Aim: The aims of this audit were: To determine the proportion of hyperthyroid patients receiving I-131 therapy in whom treatment with a single fixed dose was successful, as defined by the achievement of euthyroidism or hypothyroidism 6-months after the therapy; To identify patients in whom treatment was not successful and a second dose needed; And, if possible, to establish the factors associated with treatment failure. Methods: A single observer reviewed the records of all patients who received I-131 therapy for hyperthyroidism between 23rd April 2010 and 23rd November 2017 in conjunction with their pre and post treatment thyroid function tests. Results of their thyroid ultrasound were retrieved and documented. The images of their Tc-99m sodium pertechnetate thyroid scans were also retrieved and reprocessed. Results: The records of 409 patients treated between April 2010 and November 2017 were retrieved. 223 (63%) patients were referred by the endocrine clinic at Groote Schuur hospital (GSH. Of the 409 patients, 56 (14%) patients that were excluded because their post therapy records were not available for analysis. Majority of our patients were females 310 (88%). Patients between the ages of 15 and 45 years are more likely to present with Grave’s disease while those aged more than 45 years presented with toxic multinodular gland (p=0.000). Patients that presented between the ages of 15 and 45 years are more likely to have moderately increased pretreatment FT4 (12-51 mmol/L) (p=0.002). We administered a radioiodine therapy dose of 456.6±54.8 MBq (Mean ± SD) to these 409 patients. Among the 353 patients, with complete records, 314(89%) achieved cure at some stage after receiving one dose of RAI; 239(76%) achieving cure ≤ 6 months of therapy and 75(24%) patients after 6 months. In our audit the patients who failed to achieve cure following the first RAI therapy appeared to be younger (median(interquartile range) age 39(16), p= 0.03), have severe hyperthyroidism as demonstrated by higher pre-treatment FT4 (median(interquartile range) 27 pmol/L(30.6), p= 0.05) and high pertechnetate uptake (median(interquartile range) uptake 9.9%(14), p= 0.002) on thyroid scintigraphy. CONCLUSION Our audit showed RAI therapy was found to be successful in 68% of patients at 6 month and 89% at a year. A second therapy with radioactive iodine would be indicated in 32% of patients, as these patients have not achieved cure at 6 months. Patients presenting with severe thyrotoxicity are likely to require more than one RAI therapy. Due to major deficiencies in referral, record keeping and follow up, other factors responsible for treatment were not be able to be evaluated. Based on these findings, suggested areas for further research are: should patients with severe hyperthyroidism be considered for pretreatment with antithyroid medication prior to RAI; would a one year follow up after radioiodine therapy be considered before second RAI. Now that the deficiencies in our current practice have been identified and suggestions put forward to address these deficiencies, a follow up audit would be needed.

Background: Hyperthyroid cats are predisposed to thrombus formation. The mechanism for thrombogenesis is currently unknown, but could be associated with altered hemostasis as seen in hyperthyroid humans. Objective: The purpose of this study was to evaluate markers of hemostasis in hyperthyroid cats compared to healthy cats, and in hyperthyroid cats before and after treatments with radioactive iodine (RIT). Methods: Twenty-five cats with hyperthyroidism and 13 healthy euthyroid cats > 8 years of age were studied. Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, antithrombin (AT), D-dimers, thrombin-antithrombin complexes (TAT), von Willebrand Factor antigen (vWF:Ag), and activity of factors VIII and IX were measured. An echocardiogram was performed in all cats and healthy cats with abnormal echocardiograms were excluded. Measurements of hemostasis were evaluated again in 7 cats > 6 months after RIT and deemed to have restored euthyroid status. Results: There is a significant likelihood of being in hypercoagulable state based on hyperthyroid state (P = 0.019) and serum T4 level is significantly associated with predicating hypercoagulability (P = 0.043). Hyperthyroidism is associated with significantly higher median fibrinogen concentration (P < 0.0001), higher median AT activity (P < 0.0001), and higher median vWF:Ag level (P = 0.01) with all values decreasing significantly post-RIT. Fibrinogen and AT had a strong positive correlation with serum T4 value (r = 0.79; 95% CI 0.63 - 0.89 and r = 0.70; 95% CI 0.50 - 0.84, respectively). Presence of an abnormal echocardiogram in hyperthyroid cats was associated with a significantly higher median fibrinogen concentration (P = 0.03). Echocardiographic status did not have a significant impact on the remaining hemostatic markers in hyperthyroid cats. Conclusions: These results provide evidence of altered hemostasis and hypercoagulability in hyperthyroid cats that do not appear to be solely attributed to cardiac abnormalities. These differences of altered hemostasis resolved after radioiodine therapy, but further studies are warranted to determine if hypercoagulable state resolves. / Master of Science / In feline hyperthyroidism, there is a predisposition for thrombus formation. An alteration of hemostasis has been documented in hyperthyroid humans, but despite reports of thrombus formation in hyperthyroid cats, the underlying mechanism is currently unknown. Hyperthyroidism can lead to cardiac abnormalities that could possibly contribute thrombus formation, although thrombus formation has occurred in hyperthyroid cats without detected abnormalities. The goal of this study was to evaluate markers of hemostasis in hyperthyroid cats presenting for radioiodine therapy to evaluate for presence of hypercoagulability. Twenty-five hyperthyroid cats were evaluated with hemostasis panels and echocardiograms. The results were compared to a group of 13 healthy cats. Markers of hemostasis and echocardiograms in 7 hyperthyroid cats were also compared to results 6 months or greater post-radioiodine therapy. There was evidence of altered hemostasis and hypercoagulability in hyperthyroid cats. The alterations noted resolved after radioiodine therapy and do not appear to be solely attributed to cardiac abnormalities seen in hyperthyroid cats.

<p>Radioiodine has been used in nuclear medicine for the treatment of thyroid diseases such as Thyroid Cancer and Thyrotoxicosis for many years. The treatment renders the patient radioactive. To minimize the dose to the patients’ relatives and the general public, restric-tions are imposed on the behaviour of the patient. This project presents the person dose equivalents actually received by family members of radioiodine patients following such restrictions. The family members wore hospital ID-bands on left and right wrists for up to four weeks. Each ID-band contained two LiF: Mg, Ti Thermo Luminescence Dosimeters (TLD) calibrated to measure air kerma. The TLDs were analysed and a total person dose equivalent received by the relative was calculated from the measured air kerma values. The results were compared to the dose constraints imposed by The Swedish Radiation Protection Authority (SSI FS 2000:3) in order to confirm that the new set of restrictions used at Karolinska University Hospital Huddinge maintains the dose to family members below the applicable limits.</p><p>A total number of 22 relatives were recruited, 8 elderly, 7 adults and 7 children. Of the recruited relatives 4 (2 adults, 2 children) were excluded from the study as they had lost their dosimeter ID-bands or had other reasons not to participate in the study. This leaves the number of relatives used for data analysis at 18 individuals (8 elderly, 5 adults and 5 children) with a min age of 10 years and max age of 80 years.</p><p>The observed average person dose equivalent of 0.43 mSv (max, 1.27; min, 0.12) indi-cates that the new method of individualised restriction used at Karolinska University Hospital Huddinge work as desired in keeping the dose to family members at an accept-able level. The accuracy of the clinical study has been shown to depend greatly on the method by which the dose is investigated but also on the properties of the TLD material used. There is a potential underestimation of air kerma due to fading of up to 30 %. In addition there are contributing uncertainties from both the calibration method and the conversion to person dose equivalent with the combined uncertainty estimated to be 14%.</p>

Radioiodine has been used in nuclear medicine for the treatment of thyroid diseases such as Thyroid Cancer and Thyrotoxicosis for many years. The treatment renders the patient radioactive. To minimize the dose to the patients’ relatives and the general public, restric-tions are imposed on the behaviour of the patient. This project presents the person dose equivalents actually received by family members of radioiodine patients following such restrictions. The family members wore hospital ID-bands on left and right wrists for up to four weeks. Each ID-band contained two LiF: Mg, Ti Thermo Luminescence Dosimeters (TLD) calibrated to measure air kerma. The TLDs were analysed and a total person dose equivalent received by the relative was calculated from the measured air kerma values. The results were compared to the dose constraints imposed by The Swedish Radiation Protection Authority (SSI FS 2000:3) in order to confirm that the new set of restrictions used at Karolinska University Hospital Huddinge maintains the dose to family members below the applicable limits. A total number of 22 relatives were recruited, 8 elderly, 7 adults and 7 children. Of the recruited relatives 4 (2 adults, 2 children) were excluded from the study as they had lost their dosimeter ID-bands or had other reasons not to participate in the study. This leaves the number of relatives used for data analysis at 18 individuals (8 elderly, 5 adults and 5 children) with a min age of 10 years and max age of 80 years. The observed average person dose equivalent of 0.43 mSv (max, 1.27; min, 0.12) indi-cates that the new method of individualised restriction used at Karolinska University Hospital Huddinge work as desired in keeping the dose to family members at an accept-able level. The accuracy of the clinical study has been shown to depend greatly on the method by which the dose is investigated but also on the properties of the TLD material used. There is a potential underestimation of air kerma due to fading of up to 30 %. In addition there are contributing uncertainties from both the calibration method and the conversion to person dose equivalent with the combined uncertainty estimated to be 14%.

Thesis (MSc (Medical Imaging and Clinical Oncology. Nuclear Medicine))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Radioiodine therapy is reputed to yield poorer results in male patients than in females. We retrospectively reviewed the records of 308 patients treated with radioiodine-131 (RAI) for Graves’ disease (n=266, 86.4%), toxic multinodular goitres (n=35, 11.4%) and toxic solitary nodules (n=7, 2.3%). The mean age of the men was 44 ±13.6 years (range 14-77 years). Patients with GD were predominantly in the younger age groups, while those with toxic nodular goitres were in the older range. Two hundred and fifty-nine patients (84.1%) were treated with a single dose of RAI, while 49 (15.9%) required further doses. A second dose had to be administered to 38 patients, while 8 received 3 doses, 2 got 4 doses and 1 patient had 5 doses in all (these included a first dose received prior to referral to our Thyroid Clinic). Cure was determined as euthyroidism or hypothyroidism at the 3-month follow-up visit. The average pre-treatment T4 value was 68.9 ± 31.8 pmol/L (range 5.7 – 155 pmol/L); while the mean Tc-99m pertechnetate uptake value was 15.8 ± 10.9% (range 0.88 - 62.9). Patients with GD presented with more severe hyperthyroidism than the other patients; mean free T4 of 71.9 ± 31.1 pmol/L compared to 51.4 ± 29.9 pmol/L for the TMG group of patients, and 39.6 ± 26.8 pmol/L for the TSN group (ANOVA p<0.0001, confirmed by the Kruskal-Wallis test). Patients with TMG and TSN were treated with higher doses than patients with GD; mean first doses of 349.3 ± 88.5 MBq and 428.1 ± 28.6 MBq respectively, compared to a mean dose of 325.1 ± 69.3 MBq for patients with GD. Treatment with multiple doses of RAI correlated with higher values of T4 and T3 at presentation (p<0.0001). However, none of the baseline variables of age, T4 and T3, and first dose of RAI was significant predictors of free T4 outcome at 3 months. A consistently higher dose was administered to the male patients, compared to female patients of similar age, diagnosis and level of thyrotoxicosis (Tc-99m pertechnetate uptake). Despite this, male patients had similar outcomes as the female patients 3 months after therapy. Our findings lend weight to the theory that male patients are more difficult to treat than their female counterparts, seeing that the former had similar outcomes despite the significantly higher doses of RAI administered to the males. / AFRIKAANSE OPSOMMING: Radiojodium terapie lewer na bewering swakker resultate in mans as in vroulike pasiënte. Die inligting van 308 pasiënte met Grave se siekte (n=266, 86.4%), toksiese multinodulêre tiroïed (n=35, 11.4%) en enkel toksiese nodules (n=7, 2.3%) wat met radiojodium (I-131) behandel is, is retrospektief nagegaan. Die gemiddelde ouderdom van die mans was 44 ±13.6 jaar (reikwydte 14-77 jaar). Die meeste pasiënte met Grave se siekte was in die jonger ouderdomsgroep, terwyl dié met toksiese multinodulêre tiroïed, ouer was. Tweehonderd nege-en-vyftig pasiënte (84.1%) is met ‘n enkel dosis radiojodium behandel, terwyl 49 (15.9%) meer as een dosis benodig het. ‘n Tweede dosis is aan 38 pasiënte gegee, terwyl agt 3 dosisse, twee 4 dosisse en 1 pasiënt 5 dosisse in totaal ontvang het (wat ‘n eerste dosis voor verwysing na die tiroïedkliniek, ingesluit het). Herstel is gedefinieer as eutiroïdisme of hipotiroidisme tydens die drie maande opvolgbesoek. Die gemiddelde T4-waarde voor behandeling was 68.9 ± 31.8 pmol/L (reikwydte 5.7–155 pmol/L); terwyl die gemiddelde Tc-99m pertegnetaatopname 15.8 ± 10.9% (reikwydte 0.88–62.9) was. Pasiënte met Grave se siekte het met erger hipertiroidisme as die ander pasiënte gepresenteer; met ‘n gemiddelde vry T4 van 71.9 ± 31.1 pmol/L vergeleke met 51.4 ± 29.9 pmol/L vir die toksiese multinodulêre tiroïedgroep en 39.6 ± 26.8 pmol/L vir die enkel toksiese nodule groep (ANOVA p<0.0001, bevestig met die Kruskal-Wallistoets). Pasiënte met toksiese multinodulêre tiroïed en enkel toksiese nodule, is met hoër dosisse as dié met Grave se siekte behandel; met ‘n gemiddelde eerste dosis van 349.3 ± 88.5 MBq en 428.1 ± 28.6 MBq onderskeidelik, vergeleke met ‘n gemiddelde dosis van 325.1 ± 69.3 MBq vir pasiënte met Grave se siekte. Behandeling met meer as een dosis radiojodium het gekorreleer met hoër T4- en T3- waardes by (p<0.0001). Geen van die basislyn veranderlikes (ouderdom, T4 en T3, en die eerste dosis radiojodium) was egter ‘n betekenisvolle voorspeller van die vry T4 uitkoms op 3 maande nie. Die dosis wat aan manlike pasiënte toegedien is, was konstant hoër, vergeleke met die vroulike pasiënte van dieselfde ouderdom, diagnose en vlak van tirotoksikose. (Tc-99m pertegnetaatopname). Ongeag hiervan, was die uitkoms by manlike en vroulike pasiënte 3 maande na terapie dieselfde. Ons bevindinge dra by tot die teorie dat manlike pasiënte moeiliker is om te behandel as hul vroulike eweknieë, aangesien mans soortgelyke uitkomste gehad het ten spyte van betekenisvol hoër dosisse radiojodium.

Pacientes que sofrem de doenças na tireoide, como hipertireoidismo causado pela doença de Graves, ou câncer de tireoide, têm como principal forma de tratamento a chamada terapia por radioiodo. Este tratamento consiste na ingestão de um radionuclídeo, no caso, o isótopo de massa atômica 131 do iodo (131I). A terapia utilizando radioisótopos é aplicada em uma variedade de tumores e, por se tratar de um material radioativo que o paciente recebe por via venosa ou oral, certa quantidade de radionuclídeos chegam a órgãos e tecidos diferentes do esperado e mesmo o acúmulo de material radioativo na região de interesse contribui para dose em tecidos sadios. Logo, é necessário um planejamento prévio. Em 80% dos planejamentos, a atividade a ser administrada no paciente é calculada através de valores pré-determinados, como peso, idade ou altura. Apenas cerca de 20% das terapias são realizadas com um planejamento personalizado, específico para cada paciente. Levando essas informações em consideração, este trabalho tem como objetivo realizar um estudo dosimétrico através de imagens para que no futuro seja utilizado em rotinas clínicas para planejamento de iodoterapia individualizado para cada paciente. Neste trabalho foram adquiridas imagens tomográficas (SPECT-CT) de um fantoma de tireoide preenchido com 131I. O fantoma foi construído com base na literatura, reproduzido de maneira fidedigna, e aperfeiçoado, permitindo a inserção de dosímetros termoluminescentes (TLD) em pequenas cavidades. As imagens foram inseridas no software GATE, baseado na ferramenta GEANT4, que permite a simulação da interação da radiação com a matéria pelo método Monte Carlo. Essas imagens foram convertidas em formato reconhecível pelo GATE e através da elaboração de um script de comandos, foram realizadas simulações com o intuito de estimar a dose em cada região da imagem. Uma vez que o dosímetro permanecia exposto ao material radioativo por alguns dias, para evitar um dispêndio de tempo computacional muito grande e estimar o valor final da dose no mesmo período de tempo em que o dosímetro ficou exposto através da simulação, foi necessário extrapolar uma equação e calcular a dose para este tempo. Foram realizadas duas aquisições diferentes, a primeira com uma distribuição não homogênea da fonte e a segunda com distribuição homogênea. Para a distribuição não homogênea, a comparação dos resultados da simulação com resultados obtidos por TLD mostram que ambos possuem a mesma ordem de grandeza e variam proporcionalmente em relação à distância que se encontram da fonte. A diferença relativa entre eles varia de 1% a viii 39% dependendo do dosímetro. Para a distribuição homogênea, os valores possuem a mesma ordem de grandeza, mas estão muito abaixo do esperado, com uma diferença relativa de até 70% e os valores da dose simulados estão, em sua maioria, duas vezes menores que o real. A técnica ainda não está pronta para ser implementada na rotina clínica, mas através de estudos de fatores de correção e novas aquisições, essa técnica pode, em um futuro próximo, ser utilizada. / Radio-iodine therapy is the main form of treatment for patients with diseases on the thyroid, such as hyperthyroidism caused by Graves\' disease or thyroid cancer. This treatment consists in the intake of a radionuclide, the iodine isotope of atomic mass 131 (131I). The radioisotope therapy is applied in a variety of tumors and since the patient receives it intravenously or orally, certain amount of radionuclide reaches different organs and tissues than the ones expected. Even the radioactive material accumulated in the region of interest contributes to the energy deposition on healthy tissues. Therefore, it is necessary a treatment planning. However, 80% of nuclear medicine therapy the administered activity is based in quantity as patients weight, age or height. The patient-specific therapy planning occurs in less than 20% of applications in nuclear medicine. Considering that information, this work aims to conduct a dosimetric study based on images so that in the future could be used in clinical routines for patient-specific radioiodine therapy. Were acquired tomographic images (SPECT-CT) of a thyroid phantom filled with 131I. The phantom was consistently reproduced according to the literature, with some improvements allowing the placement of thermoluminescent dosimeters into small cavities. Such phantom was used for the acquisition of SPECT-CT images. The images were inserted into the GATE software, based on GEANT4 tool, which allows the simulation of radiation interaction with matter, through the Monte Carlo method. Those images were converted into acceptable format for GATE and through the development of a command script, the simulations were performed in order to estimate the dose in each region of the image. Since the dosimeter remained exposed to the radioactive material for a few days, to reduce computational time and estimate, by simulation, the dose over the same period of time which the dosimeter has been exposed, it was necessary to extrapolate the equation and calculate the dose for this time. Two images acquisitions were made, the first with an inhomogeneous source distribution and the second with a homogeneous distribution. For the inhomogeneous acquisition, the simulation and TLD values have the same magnitude and both of them vary in proportion to the source distance. The relative difference ranges from 1% to 39% depending on the dosimeter. For the homogeneous one, despite being in the same magnitude either, the values are much lower x than expected, with a difference of up to 70%, and the simulated data, in general are half the TLD values. The technique is not yet ready to be implemented in clinical routine, but through studies of correction factors and new acquisitions, this technique may in the near future, be used.

Pacientes que sofrem de doenças na tireoide, como hipertireoidismo causado pela doença de Graves, ou câncer de tireoide, têm como principal forma de tratamento a chamada terapia por radioiodo. Este tratamento consiste na ingestão de um radionuclídeo, no caso, o isótopo de massa atômica 131 do iodo (131I). A terapia utilizando radioisótopos é aplicada em uma variedade de tumores e, por se tratar de um material radioativo que o paciente recebe por via venosa ou oral, certa quantidade de radionuclídeos chegam a órgãos e tecidos diferentes do esperado e mesmo o acúmulo de material radioativo na região de interesse contribui para dose em tecidos sadios. Logo, é necessário um planejamento prévio. Em 80% dos planejamentos, a atividade a ser administrada no paciente é calculada através de valores pré-determinados, como peso, idade ou altura. Apenas cerca de 20% das terapias são realizadas com um planejamento personalizado, específico para cada paciente. Levando essas informações em consideração, este trabalho tem como objetivo realizar um estudo dosimétrico através de imagens para que no futuro seja utilizado em rotinas clínicas para planejamento de iodoterapia individualizado para cada paciente. Neste trabalho foram adquiridas imagens tomográficas (SPECT-CT) de um fantoma de tireoide preenchido com 131I. O fantoma foi construído com base na literatura, reproduzido de maneira fidedigna, e aperfeiçoado, permitindo a inserção de dosímetros termoluminescentes (TLD) em pequenas cavidades. As imagens foram inseridas no software GATE, baseado na ferramenta GEANT4, que permite a simulação da interação da radiação com a matéria pelo método Monte Carlo. Essas imagens foram convertidas em formato reconhecível pelo GATE e através da elaboração de um script de comandos, foram realizadas simulações com o intuito de estimar a dose em cada região da imagem. Uma vez que o dosímetro permanecia exposto ao material radioativo por alguns dias, para evitar um dispêndio de tempo computacional muito grande e estimar o valor final da dose no mesmo período de tempo em que o dosímetro ficou exposto através da simulação, foi necessário extrapolar uma equação e calcular a dose para este tempo. Foram realizadas duas aquisições diferentes, a primeira com uma distribuição não homogênea da fonte e a segunda com distribuição homogênea. Para a distribuição não homogênea, a comparação dos resultados da simulação com resultados obtidos por TLD mostram que ambos possuem a mesma ordem de grandeza e variam proporcionalmente em relação à distância que se encontram da fonte. A diferença relativa entre eles varia de 1% a viii 39% dependendo do dosímetro. Para a distribuição homogênea, os valores possuem a mesma ordem de grandeza, mas estão muito abaixo do esperado, com uma diferença relativa de até 70% e os valores da dose simulados estão, em sua maioria, duas vezes menores que o real. A técnica ainda não está pronta para ser implementada na rotina clínica, mas através de estudos de fatores de correção e novas aquisições, essa técnica pode, em um futuro próximo, ser utilizada. / Radio-iodine therapy is the main form of treatment for patients with diseases on the thyroid, such as hyperthyroidism caused by Graves\' disease or thyroid cancer. This treatment consists in the intake of a radionuclide, the iodine isotope of atomic mass 131 (131I). The radioisotope therapy is applied in a variety of tumors and since the patient receives it intravenously or orally, certain amount of radionuclide reaches different organs and tissues than the ones expected. Even the radioactive material accumulated in the region of interest contributes to the energy deposition on healthy tissues. Therefore, it is necessary a treatment planning. However, 80% of nuclear medicine therapy the administered activity is based in quantity as patients weight, age or height. The patient-specific therapy planning occurs in less than 20% of applications in nuclear medicine. Considering that information, this work aims to conduct a dosimetric study based on images so that in the future could be used in clinical routines for patient-specific radioiodine therapy. Were acquired tomographic images (SPECT-CT) of a thyroid phantom filled with 131I. The phantom was consistently reproduced according to the literature, with some improvements allowing the placement of thermoluminescent dosimeters into small cavities. Such phantom was used for the acquisition of SPECT-CT images. The images were inserted into the GATE software, based on GEANT4 tool, which allows the simulation of radiation interaction with matter, through the Monte Carlo method. Those images were converted into acceptable format for GATE and through the development of a command script, the simulations were performed in order to estimate the dose in each region of the image. Since the dosimeter remained exposed to the radioactive material for a few days, to reduce computational time and estimate, by simulation, the dose over the same period of time which the dosimeter has been exposed, it was necessary to extrapolate the equation and calculate the dose for this time. Two images acquisitions were made, the first with an inhomogeneous source distribution and the second with a homogeneous distribution. For the inhomogeneous acquisition, the simulation and TLD values have the same magnitude and both of them vary in proportion to the source distance. The relative difference ranges from 1% to 39% depending on the dosimeter. For the homogeneous one, despite being in the same magnitude either, the values are much lower x than expected, with a difference of up to 70%, and the simulated data, in general are half the TLD values. The technique is not yet ready to be implemented in clinical routine, but through studies of correction factors and new acquisitions, this technique may in the near future, be used.

No description available.