Thesis (M.S.) --University of Texas Graduate School of Biomedical Sciences at San Antonio, 2008. / Vita. Includes bibliographical references.

Thesis (M. Sc.)--Carleton University, 2002. / Includes bibliographical references (p. 69-74). Also available in electronic format on the Internet.

Thesis (M. Sc.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 76-82). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 221-227).

Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). "August 2006." Includes bibliographical references (leaves 90-92). Also available via the World Wide Web.

The aim of this research project was to investigate ways of improving the accuracy of dosimetric measurements in pion radiotherapy. Interest in this area was stimulated by the results of recent experimental work which revealed that materials from which dosimeters in pion radiotherapy are routinely constructed are not tissue equivalent for pi-. Two means of achieving the stated objective were identified: 1. To produce materials which are tissue equivalent for pions, to use in the construction of phantoms and dosimeters. 2. To evaluate correction factors necessary to convert dose recorded under non-tissue equivalent conditions to that for tissue. An attempt was made to produce muscle and bone equivalent phantom materials. The extent to which the materials produced could be considered tissue equivalent was judged by comparing experimentally determined carbon to oxygen (C:O) and nitrogen to oxygen (N:O) pion atomic capture ratios with those for the corresponding tissue type. Negative pion atomic capture ratios were also evaluated for sets of simple organic compounds to aid further development of the theoretical models necessary to determine correction factors.

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Orientador: Solange Maria de Almeida / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-10T00:43:38Z (GMT). No. of bitstreams: 1 Freitas_DeborahQueirozde_D.pdf: 863530 bytes, checksum: bf09329a36f133306020d488b7ecaa3c (MD5) Previous issue date: 2007 / Resumo: A osteoporose e a irradiação são fatores que interferem no processo de reparação óssea e podem ocorrer simultaneamente, especialmente em mulheres idosas. Atualmente, várias substâncias, conhecidas como radioprotetores, têm sido estudadas, pois minimizam os efeitos deletérios da radiação; dentre eles, pode-se citar o selênio. O objetivo desse trabalho foi avaliar o efeito radioprotetor do selenito de sódio no processo de reparo ósseo em ratas ovariectomizadas submetidas à irradiação. Para isso, oitenta ratas foram submetidas à ovariectomia e divididas em quatro grupos: ovariectomizado, ovariectomizado/selênio, ovariectomizado/irradiado e ovariectomizado/selênio/irradiado. Quarenta dias após, um defeito ósseo foi confeccionado nas tíbias dos animais. Dois dias após essa cirurgia, os animais dos grupos ovariectomizado/selênio eovariectomizado/selênio/irradiado receberam 0,8 mg Se/Kg de peso corpóreo. No dia seguinte, apenas os animais pertencentes aos grupos ovariectomizado/irradiado e ovariectomizado/selênio/irradiado receberam 10 Gy de radiação X na região dos membros inferiores. Os animais foram sacrificados 7, 14, 21 e 28 dias após a cirurgia. O processo de reparação óssea foi avaliado por análise morfológica, utilizando-se a coloração pelo Tricrômico de Masson, e por análise do número de trabéculas ósseas e da birrefrigência (coloração pelo Picrosírius). Pela análise morfológica, foi possível observar um atraso no processo de reparo ósseo nos animais do grupo ovariectomizado/irradiado e similaridade entre os grupos ovariectomizado, ovariectomizado/selênio e ovariectomizado/selênio/irradiado, o que demonstrou o efeito radioprotetor do selênio sem toxicidade / Abstract: Osteoporosis and ionizing radiation affect the bone healing and people can suffer both conditions, especially older women. At the moment, antioxidant radioprotectors have been evaluated, such selenium compounds. This study aimed at evaluating the selenium protection in the bone repair process in ovariectomized rats submitted to an irradiation procedure. For this purpose, eighty ovariectomized female Wistar rats were randomly divided in four experimental groups: ovariectomized, ovariectomized/selenium, ovariectomizedlirradiated and ovariectomized/selenium/irradiated. Abone defect was made on all animals' tibias forty days after ovariectomy. Two days after surgery, only ovariectomized/selenium and ovariectomized/seleniumlirradiated rats received 0.8 mg Se/Kg. Three days after surgery, only ovariectomized irradiated and ovariectomized/selenium/irradiated rats received 10 Gy of X rays on the lower limbs region. The animals were sacrificed 7, 14, 21 and 28 days after surgery in order to assess the repair process, which was evaluated by morphologic analysis in Masson Tricromic. lt was also evaluated by analysis of trabecular bone number in Masson Tricromic and birefringence analysis in Picrosirius. It was possible to observe a delay in the bone repair process in the irradiated/ovariectomized group and similarity between ovariectomized, ovariectomized/selenium and ovariectomized/selenium/irradiated, which proved the selenium radioprotection without its toxicity / Doutorado / Radiologia Odontologica / Doutor em Radiologia Odontológica

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