Charged particle therapy is a rapidly developing way for tumor treatment. During irradiation, the primary beam interacts with tissues nuclei results in the production of radioactive isotopes and secondary particles emission, e.g. electrons, gammas and neutrons. Estimation of the treatment effect of secondary radiation using only Monte Carlo is not precise and, depends on the type of radiation, the direct measurement of it is difficult. During presentation the experimental results of induced radioactivity will be discussed. Such experiments have been done at the Institute of Nuclear Physics PAS. Moreover method of neutron energy spectrum measurement will be presented. Measured spectra and geometry of experimental set-ups allow appraising the cross-section of reactions that occurs in the target and then calculate the dose that is deposited in human tissues as a result of therapy aside from the primary beam.