A model of an applicator for intracavitary brachytherapy of liver using Re188 which is a beta- and gamma-emitting isotope has been made at MEPhI “Medical Physics” Department with the help of Russian scientific center of radiology and nuclear medicine. A mathematical model of an applicator worked out in GATE/Geant4 environment has been used to determine optimal parameters. This software environment has been used for modelling of radiation transfer process based on "Monte Carlo" method. GATE (GEANT4 Application for Tomographic Emission) has tools for calculating dose distribution and characteristics of scattered fields while making radiation therapy, and allow to use radionuclides and materials of system simulation Geant4 (Geometry ANd Tracking).

Implementation of radiation safety standards for the most radiosensitive organs has been checked with the help of the model, and received results became a basis for a conclusion about the possibility of using this applicator in medicine.

The future project development requires a series of experiments with different constructions and their parameters. Following its results it will be possible to choose the ones which best fulfill medical and technical requirements. If necessary scientists will make further changes and check experimentally again.

As nowadays similar technologies are not applied in medicine, the development of such project will significantly improve existing methods of liver cancer treatment and consider possibilities of its application for other organs.

Unfortunately, nowadays liver cancer is a wide-spread oncological disease of abdominal cavity. The main task for a specialist in realization of this method is the choice of applicator construction and its parametres.