Soutenance de thèse
mardi 6 décembre 2022 à 13:30
Radionuclides of terbium have attracted much attention for their potential applications in nuclear medicine. However, the short supply of terbium isotopes has limited their applications. This work proposes to use enriched gadolinium targets to produce terbium radioisotopes in biomedical cyclotrons via light-particle-induced reactions. The Auger and gamma emitter 155Tb is taken as a study case, the involved production reaction is 155Gd(d, 2n)155Tb.
To estimate the production yield, thin Gd containing targets have been firstly developed to measure the reaction cross sections. To this end, the electrochemical co-deposition method has been chosen to manufacture Ni-Gd2O3 composite targets. Several process parameters that have an impact on the deposit quality have been investigated to increase the incorporation of Gd mass (up to 3 mg). The cross section measurement of the reaction natGd(d,x)Tb, as the proof-of-conception experiment, have been carried out at GIP ARRONAX using natural Ni-natGd2O3 targets. The obtained results are consistent with existing data. Then the cross section of 155Gd(d,x)Tb has been measured using enriched Ni-155Gd2O3 composite targets. The beam energy ranges from 8 MeV to 30 MeV. The production yield is estimated using these measured results.
Thick targets are also developed via pelletizing method for mass production. The optimal experimental conditions and the physical and thermal properties of the pellets under these conditions are investigated. A manufactured enriched 155Gd2O3 target was irradiated with an incident energy of 15 MeV. The production yield of 155Tb was found to be 10 MBq/µAh and the purity is 89% in good agreement with the estimate obtained using the measured cross section.
The coproduction of other Tb isotopes, and the recycle of Gd are also part of this thesis.
Keywords: terbium production, cross-section measurement, production yield, deuteron irradiation, theranostics radioisotope, cyclotron-produced radionuclide