Development of a Phase Space Generator software for Medical Linear Accelerator Applications

Introduction: During the last decades, simulation of radiation therapy treatment conditions in treatment room for studying with more details in comparison with treatment planning system (TPS) is taken into consideration. The most problem with starting these kind of researches is the geometry of Medical linacs and verification of the accelerators. Therefore, researchers tried to produced phase space after constant parameters of linacs (target, primary collimator, flattening filters) before jaws and offering them to the other researchers specially by International atomic energy agency in IAEA or ROOT format. The goal of this study is to write a phase space generator software which can produced phase space for multiple medical linear accelerators in ROOT and IAEA format. These phase space can have been used in Geant4, Gate, EGSnrc and PENELPOE as a source.   Materials and Methods: In the first step, the head of multiple medical linac accelerators like Varian (Novalis TX, Trilogy, Clinac iX, Clinac DX, Clinac 2100 C/D, Clinac 21 EX, Clinac CX, Truebeam), Simens (Primus, Primus pulse, Artiste and ONCOR) and Elekta (Synergy, Compact, SL) in photon and electron mode in the present of wedge and different applicators were simulated and verified with Geant4. For verification of the simulated linac’s heads, the percentage depth doses (PDDs) and Profiles were compared with experimental data. The comparisons were done with Gamma Index code (3%, 3mm) in MATLAB. In the second step, a software was written which can produce phase space in two formats for the simulated heads without accessing the users to the heads geometry. To validate the accuracy and precision of written software results (Phase space files, PDDs and Profiles), the data which were extracted from these software was evaluated with the Geant4 results.   Results: Based on the Gamma Index results in the first step and evaluation of the produce Phase Space files, the software’s results have a good agreement with Geant4 and Experimental data.   Conclusion: In the written software several medical linacs were modeled and the users can produce ROOT and IAEA phase space format after adjust (regulate) the jaws or MLCs in needed positions and use them in different Monte Carlo codes. In this code most of the Varian, Siemens and Elekta models were implemented and the users can select the present of wedge and change its angel and even positioned the different form of shield in the beam line. Furthermore, user can define new accelerator using simple input Like EGS Code. These parameters are the advantages of this software related to the similar softwares like PRIMO.