No description available.

No description available.

Thesis (Ph. D.)--University of Adelaide, Dept. of Medicine, 1984. / Some mounted ill. Includes bibliographical references (leaves 203-263).

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / "m in ⁹⁹mTc on short title page is supercript." Typescript. Vita. Includes bibliographical references (leaves 131-136). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / "M in ⁹⁹mTc on short title page is supercript." Typescript. Vita. Includes bibliographical references (leaves 131-136). Also available on the Internet.

Some mounted ill. / Bibliography: leaves 203-263 / vii, 263, [52], [29] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1984

Thesis (Ph.D.)--McMaster University (Canada), 1993. / Source: Dissertation Abstracts International, Volume: 55-06, Section: B, page: 2216. Adviser: R. A. Bell.

Thesis (MScMed)--Stellenbosch University, 2004. / Copy not signed by author. / ENGLISH ABSTRACT: This study involved 33 patients, 19 men and 14 women. The age range was wide (20-90 years) and median age was 57 years. These patients had a single pulmonary nodule (SPN) defined radiologically as a well defined, round or oval intrapulmonary lung lesion not associated with atelectasis or adenopathy on chest radiography or computed tomography. Patients were investigated with Tc-99m MIBI and TI-201 (25 patients) and with Tc-99m MIBI alone (8 patients). Single photon emission computed tomography images were reconstructed using both iterative reconstruction (Ordered Subsets - Expectation Maximisation: aSEM) and filtered backprojection (FBP), on the Hermes system. Transverse, coronal and sagittal slices were displayed on the screen using a grey scale. The aSEM and FBP images for each study were co-registered semi-automatically using the multimodality programme on the Hermes. The best slice for the lesion was chosen according to the best view used to locate the SPN on chest radiograph. Regions of interest (Ral) were drawn manually outside the outer margin of the detected lesion, first on the aSEM image. This was automatically mirrored on the co-registered FBP image. For most patients, the background was automatically mirrored horizontally on the contralateral side, again, first on the OSEM then automatically on the FBP image. Automatic vertical mirroring or manual horizontal mirroring was used when background was found to be in a visually 'hot' area like the heart or vertebrae. The average counts and standard deviation of the Ral and background were generated automatically. Semi-quantitative image analysis was done by calculating the signal-to-noise ratio (SNR) and tumour-to-background (TIB) ratio using the following formulae: SNR = Mean counts ROI(lesion) - Mean counts background Standard deviation background TIB rati.o = -M---e-a-n-'--c-o--u-n-'t-s- ROI(lesion) Mean counts background Detection was found to be the same for the two reconstruction algorithms, that is, every lesion detected by using OSEM could also be detected by using FBP. However lesion detection did differ between Tl-201 and Tc-99m-MIBI. Sensitivity and specificity were calculated for different thresholds of SNR and TIB ratios. Receiver operating characteristics (ROC) curves were drawn to represent the different sensitivities and specificities at each threshold. Tuberculosis (TB) was not included in this analysis as uptake of Tl-20l was found to be significantly high and comparable to that of malignant nodules. However the effect of OSEM and FBP on the 'positive' TB nodules was assessed separately. By calculating the area under the ROC curves, TI-201 using OSEM was shown to be more accurate at differentiating malignant nodules from benign ones than FBP. Although this difference was not statistically significant (p=0.1 0), there was a clear tendency. The two reconstruction algorithms were found to be almost equally accurate, when using Tc-99m-MIBI, the difference between them being considerably insignificant. In conclusion, it was shown that there is a tendency that OSEM outperforms FBP for studies using Tl-201 but not for Tc-99m-MIBI. / AFRIKAANSE OPSOMMING: Hierdie studie sluit 33 pasiënte in, 19 mans en 14 vroue. Die ouderdomme wissel tussen 20 en 90 jaar met 'n gemiddelde ouderdom van 57 jaar. Elkeen van die pasiënte het 'n enkel longnodule (SPN) op borskas X-straal en/of rekenaar tomografie getoon, wat radiologies gedefinieer word as 'n goed omskrewe, ronde of ovaal intrapulmonale longletsel wat nie met atelektase of adenopatie geassosieer is nie. Pasiënte is met Tc-99m MIDI en TI-201 (25 pasiënte) of slegs met Tc-99m MIBI (8 pasiënte) ondersoek. Enkelfoton emissie rekenaar tomografiese (EFERT) beelde is met beide iteratiewe rekonstruksie (Ordered Subsets - Expectation Maximisation: OSEM) en gefilterde terugprojeksie (FBP) met die Hermes sisteem gerekonstrueer. Transvers, koronale en sagittale snitte is in grysskaal op die sisteem vertoon. Die OSEM en FBP beelde vir elke studie is semi-outomaties gekoregistreer met behulp van die multimodaliteitsprogram op die Hermes. Die optimale snit vir elke letsel is gekies volgens die beste aansig op die borskas X-straalom die SPN te lokaliseer. Gebiede van belang (ROl) is met die hand buite-om die buitenste rand van die letsel getrek op die OSEM beeld en daarna outomaties in die ooreenstemmende area op die gekoregistreerde FPB beeld geplaas. Vir die meeste pasiënte is die agtergrond outomaties as horisontale spieëlbeeld op die kontralaterale kant geplaas, eers op die OSEM en dan outomaties op die FBP beeld. 'n Outomatiese vertikale spieëlbeeld of manuele horisontale verskuiwing van die agtergrondsarea is gedoen indien die agtergrond oorvleuel het met 'n 'warm' area soos die hart of werwels. Die gemiddelde tellings en standaardafwyking van die ROl en agtergrond is outomaties gegenereer. Semi-kwantitatiewe beeldanalise is gedoen deur berekening van die sein-tot-agtergrond verhouding (signal-to-noise ratio - SNR) en tumor-tot-agtergrond (TIB) verhouding met behulp van die volgende formules: SNR = gemiddelde tellings ROI(letsel) - gemiddelde tellings agtergrond Standaard afwyking van agtergrond TIB rati.o = -g=em--id-d-e-l-d-e--te=ll-in-g-s__R:_O-I(-le-t-s'e-l) gemiddelde tellings agtergrond Opsporing is soortgelyk bevind vir die twee rekonstruksie algoritmes, dit wil sê elke letselopgespoor met behulp van OSEM kon ook met FBP opgespoor word. Letselwaameming het egter verskil tussen TI-201 en Tc-99m-MIBI. Sensitiwiteit en spesifisiteit is vir verskillende drempels van SNR en TIB verhoudings bereken. 'Receiver operating characteristics' (ROC) kurwes is getrek om die verskillende sensitiwiteite en spesifisiteite by elke drempel te verteenwoordig. Tuberkulose (TB) is nie in hierdie analise ingesluit nie aangesien opname van Tl-201 beduidend hoog en vergelykbaar met die van maligne nodules was. Die effek van OSEM en FBP op die 'positiewe' TB nodules is egter apart beoordeel. Deur berekening van die area onder die ROC kurwes, is getoon dat OSEM van Tl-201 tomografiese data meer akkuraat as FBP was om maligne van benigne nodules te onderskei. Alhoewel hierdie verskil nie statisties betekenisvol was nie (p=0.10), is daar wel 'n duidelike neiging gevind. Die twee rekonstruksie algoritmes was byna ewe akkuraat wanneer Tc-99m-MIBI gebruik is, met duidelik geen betekenisvolle verskil tussen die algoritmes nie. Gevo lgtrekking In hierdie studie is dit getoon dat daar 'n neiging is dat OSEM beter vaar as FBP vir studies met tallium-201 maar nie vir Tc-99m-MIBI nie.

One of the first concerns for forensic anthropologists in dealing with skeletal remains in the Australian context is the determination of whether the remains are of anthropological, historical or archaeological interest. If fewer than 75 years have elapsed since death, remains are classified as anthropological and of forensic interest. However, an accurate and reliable method for estimating time since death (TSD) from human skeletal remains has thus far eluded forensic anthropologists. This study investigates the application in an Australian context of a novel approach proposed by Swift (2001) to dating skeletal remains from their contained levels of radioisotopes 210Po, 238U and 226Ra and trace elements. Radionuclide activity concentrations were determined using alpha and gamma spectrometry. Trace element concentrations were measured on three separate occasions using inductively coupled plasma mass spectrometry (ICP-MS). Discriminant analysis of the combination of activity concentration values for 210Po, 238U and 226Ra indicated the possibility of separation of bones derived from individuals who had died in the three eras of interest. Additionally, variations in the concentration levels of specific trace elements and certain inter-element relationships between elements also showed significant correlations with TSD. The study could not be exhaustive as access to human skeletal material was limited and additionally, the archaeological material had a different origin and post-death history to material from the more recent past. However, trend lines for inter-relationships between specific metals and for radionuclides indicated that all material fitted the same generally projected trends and as such, inferences with respect to variations of trace elements and radionuclides could be made with confidence. Bone radionuclide activity and calcium concentrations were all significantly higher in bones from the archaeological era than those from more recent eras, while trace lead concentrations contained in samples from the more recent historical era were significantly higher than those from other eras. Barium, lanthanum, rubidium, strontium, cerium and neodymium concentrations were all significantly correlated with one another and with radionuclide activity concentrations. Differences were found between the patterns of radionuclide activity and trace element concentrations between the skull and femur. The results of this study lend support to suggestions that multivariate analysis of trace element concentrations and radionuclide activity levels could aid in the estimation of time since death from skeletal remains in Australia. Although this study made use of only a limited amount of material, results clearly indicated the need to take into account variations arising from lifetime activities, diagenesis and bone type in applying the techniques to estimations of time since death. It highlights the need for a large-scale study using bone of known ages that systematically examines these influences on the estimation of time since death.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Os radionuclídeos utilizados na tomografia por emissão de posítrons (PET) são produzidos utilizando um acelerador cíclotron. Os nêutrons produzidos durante a operação do cíclotron contribuem para exposição direta ou indireta dos Indivíduos Ocupacionalmente Expostos (IOEs), devido ao aumento da radiação de fundo da casamata. Além disso, há um aumento nas emissões de gases radioativos provenientes da ativação dos elementos do ar dentro da casamata, que quando liberados constitui um problema para radioproteção dos indivíduos do público. Dos vários métodos utilizados para caracterizar o espectro neutrônico, o espectrômetro de multiesferas de Bonner (EB) é um dos sistemas espectrométricos mais utilizados. Neste trabalho foi utilizado o sistema EB com detectores termoluminescentes (TL), do tipo TLD600 e TLD700 como detector de nêutrons, para medir os espectros de energia de nêutrons em quatro pontos no interior da casamata do cíclotron GE PETtrace-8 do Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). Foram realizadas medidas em quatro pontos em torno do cíclotron. Os espectros de nêutrons foram desdobrados utilizando os códigos BUMS, NSDUAZ e BUNKIUT e os resultados convertidos em equivalente de dose ambiente H*(10). Considerando o termo fonte de radiação fornecido pelo fabricante do cíclotron, pôde-se constatar a grande influência dos nêutrons de recuo nos espectros de energia encontrados em todos os pontos. Houve uma boa concordância nos espectros de nêutrons obtidos, utilizando os códigos BUNKIUT (com espectros iniciais retangular e Maxwelliano) e NSDUAZ. Os valores de taxa de fluência encontrados no presente trabalho foram da mesma magnitude dos valores reportados na literatura e são coerentes com os obtidos por cálculos téóricos utilizando o termo fonte de radiação disponibilizado pelo fabricante. Com relação aos valores de equivalente de dose ambiente, as taxas horárias por A (microampère) variaram de aproximadamente 67 mSv/h a 936 mSv/h . Para uma corrente típica de 40 A, esses valores são próximos de 2,7 Sv/h a 37 Sv/h, valores da mesma ordem dos reportados na literatura. A metodologia empregada para a caracterização do campo de radiação em torno do cíclotron do CDTN mostrou-se adequada e pode ser utilizada em mais pontos da casamata, de maneira a descrever melhor o espectro e, consequentemente, estimar o equivalente de dose ambiente. / The radionuclides used in positron emission tomography (PET) are generally produced using a cyclotron accelerator. The operation of the cyclotron produces an undesirable neutron radiation field. The knowledge of the neutron radiation field around not-self-shielded PET cyclotrons is an important issue for optimization of radiation protection of the workers and individuals of the public. For the workers, neutrons contribute not only for immediate radiation exposure as for long-term exposure due to activation of cyclotron components and the concrete in the bunker walls. For the individuals of the public the main concern is the dispersal of radioactive gases produced by activation of the air inside the cyclotron vault. The multisphere system, or Bonner sphere spectrometer (BSS), has been widely used to measure neutron spectrum. The substitution of the active detectors of the BSS system by thermoluminescent detectors (specifically TLD-600 and TLD-700 pairs) has become a reliable procedure in spectrometry of high intensity mixed radiation field. In this study we utilized the BSS system with TLD600 and TLD700 to measure the energy spectra of neutrons at four points inside the bunker of the cyclotron GE PETtrace-8 of the Development Centre of Nuclear Technology (CDTN). Four points inside the bunker of the cyclotron were studied. The neutron spectra were unfolded using codes BUMS, NSDUAZ e BUNKIUT and the results converted to ambient dose equivalent H*(10). Considering the source-term of radiation provided by the manufacturer of the cyclotron, we could see the great influence of room return effect in energy spectra at all points. The values of total fluence rates for all points have the same magnitudes of values reported in the literature and are consistent with those obtained by theoretical calculations using the source-term of radiation provided by the manufacturer of the cyclotron. The ambient equivalent dose rates for 1 A ranged from about 67 mSv/h to 936 mSv/h. For a typical 40 A typical current these values were 2.7 Sv/h and 37 Sv/h. These values are of the same order than the reported in the literature. The methodology utilized in this study to characterize the neutron radiation field around the CDTN cyclotron proved to be adequate and can be used in more points inside the bunker in order to better describe the spectrum and thereby estimate the ambient dose equivalent.