The work approaches the study of the dispersion of low energy radiations, which made possible contributions in nuclear and medical physics. There were developed several programs and calculation methodologies based on the numeric simulation by the monte carlo method. It stands out the determination of parameters of the radiation dose of neutrons and gamma ray sources used in medicine for brachytherapy. The authors overcome the difficulty of determining theoretically or experimentally the dispersion of particles such as neutrons and low energy gamma rays in a material environment as water or the human body. They have been able to solve this current problem of science through simulation techniques and the theory of the effective section of particle dispersion in a given environment.

The scientific contribution of these results is endorsed by:

• - 8 publications, 6 of them in international prestigious magazines,
• - 10 works published in memoirs of scientific events,
• - Technical documents of the OIEA, of the French commission of atomic energy,
• - Oral presentations in national and international events.

The works carried out made possible the creation of a software product that has national medical record to the "calculation module of dose absorbed in water of sources of iodo and iridium wire covered with platinum". This software allows calculating the dose absorbed in cerebral tissue around radio-active sources used in brachytherapy.