Gamma spectrometry and chemical characterization of bioactive glass seeds with Samarium-153 for oncological implants

Bioactive glass seeds synthesized by the sol-gel technique with Si:Sm:Ca composition with natural Samarium incorporated were irradiated in the TRIGA type nuclear reactor IPR-R1 at 100 kW, in a place where the thermal neutron flux is 6.6x1011 n/cm2.s. After irradiated for about 4 hours, with an induced activity around 1.2 MBq/seed, a set of micro seeds was submitted to Gamma Spectrometry Analysis in a counting system with a HPGe detector, ORTEC electronic instrumentation and a Camberra Multichannel Analyser, to determine all radionuclides present on the sample as well as its individual activities. Special attention was paid on the discrimination of Si, 40Ca, 44Ca, C and Sm as the other expected elements like 48Ca, 2H and 18O were present in traces or have very short half-lives. The second sample was submitted to Plasma spectrometry to determine the 153Sm concentration in weight. The third sample was submitted to an X-ray spectrometry in a JEOL-JXA- 8900RL equipment to determine its qualitative chemical composition, in order to evaluate impurities and nominal composition. It was determined that most of the activity, after decaying of short half-life elements, was due to 153Sm present on the sample, with a well-characterized β and gamma spectra. The homogeneity of the seeds was tested on the X-ray spectrometry, and verified that there is no discrepancy in composition from distinct seeds or in a same seed. The results are relevant on the investigation of the viability of producing 153Sm radioactive seeds for oncological implants. (author)