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Master's Dissertation
DOI
https://doi.org/10.11606/D.59.2020.tde-28022020-103544
Document
Author
Full name
Danny Giancarlo Apaza Veliz
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2019
Supervisor
Committee
Moraes, Eder Rezende (President)
Brunetto, Sergio Querino
Nicolucci, Patrícia
Rocha, Euclides Timoteo da
Title in Portuguese
Dosimetria em terapia radioablativa com iodo 131
Keywords in Portuguese
Dosimetria interna
Medicina nuclear
Terapia ablativa
Abstract in Portuguese
Foi realizada a dosimetria externa de pacientes, após ressecção total da tireóide, submetidos à terapia ablativa com Iodo 131 (131I), o estudo envolveu 43 pacientes (11 homens e 32 mulheres; faixa etária: de 26 a 60 anos) no Departamento de Medicina Nuclear do Hospital de Câncer de Barretos. Foi feita uma comparação da metodologia observada na bibliografia de medida da taxa de dose a 1 metro e a metodologia da CNEN que indica a mesma medida a 2 metros. Os parâmetros biocinéticos dos pacientes foram determinados usando-se o ajuste biexponencial da evolução temporal da taxa de dose equivalente externa proposto, obtiveram-se valores da constante de eliminação do resto do corpo (λc) de 1,47±0,37 d-1 e 1,40±0,38 d-1 a 1 e 2 metros, respectivamente. Para os valores da constante de eliminação da tireoide (λt) obtiveram-se valores de 0,27±0,19 d-1 e 0,26±0,13 d-1 a 1 e 2 metros, respectivamente. Também foram obtidos os valores da constante de taxa de dose no ar (h), 40,53±9,76 e 50,94±15,46 µSv.GBq.h-1 a 1 e 2 metros, respectivamente. Na segunda parte do trabalho realizou-se o desenvolvimento de um protocolo simples para quantificação da atividade através de imagens planas com 131I feitas em objetos simuladores da tireóide para obtenção do coeficiente de calibração da gama câmara (Ccg), obtendo-se um valor de Ccg de 0,07±0,01 MBq.cps-1. Também foi desenvolvida uma metodologia para determinar o volume e a massa ou remanescente da tireóide. Para isto foram utilizadas 7 diferentes configurações dos objetos simuladores para adquirir imagens que permitam quantificar os volumes e massas usando nas imagens obtidas com as diversas montagens dos objetos simuladores como, tireoide de lóbulos simétricos, tireoide de lóbulos assimétricos e o cilindro do fantoma comercial Jacszack, no análise das imagens foram usados os softwares ImageJ (livre descarga) e Xeleris 4.0 (software da gama câmara). O resultado de todas estas avaliações e quantificações mostra que podem ser utilizados e ainda melhorados com fins de dosimetria em terapia ablativa com 131I.
Title in English
Dosimetry in radioablative therapy with iodine 131
Keywords in English
Ablative therapy
Internal dosimetry
Nuclear medicine
Abstract in English
It was performed on external dosimetry of patients, after total thyroid resection, immersion in ablative therapy with Iodine 131 (131I) or study involving 43 patients (11 men and 32 women; age range: 26 to 60 years) at the Department of Medicine Nuclear of the Barretos Cancer Hospital. A compilation of the methodology observed in the bibliography of dose rate measurements at 1 meter was made and the CNEN methodology that indicates the same measurement at 2 meters. The biokinetic parameters are two patients determined through a bi-exponential adjustment of the temporal evolution of the proposed external equivalent dose rate, values obtained from the corporate elimination constant (λc) of 1.47±0.37 d-1 and 1.40±0.38 d-1 at 1 and 2 meters, respectively. For the tire removal constant values (λt), values of 0.27±0.19 d-1 and 0.26±0.13 d-1 were obtained at 1 and 2 meters, respectively. Values of constant rate in the air dose (h), 40.53±9.76 and 50.94±15.46 µSv.GBq.h-1 at 1 and 2 meters, respectively, were also obtained. In the second part of the work carried out or in the development of a simple protocol for quantifying the activity, using flat images with the simulating objects of the thyroid objects through the calibration coefficient of the range of cameras (Ccg), obtaining a value of 0.07 ± 0.01 MBq.cps-1 for Ccg. I also developed a methodology to determine the volume and volume of the thyroid. For this purpose, 7 different configurations are used for two simulator objects to obtain images that allow quantifying volumes and masses using two images obtained with different assemblies, two simulator objects such as symmetrical lobe thyroid, asymmetric lobe eyelid or commercial ghost cylinder Jacszack, no Analysis of imagers used for the ImageJ software (free download) and Xeleris 4.0 (camera line software). Or as a result of all these assessments and quantifications, we have shown that they can be used in addition to the dosimetry purposes in 131I ablative therapy.
 
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Publishing Date
2020-05-15
 
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