In the present work, based on publications dedicated to ^natGd natural gadolinium isotopes, characteristics of secondary particles are analysed in details for various neutron-induced reactions. Characteristics of the ...In the present work, based on publications dedicated to ^natGd 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 ^155Gd and ^157Gd isotopes. From comparison of gamma-radiation spectra it is defined that the amount of γ-quanta with energies 0-400 keV （i.e. effective γ-quanta） produced in the （n,γ）-reaction by ^155Gd is higher than that by ^157Gd. 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 ^natGd NCT （Gadolinium-based neutron-capture therapy）, one should take into account energies of secondary particles produced by ^152Gd, ^154Gd, ^156Gd, ^158Gd and ^160Gd 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 ^natGd NCT technique.展开更多
文摘In the present work, based on publications dedicated to ^natGd 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 ^155Gd and ^157Gd isotopes. From comparison of gamma-radiation spectra it is defined that the amount of γ-quanta with energies 0-400 keV （i.e. effective γ-quanta） produced in the （n,γ）-reaction by ^155Gd is higher than that by ^157Gd. 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 ^natGd NCT （Gadolinium-based neutron-capture therapy）, one should take into account energies of secondary particles produced by ^152Gd, ^154Gd, ^156Gd, ^158Gd and ^160Gd 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 ^natGd NCT technique.
