IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
MOLECULAR STRUCTURE EFFECTS ON THE POST IRRADIATION DIFFUSION IN POLYMER GEL DOSIMETERS
Autor/es:
FACUNDO MATTEA; MARCELO ROMERO; JOSE VEDELAGO; ANDRES QUIROGA; MAURO VALENTE; MIRIAM STRUMIA
Lugar:
Cusco
Reunión:
Congreso; 14th INTERNATIONAL SYMPOSIUM OF SOLID STATE DOSIMETRY; 2014
Institución organizadora:
Soc. Peruana de Proteccion Radiologica
Resumen:
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Polymer gel dosimeters have
specific advantages for recording 3D radiation dose distribution
representing a key factor for most of the therapeutic and diagnostic
radiation techniques. Radiation-induced polymerization and
crosslinking reactions that take place in the dosimeter have been
studied for different monomers like acrylamide and
N,N?-methylene-bisacrylamide (BIS) and most recently for less toxic
monomers like N-isopropylacrylamide and BIS. In this work a novel
system based on itaconic acid and BIS is proposed, the radical
polymerization or gel formation of these monomers has been already
studied for the formation of an hydrogel for non dosimetric
applications and their reactivity are comparable with the already
mentioned systems. Although the 3D structure is maintained after the
dosimeter has been irradiated, it is not possible to eliminate the
diffusion of the reacted and monomer species in regions of dose
gradients within the gel after irradiation. As a consequence the dose
information of the dosimeters loose quality over time. The mobility
within the gelatin structure of the already mentioned species is
related to their chemical structure, and nature. In this work the
effect of changes in the chemical structure of the monomers over the
dosimetric sensitivity and over the post-irradiation diffusion of
species is studied. One of the acrylic acid groups of the itaconic
acid molecule is modified to obtain molecules with similar reactivity
but different molecular sizes. Dosimetric systems with these modified
species, BIS, an antioxidant to avoid oxygen polymerization
inhibition, water and gelatin are irradiated in an X-ray tomography
at different doses, and the resulting dosimeters are characterized by
Raman spectroscopy and optical absorbance to study their feasibility
and capabilities as dosimetric systems, and by optical-CT to analyze
the diffusion degree after being irradiated.