergetic pencil beams at 8-10 depths – Calculate dose by interpolation between convolutions

Slide from Dr. James Bedford

ESTRO physics course, June 2017