Monte Carlo codes applications to the low let rays in radiation therapy

In radiation therapy, there is low LET rays: photons of 60Co, photons and electrons to 4 at 25 MV created in a linac, photons of 137Cs, of 192Ir and of 125I. To know the most exactly possible the dose to the tissue by this rays, software and measurements are used. With the development of the power and the capacity of computers, the application of Monte Carlo codes expand to the radiation therapy which have permitted to better determine effects of rays and spectra, to explicit parameters used in dosimetric calculation, to verify algorithms, to study measurements systems and phantoms, to calculate the dose in inaccessible points and to consider the utilization of new radionuclides. (author)