344. Radiobiological supplying of oncological patient radial therapy

AimThe examination of radiobiological peculiarities of therapeutic ionizing radiation source action gives an opportunity of preferable choice of exposure requirements of the oncological patients. The therapeutic ionizing radiation source, inlet into operation, should pass radiobiological examination, including with the purpose of definition of relative biological effectiveness (RBE) depending on quality, radiation dose, radiosensitiveness of cells etc.Materials and methodsThe cytogenetic dosimetry is carried out at an exposure of man Iymphocyte culture the on therapeutic source 137Cs, 60Co, neutrons with average energy 6 and 22 MeV.ResultsIs shown that isoeffective distribution of the neutron energy does not correspond with physical isodose distribution allowing for RBE constant value. For the first time is shown that for optimization of patient exposure therapeutic effect rationally to use neutron RBE variable values. For the first time is shown that RBE value of 137Cs gamma-quantum used for intracavitary radiotherapy, exceed 1 (in comparison with 60Co) and in dose range 0,15 – 5,0 Gy makes 3,5 – 1,2 accordingly. The method of approximating of association “dose - effect” on basis of spline regression which is characterized by smaller values of model parameter errors for various cytogenetic indexs and enables to forecast effect of calibrating curve outlet on a plateau is designed and proposed.ConclusionThe dose curves for RBE definition of therapeutic ionizing radiation source on the basis of spline regression model have to be taken into consideration for decrease of frequency and expressiveness of radiocomplications at an oncological patient exposure