Abstract Objective: To measure the potential radiation dose emitted by patients who have recently undergone diagnostic nuclear medicine procedures, in order to establish optimal radiation safety measures for such procedures. Materials and Methods: We evaluated the radiation doses emitted by 175 adult patients in whom technetium-99m, iodine-131, and fluorine-18 radionuclides were administered for bone, kidney, heart, brain, and whole-body scans, as measured with a radiation detector. Those values served as the basis for evaluating whole-body radiopharmaceutical clearance, as well as the risk for the exposure of others to radiation, depending on the time elapsed since administration of the radiopharmaceutical. Results: The mean time to clearance of the radiopharmaceuticals administered, expressed as the effective half-life, ranged from 1.18 ± 0.30 h to 11.41 ± 0.02 h, and the mean maximum cumulative radiation dose at 1.0 m from the patients was 149.74 ± 56.72 µSv. Even at a distance of 0.5 m, the cumulative dose was found to be only half and one tenth of the limits established for exposure of the general public and family members/caregivers (1.0 mSv and 5.0 mSv per episode, respectively). Conclusion: Cumulative radiation doses emitted by patients immediately after diagnostic nuclear medicine procedures are considerably lower than the limits established by the International Commission on Radiological Protection and the International Atomic Energy Agency, and precautionary measures to avoid radiation exposure are therefore not required after such procedures.

Resumo Objetivo: O objetivo deste trabalho foi levantar o potencial de dose de radiação emitida por pacientes em procedimentos diagnósticos, visando a estabelecer cuidados de radioproteção mais otimizados. Materiais e Métodos: Taxas de dose de radiação emitidas por 175 pacientes administrados com os radionuclídeos 99mTc, 131I e 18F para cintilografias óssea, renal, cardíaca, cerebral e corpo inteiro, foram mensuradas com um detector de radiação, servindo para avaliar o clareamento do radiofármaco no organismo e risco de exposição após administração dos radiofármacos. Resultados: O clareamento, representado pela meia-vida efetiva, variou de 1,18 ± 0,30 h até 11,41 ± 0,02 h e a dose de radiação máxima acumulada oferecida pelos pacientes a 1,0 m foi de 149,74 ± 56,72 µSv. Mesmo para distâncias de 0,5 m, as doses estimadas foram, respectivamente, duas e dez vezes inferiores ao nível de restrição para o público geral (1,0 mSv) e exposição médica (5,0 mSv/episódio). Conclusão: Doses de radiação oferecidas por pacientes em procedimentos diagnósticos são inferiores aos níveis de restrição recomendados pela International Commission on Radiological Protection e International Atomic Energy Agency, e assim, cuidados de radioproteção são geralmente desnecessários.

ABSTRACT Introduction: Prostate cancer (PC) is the second most commonly diagnosed cancer in males. 68Ga-PSMA PET/CT, a non-invasive diagnostic tool to evaluate PC with prostate-specific membrane antigen (PSMA) expression, has emerged as a more accurate alternative to assess disease staging. We aimed to identify predictors of positive 68Ga-PSMA PET and the accuracy of this technique. Materials and methods: Diagnostic accuracy cross-sectional study with prospective and retrospective approaches. We performed a comprehensive literature search on PubMed, Cochrane Library, and Embase database in search of studies including PC patients submitted to radical prostatectomy or radiotherapy with curative intent and presented biochemical recurrence following ASTRO 1996 criteria. A total of 35 studies involving 3910 patients submitted to 68-Ga-PSMA PET were included and independently assessed by two authors: 8 studies on diagnosis, four on staging, and 23 studies on restaging purposes. The significance level was α=0.05. Results: pooled sensitivity and specificity were 0.90 (0.86-0.93) and 0.90 (0.82-0.96), respectively, for diagnostic purposes; as for staging, pooled sensitivity and specificity were 0.93 (0.86-0.98) and 0.96 (0.92-0.99), respectively. In the restaging scenario, pooled sensitivity and specificity were 0.76 (0.74-0.78) and 0.45 (0.27-0.58), respectively, considering the identification of prostate cancer in each described situation. We also obtained specificity and sensitivity results for PSA subdivisions. Conclusion: 68Ga-PSMA PET provides higher sensitivity and specificity than traditional imaging for prostate cancer.

To systematically review and analyze the medical literature to assess ultrasonography echotexture changes in thyroid cancer patients for the detection of chronic sialadenitis caused by radioiodine therapy. Methods: Sources were retrieved from PubMed, Scopus, EMBASE and LILACS through November 2018. All studies that assessed ultrasonographic features before 131I administration and at 12 months after 131I administration were selected. After data extraction, statistical analysis was performed by using Stata software. Results: From a total of 435 studies, 4 studies involving 665 patients were considered eligible, and echotexture heterogeneity was found with a significant difference. Conclusions: Ultrasound echotexture may detect chronic sialadenitis secondary to salivary radioiodine therapy.

Summary Total thyroidectomy, radioiodine (RAI) therapy, and TSH suppression are the mainstay treatment for differentiated thyroid carcinomas (DTCs). Treatments for metastatic disease include surgery, external-beam radiotherapy, RAI, and kinase inhibitors for progressive iodine-refractory disease. Unresectable locoregional disease remains a challenge, as standard therapy with RAI becomes unfeasible. We report a case of a young patient who presented with unresectable papillary thyroid carcinoma (PTC), and treatment with sorafenib allowed total thyroidectomy and RAI therapy. A 20-year-old male presented with severe respiratory distress due to an enlarging cervical mass. Imaging studies revealed an enlarged multinodular thyroid gland, extensive cervical adenopathy, severe tracheal stenosis, and pulmonary micronodules. He required an urgent surgical intervention and underwent tracheostomy and partial left neck dissection, as the disease was deemed unresectable; pathology revealed PTC. Treatment with sorafenib was initiated, resulting in significant tumor reduction allowing near total thyroidectomy and bilateral neck dissection. Postoperatively, the patient underwent radiotherapy for residual tracheal lesion, followed by RAI therapy for avid cervical and pulmonary disease. The patient's disease remains stable 4 years after diagnosis. Sorafenib has been approved for progressive RAI-refractory metastatic DTCs. In this case report, we describe a patient with locally advanced PTC in whom treatment with sorafenib provided sufficient tumor reduction to allow thyroidectomy and RAI therapy, suggesting a potential role of sorafenib as an induction therapy of unresectable DTC.

Resumo Objetivo: Comparar o grau de absorção benigna de 18F-fluordesoxiglicose (18F-FDG) na medula óssea de pacientes com linfoma de Hodgkin com e sem sintomas B. Materiais e Métodos: Analisamos os prontuários de 74 pacientes com linfoma de Hodgkin submetidos a tomografia por emissão de pósitrons/tomografia computadorizada (PET/CT) com 18F-FDG antes do início da terapia entre outubro de 2010 e setembro de 2013. Em todos os pacientes, a biópsia da medula óssea foi negativa e as imagens de 18F-FDG PET/CT não sugeriram envolvimento da medula óssea. Dos 74 pacientes avaliados, 54 apresentaram sintomas inflamatórios (B) e 20 não. As regiões de interesse (ROIs) foram desenhadas no esterno, nos terços proximais dos úmeros, nos terços proximais dos fêmures e nas duas asas ilíacas (totalizando sete ROIs por paciente). Para comparar os pacientes com e sem sintomas B, em termos dos standardized uptake values (SUVs) para as sete ROIs, utilizamos o teste U de Mann-Whitney. Resultados: Para seis das ROIs, os SUVs foram maiores nos pacientes com sintomas B do que nos pacientes sem, e a diferença foi estatisticamente significante (p < 0,05). Houve também tendência para uma diferença estatisticamente significante entre os dois grupos em termos do SUV para a ROI da asa ilíaca direita (p = 0,06). Conclusão: Na nossa amostra, a presença de sintomas B foi associada ao aumento da captação de 18F-FDG na medula óssea.

Abstract Objective: To compare the degree of benign bone marrow uptake of 18F-fluorodeoxyglucose (18F-FDG) between Hodgkin lymphoma patients with and without B symptoms. Materials and Methods: We analyzed the medical charts of 74 Hodgkin lymphoma patients who underwent 18F-FDG positron emission tomography/computed tomography (PET/CT) prior to the initiation of therapy between October 2010 and September 2013. In all of the patients, the bone marrow biopsy was negative and the 18F-FDG PET/CT images did not suggest bone marrow involvement. Of the 74 patients evaluated, 54 presented inflammatory (B) symptoms and 20 did not. Regions of interest (ROIs) were drawn on the sternum, the proximal thirds of the humeri, the proximal thirds of the femora, and both iliac wings (totaling seven ROIs per patient). To compare the patients with and without B symptoms, in terms of standardized uptake values (SUVs) for the seven ROIs, we used the Mann-Whitney U test. Results: For six of the ROIs, the SUVs were higher in the patients with B symptoms than in those without, and the difference was statistically significant (p < 0.05). There was also a tendency toward a statistically significant difference between the two groups in terms of the SUV for the right iliac wing ROI (p = 0.06). Conclusion: In our sample, the presence of B symptoms was associated with increased 18F-FDG uptake in bone marrow.

ABSTRACT Introduction Prostate cancer still represents a major cause of morbidity, and still about 20% of men with the disease are diagnosed or will progress to the advanced stage without the possibility of curative treatment. Despite the recent advances in scientific and technological knowledge and the availability of new therapies, there is still considerable heterogeneity in the therapeutic approaches for metastatic prostate cancer. Objectives This article presents a summary of the I Brazilian Consensus on Advanced Prostate Cancer, conducted by the Brazilian Society of Urology and Brazilian Society of Clinical Oncology. Materials and Methods Experts were selected by the medical societies involved. Forty issues regarding controversial issues in advanced disease were previously elaborated. The panel met for consensus, with a threshold established for 2/3 of the participants. Results and Conclusions The treatment of advanced prostate cancer is complex, due to the existence of a large number of therapies, with different response profiles and toxicities. The panel addressed recommendations on preferred choice of therapies, indicators that would justify their change, and indicated some strategies for better sequencing of treatment in order to maximize the potential for disease control with the available therapeutic arsenal. The lack of consensus on some topics clearly indicates the absence of strong evidence for some decisions.

Resumo Objetivo: Comparar o desempenho dos métodos de detecção de sonda e quantificação de imagens na estimativa da biocinética do radioisótopo 131I e das doses de radiação na medula óssea vermelha e no corpo inteiro durante a radioiodoterapia em pacientes com câncer de tireoide. Materiais e Métodos: Catorze pacientes portadores de câncer metastático de tireoide, sem acometimento ósseo, foram submetidos ao planejamento terapêutico visando estabelecer a melhor atividade de 131I a ser empregada na radioiodoterapia. Imagens cintilográficas e captações de corpo inteiro foram adquiridas 4, 24, 48, 72 e 96 h após a administração de atividades traçadoras de 131I, visando estimar a meia-vida efetiva (T1/2ef) e o tempo de residência do 131I no organismo dos pacientes. Resultados: Os valores médios de T1/2ef e tempo de residência foram, respectivamente, 19 ± 9 h e 28 ± 12 h pelo método de detecção de sonda e 20 ± 13 h e 29 ± 18 h pela quantificação de imagens. As doses médias na medula óssea vermelha e no corpo inteiro foram, respectivamente, 0,061 ± 0,041 mGy/MBq e 0,073 ± 0,040 mGy/MBq pelo método de detecção de sonda e 0,066 ± 0,055 mGy/MBq e 0,078 ± 0,056 mGy/MBq pela quantificação de imagens. A análise estatística demonstrou que os dois métodos apresentam desempenho semelhante no tocante à estimativa de T1/2ef (p = 0,801), tempo de residência (p = 0,801) e doses, tanto na medula óssea vermelha (p = 0,708) como no corpo inteiro (p = 0,811), mesmo com métodos otimizados de dosimetria que levam em consideração somente dois pontos de medida (4 h e 96 h) após a administração de 131I (p > 0,914). Conclusão: Existe excelente concordância entre o método de detecção de sonda e a quantificação de imagens quanto à estimativa da biocinética do 131I e das doses absorvidas de radiação. Contudo, o método de detecção de sonda deve ser usado com cuidado por ser incapaz de identificar regiões metastáticas e órgãos críticos durante a terapia com radionuclídeos, podendo distorcer ajustes da atividade de 131I a ser administrada durante a radioiodoterapia.

Abstract Objective: To compare the probe detection method with the image quantification method when estimating 131I biokinetics and radiation doses to the red marrow and whole body in the treatment of thyroid cancer patients. Materials and Methods: Fourteen patients with metastatic thyroid cancer, without metastatic bone involvement, were submitted to therapy planning in order to tailor the therapeutic amount of 131I to each individual. Whole-body scans and probe measurements were performed at 4, 24, 48, 72, and 96 h after 131I administration in order to estimate the effective half-life (Teff) and residence time of 131I in the body. Results: The mean values for Teff and residence time, respectively, were 19 ± 9 h and 28 ± 12 h for probe detection, compared with 20 ± 13 h and 29 ± 18 h for image quantification. The average dose to the red marrow and whole body, respectively, was 0.061 ± 0.041 mGy/MBq and 0.073 ± 0.040 mGy/MBq for probe detection, compared with 0.066 ± 0.055 mGy/MBq and 0.078 ± 0.056 mGy/MBq for image quantification. Statistical analysis proved that there were no significant differences between the two methods for estimating the Teff (p = 0.801), residence time (p = 0.801), dose to the red marrow (p = 0.708), and dose to the whole body (p = 0.811), even when we considered an optimized approach for calculating doses only at 4 h and 96 h after 131I administration (p > 0.914). Conclusion: There is full agreement as to the feasibility of using probe detection and image quantification when estimating 131I biokinetics and red-marrow/whole-body doses. However, because the probe detection method is inefficacious in identifying tumor sites and critical organs during radionuclide therapy and therefore liable to skew adjustment of the amount of 131I to be administered to patients under such therapy, it should be used with caution.

Resumo Objetivo: Acessar valores de corte estabelecidos pela curva ROC para classificar a captação de 18F-NaF como normal ou maligna. Materiais e Métodos: Imagens de PET/CT foram realizadas 1 hora após a administração de 185 MBq de18F-NaF e volumes de interesse (VOIs) foram desenhados em três regiões do esqueleto: diáfise umeral proximal direita (UD), diáfise femoral proximal direita (FD) e corpo da primeira vértebra lombar (VB1), em 254 pacientes, totalizando 762 VOIs. A captação nos VOIs foi classificada como normal ou maligna baseada no padrão de distribuição do radiofármaco e nas imagens de CT. Um total de 675 volumes foi classificado como normais e 52 como malignos. Trinta e cinco VOIs classificados como indeterminados ou lesões não malignas foram excluídos da análise. Os valores de captação (SUVs) medidos nos VOIs foram plotados em uma curva ROC para cada uma das três regiões. Foi calculada a área sob a curva (AUC), bem como os valores de SUV mais adequados para a classificação dos VOIs (maior resultado da soma da sensibilidade e especificidade). Resultados: As AUCs foram 0,933, 0,889 e 0,975 para UD, FD e VB1, respectivamente. Os valores de corte mais adequados de SUV foram 9,0 (sensibilidade: 73%; especificidade: 99%), 8,4 (sensibilidade: 79%; especificidade: 94%) e 21,0 (sensibilidade: 93%; especificidade: 95%)para UD, FD e VB1, respectivamente. Conclusão: O valor de corte de SUV mais adequado varia de acordo com a região óssea em análise e não é possível estabelecer um valor adequado para todo o esqueleto.

Abstract Objective: To assess the cutoff values established by ROC curves to classify18F-NaF uptake as normal or malignant. Materials and Methods: PET/CT images were acquired 1 hour after administration of 185 MBq of18F-NaF. Volumes of interest (VOIs) were drawn on three regions of the skeleton as follows: proximal right humerus diaphysis (HD), proximal right femoral diaphysis (FD) and first vertebral body (VB1), in a total of 254 patients, totalling 762 VOIs. The uptake in the VOIs was classified as normal or malignant on the basis of the radiopharmaceutical distribution pattern and of the CT images. A total of 675 volumes were classified as normal and 52 were classified as malignant. Thirty-five VOIs classified as indeterminate or nonmalignant lesions were excluded from analysis. The standardized uptake value (SUV) measured on the VOIs were plotted on an ROC curve for each one of the three regions. The area under the ROC (AUC) as well as the best cutoff SUVs to classify the VOIs were calculated. The best cutoff values were established as the ones with higher result of the sum of sensitivity and specificity. Results: The AUCs were 0.933, 0.889 and 0.975 for UD, FD and VB1, respectively. The best SUV cutoffs were 9.0 (sensitivity: 73%; specificity: 99%), 8.4 (sensitivity: 79%; specificity: 94%) and 21.0 (sensitivity: 93%; specificity: 95%) for UD, FD and VB1, respectively. Conclusion: The best cutoff value varies according to bone region of analysis and it is not possible to establish one value for the whole body.

Objetivo: Avaliar a viabilidade de substituir o radioisótopo 18F pelo 99mTc no teste de linearidade em medidores de atividade. Materiais e Métodos: O teste foi realizado empregando-se fontes de 99mTc (62 GBq) e 18F (12 GBq), cujas atividades foram mensuradas até valores abaixo de 1 MBq. As razões e desvios entre as atividades experimentais e teóricas foram calculados e comparados. Resultados: Os desvios médios entre as atividades experimentais e teóricas para o 99mTc e 18F foram, respectivamente, 0,56 (± 1,79)% e 0,92 (± 1,19)%. A razão média entre as atividades indicadas pelo equipamento para a fonte de 99mTc quando mensurada no equipamento pré-ajustado para medir o 99mTc e 18F foi 3,42 (± 0,06), e para o 18F este valor foi 3,39 (± 0,05), razões consideradas constantes ao longo de todo o período de medida. Conclusão: Os resultados do teste utilizando o 99mTc são compatíveis com os adquiridos com o 18F, implicando na possibilidade de utilização de ambos os radioisótopos na realização do teste de linearidade. Esta informação, aliada ao elevado potencial de exposição e custos de aquisição do 18F, sugere que o 99mTc seja empregado na realização do teste de linearidade para clínicas que utilizam 18F, sem prejuízo para o procedimento e garantia da qualidade de um serviço de medicina nuclear.

Objective: The present study was aimed at evaluating the viability of replacing 18F with 99mTc in dose calibrator linearity testing. Materials and Methods: The test was performed with sources of 99mTc (62 GBq) and 18F (12 GBq) whose activities were measured up to values lower than 1 MBq. Ratios and deviations between experimental and theoretical 99mTc and 18F sources activities were calculated and subsequently compared. Results: Mean deviations between experimental and theoretical 99mTc and 18F sources activities were 0.56 (± 1.79)% and 0.92 (± 1.19)%, respectively. The mean ratio between activities indicated by the device for the 99mTc source as measured with the equipment pre-calibrated to measure 99mTc and 18F was 3.42 (± 0.06), and for the 18F source this ratio was 3.39 (± 0.05), values considered constant over the measurement time. Conclusion: The results of the linearity test using 99mTc were compatible with those obtained with the 18F source, indicating the viability of utilizing both radioisotopes in dose calibrator linearity testing. Such information in association with the high potential of radiation exposure and costs involved in 18F acquisition suggest 99mTc as the element of choice to perform dose calibrator linearity tests in centers that use 18F, without any detriment to the procedure as well as to the quality of the nuclear medicine service.

Objetivo: Analisar os valores de captação (SUVs) utilizando três diferentes intensidades de mAs para realização de correção de atenuação na 18F-NaF PET/CT. Materiais e Métodos: Um total de 254 exames de 18F-NaF PET/CT foi estudado utilizando 10, 20 e 30 mAs. Os SUVs foram calculados utilizando volumes de interesse (VOIs) desenhados em três regiões do esqueleto: diáfise proximal do úmero direito (UD), diáfise proximal do fêmur direito (FD) e primeira vértebra lombar (VB1), totalizando 712 VOIs. Desse total, 675 regiões classificadas como normal foram analisadas (236, 232 e 207 na UD, FD e VB1, respectivamente). Resultados: A média dos SUVs para cada região óssea foi 3,8, 5,4 e 14,4 para UD, FD e VB1, respectivamente. Quando os exames foram agrupados pelo valor da corrente mAs, a média de valores de captação foi 3,8, 3,9 e 3,7 para 10, 20 e 30 mAs, respectivamente, na UD; 5,4, 5,5 e 5,4 para 10, 20 e 30 mAs, respectivamente, na FD; e 13,8, 14,9 e 14,5 para 10, 20 e 30 mAs, respectivamente, na VB1. Conclusão: As três correntes analizadas apresentaram resultados similares para o cálculo de SUV.

Objective: To analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on 18FNaF PET/CT scans. Materials and Methods: A total of 254 18F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: Mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: The three tube current values yielded similar results for SUV calculation.

Objetivo: Investigar o acesso a procedimentos ambulatoriais de medicina nuclear por intermédio do Sistema Único de Saúde (SUS) do Brasil e analisar a correspondência dos dados fornecidos por este sistema com os da Comissão Nacional de Energia Nuclear (CNEN). Materiais e Métodos: Foram obtidos e avaliados os dados disponíveis no Datasus quanto a quantidade de câmaras de cintilação, procedimentos ambulatoriais de 2008 a 2012, esfera administrativa responsável por estes procedimentos, tipo de prestador de serviços e terceirização de serviços. Também foi feita comparação com os dados de estabelecimentos autorizados pela CNEN. Resultados: O estudo mostrou que ainda falta amadurecimento do sistema quanto à sua completa alimentação, especialmente no campo de equipamentos disponíveis. Foi possível elencar os procedimentos mais realizados e verificar o crescimento da especialidade no período estudado. Estabelecimentos privados são responsáveis pela maior parte dos procedimentos cobertos pelo SUS. Entretanto, muitos estabelecimentos de saúde não são autorizados pela CNEN. Conclusão: O Datasus oferece dados importantes para uma análise como a feita neste estudo, embora alguns pontos ainda demandem atenção. O trabalho mostrou, quantitativamente, a realidade brasileira quanto ao acesso a procedimentos de medicina nuclear oferecidos pelo/para o SUS.

Objective: To investigate the outpatient access to nuclear medicine procedures by means of the Brazilian Unified Health System (SUS), analyzing the correspondence between data provided by this system and those from Comissão Nacional de Energia Nuclear (CNEN) (National Commission of Nuclear Energy). Materials and Methods: Data provided by Datasus regarding number of scintillation chambers, outpatient procedures performed from 2008 to 2012, administrative responsibility for such procedures, type of service providers and outsourced services were retrieved and evaluated. Also, such data were compared with those from institutions certified by CNEN. Results: The present study demonstrated that the system still lacks maturity in terms of correct data input, particularly regarding equipment available. It was possible to list the most common procedures and check the growth of the specialty along the study period. Private centers are responsible for most of the procedures covered and reimbursed by SUS. However, many healthcare facilities are not certified by CNEN. Conclusion: Datasus provides relevant data for analysis as done in the present study, although some issues still require attention. The present study has quantitatively depicted the Brazilian reality regarding access to nuclear medicine procedures offered by/for SUS.

INTRODUÇÃO: A doença de Graves (DG) é a causa mais comum de hipertireoidismo e, entre as abordagens terapêuticas mais utilizadas para o tratamento do hipertireoidismo por doença de Graves, encontram-se a cirurgia, o uso de drogas antitireoidianas e a radioiodoterapia. No cálculo dosimétrico para determinação da dose de radioiodo a ser utilizada, é possível empregar a ultrassonografia e a cintilografia para avaliar o volume tireoidiano. OBJETIVO: O presente estudo visa correlacionar essas metodologias com ênfase no volume obtido e nas implicações dosimétricas. SUJEITOS E MÉTODOS: Foram incluídos no estudo 103 pacientes com diagnóstico de DG encaminhados para radioiodoterapia. Esses foram submetidos à ultrassonografia da tireoide e à cintilografia tireoidiana, com cálculo de volume pela cintilografia baseado na fórmula de Allen. RESULTADOS E CONCLUSÕES: Observou-se boa correlação entre os dois métodos, porém com massa estimada pela cintilografia sistematicamente maior que a estimada pela ultrassonografia, o que pode acarretar em menor estimativa de dose absorvida quando utilizado o método cintilográfico.

INTRODUCTION: Graves disease (GD) is the most common cause of hiperthyroidism, and the most common treatment options are surgery, antithyroid drugs and radioiodine therapy. In radiodosimetric calculations to determine radioiodine dosage it is possible to use thyroid volume estimatives based on ultrasound or scintigraphy. OBJECTIVE: The present study aimed to correlate these methodologies emphasizing volume estimatives and dosimetric implications. SUBJECTS AND METHODS: Were included 103 patients with GD diagnosis and indication of radioiodine treatment. They were submitted to thyroid ultrasound and thyroid scintigraphy. RESULTS AND CONCLUSIONS: Good correlation between both methods was observed, although scintigraphy systematically obtained greater volumes than ultrasound implying in lower estimatives of absorbed dose when scintigraphy is used.