About Radiation in natGd for Neutron Capture Therapy
Annotatsiya
In the present work, based on publications dedicated to nat Gd natural gadolinium isotopes, characteristics of secondary particles are analysed in details for various neutron-induced reactions. Characteristics of the secondary particles produced in these reactions that make significant contribution to absorbed dose are estimated. It is also established that the main contribution to the absorbed dose is made by secondary particles produced in interactions of neutrons and 155 Gd and 157 Gd isotopes. From comparison of gamma-radiation spectra it is defined that the amount of -quanta with energies 0-400 keV (i.e. effective -quanta) produced in the (n,)-reaction by 155 Gd is higher than that by 157 Gd. Compared spectra of other particles (internal conversion electrons, Auger electrons, x-ray radiation) have shown that earlier used average values of their energy must be defined more precisely. When biological objects are irradiated for approximately 30 minutes by epithermal neutrons in the nat Gd NCT (Gadolinium-based neutron-capture therapy), one should take into account energies of secondary particles produced by 152 Gd, 154 Gd, 156 Gd, 158 Gd and 160 Gd isotopes as they have high linear energy transfer (LET). It is demonstrated that when combined, all these secondary particles can make significant contribution to the absorbed dose at neutron-irradiation of biological objects by the nat Gd NCT technique.