Differential pencil beam dose computation model for photons

摘要: Differential pencil beam (DPB) is defined as the dose distribution relative to position of first collision, per unit collision density, for a monoenergetic photons in an infinite homogeneous medium density. We have generated DPB tables number photon energies water using Monte Carlo method. The three-dimensional (3D) nature transport and electrons automatically incorporated distributions. Dose computed by evaluating 3D integrals dose. computation model has been applied calculate distributions 60Co accelerator beams. Calculations latter are performed energy spectra with program. To predict near boundaries collimation system well blocks, we utilize angular incident photons. Inhomogeneities taken into account attenuating primary fluence exponentially utilizing average total linear attenuation coefficient intervening tissue, multiplying yield collisions scattering volume, scaling path between volume element point effective