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The Global ETD Search service is a free service for researchers
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 31 to 33 of 33 (0.112 seconds)| 31 |
Comparação da técnica de radioterapia em arco modulada volumetricamente (VMAT) em relação à técnica de radioterapia de intensidade modulada (IMRT) para tumores de próstata e cabeça e pescoço / Volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) techniques comparison for prostate and head and neck tumorsÉrika Yumi Watanabe 12 January 2016 (has links)
As técnicas de radioterapia vem sendo constantemente modificadas com a implementação de novas tecnologias visando aumentar a eficiência e diminuir a toxicidade dos tratamentos com radiação ionizante. Esse trabalho visa comparar as técnicas de radioterapia de intensidade modulada (IMRT) e a radioterapia em arco modulada volumetricamente (VMAT) em termos dosimétricos para o alvo e órgãos em risco além de avaliar a diferença do tempo de tratamento utilizando cada técnica. Para assegurar que os planejamentos seguiriam um padrão aceitável para ambas as técnicas, realizou-se primeiramente os planejamentos sugeridos pelo TG 119 da Associação Americana de Física Médica e compatibilidade dos resultados obtidos comparados com os dados da literatura. Tal comparação permitiu prosseguir para uma próxima etapa que consistiu da utilização de imagens de pacientes reais que foram submetidos a tratamentos de próstata e cabeça e pescoço, para a realização dos planejamentos utilizando as técnicas de IMRT e VMAT. A qualidade dosimétrica dos planejamentos utilizando ambas as técnicas foi avaliada em termos de conformidade e homogeneidade da dose no alvo e para os casos de pacientes com câncer de próstata, foram investigados os limites de dose em reto, bexiga e cabeça de fêmur, sendo avaliada a associação entre o volume de intersecção de reto e bexiga com o alvo. Para os casos de pacientes com câncer de cabeça e pescoço, em termos dos limites de dose em medula, tronco cerebral e parótidas. Os planejamentos nos quais fez se uso da técnica de VMAT apresentaram valores semelhantes aos dos planos de IMRT. A análise dos tempos de tratamento para cada técnica avaliada mostrou que a VMAT reduz significativamente o tempo, até 67% para os casos de pacientes com câncer de próstata e até 36% para os casos de pacientes com câncer de cabeça e pescoço / The goal of this study was to compare the dosimetric aspects of volumetric-modulated arc therapy (VMAT) with those of intensity-modulated radiotherapy (IMRT) and to evaluate the delivery time and monitor unit differences between the two techniques, for applications in prostate and head and neck cancer treatment. First of all, to assure an acceptable pattern of treatment planning using both techniques, the TG119 of American Association of Medical Physics instructions were followed and the results of plans were compared to TG119 published data. The next step consisted of using real patients\' images, whose underwent prostate radiotherapy or head and neck radiotherapy, to planning IMRT and VMAT. The dosimetric quality of plans using both techniques was evaluated in terms of target dose conformity and target dose homogeneity The dose constraints for rectum, bladder and femoral head were analyzed and the association between the rectum intersection volume and bladder intersection volume to the target volume were evaluated for the prostate cases. The dose constraints for spinal cord, brainstem and parotids were investigated for the head and neck cases. Best or similar values were obtained for the VMAT plans in relation to IMRT plans. The analysis of treatment time indicated a significant reduction using VMAT, until 67% to the prostate cases and 36% to the head and neck cases
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Утицај дозе и фракционирања у интерстицијалној брахитерапији на исход лечења код пацијената са локализованим карциномом простате / Uticaj doze i frakcioniranja u intersticijalnoj brahiterapiji na ishod lečenja kod pacijenata sa lokalizovanim karcinomom prostate / Impact of the Dose and Fractionation in the Interstitial Brachytherapy to the Treatment Outcome for Patients with Localized Prostate CarcinomaDabić Stanković Kata 16 October 2020 (has links)
<p>Brahiterapija visokim brzinama doze (HDR–BT) predstavlja efikasan modalitet zračenja kod pacijenata sa lokalizovanim karcinomom prostate (CaP) svih rizika. Za razliku od transkutane radioterapije i brahiterapije niskim brzinama doze (LDR–BT), kod ove grupe pacijenata u intersticijalnoj HDR–BT još uvek nisu jednoznačno definisane ukupne doze zračenja, način frakcionisanja kod pacijenata sa lokalizovanim CaP različitih rizika. U periodu od 2009–2018.god. HDR–BT kao jedinim načinom lečenja (monoterapija) u Opštoj bolnici Medicinski sistem Beograd, lečeno je 35 pacijenata (6 (17,1%) pacijenata niskog rizika, 21 (60%) pacijent srednjeg rizika i 8 (22,9%) pacijenata visokog rizika) sa lokalizovanim CaP različitih rizika od relapsa i progresije bolesti. Grupe pacijenata sa srednjim i visokim rizikom spojene su u jednu grupu (grupa sa višim rizikom). Tehnika sprovođenja HDR–BT, osim u pojedinačnim specifičnim detaljima, bila je slična kao i kod LDR–BT. Aplikacija igala, segmentacija, delineacija i planiranje HDR–BT vršeno je korišćešem transrektalnog ultrazvuka (TRUS) i izocetričnog radioskopskog C–luka, a zračenje je sprovedeno na uređaju Microselectron HDR sa zatvorenim radioaktivnim izvorom 192Ir početne aktivnosti 370 GBq. Aplikovane terapijske doze (TD), u opsegu od 30–57 Gy frakcionisane su u 3–4 nezavisne frakcije sa razmakom od 2–3 nedelje između frakcija, a individualizovane su prema nivou rizika, stanju organa u riziku (OAR) i kvalitetu aplikacije (indeksu prekrivanja CTV sa planiranom terapijskom dozom (CI100%) i mogućnošću zaštite OAR). Uspešnost terapije ocenjivana je postignutom biohemijskom kontrolom (BFS – biochemical–free–survival), prema ASTRO i Phoenix kriterijumima, kao i ukupnim preživljavanjem u periodu od 5 godina (2–9 godina) posle sprovedene terapije. U niskorizičnoj grupi pacijenata lečenih HDR–BT, BFS je postignuta kod svih pacijenata kao i ukupno preživljavanje. U grupi pacijenata sa višim rizikom BFS je postignuta kod 95,8% lečenih pacijenata, a ukupno 5–to godišnje preživljavanje je 96,4%. BFS u ovom istraživanju se pokazala statistički značajnije bolja nego ona koju su prikazali drugi autori. Na osnovu rizika, nivoa PSA, TD i indeksa pokrivenosti CTV sa TD, izvršeno je modelovanje terapijskih parametara korišćenjem MANN (multilauyer artificial neural network). Određena optimalna doza zračenja (TD) u HDR–BT lokalizovanog CaP niskog rizika je 40,7 Gy za CI100% = 1,01. Kod viših rizika TD = 50,9 Gy za CI100% = 1,6. TD se frakcioniše u 4 nezavisne frakcije sa razmakom od 2–3 nedelje. Ovakav izbor parametara HDR–BT (TD, CI100%, i način frakcionisanja), uz individualizaciju i kontrolu u toku svake aplikacije, obezbedio bi prihvatljiv nivo kasnih postiradijacionih komplikacija gradusa G1–G3 na uretri (< 17% ukupnog broja lečenih pacijenata), uz minimimalne komplikacije na rektumu (pretežno G1–G2) i zanemarljive komplikacije na mokraćnoj bešici.</p> / <p>High–dose rate brachytherapy (HDR–BT) is an effective therapy modality for patients with localized prostate cancer (CaP) of all risks. In contrast to an external beam radiotherapy and low–dose rate brachytherapy (LDR–BT), in these patients, the interstitial HDR–BT, the total radiation dose and fractionation is not unambiguously defined. Between 2009–2018 35 patients with localized CaP (6 (17.1%) low–risk patients, 21 (60%) patients medium–risk and 8 (22.9%) high–risk) were treated with HDR–BT, as the only treatment (monotherapy) in the General Hospital Medical System Belgrade. The group of patients with medium–risk and high–risk were merged into a single group (group with a higher–risk). Technique implementation of HDR–BT was similar as in the LDR–BT. Application of needles, segmentation, delineation, and planning of HDR–BT was performed with transrectal ultrasound (TRUS) and izocentrically mounted radioscopic C–arm. Irradiation was done on the Microselectron–HDR brachytherapy unit with a sealed radioactive source 192Ir (370 GBq). The dose (TD), in the range of 30–57 Gy was given fractionated in independent fractions (3–4) with a pause of 2–3 weeks between fractions. TD was individualized according to the risk, the conditions of organs at risk (OAR) and quality of the application (coverage index CI100%), as well as, the ability to protect OAR. Treatment result was evaluated by the achieved biochemical control (BFS – biochemical–free–survival) according to ASTRO and/or Phoenix criteria, as well as an overall survival in the period of 5 years (2–9 years) after the completion of the treatment. In the low–risk group, BFS has been achieved in all patients and overall survival rate is 100%. In the group of patients with higher risk BFS was achieved in 95.8% of treated patients, and 5–year survival rate was 96.4%. BFS in this study was proved to be statistically significantly better than showed by other authors. On the basis of the risk, the level of PSA, TD and CI100%, modeling was performed using the MANN (multilayer artificial neural network). The determined optimal dose TD for localized CaP of low risk is 40.7 Gy for CI100% = 1.0. At higher risk TD = 50.9 Gy for CI100% = 1.6. TD was given in 4 independent fractions with the interval of 2–3 weeks between each fraction. These HDR–BT parameters (TD, CI100%, and the fractionation scheme) with the individualization and control during each application would provide an acceptable level of late complications grade G1–G3 to the urethra (in less than 17% of treated patients), with minimum complications on the rectum (predominantly grade G1–G2) and insignificant complications rate on the urinary bladder.</p>
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Radiolabeled acetate PET in oncology imaging studies on head and neck cancer, prostate cancer and normal distribution /Sun, Aijun, January 2010 (has links)
Diss. (sammanfattning) Umeå : Umeå universitet, 2010.
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