Siga este link para ver outros tipos de publicações sobre o tema: Radioisotopes.
Teses / dissertações sobre o tema "Radioisotopes"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Radioisotopes".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja as teses / dissertações das mais diversas áreas científicas e compile uma bibliografia correta.
1
PUPILLO, Gaia. "Radioisotopes production via accelerator for nuclear medicine applications". Doctoral thesis, Università degli studi di Ferrara, 2014. http://hdl.handle.net/11392/2388938.
Texto completo da fonte
2
Egorov, Oleg B. "Automation of radionuclide separations and analysis by flow injection techniques /". Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11617.
Texto completo da fonte
3
Hou, Xinchi. "Cyclotron-based production of radioisotopes for medical imaging studies". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50862.
Texto completo da fonteResumo:
The cyclotron-based ¹⁰⁰Mo(p,2n)⁹⁹mTc reaction has been proposed as an alternative method for solving the recent shortage of ⁹⁹mTc, which is the most commonly used radioisotope in nuclear medicine. With this production method, however, even if highly enriched molybdenum is used, various radioactive and stable isotopes can be produced simultaneously with ⁹⁹mTc and they may affect the diagnostic outcome and radiation dosimetry in human studies. The objective of this thesis was to investigate the feasibility of the cyclotron-based production of ⁹⁹mTc. Towards this aim, theoretical predictions and experimental measurements were performed to investigate the quantity and purity of cyclotron-produced technetium.
In this thesis, the production cross sections and yields of cyclotron-produced ⁹⁹mTc and various other radioactive and stable isotopes were calculated. Radiation doses from three radiopharmaceuticals labeled with cyclotron-produced technetium were estimated. Different conditions were considered for both yield and dosimetry calculations in order to investigate the optimal reaction parameters for producing maximum ⁹⁹mTc and minimizing other contaminants. To facilitate the complex and time-consuming calculations, a graphical user interface was developed allowing users to perform the theoretical predictions in only a few seconds.
Besides theoretical estimations, quantitative experimental measurements of ⁹⁹mTc samples were performed. Gamma spectra from different cyclotron runs were analyzed. In order to investigate the image qualities for using cyclotron-produced technetium, phantom scans for both cyclotron- and reactor-produced ⁹⁹mTc at different times after end of beam were performed using SPECT.
Large quantities of produced ⁹⁹mTc proved the capability of cyclotron production of ⁹⁹mTc. Both theoretical predictions and experimental analysis showed over 9 Ci of ⁹⁹mTc can be produced in a 6 hours cyclotron run when using enriched ¹⁰⁰Mo target. Besides ⁹⁹mTc, the main contributors, which influenced the production activities, patient doses and quality of images, were ⁹⁴g⁻⁹⁶gTc. These results indicated the molybdenum target used in cyclotron production should have relatively small content of ⁹⁵⁻⁹⁷Mo, which are the “reaction parents” for ⁹⁴g⁻⁹⁶gTc. Furthermore, we demonstrated that incident proton beam energies in the range of 16-19 MeV, target thicknesses degrading beam energy to 10 MeV and relatively short irradiation times (3-6 hours) corresponded to the most advantageous region for ⁹⁹mTc production.Science, Faculty of
Physics and Astronomy, Department of
Graduate
4
Sitarz, Mateusz. "Research on production of new medical radioisotopes with cyclotron". Thesis, Nantes, 2019. http://www.theses.fr/2019NANT4050.
Texto completo da fonteResumo:
Aujourd’hui, les radio-isotopes sont fréquemment utilises en médecine, pour le diagnostic et la thérapie. Cependant, le développement constant de la médecine nucléaire provoque l’application de nouveaux radio-isotopes médicaux. La recherche sur leur production possible a grande échelle est la première étape d’un long processus d’études avant de pouvoir de les utilise dans des essais cliniques. Dans cette thèse, les voies de production ont été étudiées pour la formation de médicalement intéressants 43Sc, 44m,gSc, 47Sc, 97Ru et 105Rh en utilisant de cyclotrons. Les radioisotopes de scandium ont ete produits avec des cibles en calcium et en titane et avec des faisceaux de protons ou de deuterons; 97Ru a ete obtenu par irradiation de molybdene avec des particules α; et la production de 105Rh a ete etudiee avec des cibles en ruthenium et avec un faisceau de deuteron. Deux grandeurs ont été déterminés expérimentalement: la section efficace de réaction nucleaire, σ(E), et l’efficacité de la production, TTY(E), qui ont été utilisés pour discuter des conditions possibles de production optimale à grande échelle de ces radio-isotopes. De plus, la conversion de σ(E) en TTY(E) a été automatisée en développant un logiciel spécialisé, et un algorithme de reconstruction de σ(E) avec des valeurs de TTY(E) a été introduitToday, radioisotopes are commonly used in medicine, both in diagnosis and therapy. However, steady development of nuclear medicine demands the application of new medical radioisotopes. The investigation of their possible large-scale production is a first step in a long research process before they can be used in clinical trials. In this thesis, the production routes were studied for the formation of medically interesting 43Sc, 44m,gSc, 47Sc, 97Ru, and 105Rh with the use of cyclotrons. The scandium radioisotopes were produced with calcium and titanium targets and proton or deuteron beams; 97Ru was obtained through the irradiation of molybdenum with α particles; and production of 105Rh was studied with ruthenium targets and deuteron beam. Two parameters were determined experimentally: nuclear reaction cross-section, σ(E), and Thick Target Yield, TTY(E), which were used to discuss the possibility of optimal large-scale production conditions of discussed radioisotopes. Additionally, the conversion of σ(E) to TTY(E) was automatized by developing a dedicated software, and an algorithm for the reconstruction of σ(E) based on TTY(E) measurements was introduced
5
de, Sousa Fernando Nuno. "Movement of radionuclides through unsaturated soils". Diss., Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/17875.
Texto completo da fonte
6
Pan, Xiaodi. "Radioisotopes in Domestic Wastewater and Their Fate in Wastewater Treatment". Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/1247.
Texto completo da fonteResumo:
"Modern medical therapies involving radioisotopes provide radionuclide contamination in wastewater. These radioisotopes present in wastewater increase the possibility of human exposure to radiation. The objective of this work was to study the fate of radionuclides of medical sources in wastewater, and to determine the distribution of various radionuclides in different stages of wastewater treatment. Influent, return activated sludge and effluent samples were collected from four wastewater facilities in Massachusetts. Samples were collected approximately twice a month over 4 months. The radionuclides and their decay products were tested by inductively coupled plasma with mass spectrometry (ICP-MS) and broad energy germanium detector analysis (BEGe). The samples were analyzed to determine the content and radioactivity of each target radionuclide and decay product for three treatment stages (influent, return activated sludge and effluent) from each facility at different sampling times. The results indicated that I-131 is the only radionuclide in wastewater, however many decay products were identified. Recommendations are put forward according to the testing results."
7
Naidoo, Clive. "Selective separation of elements and radioisotopes by ion exchange chromatography". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53046.
Texto completo da fonteResumo:
Thesis (PhD)--Stellenbosch University, 2002.ENGLISH ABSTRACT: The equilibrium distribution coefficients of 32 metal ions [Al(llI), As(V), CdïIl), Ce(III), Ce(IV), Co(n), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), !n(III), La(III), Mn(II), Mo(VI), Nb(V), Ni(II), Pr(III), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Tb(III), Te(IV), Ti(IV), Vev), W(VI), Y(III), Yb(III), Zn(lI) and Zr(IV)] on a cation exchanger (Bio- Rad® AG50W-X8) and an anion exchanger (Bio-Rad® AG1-X8) in varying oxalic acid - sulphuric acid mixtures were successfully determined. The equilibrium distribution coefficients of these selected metal ions were determined in both 0.05 M and 0.25 M oxalic acid at various concentrations of sulphuric acid (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M and 2.00 M). Attempts to explain the sorption behaviour of the selected metal ions were made by using MINEQL+, a speciation modelling program, and the speciation systems for AI(III), Cd(II), Co(II) and Zn(lI) in varying oxalic acid - sulphuric acid mixtures were determined. Two component [Zr(IV)-La(III); AI(III)-La(III); Ga(IlI)-Zn(II); As(V)-Zn(II); Cu(II)- Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(III); Mo(VI)- Y(III); Nb(V)- Y(III); Ga(III)-Co(II); As(V)-Co(lI) and Fe(III)-Mn(II)] and three component [Fe(III)-Ga(III)-Zn(lI) and Zr(IV)-Ta(V)-Yb(III)] mixtures on a 10 ml or 13 ml cation exchange resin in a variety of oxalic acid - sulphuric acid mixtures were successfully separated. Two component [As(V)-Zr(IV); Co(II)-Fe(III); Ni(II)-Co(lI) and Ni(II)-Fe(III)] and three component [Ni(II)-As(V)-Se(IV); AI(III)-Zn(II)-Ge(IV) and As(V)-Cu(II)-Ge(IV)] mixtures on a 10 ml or 13 ml anion exchange resin in a variety of oxalic acid - sulphuric acid mixtures were also successfully separated and studied. It was also shown how some of the elution curves developed above could easily be adapted for radiochemical separations. Usin~ the relevant data from the above study, a separation for 68Gefrom a Ga20 target was developed according to a method based on acid dissolution of the target and chromatography on an anion exchange resin (Bio-Rad® AG1-X8). The separated 68Geshowed high radionuclidic purity and an acceptable chemical purity.
AFRIKAANSE OPSOMMING: Die ewewigsverdelingskoëffisiënte van 32 metaalione [Al(III), As(V), Cd(II), Ce(III), Ce(IV), Co(II), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), In(III), La(III), Mn(ll), Mo(VI), Nb(V), Ni(ll), Pr(Ill), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Th(Ill), Te(IV), Ti(IV), vrv; W(VI), Y(III), Yb(III), Zn(lI) en Zr(IV)] op 'n katioonruiler (Bio-Rad® AG50W-X8) en 'n anioonruiler (Bio-Rad® AG1-X8) in veranderende oksaalsuurswaelsuurmengsels is met welslae bepaal. Die ewewigsverdelingskoëffisiënte van hierdie geselekteerde elemente is in beide 0.05 Men 0.25 M oksaalsuur by verskeie konsentrasies swaelsuur (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M en 2.00 M) bepaal. Daar is gepoog om die sorpsiegedrag van die geselekteerde metaalione te verklaar deur die gebruik van MINEQL+, 'n spesiëringmodelleringsprogram, en die spesiëringsisteme vir AI(III), Cd(II), Co(II) en Zn(lI) in veranderende oksaalsuur-swaelsuurmengsels is bepaal. Tweekomponent [Zr(IV)- La(III); AI(III)-La(II!); Ga(III)-Zn(Il); As(V)-Zn(II); Cu(II)-Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(Il!); Mo(VI)- Y(III); Nb(V)- Y(ll!); Ga(Ill)-Co(Il); As(V)-Co(lI) en Fe(III)- Mn(II)] en driekomponent [Fe(III)-Ga(III)-Zn(ll) en Zr(IV)- Ta(V)- Yb(III)] mengsels op 'n 10 ml of 13 ml katioonruilhars in 'n verskeidenheid oksaalsuurswaelsuurmengsels is met welslae geskei. Tweekomponent [As(V)-Zr(IV); Co(II)- Fe(III); Ni(Il)-Co(lI) en Ni(II)-Fe(III)] en driekomponent [Ni(II)-As(V)-Se(IV); AI(III)-Zn(Il)-Ge(IV) en As(V)-Cu(II)-Ge(IV)] mengsels op 'n 10 ml of 13 ml anioonruilhars in 'n verskeidenheid oksaalsuur-swaelsuurmengsels is ook met welslae geskei en bestudeer. Daar is ook aangetoon hoe sommige van die elueringskrommes wat hierbo ontwikkel is, maklik vir radiochemiese skeidings aangepas sou kon word. Deur gebruik te maak van die relevante data uit die studie hierbo, is 'n skeiding vir 68Geuit 'n Ga20-teiken ontwikkel volgens 'n metode gebaseer op suurdissolusie van die teiken en chromatografie op 'n anioonruilhars (Bio-Rad® AG1-X8). Die geskeide 68Gehet hoë radionukliedsuiwerheid en 'n aanvaarbare chemiese suiwerheid getoon.
8
MARTINI, Petra. "High-Yield Cyclotron Production of Metallic Radioisotopes for Nuclear Medicine". Doctoral thesis, Università degli studi di Ferrara, 2018. http://hdl.handle.net/11392/2487885.
Texto completo da fonteResumo:
The main purpose of LARAMED project (LAboratoty of Radioisotopes for MEDicine), founded at LNL-INFN, is the R&D on cyclotron production of conventional, such as Tc-99m (TECHN-OSP projects), and emerging, such as Cu-67 (COME project), metallic medical radioisotopes. The aim of my PhD has been the development, optimization and automation of post-irradiation target processing systems, enabling to recover in high yield highly pure radioisotopes (RI), one of the most critical steps in the RI cyclotron production.
The possibility of a reactor-produced molybdenum-99 shortage, used as parent nuclide of in 99Mo/99m Tc generators, is still a potential scenario. The direct cyclotron-production of Tc-99m through the (p,2n) reaction on a Mo-100 target seemed to be a reliable solution. In the framework of TECHN-OSP project, a technology for enabling the in-hospital cyclotron self-production of Tc-99m, in order to afford the availability of the most used radiometal in diagnostic applications in case of shortages, has been developed. The Tc-99m cyclotron-production optimization included the design of a solid target, the development of an automatic module for target processing and enriched target material recovery study. In this thesis, the description of Tc-99m production experiments, performed in collaboration with the Sant’Orsola Hospital in Bologna, and the development of the automatic module for target processing, are well detailed.
During my PhD I had the opportunity to collaborate with the Canadian research group at TRIUMF (Vancouver, CA), also working on Tc-99m cyclotron-production, by contributing at the optimization and automation of molybdenum target dissolution and purification procedure of cyclotron-produced Tc-99m. In this thesis a comparison between the two developed, Italian and Canadian, target processing setup is also reported.
Alongside that, I have collaborated to COME project whose purpose is the evaluation of the cyclotron production efficiency of Cu-67, a particularly interesting RI for its application in “theranostics”. The large scale cyclotron-production of this RI is still a poorly studied key point. In order to define the Cu-67 best cyclotron-production route, we focused our attention on unknown cross-section measurement of nuclear reactions on a Zn-70 target (35-70MeV energy range). Essential for this project was the development and optimization of a high yield separation and purification procedure of Cu-67 from the Zn-70 bulk and the co-produced Ga-67 contaminant that, having the same γ-lines of Cu-67 (both decay to Zn-67 with similar half-lives), poses a serious issue for the determination of the activity of Cu-67. The description of the experiments, performed in collaboration with ARRONAX, is reported in this thesis.
Finally, the clinical needs of larger amount of the PET radiometal generator-produced Ga-68 prompted TRIUMF Life Sciences division to investigate Ga-68 cyclotron-production from liquid target since it is based on the existing medical-cyclotron network and technology. This technique will improve the availability of Ga-68 in hospitals housing an appropriate cyclotron by making them independent self-producers. Since the major problem affecting liquid targets is the contamination with radioactive/stable metals (e.g. iron) coming from the dissolution of some material from vacuum isolation or target body components during the irradiation, a separation and purification procedure together with a semi-automatic system, particularly focused on the purification of Ga-68 from Zn and Fe, have been developed. The main purpose is to obtain a final product suitable for medical use and to enable radiolabeling and in-vivo imaging studies with cyclotron produced 68Ga-DOTATOC.Il progetto LARAMED (LAboratoty of Radioisotopes for MEDicine), fondato presso i LNL-INFN, ha come scopo l’R&D per la produzione da ciclotrone di radioisotopi metallici convenzionali, come il Tc-99m (progetto TECHN-OSP, ed emergenti, come il Cu-67 (progetto COME), per uso medicale. L'obiettivo del mio dottorato di ricerca è stato lo sviluppo, ottimizzazione e automazione di sistemi di processamento dei target irraggiati al fine di estrarre, in alta resa e purezza, il radioisotopo (RI) di interesse, uno dei passaggi più critici nella produzione da ciclotrone dei RI per la medicina. La possibilità di un’ulteriore crisi di produzione da reattori nucleari di Mo-99, nuclide genitore nei generatori Mo-99/Tc-99m, è ancora uno scenario possibile. La produzione diretta di Tc-99m da ciclotrone per mezzo della reazione nucleare Mo-100(p,2n) sembra essere una soluzione alternativa affidabile. Nell’ambito del progetto TECHN-OSP è stata sviluppata una tecnologia in grado di rendere le radiofarmacie delle Medicine Nucleari, che ospitano un ciclotrone appropriato, indipendenti nella produzione di Tc-99m al fine di sopperire ad ogni eventuale carenza nell’approvvigionamento dei generatori. L’ottimizzazione della produzione ha previsto la progettazione di un target, lo sviluppo di un modulo automatico per il processamento del target e lo studio del recupero del materiale arricchito costituente il target stesso. In questa tesi sono descritti i test di produzione di Tc-99m, eseguiti in collaborazione con l'ospedale Sant'Orsola di Bologna, ed in particolare lo sviluppo di un modulo automatico di processamento del target. Nel corso del dottorato, ho avuto l'opportunità di collaborare con il gruppo di ricerca canadese al TRIUMF (Vancouver, CA), anch’esso coinvolto nell’ottimizzazione della produzione di Tc-99m da ciclotrone, contribuendo all'ottimizzazione e automazione delle procedure di dissoluzione e purificazione di Tc-99m da target di Mo-100. In questa tesi viene anche riportato un confronto tra i due sistemi di processamento target da me sviluppati, in Italia e in Canada. Parallelamente ho collaborato al progetto COME il cui obiettivo risiede nella valutazione dell'efficienza di produzione di Cu-67 da ciclotrone, RI particolarmente interessante per le sue applicazioni in “teranostica”. La produzione da ciclotrone su larga scala di questo RI è ancora un punto chiave scarsamente studiato. Al fine di definire la migliore via di produzione di Cu-67, abbiamo focalizzato l’attenzione su misure di sezioni d’urto inedite (target Zn-70, protoni incidenti di energie 35-70MeV). Essenziale per questo progetto è stato lo sviluppo di un processo altamente efficiente di separazione di Cu-67 dal target e dal Ga-67, coprodotto che, avendo le stesse linee γ del Cu-67, crea problemi nella determinazione dell'attività di Cu-67. La descrizione degli esperimenti, eseguita in collaborazione con ARRONAX, è riportata in questa tesi. Infine, le esigenze cliniche di una maggiore quantità di Ga-68, RI PET attualmente prodotto da generatore Ge-68/Ga-68, hanno spinto il gruppo di ricerca del TRIUMF a studiare la produzione di Ga-68 da ciclotrone a partire da un target liquido di Zn-68, al fine di migliorare la disponibilità di Ga-68 negli ospedali che ospitano un ciclotrone appropriato rendendoli produttori indipendenti. Poiché il problema principale che colpisce la produzione da target liquido è la contaminazione da metalli (es. Fe) provenienti dalla degradazione di alcuni componenti del corpo del target, è stata sviluppata una procedura di separazione e purificazione del Ga-68 da Zn e Fe. Lo scopo principale è quello di ottenere un prodotto finale adatto all’uso medico e di consentire la radio-marcatura di (Ga-68)-DOTATOC e studi di imaging in vivo con Ga-68 prodotto da ciclotrone.
9
Curtis, Nicola. "Tritium NMR studies of protein-ligand interactions". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/842983/.
Texto completo da fonteResumo:
Tritium NMR studies provide a convenient way of obtaining detailed information about conformational equilibria, dynamic processes and specific interactions in protein-ligand complexes provided that suitably 3H-labelled molecules are available. In this study [7,9-3H]- and [3',5',7-3H]folic acid, and [3',5',7-3H]methotrexate were synthesised and the NMR spectra of their complexes with Lactobacillus casei dihydrofolate reductase (DHFR) were assigned and analysed as a function of pH (DHFR-folate complexes) and temperature (DHFR-methotrexate complexes). From these data it was possible to obtain further evidence about the orientation of the pteridine ring in the complexes, and to monitor the dynamic processes in the bound ligands. In the 3H NMR spectra of the ternary complexes of the 3H-labelled folic acids with DHFR and NADP+, each labelled tritium gave rise to multiple signals, confirming previous findings that there are three interconverting, pH dependent, conformational forms of bound folate (forms I, IIa and IIb) in the ternary complex. The folate benzoyl ring could be shown to be in essentially the same environment in the different forms with the major differences being associated with the pterin ring. The appearance of a single resonance for the 3',5'-tritons showed that the benzoyl ring is flipping rapidly in all three forms. In contrast, the methotrexate binary complex and also the ternary complex with NADPH were shown to exist as a single conformational state with the benzoyl ring flipping rate being too slow to give a single averaged signal for the 3',5'-tritium nuclei over the temperature range 283 - 313 K. 3h{1h} Nuclear Overhauser enhancement experiments have been conducted on the small molecules, [3H]dimethyl sulphoxide, [3',5',7-3H]folic acid and [3',5',7-3H]methotrexate as a prelude to 3H-1H heteronuclear NOE experiments on binary and ternary complexes formed using Lactobacillus casei DHFR and the ligands [3',5',7-3H]methotrexate and [3',5',7-3H]folic acid.
10
Valsborg, Jacob Stenmann. "Design and synthesis of radioligands in drug development /". [Cph.] : Royal danish School of Pharmacy, Department of Medicinal Chemistry, 2002. http://www.dfh.dk/phd/defences/jacobvalsborg.htm.
Texto completo da fonte
11
Majibur, Rahman Mohammad. "Development of Analytical Strategies to Measure Radioisotopes of Tin in the Environment". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38606.
Texto completo da fonteResumo:
Quantification of tin isotopes in environmental samples, particularly the radioactive 126Sn, is important for processes such as the biomonitoring of organotin species, long-term nuclear waste storage and treatment planning. The detection of 126Sn by mass spectrometric methods is, however, hampered by the presence of the stable 126Te isotope. Therefore, separation of tin from tellurium is crucial to minimize isobaric interferences that limit the quantification of 126Sn by Accelerator Mass Spectrometry (AMS) and other instrumental techniques. In the present study, three major accomplishments are discussed: i) development of an analytical strategy to separate tin from tellurium, ii) monitoring of anionic interferences in the separation of tin from tellurium, and iii) suppression of 126Te background to allow the detection of 126Sn by AMS.
12
Jensen, M., T. Eriksson, G. Severin, M. Parnaste e J. Norling. "Experimental yields of PET radioisotopes from a prototype 7.8 MeV cyclotron". Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166159.
Texto completo da fonteResumo:
Introduction
The worldwide use of PET has proven beyond dispute the importance for both routine diagnosis and physiological, oncological and pharmacological research. In many ways the present success of PET relies on the mature technology of PET compact medical cyclotrons. As long time developers of new targets, isotopes and com-pounds, we have been inclined to look for new block-buster applications, high power targets and sustainable ways of embracing the GMP and regional distribution, but recent pioneering development [1] around very small cyclotrons and “embedded synthesis and qc” has pointed out an old, but important nuclear physics lesson now halfway forgotten: that many PET isotopes can be made in high yields with proton energies far below 10 MeV [2]. This has opened a new interest in small cyclotrons and their targets.
We have been testing the first GE Healthcare Prototype for a 7.8 MeV negative ion, internal ion source cyclotron with 3 production targets mounted on a short beamline. Here we present the first experimental yields of some of the important PET radionuclides.
Materials and methods
The prototype cyclotron (FIG. 1) has been in-stalled and tested without self-shield in designated experimental area in order to establish the neutron field around accelerator and targets in order to qualify design calculations for a future integrated shield.
The cyclotron energy is fixed by the radial position of the extraction foil, while the azimuth determines which of the 3 targets are being irradiated. The beam energy at front of target foil was determined on several occasions: 7.8 ± 0.1 MeV by a 2 copper-foil sandwich method (adopted from [3]). The available beam inside the cyclotron at extractor position is > 50 μA, and 35 μA are easily and long term reliably extracted (> 90 %) on to any of the 3 target positions. The prototype is capable of delivering more than 40 μA to target, but target current was limited to 35 μA under present unshielded conditions.
Results 18F
We have tested the prototype gridded (> 80 % transmission) niobium body target with 10μm Havar foil using 95 % 18O water and 35 μA on target + grid with yields given in TABLE 1. The observed yields corrected for stopping in foil, grid loss and water enrichment are 75 % of theoretical. One Fastlab FDG run using 2 h irradiation yielded 16 GBq FDG EOS, confirming the “usual” 18F activity.
Results 11C
Using gridded target and a 10μm foil with 99% N2 + 1 % O2 at 10 bar followed by trapping into ascarite gave EOB activity as shown in TABLE 2.
Results 13N
We know that the 16O(p,alpha)13N cross section is a very steep function of energy around 7.8 MeV. In the hope of using the simple water target route to 13N NH3 we have measured the 13N yields (corrected for 18F contribution). It is still unclear if these yields can be improved to make useful single doses of ammonia.
Results for other isotopes
We have used solid targets to make 45Ti, 64Cu, 68Ga and 89Zr. The development of these solid targets is still in progress, but especially the 68Ga yield looks promising (3 GBq EOB after 1 h on natural Zn will give > 15 GBq on enriched 68Zn).
13
Lerner, Paul (Paul Edmund). "Scavenging and transport of thorium radioisotopes in the North Atlantic Ocean". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119989.
Texto completo da fonteResumo:
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 321-351).
Many chemical constituents are removed from the ocean by attachment to settling particles, a process referred to as "scavenging." Radioisotopes of thorium, a highly particle-reactive element, have been used extensively to study scavenging in the ocean. However, this process is complicated by the highly variable chemical composition and concentration of particles in oceanic waters. This thesis focuses on understanding the cycling of thorium as affected by particle concentration and particle composition in the North Atlantic. This objective is addressed using (i) the distributions 228,230,234 Th, their radioactive parents, particle composition, and bulk particle concentration, as measured or estimated along the GEOTRACES North Atlantic Transect (GA03) and (ii) a model for the reversible exchange of thorium with particles. Model parameters are either estimated by inversion (chapter 2-4), or prescribed in order to simulate 230Th in a circulation model (chapter 5). The major findings of this thesis follow. In chapters 2 and 3, I find that the rate parameters of the reversible exchange model show systematic variations along GA03. In particular, k1 , the apparent first-order rate "constant" of Th adsorption onto particles, generally presents maxima in the mesopelagic zone and minima below. A positive correlation between k, and bulk particle concentration is found, consistent with the notion that the specific rate at which a metal in solution attaches to particles increases with the number of surface sites available for adsorption. In chapter 4, I show that Mn (oxyhydr)oxides and biogenic particles most strongly influence k1 west of the Mauritanian upwelling, but that biogenic particles dominate ki in this region. In chapter 5, I find that dissolved 230Th data are best represented by a model that assumes enhanced values of k, near the seafloor. Collectively, my findings suggest that spatial variations in Th radioisotope activities observed in the North Atlantic reflect at least partly variations in the rate at which Th is removed from the water column.
by Paul Lerner.
Ph. D.
14
Remonato, Isabelle. "Les radioisotopes et leurs utilisations thérapeutiques : applications dans les explorations fonctionnelles". Strasbourg 1, 1988. http://www.theses.fr/1988STR15089.
Texto completo da fonte
15
Chen, Ji. "Quantitative cardiac spect in the presence of changing radionuclide distributions". Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17941.
Texto completo da fonte
16
Vermeulen, Christiaan. "The production of ¹³⁹Pr and ¹³⁹Ce in proton-induced reactions /". Link to the online version, 2007. http://hdl.handle.net/10019/728.
Texto completo da fonte
17
Manuel, Y. Keenoy Maria Begona. "Use of radioisotopes in the study of glucose metabolism: the erythrocyte model". Doctoral thesis, Universite Libre de Bruxelles, 1993. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212873.
Texto completo da fonte
18
Shaheen, Tahira. "Influence of speciation on the uptake of radioisotopes by zeolite cation exhangers". Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315385.
Texto completo da fonte
19
Long, Mark. "Application of radioisotopes to polymer chemistry : investigation of radiolabelled atom transfer polymerization". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/application-of-radioisotopes-to-polymer-chemistryinvestigation-of-radiolabelled-atom-transfere-polymerization(deb5aaf4-1bcf-423b-99c2-f9f319f2049a).html.
Texto completo da fonteResumo:
The use of the radioisotope 14C in polymer chemistry has been reviewed, showing how it has been used to investigate the mechanistic aspects of free radical polymerizations, and the use of polymers in other scientific disciplines such as environmental, physical, chemical and medical sciences. An overview of the application of fluorescent spectroscopy to polymer chemistry is also reported. It covers the fundamentals of fluorescence chemistry, its application and the potential problems of the use of fluorescent labels in polymer chemistry. The application of radioisotopes to atom transfer radical polymerisation (ATRP) to investigate the fate of initiators used in the ATRP of 2-hydroxypropyl methacrylate (2- HPMA) is also reported. By using 14C radiolabelled initiators, radio thin layer chromatography (Radio TLC) and the liquid scintillation counting of fractions, collected from gel permeation chromatography (GPC), the fate of the initiating species where monitored during the polymerization of samples of 14C poly(2-HPMA), with degrees of polymerization of 10, 25 and 50 was assessed. GPC and Radio TLC, data showed that there was an under-utilisation of the initiator, 16% clearly observable at high monomer conversion (>97%), which could result in the initiation of new chains at monomer conversions of >90% and as late as 300 minutes after the polymerisation had started. These results contradict ATRP theory which states all initiator is consumed immediately at the commencement of the polymerization. 14C poly(2-HPMA) was also used to determine the efficiencies of the polymer purification methods, flash chromatography and precipitation. Although repeated precipitation increased fractionation, it was shown to be superior to flash chromatography in removing residual unreacted or terminated initiator. Finally, the possible effects of fluorescent labels on adsorption of low molecular weight 14C poly(DEAEMA) onto real surfaces (filter paper, photo graphic paper and hair) from aqueous solutions at pH=2 were investigated. Three low molecular weight samples of 14C poly(DEAEMA) were prepared by ATRP using 14C labelled initiators synthesized from alcohols of increasing hydrophobicity i.e. methyl, benzyl and 9-hydroxyfluorene (fluorescent label). The levels of adsorption were determined using phosphor imaging, oxidation of organic samples and liquid scintillation counting. Results indicated that differences in the chemistry of the polymer end groups can affect adsorption of the 14C poly(DEAEMA) and polymer assembly at the air/water interface. There was greater adsorption of polymers with a fluorescent end group. The increasing deposition was attributed to the increasing hydrophobicity of the polymer end group. Moreover, the controlled placement of one fluorescent label per polymer chain can influence the polymer’s properties, prompting the question, is the use of fluorescent groups to assess polymer behaviour and properties viable?
20
Garrido, Eric. "Production de radioisotopes : de la mesure de la section efficace à la production". Phd thesis, Université de Nantes, 2011. http://tel.archives-ouvertes.fr/tel-00662649.
Texto completo da fonteResumo:
De nouveaux radio-isotopes pour la médecine nucléaire peuvent être produits par des accélérateurs de particules. C'est l'un des buts d'Arronax, un cyclotron de hautes énergies - 70 MeV - et hautes intensités - 2*350 µA - installé à Nantes. Une liste d'émetteurs b- - 47Sc, 67Cu - b+ - 44Sc, 64Cu, 82Sr/82Rb, 68Ge/68Ga - et a - 211At - à étudier en priorité a été établie. Parmi ceux là, le 47Sc et le 67Cu présentent un intérêt en thérapie ciblée. L'optimisation de leurs productions nécessite la bonne connaissance de leurs sections efficaces, mais aussi de celles de tous les contaminants créés. Nous avons lancé sur Arronax un programme de mesures de sections efficaces utilisant la technique des Stacked-foils. Elle consiste en l'irradiation simultanée d'un groupe de feuilles - cibles, moniteurs et dégradeurs - et la mesure par spectro-gamma de la production d'isotopes. Les moniteurs permettent un contrôle des pertes de faisceau tandis que les dégradeurs en diminuent l'énergie. Nous avons étudié les réactions natTi(p,X)47Sc et 68Zn(p,2p)67Cu. Les cibles étant respectivement des feuilles de natTi - achetées chez Goodfellow - ou des électrodépositions sur Ag de 68Zn enrichi. Nous les réalisons nous même ainsi que la séparation chimique des isotopes de Cuivre et de Gallium indispensable avant de procéder au comptage gamma. Les sections efficaces de plus de 40 réactions ont ainsi été obtenues sur l'intervalle de 18 MeV à 70 MeV. Une comparaison avec le code Talys est systématiquement faite, et plusieurs paramètres des modèles théoriques étudiés. Nous montrons qu'il est impossible de reproduire avec exactitude toutes les sections efficaces à partir d'un seul jeu de ces paramètres.
21
Yoo, Kyung Yeong. "A model for dispersion and deposition of radioisotopes in the planetary boundary layer". Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283242.
Texto completo da fonte
22
Stokes, Lee [Verfasser], e Tobias [Akademischer Betreuer] Lachenmaier. "Cosmogenic Radioisotopes in the Double Chooz Far Detector / Lee Stokes ; Betreuer: Tobias Lachenmaier". Tübingen : Universitätsbibliothek Tübingen, 2017. http://d-nb.info/1167248015/34.
Texto completo da fonte
23
Stephenson, Karin A. Valliant John Fitzmaurice. "New approaches for the preparation of peptide-targeted radiotracers". *McMaster only, 2005.
Encontre o texto completo da fonte
24
Sandell, Johan. "Development of radioligands for the serotonergic neurotransmission system for use in positron emission tomography /". Stockholm, 2001. http://diss.kib.ki.se/2001/91-628-4818-6/.
Texto completo da fonte
25
Ghosh, Sarba Bijoy. "Factors affecting the mobility of selected radionuclides codisposed with municipal refuse within landfills". Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/20752.
Texto completo da fonte
26
Shang, Zhaorong. "A study of Ag-110m in aquatic and terrestrial ecosystems and the development of a radioecological model /". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23768782.
Texto completo da fonte
27
Moustapha, Moustapha Eid. "A comparative study between no-carrier-added ¹⁸⁶Re, carrier-added ¹⁸⁶Re and no-carrier-added ¹⁸⁸Re for radiolabeling of N₃S-5Ava-BBN(7-14)NH₂ conjugate /". free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1422946.
Texto completo da fonte
28
Engle, J. W., T. E. Barnhart, H. F. Valdovinos, S. Graves, P. A. Ellison e R. J. Nickles. "Making high-value, long-lived isotopes to balance a sustainable radiotracer production facility". Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-164889.
Texto completo da fonteResumo:
Introduction
The embrace of PET by medical clinicians has been reluctant (ΔT ≈ 20 yr) primarily due to the scale of the infrastructure that is needed. The capital cost of a cyclotron (≈ 106 USD) is now dwarfed by the demand for compliance to recent regulatory standards. This is a recurring expense, not only imposing an order-of-magnitude increase in staffing and operating costs, but damping the enthusiasm of researchers recalling the brisk pace of research in earlier days. Now an academic site, with little interest or opportunity to scale up production for wider distribution, is burdened by the new regulatory terrain of good manufacturing practice (GMP), mandated for translational studies that will reach only a few subjects. With our production resources held within a basic science department, the Medical Physics cyclotron facility at the University of Wisconsin has sought a sustainable pathway. We now anchor the operating budget by providing high-value, long-lived radionuclides to off-site users, to buffer the fluctuations of local demand for conventional PET synthons.
Material and Methods: The tools of the trade
The radioisotopes discussed here belong to the 3-d and 4-d sub shell, but are now moving into the rare-earths, with applications ranging from
- targeted molecular imaging agents,
- internal radionuclide therapy using to Auger electron-emitters,
- to basic physics experiments using 163Ho (t1/2 ≈ 4500 yr) to determine the mass of the neutrino.
Rather than focusing on the dozens of radionuclides produced, a number of tools deserve mention, as they support a variety of targets, reactions and products. These will be listed in order (A-G) from cyclotron to extraction to analysis.
A. Two cyclotrons are used, a legacy RDS 112 (#1; 1985) and a GE PETtrace (2009). Neutron and gamma detectors are monitored during the long irradia-tions, signaling any subtle changes in the running conditions. (1). The PET-trace is fitted with a quick-change variable degrader target (2), as well as a beam-line with a 5-port (0 o, ±15 o, ±30 o) vertical switching magnet (3). The downward directed beam ports provide support for solid targets (e.g. Ga, S, Se, Te) that melt at low temperature. The irradiation of gas targets employs a generalized manifold to handle inert gases such as 36Ar for the production of 34mCl, as well as natural Kr and Xe for making Rb and Cs isotopes to act as fission product surrogates. These products are captured on a stainless steel target chamber liner, and rinsed off with warm water. The alkali metals are convenient tracers to study the ion exchange trapping process, pivotal in future 99Mo production from solution reactors (4).
B. The preparation of malleable solid targets employs a 10-ton hydraulic bench press, and a jeweler’s mill to roll out foils from pellets, pressed between Nb foils to avoid contamination.
C. Binary alloys are smelted in a programmable 1600o tube furnace under argon flow (eg. NiGa4). Alternatively, an induction furnace now permits highly localized heating of the binary metal charge, while allowing mechanical agitation during the smelting process.
D. Electroplating onto gold discs is used for various enriched target material or the alloys above where quantitative recovery is essential, or where heat transfer from high beam current is demanding.
E. The separation chemistry, prior to che-lation to targeted molecular imaging agents, is performed in LabView-driven, home-built “black boxes” resident in mini-cells (Radiation Shielding Inc.).
F. Analysis of the targets after irradiation makes use of HPGe spectroscopy for gammas and characteristic X-rays of decay (e.g. rare earths). The elemental constitution of target alloys is deter-mined prior to irradiation by X-ray fluorescence analysis, excited by 109Cd and 241Am sources.
G. Finally, broad-band elemental analysis at the ppb level now makes use of a microwave plasma atomic emission spectrometer (Agilent 4200), to be de-scribed elsewhere in this meeting.
Results and Conclusions
The tools above (A-G) are employed in the pro-duction of the expanded list of radionuclides offered by our cyclotron group to both local and off-site colleagues. The list below is ordered in terms of decreasing use, from regular production for national distribution (64Cu, 89Zr), to weekly inhouse use (44Sc, 66,68Ga, 68,69,71Ge, 72As, 61Cu, 86Y), to infrequent production for multi-site collaborations (163Ho, 95mTc, 206Bi):
Radionuclide Target Employs
64Cu 64Ni/Au A, D, G
89Zr natY A, E, G
44Sc natCa A, B, E, F, G
66, 68Ga Zn/Ag A, B, D, E, F, G
68, 69, 71Ge Ga, GaO2 A, B, C, E,F
72As GeO2 A, B, E, F
52Mn natCr A, E, F, G
76, 81mBr SeO A, E, F
34mCl, Rb, Cs noble gas A, E, F
95mTc,163Ho Mo, Dy A, E, F
TABLE 1. Target materials and processes.
The production of long-lived radionuclides lends itself to crowd-sourcing, with distributed irradia-tion at virtually any site with a suitable accelera-tor and a relaxed beam schedule. A number of unique challenges do arise that don’t appear in the usual production of conventional cyclotron products such as 11C or 18F. Contamination by stable metals, inadvertently introduced by target pressing or beam-induced sputtering from degraders, can cause serious interference downstream limiting effective specific activity. Long-lived manganese isotopes are ubiquitous. And some very high value products are simply not within the reach of small cyclotrons, such as 52Fe and 67Cu, being too far off the line of beta stability.
In conclusion, the research leading to a doctoral degree necessarily must focus on the physics and chemistry of novel radionuclides and tracers. On the other hand, clinical and translational research needs established imaging agents, with little room for innovation within the regulatory constraints. Our experience at Wisconsin has led us to a balancing act, with our routine production of clinical doses countered with our research program to provide high-value radionu-clides for our collaborative work with our basic science colleagues.
29
Moysey, Stephen. "Meteoric 36-Cl in the Contiguous United States". Thesis, The University of Arizona, 1999. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0121_sip1_w.pdf&type=application/pdf.
Texto completo da fonte
30
Adil-Smith, Iran. "Structural analysis of thyroid hormones by EXAFS and molecular simulation : biological effects of '1'2'5I". Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362488.
Texto completo da fonte
31
Sridhara, Bangalore Sitaramiah. "Clinical evaluation of '9'9'mTc tetrofosmin in the detection of ischaemic heart disease". Thesis, University of Surrey, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259561.
Texto completo da fonte
32
Jia, Wei. "The production of high specific activity radionuclides for radiotherapy application /". free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9720538.
Texto completo da fonte
33
Dufford, Christopher Allyn. "Feasibility of angular correlation measurements using clinical nuclear medicine equipment". Oklahoma City : [s.n.], 2009.
Encontre o texto completo da fonte
34
Xu, Yue. "Electrochemical treatment of metal-bearing aqueous wastes based on novel forms of carbon". Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=433.
Texto completo da fonteResumo:
Thesis (Ph. D.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xv, 207 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 203-207).
35
Davenport, Bradley P. "Advanced thermophotovoltaic cells modeling, optimized for use in rRadioisotope Thermoelectric Generators (RTGS) for Mars and deep space missions /". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FDavenport.pdf.
Texto completo da fonte
36
Morisset, Natalie Carleton University Dissertation Geology. "Stableisotope and radioisotope geochemistry of the Panda Hill carbonatite, Tanzania". Ottawa, 1992.
Encontre o texto completo da fonte
37
Younis, Abdul-Redha Sahib. "Biophysical damage in metallo-enzyme and mammalian cells by Cu-K X-rays and radioisotopes". Thesis, University of St Andrews, 1989. http://hdl.handle.net/10023/14089.
Texto completo da fonteResumo:
In the fields of radiobiology and nuclear medicine there is considerable interest in the important role played by Auger electron cascades caused by inner-shell ionisation in realistic risk. It is necessary to quantify this risk when radionuclides are used on a routine basis as investigative, diagnostic and radiotherapeutic tools, whether the applications involve incorporated electron capture radionuclides or K-shell ionisation of selected stable nuclides by X-rays, as in "photon activation therapy". Relevant published survival data on biological damage caused by the internal emitters 125I, 77Br, 3H, 33P, 131I and 32P which are incorporated into the DNA of mammalian cells, bacteria (E. Coli) and bacteriophages have been collected and the results re-analysed in terms of the parameters of a new damage model to determine an inactivation cross-section for each internal emitter. These quality parameters are the absolute specification of radiation quality and are compared with cross-sections similarly determined for the effects of external radiations from heavy charged particles and photons (chapter 2). The inactivation probabilities obtained for the nuclides 125I, 77Br and 3H extend over a wide range of values depending on the type of nuclide and its distribution, the type of sensitive target and its shape and distribution, and the environmental temperature during both irradiation and post-irradiation incubation. The higher values approach those determined for heavy charged particles with the same mean free path for primary ionisation, and are an order of magnitude larger than would be expected for external irradiation with photon generated electrons. The results for 33P, 131I and 32P nuclides are appreciably smaller than that expected for external irradiation since the long range electrons dissipate most of their energy out of the sensitive target. A theoretical equation for X-ray production by accelerated electrons incident on a thick target has been revised by including factors to compensate for backscattering, direct and indirect ionisation, attenuation in the target and the incident angle of electrons (chapter 3). An electron accelerator X-ray machine capable of delivering monoenergetic photons up to ~ 4.8 gray/sec exposure dose rate from four different targets has been designed, constructed and tested (chapter 4) The biophysical mechanisms of direct and indirect radiation action has also been studied using the metallo-enzyme dihydroorotic dehydrogenase. The enzyme was irradiated both in dry state and in solution at different concentrations and at different dose rates using monoenergetic Cu-K photons from our X-ray machine. A technique was developed whereby it was possible to isolate and quantify each type of radiation action (chapter 5). The inactivation of the enzyme in both solution and in dry state was found to be a single-hit/single-target process. It was also found that in solution the inactivation of the enzyme was dose-rate-and concentration-dependent with efficiency of radical inactivation has an exponential dependence on dose-rate and the inverse of the enzyme concentration. A new model for the inactivation of the enzyme has been suggested and its parameters, namely direct and indirect cross-sections, geometrical cross-section, saturated concentration constant, root mean square diffusion constant, mean free path of radicals absorption, life time and G value of radical production, have been determined. It is expected that this model can be generalised to suit other enzymes (chapter 6).
38
LIMA, CLARICE M. de. "Estudo da marcação e biodistribuição da substância P utilizando lutécio-177 como radiotraçãdor". reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9991.
Texto completo da fonteResumo:
Made available in DSpace on 2014-10-09T12:33:37Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:06:21Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
39
PERES, ANA C. "Modelo para o estabelecimento de valores orientadores para elementos radioativos no solo". reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11591.
Texto completo da fonteResumo:
Made available in DSpace on 2014-10-09T12:53:36Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:08:08Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
40
Patel, Amina. "An experimental investigation to assess the feasibility of imaging medical radioisotopes with the ProSPECTus Compton Camera". Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003463/.
Texto completo da fonteResumo:
An experimental investigation into the feasibility of imaging multiple medical radioisotopes with the ProSPECTus Compton camera is presented. The aim of the project is to develop a Compton imaging system configured with segmented solid state detectors, for the purpose of alleviating the limitations of conventional Single Photon Emission Computed Tomography (SPECT) systems. The ProSPECTus system consists of a Si(Li) and HPGe planar detector housed in a magnetic field compatible custom made cryostat. The investigation presented in this thesis has been undertaken with a prototype ProSPECTus system, which consists of Si(Li) and HPGe planar detectors housed in separate cryostats. Analysis of the results attained from investigations into the optimum coincidence window, noise thresholds and image reconstruction techniques as part of this thesis are to be used to inform future developments and measurements. The work presented focuses on an investigation of simultaneous data acquisition with the medical radioisotopes 99mTc and 123I, which emit gammarays with energies of 141 keV and 159 keV, respectively. The experimental methodology of defining parameters for timing and noise thresholds is described along with system performance in terms of image quality and efficiency. A custom designed phantom is used to build source complexity and to provide qualitative and quantitative assessment of the imaging capabilities of ProSPECTus using analytical and iterative reconstruction algorithms. It has been determined that a spatial resolution of 3 mm is achievable, using iterative reconstruction of data acquired from a 139Ce point source of energy 166 keV. Quantitative analysis has revealed that an Edge Response is a good measure of determining the resolvability of extended source distributions. It has been proved that the spectroscopic response enables ProSPECTus to image 99mTc and 123I simultaneously. This would otherwise require complex peak deconvolution techniques in clinical SPECT systems. An improvement in efficiency of up to a factor of 2.5 over conventional SPECT systems is demonstrated, with suggestions for further improvements, indicating a factor of 23 is achievable with the next generation system. This would potentially reduce patient dose or increase patient throughput. Suggestions are presented for the iterative reconstruction algorithm to facilitate enhanced imaging with the next generation ProSPECTus system.
41
Huet-Dales, Aline. "Développement de nouvelles espèces organométalliques pour le marquage par des radioisotopes de courte durée de vie". Bordeaux 1, 2003. http://www.theses.fr/2003BOR12735.
Texto completo da fonteResumo:
La réactivité d'organoétains originaux et non polluants a été étudiée lors du couplage de Stille dans des conditions rapides, compatibles avec l'utilisation de radioisotopes de courte durée de vie. Dans un premier temps, les conditions réactionnelles ont été développées afin de transférer un groupement méthyle par couplage de Stille, via la formation du monoorganoétain correspondant. Le temps de réaction a été optimisé sur des modèles, puis les conditions réactionnelles ont été appliquées en chimie du carbone-11. Dans un second temps, la méthodologie mise au point a été utilisée afin de synthétiser des radioligands des récepteurs NK3, en chimie du carbone-12 et du carbone-11. Les études biologiques ont montré que les ligands synthétisés ont une bonne affinité avec les récepteurs NK3, et représentent des radiotraceurs potentiels utilisables en tomographie par émission de positonsThe reactivity of clean organotins have been studied in the Stille coupling reaction under fast conditions, wich can be used with short half-lives isotopes. Firstly, the development of the reaction conditions have been studied for the transfer of a methyl group by the Stille coupling reaction, via the synthesis of the corresponding monoorganotin. The reaction time was optimized onto model compounds for carbon-12 as well as for carbon-11 chemistry. Secondly, this reaction was applied to the synthesis of NK3 receptors radioligands, in carbon-12 and carbon-11 chemistry. Biological studies showed that these ligands have a good affinity with NK3 receptors and can considered as potential tracers for the Positron Emission Tomography
42
Speed, Mark. "The isotope hydrology of the River Dee, North East Scotland". Thesis, University of Aberdeen, 2011. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=182254.
Texto completo da fonteResumo:
Identifying how the dominant runoff processes of sub-catchments integrate to determine hydrological responses at larger scales (> 1000 km2) remains a major challenge in hydrology. At these larger scales, major environmental differences such as climate, geology and land use may have increased influence on runoff dynamics. While process investigations at smaller scales (< 10km2) have been important in establishing the influence of topography and soils on runoff generation, more research at larger spatial scales is needed, since it is at such scales where important water management decisions are made in relation to applied problems such as floods and droughts. Tracers, such as stable isotopes of water, have proven utility as tools since they reflect the integration of processes at much smaller scales. In addition, geochemical tracers, such as alkalinity, help identify the geographical sources of runoff in larger catchments. This thesis focuses on their use to study catchment hydrological processes in the River Dee (~2,100 km2), NE Scotland, and to determine how these processes integrate at larger scales. Runoff from soil derived hydrological responsive pathways dominates during high flow facilitating a relatively rapid translation of precipitation isotope signatures into the channel network. Increased coverage of responsive soils resulted in reduced Mean Transit Time (MTT) estimates. High coverage of freely draining soils and certain landscape features often resulted in greater MTT estimates. Small scale heterogeneity appears to be averaged out at larger scales with MTTs indicating that the montane headwaters of the river are the dominant source of runoff. Transit Time Distributions (TTDs) suggest that catchment waters may have transit times of less than 2 weeks during high flows and greater than 10 years in summer baseflows.
43
Livieratos-Petratos, George N. "Neural networks for computer aided diagnosis of pulmonary images in nuclear medicine". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295017.
Texto completo da fonte
44
Van, Rooy Milton William. "An investigation of a possible effect of reactor antineutrinos on the decay rate of 22Na". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97145.
Texto completo da fonteResumo:
Thesis (PhD)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Reported claims of a solar neutrino influence on radioactive β - -decay rates prompted a series of three long term measurements that were carried out at the Koeberg nuclear power plant North of Cape Town to investigate the mirror reaction of reactor antineutrinos with a β + - source. The β + -emitter 22Na was exposed to a changing reactor antineutrino flux of the order of ~1012 cm-2 s -1 through the various phases of reactor operation, from off to on or vice versa, to investigate the antineutrino effect on its decay rate. 22Na sources were placed on the face of or inside a scintillation detector while γ-ray energy spectra were measured at source-toreactor-core distances of 17 m and 23 m for reactor unit #1 and unit #2 respectively. The analytical method employed uses ratios of the net-peak count rates of the photopeaks in the γ- ray energy spectra while the antineutrino flux changes during the various phases of reactor operation. These ratios reduce some potential systematic factors such as dead time, but should also remain constant during all phases of reactor operation and be independent of antineutrino flux if antineutrinos have no significant effect on the decay rate of 22Na. Measurement series 1 employed a LaBr3(Ce) detector. Results indicated an effect between reactor-off and –on corresponding to an antineutrino interaction cross section upper limit of the order of barns, assuming that antineutrinos are indeed the cause. Subsequently, two confirmation measurements were performed using a normal (cylindrical) NaI(Tl) detector as well as a NaI(Tl) well-counter. Results of these two measurements did not indicate any correlation with the reactor status. Measurements series 3 proved to be the most sensitive measurement for detecting changes in the decay rate of 22Na and an upper limit of ~10-25 cm 2 was estimated for the cross section of antineutrinos interacting with 22Na. This upper limit is one order of magnitude smaller compared to measurements series 1 and two orders of magnitude smaller compared to measurement series 2. It is also one of magnitude smaller than the effect reported by Jenkins et al. and two orders of magnitude smaller than observed by de Meijer et al. at the Delft reactor. Considering the systematic effects encountered during each measurement series we find no significant evidence for antineutrinos affecting β + -decay in 22Na.
AFRIKAANSE OPSOMMING: Berigte bewerings van son-afkomstige neutrinos se invloed op β - -verval het gelei tot drie lang termyn metings wat uitgevoer is by die Koeberg kernkrag stasie Noord van Kaapstad om die spieëldbeeld reaksie van antineutrinos met ‘n β + -bron te ondersoek. Die 22Na β + -bron is blootgestel aan ‘n veranderende reaktor antineutrino vloed van die order ~1012 cm -2 s -1 soos die reaktor deur verskeie fases van operasie gaan, vanaf afgeskakel na aangeskakel of omgekeerd, om die effek van antineutrinos op die bron se vervaltempo te ondersoek. 22Na bronne was teen die voorkant of binne ‘n sintillator detektor geplaas terwyl γ-straal energie spektra gemeet was by bron-tot-reaktor kern afstande van 17 m en 23 m vir reaktor eenheid #1 en #2 afsonderlik. Die analitiese metode gebruik verhoudings van die netto-piek teltempos van die fotopieke in die γ-straal energie spektra terwyl die antineutrino vloed verander tydens verskeie fases van reaktor operasie. Hierdie verhoudings verminder sekere potensiële systematiese effekte soos dooietyd en moet konstant bly tydens alle fases van reaktor operasie en moet ook onafhanklik wees van die antineutrino vloed indien antineutrinos geen effek het op die vervaltempo van 22Na nie. Die eerste reeks metings het gebruik gemaak van ‘n LaBr3(Ce) detektor. Resultate het ‘n effek getoon tussen reaktor-af en reaktor-aan wat ooreenstem met ‘n boonste limiet vir die interaksie kansvlak van antineutrinos met grootteorde van barns, indien antineutrinos wel die oorsaak is. Twee reekse van opvolgende metings is uitgevoer wat gebruik gemaak het van ‘n gewone (silindriese) NaI(Tl) detektor asook ‘n NaI(Tl) put detektor. Resultate van hierdie metings het geen korrelasie met die reaktor status gewys nie. Die derde reeks metings was die sensitiefste om veranderinge in die verval tempo van 22Na te wys en ‘n boonste limiet vir die interaksie kansvlak van antineutrinos op 22Na was beraam as ~10-25 cm 2 . Hierdie boonste limiet is een grootteorde kleiner in vergelyking met reeks 1 en twee grootteordes kleiner as reeks 2. Dit is ook een grootteorde kleiner as die waarde van Jenkins et al. en twee grootteordes kleiner as wat de Meijer et al. berig het by die Delft reaktor. In agneming van die systematise probleme wat ondervind was tydens die drie reeks metings vind ons geen beduidende effek van antineutrinos op die vervaltempo van 22Na nie.
45
Adams, B. K. "The role of imaging with iodine-131-meta-iodobenzylguanidine in the diagnosis and localisation of suspected phaeochromocytoma". Thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/25826.
Texto completo da fonte
46
Duringer, Cathy. "La contamination de la thyroide par les radioisotopes de l'iode en cas d'accident nucleaire : methodes de prevention". Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR1M007.
Texto completo da fonte
47
Dess, Brian William. "Signal processing and pattern recognition methods for the remote, airborne detection of radioisotopes by gamma-ray spectroscopy". Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2068.
Texto completo da fonteResumo:
The U.S Environmental Protection Agency (USEPA) Airborne Spectral Photometric Environmental Collection Technology (ASPECT) program is designed in part to provide first responders with radiological mapping of potentially hazardous locations. This program utilizes an aircraft fitted with a gamma-ray spectrometer capable of remote detection of radioisotopes. The challenges present in detecting a radioisotope signal remotely are strongly tied to the signal-to-noise ratio of the collected gamma-ray spectra and the specific signal processing and pattern recognition methods used in the data analysis. Depending on the distance from the detector to the radioisotope source, Compton scattering can significantly reduce the analyte signal, and weakened signals pose a significant challenge when attempting to design an effective classifier for detecting radioisotopes of interest.
In this research, a basic methodology has been developed for the detection of cesium-137 (¹³⁷Cs) and cobalt-60(⁶⁰Co) utilizing only laboratory collected spectra and backgrounds from the field collected only once. The presented classifier methodology has been proven to provide a fundamental structure for which more advanced algorithms can be developed. Furthermore, this methodology has demonstrated the ability to strongly associate a level of confidence in a detection which allows for intelligent decision making. From this basic methodology, more sensitive and selective algorithms can be designed.
The Compton effect has previously been problematic in the development of gamma-ray pattern recognition systems. In this research, a background suppression methodology utilizing linear regression has been implemented to enhance the basic pattern recognition methodology. This background correction strategy has led to significant improvements in the remote detection of radioisotopes and enables the classification of more complex radioisotopes such as europium-152 (¹⁵²Eu). This research demonstrates not only the capabilities of the pattern recognition methodology, but also the flexibility of the procedure.
In the remote detection of radioisotopes, false detections and low sensitivity are the key challenges when developing a classifier. While the background corrected methodology was shown to greatly enhance the classifier performance, further advances can be made into the methodology through the use of committee classifiers. Since every classifier utilizes a different dataspace, a standardization procedure has been developed from which the classifier result can be averaged and generate a committee classifier result. This classifier methodology has been demonstrated to further improve the radioisotope classifier performance without sacrificing either sensitivity or selectivity.
While the development of targeted radioisotope classifiers is invaluable to the first responder, developing a general gamma-ray anomaly classifier can handle those radioisotopes that have no dedicated classifier. From this objective, a unique anomaly classifier based on the Compton region of the gamma-ray spectrum has been developed and demonstrated to operate in the field. Utilizing all of the strategies and techniques developed for single radioisotope classifiers, the anomaly classifier has been proven to detect background and natural radioactive sources as well as controlled and man-made radioisotope targets.
From the developed remote detection classifiers via pattern recognition techniques, robust radiation detection classifiers have been developed. This pattern recognition methodology eschews the need for extensive field data collection for training the algorithms, while also removing the need for on-site calibrations. When used in conjunction with one another, the dedicated radioisotope and anomaly classifiers provide a thorough and rugged remote detection capability to the first responder. The presented methodology also demonstrates that any radioisotope classifier can be generated, implying that this method can be used for the detection of any radioisotope in the field.
48
MADUAR, MARCELO F. "Desenvolvimento de um codigo computacional aberto de analise quantitativa para determinacao de radionuclideos por espectrometria gama com detectores semicondutores". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9534.
Texto completo da fonteResumo:
Made available in DSpace on 2014-10-09T12:27:44Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:05:16Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
49
Leigh, Sasha Naomi Bharier. "A study of the dynamics of the British Ice Sheet during Marine Isotope Stages 2 and 3, focusing on Heinrich Events 2 and 4 and their relationship to the North Atlantic glaciological and climatological conditions /". St Andrews, 2007. http://hdl.handle.net/10023/525.
Texto completo da fonte
50
Shang, Zhaorong, e 商照榮. "A study of Ag-110m in aquatic and terrestrial ecosystems and the development of a radioecological model". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B29747326.
Texto completo da fonte