Affiliation:
1. Department of Radiation Oncology Fudan University Shanghai Cancer Center Shanghai China
2. Department of Oncology Shanghai Medical College Fudan University Shanghai China
3. Shanghai Clinical Research Center for Radiation Oncology Shanghai China
4. Shanghai Key Laboratory of Radiation Oncology Shanghai China
5. Department of Medical Physics Shanghai Proton and Heavy Ion Center Shanghai China
6. Shanghai Engineering Research Center of Proton and Heavy Ion Radiation Therapy Shanghai China
Abstract
AbstractBackgroundMonte Carlo (MC) code FLUKA possesses widespread usage and accuracy in the simulation of particle beam radiotherapy. However, the conversion from computer‐aided design (CAD) mesh format models to FLUKA readable geometries could not be implemented directly and conveniently. A simple method was required to be developed.PurposeThe present study proposed a simple method to voxelize CAD mesh format files by using a Python‐based script and establishing geometric models in FLUKA.MethodsFive geometric models including cube, sphere, cone, ridge filter (RGF), and 1D‐Ripple Filter (1D‐RiFi) were created and exported as CAD mesh format files (.stl). An open‐source Python‐based script was used to convert them into voxels by endowing X, Y, and Z (following the Cartesian coordinates system) of solid materials in the three‐dimensional (3D) grid. A FLUKA (4‐2.2, CERN) predefined routine was used to establish the voxelized geometry model (VGM), while Flair (3.2‐1, CERN) was used to build the direct geometry model (DGM) in FLUKA for comparison purposes. Uniform carbon ion radiation fields 8×8 cm3 and 4×4 cm3 were generated to transport through the five pairs of models, 2D and 3D dose distributions were compared. The integral depth dose (IDD) in water of three different energy levels of carbon ion beams transported through 1D‐RiFis were also simulated and compared. Moreover, the volume between CAD mesh and VGMs, as well as the computing speed between FLUKA DGMs and VGMs were simultaneously recorded.ResultsThe volume differences between VGMs and CAD mesh models were not more than 0.6%. The maximum mean point‐to‐point deviation of IDD distribution was 0.7% ± 0.51% (mean ± standard deviation). The 3D dose Gamma‐index passing rates were never lower than 97% with criteria of 1%–1 mm. The difference in computing CPU time was 2.89% ± 0.22 on average.ConclusionsThe present study proposed and verified a Python‐based method for converting CAD mesh format files into VGMs and establishing them in FLUKA simply as well as accurately.
Subject
Radiology, Nuclear Medicine and imaging,Instrumentation,Radiation