New calculation method for 3D dose distribution in tetrahedral-mesh phantoms in Geant4

Abstract

The tetrahedral-mesh (TM) geometry, which is a very promising geometry for computational human phantoms, has a limitation in 3D dose distribution calculation for medical applications. Even though Geant4 provides the read-out geometry for calculating 3D dose distribution in the TM geometry, this method significantly slows down the computation speed. In the present study, we developed a new method, called Moving Voxel-based Dose-Distribution Calculator (MVDDC), to rapidly calculate a 3D dose distribution in a TM geometry. To evaluate the performance of the MVDDC method, a simple TM cubic phantom and a human phantom were implemented in Geant4. Subsequently, the phantoms were irradiated with proton spot beams under various conditions, and the obtained results were compared with those of the read-out geometry method. The results show that there is no significant difference between the dose distributions calculated using the new method and the read-out geometry method. With respect to the computational performance, the speeds of simulations using the MVDDC were approximately 1.4–2.7 times faster than those of the simulations using the read-out geometry method.