Page 85 - 00. Complete Version - Progress Report IPEN 2014-2016

Application of Ionizing Radiations | Progress Report 85

seeds consist of a welded titanium capsule (0.8 Iodine-125 seeds can be placed loose or strand-
mm diameter and 4.5 mm length) containing ed in bioabsorbable polymers. Stranded seeds
Iodine-125 adsorbed onto a silver rod. During show some advantages, since they reduce the
the project execution, the following methods rate of seed migration, an event that could af-
were developed: the seed core fect the dosimetry of the prostate and cause
unnecessary damage to healthy tissues or or-
(silver) cutting, the titanium tube cutting, the gans. For Iodine-125 stranded seeds, polygla-
iodine immobilization through its deposition ctin 910 (poly(lactic-co-glycolic acid)) (PLGA),
in silver substrate and the sealing of the seeds with a coverage of polyglactin 370 (Vicryl ®)
through welding process, so that the classifi- is used.
cation of the seeds, as sealed sources, and the
leakage tests can be done according to the in- It was purposed, in this project, the study and
ternational norms. In the moment, the routine development of the synthesis methodology for
production line is settling up. The production PLGA via ring-opening polymerization, as well
line consists in three gloves-boxes. In the first as its characterization, with the objective of us-
one(,) the Iodine-125 will be adsorbed in the sil- ing the synthesized material to manufacture a
ver core. In the second one, the titanium tube material similar to RAPID Strand®. The results
will be sealed. And finally, in the third one, all obtained show that it was possible to deter-
the assurance tests will be carried out. All the mine the optimal reaction parameters (time
automation process of the welding glove and and temperature) for PLGA in 80/20 (lactide/
the quality control glove are finished. glycolide) ratio. Using a temperature of 110° C
and reaction time of 24h, a yield of 86% was
Methods for Iodine-125 obtained, and increasing the reaction time to
deposition in silver substrate 72 hours, the yield was higher than 90%. The

molecular mass values obtained from the sam-
Among the different ways to treat prostate ples are still very low compared to those ob-
cancer, brachytherapy with Iodine-125 seeds tained by other authors in the literature (about
is an option that provides good results and 20%). Failures in the sealing of vials, leaving
fewer side effects. In the present study, sev- them vulnerable to moisture and oxygen, or
eral methods of deposition of radioactive io- lack of an efficient stirring system might be
dine in a silver substrate were compared in possible explanations for these results. A suit-
order to choose the most suitable alternative able chemical reactor could solve the problem.
for the routine production to be implement- Regarding polymer characterization, all tech-
ed at IPEN’s laboratory. The methodology used niques used not only confirmed the expected
was chosen based on the available infrastruc- structure of the polymer, but also showed the
ture and experience of the researchers pres- highest proportion of lactide units compared
ent. The better method will be implement- to glycolide units.
ed in the IPEN’s laboratory for brachytherapy
sources production. Study and parameters survey for
Iodine-125 source dosimetry to
Development of methodology for be applied in brachytherapy
the synthesis of Poly(Lactic Acid-
Co-Glycolic Acid) for use in the The objectives of this work are the develop-
production of radioactive sources ment and the study of dosimetric procedures