Radioiodine (131I) treatment decision-making for low- and intermediate-risk differentiated thyroid cancer

ABSTRACT Objective: The purpose of this study was to investigate the effect and influencing factors of post-surgical radioactive iodine (RAI) therapy for patients with low- and intermediate-risk differentiated thyroid cancer (DTC). Subjects and methods: A retrospective analysis of 423 low- and intermediate-risk DTC patients admitted to the Department of Nuclear Medicine, Sichuan Provincial People's Hospital from January 2005 to December 2020 was performed. All patients were treated with surgery, had a postoperative pathological diagnosis, and were treated with RAI, including 89 males and 334 females. Recurrence risk stratification: 143 cases were low-risk, and 280 cases were intermediate-risk. Results: The excellent response (ER) rate for low- and intermediate-risk were 93.7% and 78.2%, respectively (P < 0.05). There were significant differences in age, cumulative dose of [131I], and pretreatment stimulated-Tg (pre-Tg) levels between the low- and intermediate-risk groups (P < 0.05). There were significant differences in the cumulative dose of 131I and pre-Tg levels between ER and the non-ER group (P < 0.05). The area under the curve (AUC) values were 0.799 in the low-risk group, and 0.747 in the intermediate-risk group for the ROC curve by ER status of pre-Tg. The ER rate with RAI treatment decreased with an increase in pre-Tg levels. Conclusion: Pre-Tg was an important factor for RAI treatment decision-making and prognostic evaluation and differed between low-risk and intermediate-risk DTC. Aggressive RAI therapy was recommended for low-risk DTC with pre-Tg ≥ 20.0 ng/mL and in intermediate-risk group with pre-Tg ≥ 10.0 ng/mL.

Radiological Impact of Atmospheric Nuclear Weapons Tests at Mururoa and Fangataufa Atolls to Populations in Oceania, South America and Africa: Comparison with French Polynesia.

OBJECTIVE: To evaluate the potential radiological impact of atmospheric nuclear weapons tests conducted in 1966-1974 at Mururoa and Fangataufa atolls on populations in Oceania, South America and Africa. METHODS: Results of measurements of total beta(ß)-concentrations in filtered air and 131I activity concentrations in locally produced cow's milk in Oceania, South America and Africa after the tests were compared with those in French Polynesia. Radiation doses due to external irradiation and thyroid doses due to 131I intake with milk by local populations were also compared. RESULTS: Higher total ß-concentrations in filtered air, 131I activity concentrations in locally produced milk and radiation doses to local population were, in general, observed in French Polynesia than in other countries in the southern hemisphere. However, for specific years during the testing period, the radiological impact to South America was found to be similar or slightly higher than that to Tahiti. The resulting thyroid doses in the considered countries were lower than those in French Polynesia with two exceptions: thyroid doses due to 131I intake with cow's milk for 1-y old child in 1968 were higher in Peru (0.35 mGy) and in Madagascar (0.30 mGy) than in Tahiti (0.25 mGy). However, the populations outside French Polynesia received doses lower than those from the natural sources of radiation. CONCLUSION: According to the current knowledge in radiation epidemiology, it is very unlikely that nuclear fallout due to French nuclear tests had a measurable radiological and health impact outside French Polynesia.
.

High thyroglobulin and negative whole-body scan: no long-term benefit of empiric radioiodine therapy.

PURPOSE: Around 10-27% of patients will present elevated thyroglobulin (Tg) levels and negative diagnostic whole-body scan (dxWBS) during differentiated thyroid cancer (DTC) follow-up. Empiric radioactive iodine (RAI) therapy in this context is controversial due to the lack of good quality studies in the context. The main purpose of this study is to compare long-term response to therapy status and overall survival between empiric RAI treated and untreated DTC patients. METHODS: A retrospective study comparing differentiated thyroid cancer patients with negative diagnostic whole-body scan and elevated thyroglobulin levels submitted or not to empiric radioactive iodine therapy in a thyroid cancer referral center. The main outcome measures were ATA Response to Therapy Stratification at 6-12 months after RAI ablative dose, at 6-18 months after negative dxWBS and last follow-up visits. RESULTS: Overall, 120 DTC patients with stimulated Tg >10 ng/ml and negative dxWBS were included in this study. Overall, 53 patients were submitted to empiric RAI and 67 were in the control group. No difference was observed in ATA Response to Therapy Stratification after RAI ablation or at the end of follow-up between groups. Also, no difference was found in terms of Tg changes response. After more than 10 years of follow-up, 17 patients died (13 from treated and 4 from untreated group). CONCLUSIONS: Empiric RAI treatment was not associated with better long-term ATA response to therapy status or overall survival.

Radioiodine-Induced Salivary Gland Damage Detected by Ultrasonography in Patients Treated for Papillary Thyroid Cancer: Radioactive Iodine Activity and Risk.

Background: An important side effect of radioactive iodine (RAI) therapy in patients treated for papillary thyroid cancer (PTC) is chronic sialadenitis. Neck ultrasonography (US) easily recognizes radioiodine-induced salivary gland abnormalities. The objectives of this study were to determine the prevalence of US-detected sialadenitis caused by RAI and to identify the risk factors associated with this damage. Methods: This nonconcurrent cohort study includes all PTC-operated patients who were treated with RAI between 2007 and 2017 and were systematically evaluated with preoperative and follow-up neck US that included targeted exploration of the major salivary glands. Patients with pre-existing salivary gland diseases were excluded. The anatomical damage (diminished glandular volume, wavy contours, hypoechogenicity, and heterogeneity) was qualitatively assessed and compared with the preoperative study. RAI activity, sex, age, and preparation method were evaluated as risk factors using univariate and multivariate analyses with logistic regression. Results: Enrolled in this study were 570 patients who received a median RAI activity of 3700 MBq (100 mCi). On US, we found 143 patients (25.1%) with damage in at least one of their salivary glands: all had parotid damage (77 bilaterally) and 14 (9.8%) also had submandibular gland damage (7 of them bilaterally). The multivariate analysis indicated that the risk of sialadenitis was significantly (p < 0.01) correlated with both RAI activity and sex (14.1% of males vs. 28.5% of females). However, the main risk factor was RAI activity; no injury was detected in 156 patients who received 1110 MBq (30 mCi) and 1850 MBq (50 mCi) of RAI. In the groups of patients receiving 3700 MBq (100 mCi), 5550 MBq (150 mCi) and ≥7400 MBq (≥200 mCi), atrophy was found in 21%, 46.9%, and 77.7% of patients, respectively. Age and preparation method were not related to an increased risk of atrophy in this study. Conclusions: Chronic sialadenitis is common and affects approximately one fourth of patients who receive 3700 MBq (100 mCi) or higher RAI activity. The main risk factor for this injury is the total RAI activity administered. By using the lowest effective activity possible, irreversible anatomical damage in salivary glands can be minimized. US is an excellent tool to diagnose post-RAI atrophy.

Evaluation of Parotid Salivary Gland Echo Texture by Ultrasound Examinations and Correlation With Whole-Body Scintigraphy After Radioiodine Therapy in Patients With Differentiated Thyroid Carcinoma.

OBJECTIVES: This study aimed to evaluate the echo texture of the parotid salivary glands before and after radioiodine therapy (RIT) using ultrasound (US) images in patients with differentiated thyroid cancer and to evaluate the correlations between post-RIT whole-body scintigraphy (WBS) images and US image patterns in salivary and cervical areas. METHODS: A retrospective study was performed with data on demographic and clinical information, US examinations, and WBS images collected through medical recordings. RESULTS: Comparing the US features before and after RIT, significant echo texture heterogeneity was found in 31.3% of all patients evaluated. When evaluated according to the level of iodine 131 (I-131) radioactivity (<5.6, 5.6-<9.3, and ≥9.3 GBq), echo texture heterogeneity was significantly associated with the 5.6-GBq I-131 radioactivity group (P < .001). No association was found for any level of I-131 post-RIT WBS uptake intensity and changes in US feature patterns. CONCLUSIONS: Ultrasound may be a useful tool for evaluating chronic sialadenitis after RIT, and the I-131 uptake intensity using a routine post-RIT WBS is not associated with US echo texture changes.

Health-related quality of life of thyroid cancer patients undergoing radioiodine therapy: a cohort real-world study in a reference public cancer hospital in Brazil.

PURPOSE: The purpose of this study was to access changes in health-related quality of life (HRQoL) caused by radioiodine therapy (RAI) in thyroid cancer patients. METHODS: Prospective cohort study at Brazilian National Cancer Institute with patients enrolled between March 2015 and June 2017. RAI was performed by administration of 1.11 to 9.25 GBq of Na131I. EORTC QLQ-C30 v3 and EORTC QLQ-H&N35 questionnaires were applied to determine HRQoL at baseline, 1 week and 3 months after RAI. HRQoL during follow-up was evaluated by calculation of score absolute changes in each domain. Descriptive analysis was performed by measures of central tendency and dispersion. Changes in HRQoL were evaluated by paired t-test. The association between social demographic and clinical data and HRQoL was assessed by univariate linear regression for significantly changed domains, and p < 0.05 was considered significant. RESULTS: An improvement on global HRQoL and social Function post-therapy (p = 0.002 and p < 0.001) and on role (p = 0.038), emotional (p < 0.001), and cognitive function (p = 0.016) during RAI were observed. Nausea and vomiting (p < 0,001), pain (p < 0.001), sensitivity problems (p < 0.001), problems with social contact (p < 0.001), dry mouth (p = 0.007), and sticky saliva (p = 0.001) increased during RAI. Females were more sensible to changes in nausea and vomiting, and patients < 55 years experienced higher changes in sense during RAI. CONCLUSIONS: Although RAI might affect HRQoL negatively, patients experienced an improvement on global HRQoL and symptoms reduction post-therapy.

Estimación de las desviaciones volumétricas de dosis entregada vs. planificada durante el tratamiento de hipertiroidismo con 131I: resultados preliminares / Estimation of volumetric dose distribution delivery deviations vs. dose planned in 131I hyperthyroidism treatment: preliminary results

Resumen En 2013, la Asociación Europea de Medicina Nuclear (AEMN) recomendó un "Procedimiento estándar" para desarrollar la dosimetría individual pretratamiento del Hipertiroidismo con 131I basada en la captación y en cinética tiroidea del paciente. Para estimar las desviaciones en la distribución de dosis entregada vs planificada al volumen tiroideo bajo este procedimiento, se desarrolló y verificó una aplicación en Matlab. Esta aplicación desarrolla el ajuste de la farmacocinética tiroidea, los cálculos de actividad acumulada, la estimación de la masa funcional tiroidea, el cálculo de la actividad a administrar para garantizar la dosis prescrita por el médico, y estimar el mapa tridimensional (3D) de dosis y los parámetros estadísticos relacionados que la caracterizan. La aplicación desarrollada se verificó empleando una imagen-maniquí y 6 farmacocinéticas conocidas. Además, se estimaron y verificaron los parámetros dosimétricos de planificación en 6 pacientes con dosis prescritas entre 150-400 Gy (promedio 241,67 Gy). Las distribuciones de actividad acumulada y de dosis absorbida fueron marcadamente heterogéneas. La distribución de dosis 3D mostró desviaciones estándar entre 18,01-27,08 % de la dosis prescrita. Las diferencias entre la dosis máxima y mínima por voxel/MBq de actividad administrada fue de 74-129 %. De acuerdo a los resultados, sólo entre el 50,2 % y 71,4 % de volumen tiroideo se tratará con la dosis prescrita ±20 %. Conclusiones: la dosis administrada al tejido tiroideo es no-homogénea y discrepa significativamente de la prescrita en algunas regiones, situación que requiere estudios posteriores más profundos con el objetivo de optimizar el tratamiento y sus resultados.

Abstract In 2013, the European Association of Nuclear Medicine Dosimetry Committee recommends a "Standard Operational Procedures for Hyperthyroidism Pre-Therapeutic Dosimetry" based on the assessment of the individual 131I uptake and kinetics. To estimate the 3D dose delivery deviations from prescribed dose during patient specific application of this SOP, a computer Matlab application was developed and verified. It was design to execute: radiopharmaceutical curve fitting, cumulated activity calculations, functional thyroid mass estimation, obtain the therapeutic planning activity to warranty the prescribed dose and produce the 3D planning dose map and related dosimetry parameters. 6 patients with 150-400Gy prescribed dose data planning (average 241,67Gy) were analysed using the developed application. The developed system was verify successfully using a test image phantom and 6 known pharmacokinetics data. The tridimensional thyroid volume cumulated activity and dose distributions were heterogeneous. 3D dose distribution showed standard deviations between 18.01-27.08 % of prescribed dose. The differences between maximum and minimum dose value per voxel/MBq were 74-129%. According to the result, between 50,2 % and 71,4 % of patient's thyroid will be treat with a dose of DP±20 % of planned dose, the rest will be overdose or sub dose. Conclusions: the 3D treatment planning dose distribution were completely no-homogenous, the significant difference observed should be study in the future more deeply in order to optimized the hyperthyroidism iodine treatment.

Design shielding assessment for a nuclear medicine service / Evaluación del diseño de blindaje de un servicio de medicina nuclear

Abstract It is recognized worldwide that the security of radioactive substances is very important and that the design of facilities where these sources are used and stored must cater for the implementation of good security measures, including the shielding of some treatment and diagnostic rooms. The radiation protection assessment of a nuclear medicine facility consists of the evaluation of the annual effective dose both to workers occupationally exposed and to members of the public. This assessment take into account the radionuclides involved, the facility features, the working procedures, the expected number of patients per year, the administered activity, the distribution of rooms, the thickness and physical materials of walls, floors and ceilings and so on. The assessment results were compared to the design requirements established by the Cuban regulatory body in order to determine whether or not, the nuclear medicine facility complies with those requirements, both for workers and for members of the public. The work presented is useful for facility designer that uses unsealed radionuclides and for the regulatory body.

Resumen A nivel mundial se reconoce que la seguridad de las sustancias radiactivas es muy importante y que el diseño de las instalaciones, donde se utilizan y almacenan las mismas, tienen que implementar medidas de seguridad adecuadas, incluyendo el blindaje de algunos locales de tratamiento y diagnóstico. La evaluación de la protección radiológica de una instalación de medicina nuclear consiste en la determinación de la dosis efectiva anual, tanto para los trabajadores ocupacionalmente expuestos a las radiaciones como para los miembros del público. Esta evaluación tuvo en consideración los radionúclidos involucrados, las características de la instalación, los procedimientos de trabajo, la cantidad de pacientes que se espera tratar o diagnosticar por año, la actividad administrada, la distribución de los locales y el espesor de los materiales empleados en las paredes, pisos y techo, entre otros. Los resultados obtenidos de la evaluación fueron comparados con los requerimientos de diseño establecidos por el órgano regulador cubano para determinar si cumplen o no con tales requerimientos para los trabajadores expuestos y miembros del público. El trabajo presentado resulta útil para diseñadores de instalaciones que utilizan sustancias abiertas y para el órgano regulador.

Comparative Study of Two Oxidizing Agents, Chloramine T and Iodo-Gen®, for the Radiolabeling of ß-CIT with Iodine-131: Relevance for Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to alteration of the integrity of dopaminergic transporters (DATs). In recent years, some radiopharmaceuticals have been used in the clinic to evaluate the integrity of DATs. These include tropane derivatives such as radiolabeled ß-CIT and FP-CIT with iodine-123 (123I), and TRODAT-1 with metastable technetium-99 (99mTc). Radiolabeling of ß-CIT with radioactive iodine is based on electrophilic radioiodination using oxidizing agents, such as Chloramine T or Iodo-Gen®. For the first time, the present work performed a comparative study of the radiolabeling of ß-CIT with iodine-131 (131I), using either Chloramine T or Iodo-Gen® as oxidizing agents, in order to improve the radiolabeling process of ß-CIT and to choose the most advantageous oxidizing agent to be used in nuclear medicine. Both radiolabeling methods were similar and resulted in high radiochemical yield (> 95%), with suitable 131I-ß-CIT stability up to 72 h. Although Chloramine T is a strong oxidizing agent, it was as effective as Iodo-Gen® for ß-CIT radiolabeling with 131I, with the advantage of briefer reaction time and solubility in aqueous medium.

Evaluación por Monte Carlo de los métodos de corrección de dispersión con empleando colimador pinhole / Monte Carlo evaluation of scattering correction methods in studies using pinhole collimator

La dispersión es un efecto significativo a corregir para la cuantificación de actividad. El objetivo del trabajo fue estimar la influencia de la dispersión en estudios de tiroides con 131I y colimador pinhole (5 mm) empleando el método de Monte Carlo (MC) y evaluar la eficacia de los métodos de corrección de múltiples ventanas en este tipo de estudios. Para simular la geometría de la cámara gamma y el estudio de tiroides se utilizó el código de Monte Carlo GAMOS. Para validar la geometría del cabezal se simuló y verificó experimentalmente un maniquí de tiroides, comparando la sensibilidad estimada con la medida, experimentalmente en agua y aire. Para evaluar la influencia de la dispersión a escala clínica se simularon diferentes tamaños de tiroides y profundidades del tejido, se estimaron y compararon los resultados de los métodos de Triple Ventana, Doble Ventana y Doble Ventana Reducida. Se calcularon las diferencias relativas al valor de referencia obtenido por MC. La geometría modelada fue verificada y validada. La contribución de la dispersión a la imagen fue significativa y se ubicóentre el 27 y 40 % a escala no clínica. Las discrepancias de los resultados de los diferentes métodos de corrección de dispersión a escala clínica fueron significativas (p>95 %) y estuvieron en el rango entre 9 y 86 %. El método de mejores resultados fue el de la Doble Ventana Reducida (15 %) que mostró discrepancias entre 9 y 16 %. Se concluyó que el método de la Doble Ventana Reducida (15 %) fue el más eficiente de los estudiados

Scattering is quite important for image activity quantification. In order to study the scattering factors and the efficacy of 3 multiple window energy scatter correction methods during 131I thyroid studies with a pinhole collimator (5 mm hole) a Monte Carlo simulation (MC) was developed. The GAMOS MC code was used to model the gamma camera and the thyroid source geometry. First, to validate the MC gamma camera pinhole-source model, sensibility in air and water of the simulated and measured thyroid phantom geometries were compared. Next, simulations to investigate scattering and the result of triple energy (TEW), Double energy (DW) and Reduced double (RDW) energy windows correction methods were performed for different thyroid sizes and depth thicknesses. The relative discrepancies to MC real event were evaluated. Results: The accuracy of the GAMOS MC model was verified and validated. The image’s scattering contribution was significant, between 27-40 %. The discrepancies between 3 multiple window energy correction method results were significant (between 9-86 %). The Reduce Double Window methods (15%) provide discrepancies of 9-16 %. Conclusions: For the simulated thyroid geometry with pinhole, the RDW (15 %) was the most effective

Obtención combinada de parámetros para la planificación dosimétrica 2D y 3D de tratamientos con en Hipertiroidismo / Combined parameters estimation for dosimetry treatment planning in Hyperthyroidism using 2D and 3D

La planificación, optimización y verificación de los tratamientos-paciente específico con fuentes abiertas de es objeto de investigación constante desde el punto de vista médico y de protección radiológica. El objetivo de este estudio fue verificar el uso combinado de varios equipos médico-nucleares para la estimación de los parámetros de biodistribución y farmacocinética necesarios para la planificación y verificación del tratamiento-paciente específico del hipertiroidismo. Para ello se estudiaron las respuestas de tres equipos médico-nucleares (Captor de Yodo, Cámara Gamma Philips Forte con colimador de pinhole, Cámara Mediso Nucline con colimadores de alta energía y propósitos generales para estudios planares y SPECT) empleando el maniquí de tiroides. Se comprobó la linealidad de la respuesta a la actividad en condiciones clínicas y se obtuvieron índices de correlación del ajuste superiores a 0,99 para actividades diagnósticas y terapéuticas. Se evaluó la concordancia de los parámetros calculados por los diferentes equipos y se encontró una discrepancia menor del 6 % para los índices de captación en actividades terapéuticas y del 1,1 % para las diagnósticas. Se estableció y verificó un protocolo que permite, con una sola administración de , desarrollar la cuantificación dosimétrica 2D y 3D para pacientes hipertiroideos, con un uso optimizado de los equipos imagenológicos

Optimization and verification of Specific Patient Treatment Planning with unsealed sources in hyperthyroidism diseases is a desirable goal from medical and radiation protection viewpoints. In order to verify the estimation of patient’s specific treatment dose and his/her related parameters, a combination of 3 different apparatus or pieces of equipment used in nuclear medicine were studied - the Iodine Probe, a Philips Forte Camera with pin-hole collimators and a Mediso Nucline with HEGP for planar and SPECT techniques- by using the typical neck phantom and sources simulating diagnosis and treatment procedure. The linear behavior on diagnostic and therapeutic activity range was verified, showing a linear correlation fitting factor > 0,99. The differences between thyroid uptake determinations in all equipment were less than 6 % for therapeutic activities and less than 1,1 % in the diagnostic range. The combined protocol to calculate all the necessary parameters for the patient treatment dose planning using 2D or 3D approach was established and verified, avoiding wasting time with gamma cameras and with only one administration of

Iodine-131 treatment of thyroid cancer cells leads to suppression of cell proliferation followed by induction of cell apoptosis and cell cycle arrest by regulation of B-cell translocation gene 2-mediated JNK/NF-kappaB pathways

Iodine-131 (131I) is widely used for the treatment of thyroid-related diseases. This study aimed to investigate the expression of p53 and BTG2 genes following 131I therapy in thyroid cancer cell line SW579 and the possible underlying mechanism. SW579 human thyroid squamous carcinoma cells were cultured and treated with 131I. They were then assessed for 131I uptake, cell viability, apoptosis, cell cycle arrest, p53 expression, and BTG2 gene expression. SW579 cells were transfected with BTG2 siRNA, p53 siRNA and siNC and were then examined for the same aforementioned parameters. When treated with a JNK inhibitor of SP600125 and 131I or with a NF-κB inhibitor of BMS-345541 and 131I, non-transfected SW579 cells were assessed in JNK/NFκB pathways. It was observed that 131I significantly inhibited cell proliferation, promoted cell apoptosis and cell cycle arrest. Both BTG2 and p53 expression were enhanced in a dose-dependent manner. An increase in cell viability by up-regulation in Bcl2 gene, a decrease in apoptosis by enhanced CDK2 gene expression and a decrease in cell cycle arrest at G0/G1 phase were also observed in SW579 cell lines transfected with silenced BTG2 gene. When treated with SP600125 and 131I, the non-transfected SW579 cell lines significantly inhibited JNK pathway, NF-κB pathway and the expression of BTG2. However, when treated with BMS-345541 and 131I, only the NF-κB pathway was suppressed. 131I suppressed cell proliferation, induced cell apoptosis, and promoted cell cycle arrest of thyroid cancer cells by up-regulating B-cell translocation gene 2-mediated activation of JNK/NF-κB pathways.

Aggressive form of thyroglossal duct cyst carcinoma: role of ablative dose of Iodine-131

Ectopic thyroid tissue carcinoma is very rare and has usually good prognosis. It could arise in 1 percent of thyroglossal duct cysts (TDC), the most common nonodontogenic cysts that occur in the neck, which results from a failure in obliterating the embryogenic duct produced during thyroid migration. TDC is most often diagnosed during the childhood but may be discovered later in adult age. In most of the cases reported in the literature, thyroid carcinoma arising in the TDC is limited to the cyst without local extension and its efficient treatment consist of the surgical removal of the cyst by Sistrunk's operation. However, some controversies remain regarding the indication of total thyroidectomy when thyroid investigations are normal. Cases of aggressive thyroid carcinomas of the TCD with metastatic cervical lymph nodes are exceptional, mainly when histological findings of the thyroid gland are normal. We report a case of an aggressive form of a thyroglossal duct cyst carcinoma complicated with several infiltrated cervical lymph nodes but normal thyroid gland. The therapeutic strategy adopted in this case shows the decisive role of the post-operative ablative dose of Iodine-131 both for treatment and staging of aggressive form of thyroid carcinoma arising in thyroglossal duct cyst.

Trazabilidad de las mediciones realizadas con activímetros en medicina nuclear / Traceability of radionuclide calibrators measurements in nuclear medicine

RESUMEN En medicina nuclear, las dosis del radiofármaco administradas se expresan mediante la actividad del radionucleido en el preparado. La medición de esa actividad se realiza en el activímetro y resulta primordial para garantizar la comparabilidad nacional e internacional de los resultados clínicos relacionados y la seguridad radiológica del paciente. En este trabajo se detalla la transferencia de la unidad becquerel a los activímetros empleados en medicina nuclear en Cuba. Se presentan los resultados de la implantación de un servicio de calibración in situ, basado en la comparación directa con muestras de referencia de los radionucleidos específicos sujetos a medición. Los resultados de las comparaciones de medición internacionales y nacionales que se muestran, validan los estimados de incertidumbre de los coeficientes de calibración, determinados para la medida en estos instrumentos de la actividad de los principales emisores gamma que se han utilizado en la medicina nuclear cubana: technetium 99,iodine 131, radiopharmaceuticals thallium 201.

ABSTRACT In nuclear medicine, the administered doses of the radiopharmaceutical are expressed through the amount of radioactivity contained in the drug. The measurement of this activity, performed using a radionuclide calibrator, is of the utmost importance to guarantee the national and international comparability of clinic results and the radiological safety of the patient. In this paper, the transferring of the becquerel unit to the radionuclide calibrators employed in the nuclear medicine practice in Cuba is detailed. The obtained results with an in situ calibration service, which is based on the direct comparison with standards of the specific measured radionuclides, are presented. Outcomes of international and national measurement comparisons are shown. They validate the uncertainty estimates of the calibration coefficients installed in the instruments for measurements of technetium 99,iodine 131, radiopharmaceuticals thallium 201, the main gamma emitters that have been used in Cuban nuclear medicine.

Valores normales de captación de 131Yodo de 2 y 24 horas / Normal 131Iodine uptake values at 2 ano 24 hours

Background: Radiolabeled iodine uptake is a useful tool in the study of thyroid diseases. Aim: To obtain normal values for 131 Iodine thyroid uptake in healthy volunteers. Material and methods: A total of 105 subjects were included (52 males and 53 females), with a mean age of 45 years (range: 20 to 68, evenly distributed in decades). A questionnaire was applied and a clinical examination was performed to rule out endocrine diseases. Serum TSH and anti-thyroperoxidase antibodies were also measured. The oral 131I dose was 5-10 fiCi, and a Thyrad equipment was used for measurements at 2 and 24 h. Results: Mean global iodine uptake was 5.5 percent±1.8 percent (range: 2.3-12.0) at 2 h and 16.2±4.8 percent (range: 6.5-30.1) at 24 h. The values at 2 h among women and men were 6.0±1.8 and 4.9±1.6 percent, respectively, (p <0.02). At 24 h, the figures were 17.3±4.5 and 15.0±4.9 percent, respectively (p =0.01). Compared to their younger counterparts, radioactive iodine uptake was lower among volunteers older than 40 years, at 2 h (5.0±1.7 and 6.0±1.8, respectively, p <0.02) and at 24 h (14.9±4.4 and 17.6±4.9 percent, respectively, p <0.01). Conclusions: Normal thyroid uptake values in adults are influenced bygender and age. Normal thyroid iodine uptake values are slightly higher in females. Iodine thyroid uptake values decrease slightly in subjects aged more than 40years.

Comparación de la medición de actividad de 131I con activímetros en medicina nuclear en cuba / Comparison of 131I activity measurements with radionuclide calibrators in nuclear medicine in cuba

Se presentan los resultados de la comparación nacional de la medición de actividad de 131I con activímetros, organizada en Cuba en el 2007. Estos resultados contribuyen a establecer la incertidumbre y la trazabilidad de los valores de actividad de 131I, determinados en los activímetros de las diferentes instituciones participantes: 9 hospitales y dos laboratorios del Centro de Isótopos que participaron directamente en la producción de los radiofármacos. Si consideramos solamente la proporción de resultados satisfactorios, el desempeño evidenciado por los participantes es igual al alcanzado en las comparaciones de este tipo, organizadas del 2002 al 2004 en el país. No obstante, la estimación razonable de la incertidumbre de la actividad de 131I medida en el activímetro, realizada por la mayoría de los participantes en el 2007, muestra un resultado cualitativamente superior con respecto al obtenido en el 2002-2004. Se reportaron los resultados del ejercicio bilateral de medición de 131I entre el Departamento de Metrología de Radionúclidos del Centro de Isótopos y el Laboratorio Nacional de Metrología de las Radiaciones Ionizantes del Instituto de Protección Radiológica y Dosimetría de Brasil. Concebido como complemento de la comparación nacional, este ejercicio bilateral proporciona evidencias adicionales de la comparabilidad de los patrones de medición utilizados para calibrar las disoluciones y muestras de referencia de 131I en el Departamento de Metrología de Radionúclidos del Centro de Isótopos.

Results from the national comparison of 131I activity measurements with radionuclide calibrators in Nuclear Medicine, organized in Cuba in 2007, are shown. These results contribute to establish the uncertainty and traceability of the 131I activity values measured with radionuclide calibrators of the participating institutions: 9 hospitals and two laboratories of the Isotope Centre directly involved in radiopharmaceuticals’ production. Concerning the proportion of acceptable results, no improvement was observed in the participants’ performance compared to results shown in such kind of exercises organized in the country during 2002-2004. On the other hand, the reasonable uncertainty estimate of the 131I measurements reported by most of the participants show a qualitatively superior outcome in 2007 compared to the result obtained in the previously organized exercises. Moreover, the outcome of the bilateral comparison for 131I activity measurements between the Radionuclide Metrology Department of the Isotope Centre (CENTIS-DMR) and the National Metrology Laboratory for Ionizing Radiation of the Brazilian Institute of Radiation Protection and Dosimetry (LNMRI-IRD) is also shown. This bilateral exercise provides additional evidences on comparability of the CENTIS-DMR measurement standards used to calibrate 131I reference solutions and samples.

Proposta de metodologia para tratamento individualizado com iodo-131 em pacientes portadores de hipertireoidismo da doença de Graves / Proposal of a methodology for individualized iodine-131 therapy for Graves' disease in patients with hyperthyroidism

OBJETIVO: Diferentes métodos são usados para determinar atividade do radioiodo para tratamento de hipertireoidismo (doença de Graves). Alguns não consideram a dose absorvida pela tireóide ou os parâmetros necessários para este cálculo. A relação entre dose absorvida e atividade administrada depende da meia-vida efetiva, da captação do iodo e da massa da tireóide de cada paciente. O objetivo deste trabalho é propor uma metodologia para tratamento individualizado com 131I em pacientes portadores de hipertireoidismo da doença de Graves. MATERIAIS E MÉTODOS: Usou-se um simulador de tireóide-pescoço desenvolvido no Instituto de Radioproteção e Dosimetria contendo solução de 131I, para calibração da gama-câmara e sonda cintilométrica do Serviço de Medicina Nuclear do Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTADOS: O campo de visão colimador-detector apresentou valores compatíveis com o tamanho da glândula para as distâncias de 25 cm (sonda de captação) e 45,8 cm (gama-câmara). Os fatores de calibração (cpm/kBq) foram 39,3 ± 0,78 e 4,3 ± 0,17, respectivamente. O intervalo entre 14 e 30 horas da curva de retenção permite o cálculo de atividade entre dois pontos, para determinação da meia-vida efetiva do iodo na tireóide. CONCLUSÃO: A utilização de equipamentos usualmente disponíveis em serviços de medicina nuclear é viável, tornando esta metodologia simples, eficaz e de baixo custo.

OBJECTIVE: Several methods are utilized for determining the radioiodine activity in the treatment of Graves' disease (hyperthyroidism). Some of this methods do not take into consideration the thyroid absorbed dose or the necessary parameters for this estimation. The association between absorbed dose and administered activity depends on effective half-life, iodine uptake and thyroid mass of each patient. The present study was aimed at developing a methodology for individualized 131I therapy for Graves' disease in patients with hyperthyroidism of the Graves' disease. MATERIALS AND METHODS: A neck-thyroid phantom developed at Instituto de Radioproteção e Dosimetria, containing a standard solution of 131I, was utilized for calibrating the scintillation gamma camera and uptake probe installed in the Department of Nuclear Medicine of the Hospital Universitário Clementino Fraga Filho da Universidade Federal do Rio de Janeiro. RESULTS: The view angle of the collimator/detector assembly presented values compatible with the thyroid gland size for distances of 25 cm (uptake probe) and 45.8 cm (scintillation gamma camera). Calibration factors were 39.3 ± 0.78 and 4.3 ± 0.17 cpm/kBq, respectively. The 14-30-hour interval in the retention curve allows the estimation of activity between two points for determining the effective iodine half-life in the thyroid. CONCLUSION: The utilization of equipment usually available in nuclear medicine clinics is feasible, so this is a simple, effective and low cost methodology.

Cáncer de tiroides en SOLCA 1991-2000: estudio de resultados terapéuticos / Thyroid Cancer in SOLCA 1991-2000: study of therapeutic results

Tipo de estudio: Retrospectivo y comparativo en el hospital Dr. Juan Tanca Marengo ION SOLCA de la ciudad de Guayaquil, durante el período comprendido de enero de 1991 a diciembre del año 2000, sobre cáncer de tiroides.Objetivo: Comparar en dos grupos problema de 33 pacientes cada uno, variables referentes a sexo, edad, tipo histológico, y fundamentalmente el periodo de remisión tumoral entre dos terapéuticas que se presentaron durante estos diez años como parte del protocolo utilizado en la institución donde se llevó a cabo el estudio.Resultados: De 131 pacientes, 66 participaron en el estudio, pudiéndose constatar que es una patología con mayor incidencia en las mujeres relación mujer – hombre: 2.8–1, que si bien el tipo histológico fue contundentemente el carcinoma papilar, se observó una proporción idéntica entre el cáncer folicular y el cáncer anaplásico, dato que no se reporta normalmente en otros países. Finalmente y los más importante fue que pacientes que fueron solamente operados recidivaron en un 61% vs. un 15% en pacientes que posteriormente de la cirugía recibieron Yodo 131, concluyéndose que esta asociación es el tratamiento de elección para pacientes con cáncer diferenciado de tiroides sin importar edad y estadio de la enfermedad.Conclusiones: Mujeres menores de 40 años y económicamente activas fueron la mayor incidencia por lo que el factor hormonal y laboral esta relacionado en la etiología; la terapia combinada debe ser instaurada de forma sistemática a pacientes con Ca diferenciado de tiroides.

Type of study: Retrospective and comparative study at the Dr. Juan Tanca Marengo Hospital ION SOLCA in the city of Guayaquil, during the period of time between January of 1991 to December of the year 2000, in a group of patients with thyroid cancer.Objective: To compare two groups of 33 patients. The variables are: sex, age, histological type, and fundamentally the period of tumor remission between two therapeutic treatments that were presented during these ten years as part of the protocol used in the institution where the study was carried out.Results: Of 131 patients, 66 participated in the study, being able to verify that it is pathology with more incidences in the women. Where the ratio between woman - man: 2.8 - . Overwhelmingly the most frequent malignancy was the Papillary Carcinoma. An identical ratio was observed between follicular and anaplastic carcinoma a finding that is not usually reported in other countries. The most important finding was that patients that were solely operated recurred in 61% vs. only 15% in patients that after surgery they received Iodine 131. We conclude that this association of surgery and treatment with Iodine 131 is the goal treatment for patients with differentiated thyroid cancer without emphasis on age and stage of the illness.Conclusions: Women less than 40 years of age and economically active had a higher incidence due to the hormonal and labor factor which is associated with the etiology. Patients with Differentiated thyroid Cancer should receive the combined treatment.

Variations tions in Iodine 131 uptake by some organs of white rats and its changes during the estrous cycle / Variações na captação do 131I em alguns orgãos de ratos albinos e suas relações com o ciclo estral

It has been studied the Iodine131 uptake by some organs of Wistar white rats (12 males and 20 females), with average weight of 325 g and nearly 5 months old. Females were divided into groups according to the phase of estrous 9 cycle, which was detected by vaginal smears. Iodine131 was administered subcutaneously in a concentration ratio of 0.10 µ Ci by g/weight. The organs (thyroid, liver, kidney, spleen and pancreas) were withdrawn one hour later and Iodine131 uptake was detected by a Tobor Large Sample Couting Systems with Nal crystal. Absorption of Iodine131 was the largest by the thyroid, decreasing it in the estrous rats. There was no sexual difference, saved, the estrous cycle rats. It is discussed the 12 relationship between the thyroid gland and sexual hormones.

Foi estudada a captação do 131I em órgãos de 32 ratos albinos da raça Wistar (12 machos e 20 fêmeas), pesando entre 300 a 350 g e com cerca de 5 meses de idade. As fêmeas foram separadas em grupos, de acordo com a fase do ciclo estral, determinada por esfregaços vaginais. O radioisótopo foi injetado por via subcutânea, na quantidade de 0,10 µ Ci por grama de peso do animal. Os órgãos (tireoide, fígado, rins, baço e pâncreas) foram colhidos uma hora após a injeção, sendo a captação da radiatividade determinada em detetor de cintilação com cristal de Nal. Verificou- se que as maiores quantidades de 131I foram captadas pela tireoide, diminuindo essa captação nas ratas em fase de estro. Os ratos machos comportaram-se similarmente às fêmeas em outras fases que não o estro. A interrelação existente entre a tireoide e os hormônios sexuais é discutida.

Variations tions in Iodine 131 uptake by some organs of white rats and its changes during the estrous cycle / Variações na captação do 131I em alguns orgãos de ratos albinos e suas relações com o ciclo estral

It has been studied the Iodine131 uptake by some organs of Wistar white rats (12 males and 20 females), with average weight of 325 g and nearly 5 months old. Females were divided into groups according to the phase of estrous 9 cycle, which was detected by vaginal smears. Iodine131 was administered subcutaneously in a concentration ratio of 0.10 µ Ci by g/weight. The organs (thyroid, liver, kidney, spleen and pancreas) were withdrawn one hour later and Iodine131 uptake was detected by a Tobor Large Sample Couting Systems with Nal crystal. Absorption of Iodine131 was the largest by the thyroid, decreasing it in the estrous rats. There was no sexual difference, saved, the estrous cycle rats. It is discussed the 12 relationship between the thyroid gland and sexual hormones.

Foi estudada a captação do 131I em órgãos de 32 ratos albinos da raça Wistar (12 machos e 20 fêmeas), pesando entre 300 a 350 g e com cerca de 5 meses de idade. As fêmeas foram separadas em grupos, de acordo com a fase do ciclo estral, determinada por esfregaços vaginais. O radioisótopo foi injetado por via subcutânea, na quantidade de 0,10 µ Ci por grama de peso do animal. Os órgãos (tireoide, fígado, rins, baço e pâncreas) foram colhidos uma hora após a injeção, sendo a captação da radiatividade determinada em detetor de cintilação com cristal de Nal. Verificou- se que as maiores quantidades de 131I foram captadas pela tireoide, diminuindo essa captação nas ratas em fase de estro. Os ratos machos comportaram-se similarmente às fêmeas em outras fases que não o estro. A interrelação existente entre a tireoide e os hormônios sexuais é discutida.