Visualization for volume data scored by Geant4 simulation

In radiotherapy simulations, Monte Carlo-based radiotherapy simulation is applied to a high accurate calculation of dose distributions in a patient or optimization of the beam delivery system. Geant4 toolkit has come to be utilized to build a Monte Carlo simulator for that purpose. It needs the volume rendering capability to display a complex volume data by a visualizer. However, there is no volume rendering capability in the visualization system in Geant4. A volume visualization driver for Geant4 is described in this paper, which is available to display a complex patient image and a dose distribution calculated in a Geant4-based radiotherapy simulation with an external volume visualizer. The volume visualization driver extracts a patient data set, calculated dose distributions, particle trajectories and geometrical information of beam delivery modules in the simulation, and then saves their information as a data file. With that data file, the external volume visualizer is able easily to display results of the simulation.