Prostate cancer is the most common type of cancer afflicting Canadian men. Image-guided external radiation therapy of prostate cancer requires the accurate positioning of the patient in the treatment field. The alignment process is done using three fiducial markers implanted in the prostate. The current clinical practice involves the manual localization of these markers on pre-treatment, low-resolution electronic portal images (EPI). We propose an algorithm for the automatic detection of these markers. Our approach first enhances the quality of the EPI images using a fully automatic image enhancement approach. Next, fiducial markers are detected using template matching and a novel way of integrating information across multiple views. Experimental results show a significant improvement in the detection of fiducial markers in the left lateral view with respect to state-of-the-art results in related work. One should note that the left lateral view is the most challenging view due to the low resolution and the presence of occluding bony structures. / Graduate

A technique for the in vivo dose verification of intensity modulated radiation therapy (IMRT) has been developed. An electronic portal image, calibrated in terms of absolute dose, is acquired for each radiation field following transmission through the patient at the time of treatment. For an IMRT field, the portal image signal is back-projected through a model of the patient in order to calculate the dose at the isocentric plane perpendicular to the beam central axis. The IMRT in vivo dose verification technique was adapted for volumetric modu- lated arc therapy (VMAT) treatments when a single dosimetric image is acquired over an arc. The patient dose along axis of gantry rotation can be directly related to the signal along the vertical axis of EPIs in integrated mode. In this novel VMAT in vivo dosimetry technique, the portal image signal is back-projected through a rotationally averaged model of the patient to calculate a 1D in vivo dose along the axis of gantry rotation. A research ethics board clinical study was approved and transmission portal images were acquired at regular intervals from human subjects. Portal image-derived isocenter point doses were in good agreement with treatment planning system (TPS) calculations for IMRT (mean difference δ=0.0%, standard deviation of the differences σ=4.3%) and VMAT (δ=1.1%, σ=1.7%). The one-dimensional (VMAT) and two-dimensional (IMRT) reconstructed doses were further analyzed by calculating mean dose differences and γ−evaluation pass-rates, which were also shown to be in good agreement with TPS calculations. The portal image-based in vivo dosimetry techniques were shown to be clinically feasible, with reconstruction times on the order of minutes for the first fraction and less than one minute for each fraction thereafter. / Graduate / 0760 / 0574 / 0760

Darbo tikslas Ištirti kserostomijos klinikos ypatumus ir juos lemiančius veiksnius sergant Šegreno sindromu, po radioterapijos kaklo ir galvos srityje bei vartojant triciklius antidepresantus ir pasiūlyti burnos sveikatos pagerinimo būdą. Darbo uždaviniai 1. Ištirti pagrindinius kserostomijos klinikos simptomus ir nustatyti juos įtakojančių veiksnių reikšmingumą. 2. Nustatyti kai kurių etiologinių kserostomijos veiksnių sąsają su pacientų amžiumi, lytimi ir pagrindiniais klinikos simptomais. 3. Ištirti didžiųjų ir mažųjų seilių liaukų funkcinę būklę sialometrijos ir sialoscintigrafijos metodais ir įvertinti jos įtaką klinikiniams simptomams. 4. Nustatyti kserostomijos trukmės sąsają su pagrindiniais kserostomijos simptomais. 5. Nustatyti sergančiųjų pacientų dantų, apydančio ir burnos higienos būklės sąsają su kserostomijos etiologija ir klinika. 6. Pasiūlyti kserostomijos stadijų klasifikaciją ir jos diagnostikos kriterijus. 7. Patobulinti dirbtinių seilių sudėtį ir pasiūlyti sergančiųjų kserostomija burnos sveikatos pagerinimo būdą. Medžiaga ir metodai Tyrimų medžiagą sudarė dvi grupės: I. KMU dantų ir burnos ligų klinikoje 2003 – 2005 metais 64 pacientai, pirmą kartą besikreipę konsultuotis dėl sausos burnos, buvo įtraukti į studiją. Iš jų 34 atrinkti dirbtinių seilių poveikiui tirti iš kurių 27 pacientam atliktas sialoscintigrafinis tyrimas; II. Iš KMUK archyvo atsitiktiniu būdu buvo atrinktos 481... [toliau žr. visą tekstą] / There is a continuous discussion about the basic xerostomia etiology and clinic problems in literature. Still individual authors have no unified opinion on how and to what extent the etiological factor of hyposalivation is relevant to manifestation of various aspects of xerostomia (Jensen SB et al.). There is no final objective data about the relationship of subjective patient complains with age, sex, psychological status and duration of xerostomia. There is an on-going discussion among certain authors in medical literature on when salivation should be considered as deficient, and what level of hyposalivation causes clinical xerostomia. Proper treatment of xerostomia is one of the most relevant problem. At the present, there is no unified treatment strategy that is towarded to stage or severity degree of xerostomia. However, objective criteria are not developed yet to classify xerostomia severity. Most authors, independently of absence of clear indications, recommend anticariesogenic, antibacterial treatment and to compensate the lack of saliva with artificial ones. Currently, there are not available saliva substitutes as one of the most important xerostomia treatment component on the market in our country. The study is also needed to evaluate the effectiveness of the treatment. 2. THE AIM AND THE GOALS OF THE STUDY The aim of the study was to evaluate the pecularities of xerostomia etiology and clinic and the... [to full text]

Electron beam therapy planning and custom electron bolus design were identified as areas in which improvements in equipment and techniques could lead to significant improvements in treatment delivery and patient outcomes. The electron pencil beam algorithms used in conventional Treatment Planning Systems do not accurately model the dose distribution in irregularly shaped objects, near oblique surfaces or in inhomogeneous media. For this reason, at Christchurch Oncology Centre the TPS is not relied on for planning electron beam treatments. This project is an initial study of ways to improve the design of custom electron bolus, the planning of electron beam therapy, and other radiation therapy simulation tasks, by developing a system for the accurate assessment of dose distributions under irregular contours in clinically relevant situations. A shaped water phantom system and a diode array have been developed and tested. The design and construction of this water phantom dosimetry system are described, and its capabilities and limitations discussed. An EGS/BEAM Monte Carlo simulation system has been installed, and models of the Christchurch Oncology Centre linacs in 6MeV and 9MeV electron beam modes have been built and commissioned. A test was run comparing the EGS/BEAM Monte Carlo system and the CMS Xio conventional treatment planning system with the experimental measurement technique using the water phantom and the diode array. This test was successful as a proof of the concept of the experimental technique. At the conclusion of this project, the main limitation of the diode array system was the lack of data processing software. The array produces a large volume of raw data, but not enough processed data was produced during this project to match the spatial resolution of the computer models. An automated data processing system will be needed for clinical use of the array. It has been confirmed that Monte Carlo and pencil-beam algorithms predict significantly different dose distributions for an irregularly shaped object irradiated with megavoltage electron beams. The results from the diode array were consistent with the theoretical models. This project was an initial investigation. At the time of writing, the diode array and the water phantom systems were still at an early stage of development. The work reported here was performed to build, test and commission the equipment. Additional work will be needed to produce an instrument for clinical use. Research into electron beam therapy could be continued, or the equipment used to expand research into new areas.

Total body irradiation is the irradiation of the entire patient as a conditioning for bone marrow transplants. The conditioning process involves destroying the bone marrow allowing for repopulation of the donor bone marrow cells, suppression of the immune system to allow stop graft rejection, and to eliminate the cancer cell population within the patient. Studies have been done demonstrating the importance of TBI conditioning for BMT5. A range of TBI treatment techniques exist, this department uses a bi-lateral technique which requires bolus packed around the patient to simplify the geometry of the treatment. This investigation will focus on one technique which involves using a translating bed. This technique effectively scans a radiation beam over the patient as the bed moves through the beam. Other investigations on translating beds concentrated on varying the scan speed to achieve a dose uniformity to within ±5%. The recommendations quote a dose uniformity of +5% and -10% as acceptable⁹. The dose uniformity in these investigations was along the midline in the longitudinal direction only. This investigation varied field size to achieve dose uniformity to within ±2.5% along the midline of an anthropomorphic phantom. The goal was to determine if a dynamic multi-leaf collimator could be used to give a uniform in the transverse direction as well as the longitudinal direction. An advantage of utilizing the DMLC for this treatment is the ability to shield organs at risk, i.e. lungs and kidneys, without requiring resources to produce shielding blocks14. Gafchromic-EBT film18 was used as a dosimeter but gave unreliable results due to the lack of film scanning equipment with an appropriate sensitivity for reading the dose to the film. Scans were simulated using Xio treatment planning software. The results from the simulations gave a more reliable indication of the absorbed dose to the midline of the phantom. The disadvantage of this varying field size technique was the time and complexity involved in creating a treatment plan. Within the Xio software exists a limit on the number of beams allowed to be applied in a single plan. There is a maximum of 99 beams allowed which is not enough for complete coverage of a patient. A way around this is to increase the field sizes and decrease the scan speed. This option was not investigated. The advantage of this technique was the increased dose uniformity (±2.5%) in comparison to the varying scan speed techniques (±5%). This technique also allows the patient to be unencumbered during the treatment making the process more comfortable for them.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). "Year 2006-2008"--P. i. Includes bibliographical references (p. 122-123). Also available via the World Wide Web.

L'imagerie est maintenant partie intégrante des traitements de radiothérapie. Avec la technologie CBCT embarquée sur les appareils de traitement, l'imagerie tomographique permet non seulement de repositionner fidèlement le patient tout au long de son traitement mais aussi d'adapter la planification initiale aux modifications quotidiennes de volume. C'est la radiothérapie adaptative, objet des travaux de cette thèse. Nous avons établi les limites techniques de précision de repositionnement des équipements utilisé. Ensuite, à partir des acquisitions CBCT quotidiennes de patients traités pour la prostate, nous avons élaboré une stratégie de traitement basée sur une banque de plans personnalisés. Nous avons mis au point une méthode semi-automatique de sélection du plan de traitement du jour qui a montré une efficacité supérieure à la sélection par des opérateurs expérimentés. Enfin, nous avons quantifié les doses additionnelles à la dose thérapeutique associées à l'utilisation quotidienne de l'imagerie CBCT. En conclusion, on peut dire qu'avec l'imagerie CBCT embarquée, on peut voir ce que l'on veut traiter, irradier ce que l'on a vu et contrôler ce qu'on a traité. / Imaging is now fully integrated in the radiation therapy process. With on-board CBCT systems, tomography imaging allows not only patient positioning but also treatment planning adaptation with patient anatomy modifications, throughout the entire treatment. This is called adaptive radiation therapy, and is the main subject of this PhD thesis. During this work, we measured the repositioning accuracy of the system used. We also developed a treatment strategy using daily CBCT images and a personalized plan database to adapt treatment plan to patient anatomy. We found a way to select the daily treatment plan that shows superiority over operator selection. Then we also quantified the additional dose delivered while using this technique and the impact with regards to the risks added to patients. As a conclusion, with CBCT imaging, radiation therapy has entered an era where one can see what need to be treated, can treat what has been seen and can control what has been treated.

O controle da qualidade é uma prática essencial em radioterapia para se garantir que a dose prescrita seja realmente entregue ao paciente. Essa etapa da radioterapia é fundamental para o sucesso do tratamento, pois sem executá -lo o paciente pode ser subdosado ou sobredosado sem que o físico médico possa estimar o erro estabelecido entre a dose prescrita e dose recebida. Dentre os métodos para o controle da qualidade em radioterapia, as dosimetrias in vivo permitem determinar as doses recebidas pelo paciente durante o tratamento. Diferentes técnicas podem ser utilizadas em dosimetria in vivo, sendo uma das mais comuns a dosimetria por transmissão, que compreende a comparação entre os sinais de um dado dosímetro posicionado na entrada e na saída do paciente , nas condições de irradiação. Desta forma, o conhecimento dos espectros incidente e transmitido pelo paciente podem ser utilizados tanto para o cálculo das doses em profundidade no paciente quanto para a correção de resposta de dosímetros em dosimetrias in vivo por transmissão. O método Monte Carlo pode ser utilizado para reproduzir diversas situações desejadas em radioterapia, que pode ser tanto, em controle da qualidade como, em tratamentos, por ser uma ferramenta acurada e sem restrições físicas e financeiras. Esse trabalho se propõe a determinar a perturbação sofrida pelo feixe primário ao atravessar objetos simuladores por meio da determinação da fluência energética e da energia depositada em diferentes condições de irradiação, através do método Monte Carlo. Neste trabalho foi desenvolvida uma quantidade de situações utilizando-se o código PENELOPE para possibilitar a análise do comportamento de fluências energéticas e energias depositadas. Os parâmetros clínicos que sofreram variação para a analise foram a espessura do objeto simulador, o tamanho de campo e a distância fonte-superfície (DFS). Os resultados deste trabalho mostram que a dependência em relação a cada parâmetro clínico é diferente, como é o caso da DFS, que influência mais na resposta do que o tamanho de campo, por exemplo. Portanto, esse trabalho pode ser uma ferramenta para trabalhos posteriores no estabelecimento de protocolos de relação entre fluência e dose, bem como, de armazenamento ou aplicação de dose em pacientes. / Quality control is an essential practice in radiation oncology in order to ensure that the prescribed dose is delivered to the patient. This step of radiation therapy is very important to successful treatment, because without it the patient may receive bellow dose or over dose without the physical doctor can estimate the error established between the prescribed dose and dose received. One of the methods for quality control in radiotherapy, the in vivo dosimetry let you determine the doses received by the patient during the treatment. Different techniques can be used in vivo dosimetry, being one of the most common dosimetry for transmission, which includes the comparison of the signs of a dosimeter placed on the entrance and exit of patient irradiation conditions. In this way, the knowledge of incident spectra and transmitted by the patient can be used for both the calculation of doses in depth in the patient as to the dosimeter response in vivo dosimetry for transmission. The Monte Carlo method can be used to make a variety of situations you want in radiotherapy, and may be as much in quality as in control treatments for being a tool accurately and without physical and financial constraints. This work aims to determine the disturbance suffered by primary beam across objects simulators through determination of energy flow and energy deposited in different irradiation conditions through the Monte Carlo method. This work was developed a number of situations using the PENELOPE code to enable the analysis of the behavior of energy deposited energies and skills. The clinical parameters that have suffered the assess variation ranges were the thickness of the object Simulator, the field size and source surface distance (SSD). The results show that the dependence on each clinical parameter is different, as is the case of DFS, which most influence on response than the field size, for example. Therefore, this work can be a tool for further work on the establishment of relationship between fluency and protocols, as well as dose, dose storage in patients.

Nanopartículas de ouro (AuNP) compõem o estado da arte da medicina oncológica atual sendo extensivamente investigadas para aplicações em radioterapia de câncer. O acúmulo seletivo em tecidos tumorais de vascularização desordenada causa retenção aumentada das AuNP no microambiente tumoral e aumenta a permeabilidade de drogas terapêuticas por elas carreadas. A radiossensibilização observada em células em cultura tratadas com AuNP é, contudo, resultado da resposta biológica à ambos os fenômenos bioquímicos de interação com a célula alvo e físicos de interação da AuNP com a radiação ionizante. A presença do ouro metálico no citoplasma celular durante a terapia com radiação ionizante aumenta a secção de choque de absorção fotoelétrica no tecido alvo, o que contribui para o aumento potencial do dano biológico letal. Neste contexto, o objetivo principal deste trabalho é avaliar a radiossensibilização causada por nanopartículas de ouro em radioterapia em termos de parâmetros físicos e radiobiológicos. Simulação Monte Carlo com o código PENELOPE foi utilizada para estudar como a densidade de ionização local é alterada pela criação de elétrons secundários em nanopartículas de 2-100nm após interação com os feixes primários de fótons de interesse clínico de 200kV, Ir-192, Cs-137, 6MV e Co-60. O Estudo da Nanopartícula Isolada demonstrou que a densidade de ionização é fortemente aumentada com a redução da energia do feixe primário (E) de ionização, sendo, entretanto, fracamente dependente do diâmetro das AuNP. O diâmetro da AuNP (d) modula, no entanto, o espectro de elétrons secundários ejetados ao tecido-mole disposto ao redor porque modifica o número de elétrons internamente absorvidos em cada nanopartícula. Quando concentrações de ouro (!!\") entre 0,001% e 1%, são consideradas no Estudo da Célula com Nanopartículas, é possível observar que a !!\" internalizada no citoplasma aumenta a fração de reforço da densidade de ionização no tecido alvo em até 200% para baixas energias, não ultrapassando 160% para feixes de megavoltagem. A principal conclusão desta etapa é que o reforço na densidade de ionização local é resultado do balanço entre os parâmetros estudados E e !!\", e o diâmetro da AuNP, modifica o número de fotoelétrons ejetados ao meio, influenciando portanto o potencial efeito biológico. A partir dos resultados do estudo por Monte Carlo, foram desenhados os estudos radiobiológicos in vitro e in vivo com células PC3 de adnocarcionama de próstata. Nanopartículas rod shaped (AuNR) - conjugadas com Goserelin (gAuNR) princípio ativo do quimioterápico Zoladex® foram sintetizadas com sucesso para aplicações nos sistemas biológicos e nanopartículas conjugadas com polietileno glicol (pAuNR) foram utilizadas como controle biocompatível e não bioespecífico em todos os ensaios. A dinâmica de uptake celular foi estudada in vitro demostrando que a presença do biomarcador na superfície das nanopartículas aumenta a concentração efetiva de ouro internalizada nas células alvo em 5 vezes quando comparada com pAuNR. Radiossensibilização aumentada foi observada em ensaios clonogênicos, apresentando essencialmente efetividade radiobiológica relativa 27% maior para o tecido com gAuNR incorporados, quando irradiado como feixe de 6MV, 58% e 78% maior quando irradiado com os feixes de Cs137 e Ir192 respectivamente. O estudo de biodistribuição in vivo em nude mice demonstrou que as nanopartículas bioconjugadas gAuNR tem acúmulo 3 vezes maior em tumores xenográficos de próstata do que pAuNR, e o seguimento tumoral acompanhado em 55 animais demonstrou expressiva efetividade terapêutica do uso de gAuNR em Radioterapia. Foi observado !!\"#$% de 24 e 20 dias para os grupos tratados com gAuNR e pAuNR irradiados com 6MV; Este número cresce para 28 e 18 quando as irradiações são realizadas com a fonte de Braquiterapia HDR de Ir-192. Os resultados consonantes dos estudos por Monte Carlo e ensaios radiobiológicos conduzem à proposição deste trabalho à luz de sua principal conclusão: Nanopartículas de ouro bioconjugadas, gAuNR, apresentam terapêutica efetiva na Radioterapia de câncer de próstata porque modulam o espectro de elétrons no citoplasma celular causando aumento local da densidade de ionização e reforço da probabilidade de dano letal. / Gold nanoparticles (AuNP) comprise the state of the art in medical oncology being extensively investigated for applications in cancer radiation therapy. The selective accumulation in tissues with disordered vascularization increases retention of AuNP in the tumor microenvironment, what leads to enhanced permeability of conjugated drugs carried by the AuNP. The radiosensitization observed in cells treated with AuNP however is result of a combined biological response to both biochemical and physical interactions of the conjugated AuNP with ionizing radiation. The presence of metallic gold in the cell cytoplasm during radiation therapy increases the photoelectric absorption cross-section in the target tissue, thus potentially increasing the lethal biological damage. In this context, the aim of this study is to evaluate the radiosensitization caused by gold nanoparticles in radiation therapy in terms of physical and radiobiological parameters. In order to investigate the density of ionizations in cells containing AuNP, the PENELOPE Monte Carlo code was used to simulate creation of secondary electrons in nanoparticles of 2-100nm after interaction with photon beams of clinical interest: 250kV, Ir-192, Cs-137, 6MV and Co-60. The theoretical analysis was performed in two steps: the Single AuNP Study and the Cell with AuNP Study. The first study predicts that enhancing nanoparticle diameter (d) from 2-10nm keeps the density of ionization enhanced in 22-28% for all kilovoltage beams and from 38-46% for all megavoltage beams, however increasing more than 5 times the yield of electrons ejected from the AUNP to the surrounding soft-tissue when the primary beam has its energy decreased from 6MV to 250kV. In the Cell with AuNP Study, the final concentration of gold in the cytoplasm (!!\") was increased from 0.001% to 1%, showing that concentration of gold strongly modifies the density of ionization in the cell, being up to 2 and 1.6 fold for low and high energies respectively. Sequentially, conjugated AuNP were synthesized with Goserelin Acetate (gAuNR) to target PC3 prostate cancer cells, and AuNP coated with polyethylene glycol (pAuNR) were used as non-biospecific control. The radiobiological assays were following designed based on the Monte Carlo results with 6MV, Cs-137 and the Ir-192 HDR Brachytherapy source. The in vitro cellular uptake study demonstrate that the biomarker in the surface of the nanoparticles increases the effective concentration of gold in the cytoplasm by 2.4 fold compared to pAuNR. The clonogenic assays demonstrate that the relative radiobiological effectiveness is enhanced in 27%, 58% and 78% for 6MV, Cs-137 and Ir-192 respectively when cells are treated with gAuNR for 24h prior irradiation. The conjugated nanoparticles were also submitted to ICP-MS based biodistribution study that demonstrate gAuNR accumulate 3 fold in xenografts prostate tumors than pAuNR. Following these results, a tumor re-growth study in nude mice was designed considering irradiations with the 6MV and the Ir-192 HDR Brachytherapy beam energies. Nanoparticles were administrated intravenously and tumors were followed for a maximum of 30 days. Tumor delay (!!\"#$%) of 20 and 24 days were observed for groups respectively treated with gAuNR and pAuNR and the 6MV beam; And !!\"#$% of 28 and 18 days were observed for groups respectively treated with gAuNR and pAuNR and the Ir-192 HDR Brachytherapy source. Both in vitro and in vivo studies, in consonance with the Monte Carlo predictions, demonstrate that conjugated AuNP, gAuNR, improve therapeutic effectiveness for treating prostate tumors because the gold nanoparticles modulate the effective spectrum of secondary electrons in the cytoplasm, locally enhancing the density of ionizations and thus increasing probability of lethal cellular damage.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-08-07T14:15:11Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese doutorado Keyla Mendonça.pdf: 1892604 bytes, checksum: 11d46f4a20b26b6f0556122ab34f0316 (MD5) / Made available in DSpace on 2017-08-07T14:15:12Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Tese doutorado Keyla Mendonça.pdf: 1892604 bytes, checksum: 11d46f4a20b26b6f0556122ab34f0316 (MD5) Previous issue date: 2016-08-05 / CNPQ / A radioiodoterapia (RIT) para hipertireoidismo é feita ambulatorialmente há cerca de 70 anos, com poucas restrições quanto à segurança radiológica dos familiares de convívio domiciliar. Diante disso, o objetivo do estudo foi avaliar o impacto radiológico da RIT para hipertireoidismo por meio de levantamento das exposições no ambiente domiciliar destes pacientes nos primeiros seis dias pós-tratamento, para servir como um parâmetro real na tomada de decisões relacionadas com a conduta terapêutica e estabelecimento de novas recomendações práticas e seguras desta terapia. Dosímetros termoluminescentes TLD-100 foram colocados nos acompanhantes e nos ambientes domiciliares de 25 pacientes hipertireóideos tratados com atividades de 555 MBq (n=9), 740 MBq (n=7) e 1110 MBq (n=9). Além disso, foram verificadas as contaminações superficiais de objetos e materiais desses pacientes. As doses efetivas obtidas por meio dos TLDs-100 foram de 0,9 mSv, 0,6 mSv e 0,2 mSv, para atividades administradas de 555 MBq, 740 MBq e 1110 MBq, respectivamente. Os valores médios de equivalente de dose ambiental dos locais mais frequentados dos pacientes, como quarto, cozinha, banheiro e sala foram de: 2,11; 0,15; 0,20 e 0,44 mSv, respectivamente. A monitoração de objetos e materiais de âmbito domiciliar para cada grupo de atividade 555, 740 e 1110 MBq variaram de valores indetectáveis até próximos a 150 Bq.cm-2. No Brasil, a norma 3.05 da Comissão Nacional de Energia Nuclear estabelece que pacientes tratados com 131I possam realizar terapia com atividades até 1850 MBq, em regime ambulatorial, sem nenhuma restrição de isolamento. Além disso, a norma 3.01da Comissão nacional de energia Nuclear estabelece os limites de dose efetiva para indivíduos do público e acompanhantes/voluntários, como sendo de 1 mSv e 5 mSv por ano, respectivamente. Comparando a população estudada com a norma vigente, apenas duas acompanhantes de pacientes ultrapassaram o limite estabelecido. Pressupõe-se que o contato físico próximo e constante delas aos pacientes, em consequência da exiguidade do espaço domiciliar, resultou nessas doses efetivas. Conclui-se que o tratamento do hipertireoidismo em regime ambulatorial com atividades de até 1.110 MBq, foi realizado de forma segura e forneceu informações úteis sobre a proteção e exposição dos familiares e acompanhantes de pacientes. / The radioiodine therapy (RIT) for hyperthyroidism is done on an outpatient basis for about 70 years, with few restrictions on radiological safety of household living family. Thus, the objective of the study was to evaluate the radiological impact of RIT for hyperthyroidism through survey of exposures in the home environment of these patients in the first six days after treatment, to serve as an actual parameter in making decisions related to the therapeutic approach and establishment of new practices and safe recommendations of this therapy. TLD-100 thermoluminescent dosimeters were placed in the accompanying domestic environments and 25 hyperthyroid patients treated with 555 MBq Activity (n = 9), 740 MBq (n = 7) and 1110 MBq (n = 9). Furthermore, the surface contamination of objects and materials of these patients were checked. The effective doses obtained through the TLDs-100 were 0.9 mSv 0.6 mSv and 0.2 mSv for administered activity of 555 MBq 740 MBq and 1110 MBq, respectively. The average values of ambient dose equivalent of the busiest places of the patients, such as bedroom, kitchen, bathroom and living room were: 2,11; 0.15; 0.20 and 0.44 mSv, respectively. Monitoring objects and home environment of materials for each activity group 555, 740 and 1110 MBq ranged from undetectable to near 150 Bq.cm-2. In Brazil, the standard 3:05 of the National Nuclear Energy Commission established that patients treated with 131I can perform therapy activities up to 1850 MBq, in an outpatient setting, without any isolation restriction. In addition, the standard 3.01da National Nuclear Energy Commission shall establish the effective dose limits for individuals from the public and chaperones / volunteers, as of 1 mSv to 5 mSv per year, respectively. Comparing the study population with the current regulations, only two companions of patients exceeded the limit. It is assumed that the close physical contact and constant them to patients as a result of the paucity of home space, resulted in these effective doses. We conclude that treatment of hyperthyroidism on an outpatient basis with up to 1,110 MBq activities was carried out safely and provided useful information on the protection and exposure of family members and patients companions.