Bibliography: leaves 151-206. / xxvi, 206 leaves, [8] plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines the hypothesis that HIV infected bone allografts can be sterilized with 25 kGy of gamma irradiation. / Thesis (Ph.D.)--University of Adelaide, Dept. of Orthopaedic Surgery & Trauma, 1998?

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in the field of Medical Physics. 2017 / Aim The aim of this research was to contribute to clinical implementation of the small field dosimetry Code of Practice (CoP) that is due to be published by the International Atomic Energy Agency (IAEA) in collaboration with the American Association of Physicists in Medicine (AAPM) (1). A 6 cm × 6 cm virtual machine-specific reference (fmsr) field was established in a clinical 60Cobalt teletherapy beam used for conventional radiotherapy at Charlotte Maxeke Johannesburg Academic Hospital, and relative output factors were measured down to a set field size of 1 cm × 1 cm using three different models of Physikalisch-Technische Werkstatten (PTW) small field ionization chambers. Materials and Methodology The measurements were all performed on a Cobalt teletherapy unit (MDS Nordion Equinox, S/N 2009) in a PTW MP3 water phantom. The small field ionization chambers that were used were a PTW 31016 3D pinpoint 0.016 cm3, a PTW 31006 pinpoint 0.015 cm3 and a PTW 31010 semiflex 0.125 cm3. A calibrated PTW 30013 Farmer 0.6 cm3 ionization chamber was used to provide traceability for the cross calibration. A ―daisy chain‖ methodology was used to perform the cross calibration in a virtual fmsr field of 6 cm × 6 cm and then establish the absolute dose rate in a 4 cm × 4 cm field. Relative output factors as a function of field size were measured with each small field ionization chamber and then compared to published results. Results Small square fields from a 60Cobalt beam were created using the secondary collimators integrated into the unit. Equivalent square fields were calculated using the profiles obtained by the three ionization chambers during scanning and were in agreement with the ones that were programmed into the console. The coincidence of the central axis of the beam and the point of measurement for each detector was determined from the beam profiles. The cross calibration and daisy chain measurements resulted in a consistent dose rate of within + 0.6% in the 4 cm × 4 cm field when measured with the four different ionization chambers. For 6 cm × 6 cm, 4 cm × 4 cm, 3 cm × 3 cm and 2 cm × 2 cm field sizes, relative output factors obtained from the uncorrected detectors’ response agreed to within + 0.8 % between the three small field ionization chambers. The variation in the 1 cm × 1 cm field size was + 8.1 %. When compared to published data, large differences in field size correction factors were obtained. Conclusion Small field dosimetry in a 60Cobalt photon beam using three different PTW small field ionization chamber models was investigated. A cross calibration in a virtual msr field was done followed by a daisy chain process to determine the dose rate in a small field. Dose profiles and relative output factors were then measured and compared. The lack of lateral charge particle equilibrium and volume averaging effect was evident when using the PTW 31010 semiflex chamber in a 1 cm × 1 cm field. The PTW 31006 pinpoint and 31016 3D pinpoint were in close agreement for field sizes down to 1 cm × 1 cm with the 3D pinpoint performing as the best detector in this study. The optimal positioning of a detector should be determined from beam profile scans and not the engineering diagrams. The PTW 31016 3D pinpoint and PTW 31006 pinpoint are recommended for the determination of output factors in small field sizes. However, field output correction factors are required for both detectors in field sizes under 2 cm × 2 cm. Small field data published in the British Journal of Radiology (BJR) Supplement 25 (2) should not be used to benchmark dosimetry in modern 60Cobalt teletherapy units. / MT 2017

O objetivos deste estudo foi avaliar a influência da radiação ionizante na vitalidade do tecido pulpar mensurada através dos níveis de saturação de oxigênio (%SpO2) em pacientes com tumores malígnos intraoral ou de orofaringe, passado de 4-6 anos da radioterapia (RT). Noventa pacientes com tumores malígnos intraoral ou de orofaringe, submetidos de 4-6 anos anteriores a RT foram selecionados para este estudo. Os níveis de oxigenação e sensibilidade pulpar, avaliados através do oxímetro de pulso e do spray refrigerante TFE (tetrafluoretano), foram analisados nos dentes anteriores (superior e inferior) de cada paciente selecionado (n=693),, indiferente do quadrante e da área irradiada. Como grupo controle foram selecionados noventa pacientes saudáveis (nunca submetidos a RT) e os mesmos testes foram empregados (n=693). Todos os dentes foram considerados vitais. 100% mostraram resposta positva ao teste térmico e as médias de %SpO2 foram de 92.7% no grupo dos pacientes irradiados (SD ± 1.83) e 92.6% no grupo dos não-irradiados (SD ± 1.80), sem diferença estatística observada. Houve uma tendência de valores de %SpO2 menores em dentes caninos comparados aos incisivos, entretanto sem diferença estatística significante. Passados de 4-6 anos da RT, as %SpO2 da polpa dental estão dentro dos padrões considerados normais para uma polpa vital e podese assumir que a RT não têm influência danosa a longo prazo sobre a vitalidade do tecido pulpar, assim sugerindo que este tecido pode ser apto a retornar o fluxo sanguíneo normal após a RT. As mudanças observadas na microcirculação pulpar devido a RT parecem ser temporárias, então o tratamento endodôntico preventivo ou a extração dental em pacientes que receberam radiação ionizante são desnecessários. / The aim of this study was to evaluate the influence of radioation on pulp vitality through the measurement of pulpal oxigenation levels (%SpO2) in patients with malignant intraoral and oropharyngeal tumors at 4-6 years after radiotherapy (RT). Ninety patients with malignant tumors in the oral cavity or oropharynx, submitted to RT 4-6 years prior to the study were selected. Pulp oxygenation levels and pulp sensitivity, measured by pulse oximetry and by cold refrigerant spray TFE (tetrafluoroethane), were analyzed in the anterior teeth (upper and lower) of each patient selected (n=693), regardless of the quadrant and the irradiated area. As a control group were selected ninety healthy patients (never submitted to RT) and the same tests were performed (n=693). All teeth were considered vital. 100% showed a positive response to the thermal test and the %SpO2 rates were 92.7% in irradiated group (SD ± 1.83) and 92.6% in non-irradiated group (SD ± 1.80), without statistical difference. There was a trend for lower %SpO2 values in canine teeth compared to incisors, however it was not statistically significant. After 4-6 years of RT the dental pulp %SpO2 are within the normal range considered for a vital pulp and it can be assumed that RT did not have a long term influence on the pulp vitality, therefore suggesting that the pulp tissue may be able to recover normal blood flow after RT. The changes observed in the pulp microcirculation due to RT seems to be temporary, so preventive endodontic treatment or tooth extraction in patients who will receive RT may not be necessary.

published_or_final_version / Pathology / Master / Master of Philosophy

O objetivos deste estudo foi avaliar a influência da radiação ionizante na vitalidade do tecido pulpar mensurada através dos níveis de saturação de oxigênio (%SpO2) em pacientes com tumores malígnos intraoral ou de orofaringe, passado de 4-6 anos da radioterapia (RT). Noventa pacientes com tumores malígnos intraoral ou de orofaringe, submetidos de 4-6 anos anteriores a RT foram selecionados para este estudo. Os níveis de oxigenação e sensibilidade pulpar, avaliados através do oxímetro de pulso e do spray refrigerante TFE (tetrafluoretano), foram analisados nos dentes anteriores (superior e inferior) de cada paciente selecionado (n=693),, indiferente do quadrante e da área irradiada. Como grupo controle foram selecionados noventa pacientes saudáveis (nunca submetidos a RT) e os mesmos testes foram empregados (n=693). Todos os dentes foram considerados vitais. 100% mostraram resposta positva ao teste térmico e as médias de %SpO2 foram de 92.7% no grupo dos pacientes irradiados (SD ± 1.83) e 92.6% no grupo dos não-irradiados (SD ± 1.80), sem diferença estatística observada. Houve uma tendência de valores de %SpO2 menores em dentes caninos comparados aos incisivos, entretanto sem diferença estatística significante. Passados de 4-6 anos da RT, as %SpO2 da polpa dental estão dentro dos padrões considerados normais para uma polpa vital e podese assumir que a RT não têm influência danosa a longo prazo sobre a vitalidade do tecido pulpar, assim sugerindo que este tecido pode ser apto a retornar o fluxo sanguíneo normal após a RT. As mudanças observadas na microcirculação pulpar devido a RT parecem ser temporárias, então o tratamento endodôntico preventivo ou a extração dental em pacientes que receberam radiação ionizante são desnecessários. / The aim of this study was to evaluate the influence of radioation on pulp vitality through the measurement of pulpal oxigenation levels (%SpO2) in patients with malignant intraoral and oropharyngeal tumors at 4-6 years after radiotherapy (RT). Ninety patients with malignant tumors in the oral cavity or oropharynx, submitted to RT 4-6 years prior to the study were selected. Pulp oxygenation levels and pulp sensitivity, measured by pulse oximetry and by cold refrigerant spray TFE (tetrafluoroethane), were analyzed in the anterior teeth (upper and lower) of each patient selected (n=693), regardless of the quadrant and the irradiated area. As a control group were selected ninety healthy patients (never submitted to RT) and the same tests were performed (n=693). All teeth were considered vital. 100% showed a positive response to the thermal test and the %SpO2 rates were 92.7% in irradiated group (SD ± 1.83) and 92.6% in non-irradiated group (SD ± 1.80), without statistical difference. There was a trend for lower %SpO2 values in canine teeth compared to incisors, however it was not statistically significant. After 4-6 years of RT the dental pulp %SpO2 are within the normal range considered for a vital pulp and it can be assumed that RT did not have a long term influence on the pulp vitality, therefore suggesting that the pulp tissue may be able to recover normal blood flow after RT. The changes observed in the pulp microcirculation due to RT seems to be temporary, so preventive endodontic treatment or tooth extraction in patients who will receive RT may not be necessary.

Orientador: Marcio Ajudarte Lopes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-10T08:17:58Z (GMT). No. of bitstreams: 1 Santos-Silva_AlanRoger_M.pdf: 23124065 bytes, checksum: ad207c0702a9ab0625f7962a867993bb (MD5) Previous issue date: 2008 / Resumo: Dentre as seqüelas oriundas da radioterapia para o tratamento do câncer de cabeça e pescoço, a cárie de radiação está entre as mais significativas, podendo gerar destruição dentária generalizada. Considerando os escassos trabalhos que avaliaram a morfologia e a progressão microscópica da cárie de radiação, este estudo teve por objetivo principal analisar a morfologia e o conteúdo mineral da cárie de radiação utilizando trinta e seis dentes extraídos de onze pacientes que receberam radioterapia na região de cabeça e pescoço. As características deste material foram descritas considerando os aspectos macroscópicos, radiográficos, histológicos por meio da microscopia de luz polarizada (MLP) e ultra-estruturais por meio da microscopia eletrônica de varredura (MEV). De modo complementar, o conteúdo mineral destes dentes foi quantificado com auxílio da microanálise, baseada na espectroscopia de dispersão de energia (EDS). A cárie de radiação desta amostra apresentou o mesmo perfil histológico, ultra-estrutural e o mesmo padrão de desmineralização que os descritos na literatura para cáries convencionais, com presença de dentina desmineralizada, esclerose dentinária, zona translúcida, tratos mortos dentinários, dentina reacional e deposição de dentina intra-tubular. Diminuição do conteúdo de Cálcio (Ca) e Fósforo (P) na dentina desmineralizada e razão Ca/P semelhante aos valores esperados para dentina desmineralizada convencional, dentina e esmalte sadios não irradiados também foram encontrados. Por fim, constatamos que a cárie de radiação se desenvolve seguindo os mesmos padrões morfológicos e de desmineralização das cáries convencionais e que a dentina dos dentes irradiados preserva a habilidade reparadora em resposta à progressão da cárie / Abstract: Among sequelae of radiation therapy for the treatment of the head and neck cancer, radiation caries is the one of the most significant, being able to cause generalized dental destruction. Considering the lack of works that had evaluated the morphology and the microscopical progression of the radiation caries, the main objective of this study was to analyze the morphology and the mineral content of the radiation caries using thirty and six extracted teeth of eleven patients who had undergone radiation in the head and neck region. The characteristics of this material were described considering the macroscopic, radiographic, histologic by polarized light microscopy (PLM) and ultrastructural by scanning electron microscopy (SEM). In complementary way, the mineral content of these teeth was quantified with aid of the microanalysis based on the energy dispersive x-ray (EDS). The radiation caries of this sample presented the same histological and ultrastructural profile and the same demineralization standard that the ones described in literature for conventional caries, with presence of demineralized dentin, sclerotic dentins, translucent zone, dentin dead tracts, reactional dentin and intratubular dentin deposition. Reduction of the content of Calcium (Ca) and Phosphor (P) in the demineralized dentin of radiation caries and Ca/P reason similar to the expected values for non-irradiated demineralized dentin, dentine and enamel was also found. Finally, it was also observed evidence that the radiation caries develops following the same morphological and demineralization standard of the conventional caries and that the dentin of irradiated teeth preserves the ability of repairman in reply to the progression of the caries / Mestrado / Estomatologia / Mestre em Estomatopatologia

This project deals with the issue of simulation of dose irradiation. This principle is used in a radiotherapeutic device known as a Leksell Gamma Knife for the treatment of intracranial tumours. With regard to the theoretical observations obtained by studying this device, the project suggests the use of analytical geometry for the creation of a mathematical model for calculation of the intensity in the rayed area. A demonstration program Leksell_xvecer08 has been created for this model in a MatLab software background, which enables the user to change various input arguments and simulate a picture of the dosage spread in the target scanned areas.