MultiTrans SP3 code in coupled photon-electron transport problems

Detailed modeling of photon and electron transport is advantageous in radiotherapy and dosimetry. MultiTrans radiation transport code is based on tree multigrid technique and SP3 approximation. The standard SP3 approximation has been extended into a form that takes into account anisotropic group-to-group scattering. A first collision source method has been implemented. Applicability range of standard and extended SP3 approximations in coupled photon-electron transport problems is examined by comparing calculated doses with deterministic MultiTrans and stochastic EGS4 radiation transport codes.