Objective:The purpose of the work presented here was to enable easy access to Monte Carlo dose calculation for both fast neutron therapy and boron neutron capture therapy for research purposes. The dose calculation approach was especially intended to hold high customization potential for individual user applications.Approach:The dose engine is based on the Monte Carlo code MCNP. It is integrated into the MATLAB-based open source research treatment planning software matRad as modular component.Main results:Total dose calculation is enabled for both fast neutron therapy and boron neutron capture therapy on patient CT data. The evaluation of the dose distribution is possible using the matRad graphical user interface and dose volume histograms. Customization options are provided for advanced users.Significance:The open source treatment planning software allows easy access to highly accurate Monte Carlo dose calculation for research projects.