Figure 2.

Step one (a) in medical linac simulation using phase space (Phs), different parts in the simulation are represented: electron beam, target, primary collimator, beryllium window, flattening filter, ion chamber, Phs and jaws. Step two in simulation using Phs as a source (b), the hexagonal pattern of modeled grid block (c), and the schematic diagram of the modeled linear accelerator with a grid (d).