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A radioterapia interna seletiva é uma alternativa para o tratamento de alguns tipos de cânceres como o carcinoma hepatocelular (CHC), ou câncer de fígado primário. Neste tratamento, microesferas de vidro ou polimérica contendo em sua estrutura radionuclídeos emissores de partículas β- são introduzidas no fígado por meio da artéria hepática e migram, preferencialmente, para regiões hipervascularizadas, que são características da presença de tecido canceroso. Neste trabalho, foram propostos o desenvolvimento de vidros fosfato contendo hólmio para produção de microesferas e sua aplicação em radioterapia interna seletiva no Brasil. O vidro desenvolvido apresentou durabilidade química adequada, densidade de 2,7(3)g/cm3, alta estabilidade térmica e as impurezas encontradas não inviabilizam o tratamento. As microesferas foram produzidas pelos métodos da chama e da queda gravitacional e foram caracterizadas por diversas técnicas em que se observaram forma, granulometria, atividade e biocompatibilidade apropriados para o tratamento pretendido. Propõe-se que as microesferas possam ser submetidas a testes in vivo. / The selective internal radiotherapy is an alternative for some kinds of cancer as the hepatocellular carcinoma (HCC) or primary liver cancer treatment. In this treatment, glass or polymer microspheres containing radionuclides inside their structure are introduced in the liver through hepatic artery and trapped at the arterioles that feed the tumor. In this work, the development of phosphate glasses containing holmium for production of microspheres and their application in Brazil are proposed. The developed glasses presented suitable chemical durability, density of 2,7(3) g/cm3, high thermal stability and the impurities contained therein do not preclude the treatment. The microspheres were produced by the flame method and the gravitational fall method, and were characterized by means of several techniques to evaluate shape, average particle size, activity and biocompatibility suitable for selective internal radiotherapy. Based in the main results, the submission to in vivo tests is proposed.

A radioterapia interna seletiva é uma alternativa para o tratamento de alguns tipos de cânceres como o carcinoma hepatocelular (CHC), ou câncer de fígado primário. Neste tratamento, microesferas de vidro ou polimérica contendo em sua estrutura radionuclídeos emissores de partículas β- são introduzidas no fígado por meio da artéria hepática e migram, preferencialmente, para regiões hipervascularizadas, que são características da presença de tecido canceroso. Neste trabalho, foram propostos o desenvolvimento de vidros fosfato contendo hólmio para produção de microesferas e sua aplicação em radioterapia interna seletiva no Brasil. O vidro desenvolvido apresentou durabilidade química adequada, densidade de 2,7(3)g/cm3, alta estabilidade térmica e as impurezas encontradas não inviabilizam o tratamento. As microesferas foram produzidas pelos métodos da chama e da queda gravitacional e foram caracterizadas por diversas técnicas em que se observaram forma, granulometria, atividade e biocompatibilidade apropriados para o tratamento pretendido. Propõe-se que as microesferas possam ser submetidas a testes in vivo. / The selective internal radiotherapy is an alternative for some kinds of cancer as the hepatocellular carcinoma (HCC) or primary liver cancer treatment. In this treatment, glass or polymer microspheres containing radionuclides inside their structure are introduced in the liver through hepatic artery and trapped at the arterioles that feed the tumor. In this work, the development of phosphate glasses containing holmium for production of microspheres and their application in Brazil are proposed. The developed glasses presented suitable chemical durability, density of 2,7(3) g/cm3, high thermal stability and the impurities contained therein do not preclude the treatment. The microspheres were produced by the flame method and the gravitational fall method, and were characterized by means of several techniques to evaluate shape, average particle size, activity and biocompatibility suitable for selective internal radiotherapy. Based in the main results, the submission to in vivo tests is proposed.

Envisioning novel fully monolithic fiber-optical devices, this dissertation investigates four fiber optical devices both, active and passive, that contribute to the goal of further integrating and miniaturizing fiber optics. An all phosphate glass fiber laser was designed in an effort to reduce laser intensity noise by reducing cavity losses and low mechanical strength that arise from intra-cavity fusion splices between silica fiber Bragg gratings (FBG) and phosphate active fiber in state of the art phosphate single frequency fiber lasers. Novel phosphate glass based FBGs have been fabricated utilizing high intensity laser pulses at 193 nm and a phase-mask. Net reflectivities of up to 70 % and a bandwidth of 50 pm have been achieved in the FBGs. The laser design comprised two of the novel FBGs and a short section of Er³⁺Yb³⁺ phosphate fiber to form a distributed Bragg reflector (DBR) laser. The performance of the new laser has been compared to a conventional phosphate fiber laser. Particular focus was put on the laser intensity noise due to its dependence on intra-cavity losses. Relative intensity noise (RIN) amplitudes of -80 dB/Hz have been measured for both lasers when operating at comparable output powers. For similar levels of absorbed pump power the relaxation oscillation frequencies (ROF) were shifted towards lower frequencies in the new laser. ExcessFBG scattering losses and mode-field miss-match between the active and passive fiber limited the output power of the new laser to 16 mW compared to 140 mW in the conventional laser. A monolithic all-phosphate glass fiber laser with up to 550 mW output power that is operating at a single longitudinal mode and exhibiting narrow linewidth is presented. The laser cavity has been formed by inscribing FBGs directly into heavily Er³⁺Yb³⁺ doped phosphate glass fiber using femtosecond laser pulses and a phase mask, completely eliminating the need for intra-cavity fusion splices. A linewidth of less than 60 kHz and relaxation oscillation peak amplitudes below -100 dB/Hz without active suppression of RIN have been measured. The compact form factor and higher output power combined with the low noise and narrow linewidth characteristic make this laser an ideal candidate for ranging, interferometry and sensing applications. Strong and robust Bragg gratings in optical fiber fabricated from highly photosensitive photo-thermo-refractive (PTR) glass are demonstrated. The fibers were drawn at 900 °C from a machined PTR-glass preform. A low power two beam interference pattern from a continuous wave (cw) He-Cd laser with a wavelength of 325 nm was used to write gratings into the fibers, achieving peak grating strengths of 20 dB and a spectral width of 45 pm. The gratings showed no sign of degradation when exposed to a high temperature environment of 425 °C for several hours. This is significantly higher when compared to standard Telecom FBGs which are rated for operation temperatures below 200 °C. A detailed study of novel mode-field adapters (MFA) based on multi-mode interference in graded index multi-mode fibers (GIMF) is presented. MFAs are often used in cases when low coupling losses between single mode fibers with very different mode-field diameters are needed. Here a new type of MFAs has been fabricated and characterized from a selection of commercially available single mode and graded index fibers. Compared to existing techniques the presented MFAs can be fabricated very quickly and are not limited to certain fiber types. Insertion losses of 0:5 dB over a spectral range of several hundred nm have been obtained with an ultra compact MFA with a length of 275 μm.

Made available in DSpace on 2014-10-09T12:48:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:10Z (GMT). No. of bitstreams: 1 09303.pdf: 5478849 bytes, checksum: 91eea1ce1127d155b27d04ee87ec86c7 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Made available in DSpace on 2014-10-09T12:27:27Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:46Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:48:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:10Z (GMT). No. of bitstreams: 1 09303.pdf: 5478849 bytes, checksum: 91eea1ce1127d155b27d04ee87ec86c7 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:41:59Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:51Z (GMT). No. of bitstreams: 0 / O objetivo deste estudo foi avaliar, in vitro, a resistência de união de retentores intrarradiculares previamente irradiada com laser de diodo em alta intensidade (&lambda;= 830 nm), tanto em regime contínuo como pulsado. Foram utilizados retentores intrarradiculares metálicos ou de fibra de vidro, cimentados com fosfato de zinco ou cimento resinoso auto-condicionante. Assim, as variáveis analisadas foram o regime de irradiação, o tipo de retentor intrarradicular e o tipo de agente cimentante na resistência de união. Estas variáveis foram analisadas, in vitro, nos 3 terços radiculares (cervical, médio e apical) de 90 dentes humanos endodonticamente tratados, preparados para receber retentor intrarradicular e irradiados com laser de diodo em alta intensidade (830 nm). Após a irradiação os retentores foram cimentados com cimento de fosfato de zinco ou com cimento resinoso autocondicionante. As raízes foram seccionadas por meio de cortes transversais dos terços cervical, médio e apical, obtendo-se, assim, seis amostras de cada raiz. Cada uma das amostras foi submetida ao ensaio de resistência de união de maneira cega. Conclui-se que a resistência mecânica à compressão de retentores intrarradiculares em dentina previamente irradiada com laser de diodo de alta intensidade (&lambda;= 830 nm) apresentou maiores valores na dentina intrarradicular tanto no regime contínuo como pulsado, sendo ligeiramente superior no regime pulsado. Foi possível verificar que, nos terços médio e cervical, a irradiação com laser de diodo pulsado (Pm = 1 W, I = 994 W/cm2) resultou em maiores valores de resistência de união, com ambos os cimentos e ambos os tipos de núcleo. Houve diferença estatisticamente significante nos valores de união nos diferentes terços dos grupos tratados, sendo superior para o terço cervical (p < 0,05). Assim, a técnica de irradiação do conduto com laser de diodo mostrou-se eficaz no aumento da resistência de união de retentores intrarradiculares. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP