O odontólogo frente aos cuidados paliativos na oncologia / The dental surgeon facing palliative care in oncology: a literature review / El odontólogo ante los cuidados paliativos en oncología

Cuidados paliativos são um conjunto de procedimentos ofertados ao paciente por uma equipe multidisciplinar com objetivo de garantir bem-estar, autonomia,conforto e alívio de sintomas decorrentes de doença ou tratamento quando a cura é impossibilitada. O câncer representa uma das doenças que possuem chances de evoluir o paciente ao estágio terminal, momento em que cuidados paliativos são indicados e necessários. Dentro da equipe responsável, o cirurgião-dentista atua na prevenção, diagnóstico e tratamento de lesões expressas no sistema estomatognático que se manifestam estimuladas pelo câncer ou pelos tratamentos utilizados. O objetivo desta pesquisa é destacar a função do odontólogo dentro da equipe multidisciplinar paliativista para pacientes oncológicos. Trata-se de uma revisão bibliográfica sistemáticada literatura. Foram feitas buscas nas plataformas Biblioteca Virtual em Saúde (BVS) e Scientific Electronic Library Online (SciELO) e após aplicação dos critérios de inclusão e exclusão foram selecionados 14 artigos. A literatura evidencia que alterações orais estão relacionadas com o curso da neoplasia ou seu tratamento; as lesões mais descritas foram: mucosite, xerostomia, candidíase, cárie, periodontite e osteorradionecrose. Isso faz com que o paciente sofra limitações em realizar atividades básicas, alterando negativamente a sua qualidade de vida. A complexidade da manifestação oral pode interromper o tratamento antineoplásico. As medidas de enfrentamento mais empregadas para a saúde bucal do paciente oncológico são a laserterapia, bochechos com clorexidina 0,12%, instrução de higiene oral, uso de anti-inflamatórios, analgésicos e antifúngicos. A atuação do odontólogo na equipe multidisciplinar oncológica paliativista é indispensável para o controle das manifestações orais.

Palliative care comprises a set of procedures offered by a multidisciplinary team to patients who cannot be cured, aiming to restore and ensure well-being, autonomy, independence, comfort and relief from symptoms resulting from illness or treatments. Cancer commonly leads the patient to the terminal stage, and at this stage palliative care is indicated and necessary. Composing the multidisciplinary team, the dentist works in the prevention, diagnosis and treatment of injuries that arise in the stomatognathic system, which manifest themselves due to cancer or its treatments. The objective of this research was to highlight the work of the dentist in the multidisciplinary team of palliative care for cancer patients. This is a systematic bibliographic review of the literature, with an integrative character. Study searches were performed in the Virtual Health Library (VHL) and Scientific Electronic Library Online (SciELO). After applying the inclusion and exclusion criteria, 14 articles were selected. Results showed that oral alterations are completely related to the development of the neoplasm or its treatment; the most described lesions were: mucositis, xerostomia, candidiasis, osteoradionecrosis, radiation caries and periodontitis. These injuries make the patient suffer limitations to perform basic activities, such as eating or communicating, negatively altering their quality of life. The complexity of the oral manifestation can determine the interruption of the anticancer treatment. The most used coping measures for the oral healthof cancer patients are: low- potency laser therapy, mouthwash with 0.12% chlorhexidine, instructionin oral hygiene and use of anti-inflammatory, analgesic and antifungal drugs. The role of dentists in the multidisciplinary palliative oncology team is essential for the control of oral lesions.

Los cuidados paliativos son un conjunto de procedimientos ofrecidos al paciente por un equipo multidisciplinar con el objetivo de garantizar el bienestar, la autonomía, el confort y el alivio de los síntomas derivados de la enfermedad o del tratamiento cuando la curación es imposible. El cáncer representa una de las enfermedades que tienen posibilidades de evolucionar al paciente hasta la fase terminal, momento en el que los cuidados paliativos son indicados y necesarios. Dentro del equipo responsable, el cirujano dentista actúa en la prevención, diagnóstico y tratamiento de las lesiones expresadas en el sistema estomatognático que se manifiestan estimuladas por el cáncer o por los tratamientos utilizados. El objetivo de esta investigación es destacar la función del odontólogo dentro del equipo paliativo multidisciplinar para pacientes oncológicos. Se trata de una revisión bibliográfica sistemática. Se realizaron búsquedas en las plataformas Virtual Health Library (BVS) y Scientific Electronic Library Online (SciELO) y tras aplicar los criterios de inclusión y exclusión, se seleccionaron 14 artículos. La literatura muestra que las alteraciones orales están relacionadas con el curso del cáncer o su tratamiento; las lesiones más comúnmente descritas fueron: mucositis, xerostomía, candidiasis, caries, periodontitis y osteorradionecrosis. Esto hace que el paciente sufra limitaciones para realizar actividades básicas, alterando negativamente su calidad de vida. La complejidad de la manifestación oral puede interrumpir el tratamiento antineoplásico. Las medidas de afrontamiento más utilizadas para la salud bucodental de los pacientes con cáncer son la terapia láser, los enjuagues bucales con clorhexidina al 0,12%, las instrucciones de higiene bucodental y el uso de fármacos antiinflamatorios, analgésicos y antifúngicos. La actuación del odontólogo en el equipo multidisciplinar de oncología paliativa es fundamental para el control de las manifestaciones orales.

Estimativa da necessidade de radioterapia externa no Brasil baseada em critérios epidemiológicos / Optimal utilization of radiotherapy in Brazil according to local epidemiological data

Esta tese teve como objetivo estimar a necessidade de radioterapia no Brasil a partir de dados epidemiológicos locais. O estudo foi desenvolvido em duas etapas que consistiram na estimativa de casos incidentes e, posteriormente, na classificação dos casos registrados nos Registros Hospitalares de Câncer (RHC) para integrar as árvores de decisão para o emprego do tratamento radioterápico conforme evidências e diretrizes clínicas de tratamento. As estimativas de casos incidentes em 2018 foram calculadas a partir de dados de Registros de Câncer de Base Populacional (RCBP) selecionados de acordo com critérios internacionais de qualidade e de dados corrigidos para causas mal definidas e não específicas na causa básica dos óbitos registrados no Sistema de Informação de Mortalidade (SIM) no período de 2007 a 2016. Foram calculadas razões de incidência/mortalidade (I/M) anuais para cada topografia, estratificadas por sexo e faixa etária nos RCBP selecionados. As razões I/M para 2018 foram estimadas para as regiões brasileiras a partir de modelos multiníveis de Poisson a partir de uma abordagem longitudinal com efeito aleatório no RCBP. As razões estimadas foram aplicadas ao número de óbitos ocorridos em 2018 por tipo de câncer, também corrigido para causas mal definidas e não específicas na causa básica, registrados no SIM. As distribuições dos dados por estadiamento obtidas a partir do RHC foram combinadas às frequências relativas por tipo de câncer incidente e aos dados das árvores de decisão do projeto Collaboration for Cancer Outcomes Research and Evaluation (CCORE) para uso da radioterapia. As estimativas de necessidade foram calculadas por tipo de câncer e para o conjunto das neoplasias, exceto pele não melanoma. Foram realizadas análises de sensibilidade para avaliar a relevância dos dados locais na estimativa de necessidade. O número necessário de equipamentos de radioterapia para atender os casos que se beneficiariam do tratamento em algum momento no curso da doença foi calculado e a análise da cobertura da oferta foi realizada. Para o Brasil, em 2018, foram estimados 506.462 casos novos de câncer, exceto pele não melanoma. Diferenças regionais nas razões I/M e no padrão de casos incidentes foram identificadas, podendo estar relacionadas a fatores socioeconômicos. Foi estimado que 53,55% dos casos novos no Brasil teriam necessidade de tratamento radioterápico. A maior necessidade de radioterapia foi identificada para o Norte: 55,32%, com um peso expressivo do câncer do colo do útero, tanto pela incidência como pelo número de casos em estágios avançados, para os quais a radioterapia é considerada tratamento de escolha. Para atender aos casos com necessidade de radioterapia no Brasil, foram estimados 497 equipamentos de radioterapia externa, sendo o déficit estimado em 114 para 2018 no país. Os maiores déficits foram observados para o Norte e para a rede assistencial do SUS. Em conclusão, o emprego de parâmetros internacionais não se mostrou adequado para a realidade brasileira. O planejamento de recursos para a assistência oncológica no Brasil demanda estimativas confiáveis baseadas nas necessidades locais para que as inequidades não sejam ainda mais agravadas.

This thesis aimed to estimate the need for radiotherapy in Brazil based on local epidemiological data. The study was developed in two stages which consisted of estimating incident cases and, later, classifying the cases registered in the Hospital Cancer Registries (RHC) to integrate decision trees for the use of radiotherapy according to evidence and clinical treatment guidelines. The estimates of incident cases in 2018 were calculated based on data from Population-Based Cancer Registries (RCBP) selected according to international quality criteria and from data corrected for ill-defined and non-specific causes in the underlying cause of deaths recorded in the System of Mortality Information (SIM) from 2007 to 2016. Annual incidence/mortality ratios (I/M) were calculated for each topography, stratified by sex and age group in the selected RCBP. The I/M ratios for 2018 were estimated for Brazilian regions using multilevel Poisson models from a longitudinal approach with random effect on the RCBP. The estimated reasons were applied to the number of deaths that occurred in 2018 by type of cancer, also corrected for ill-defined and non-specific causes in the underlying cause, recorded in the SIM. The staging data distributions obtained from the RHC were combined with the relative frequencies by type of incident cancer and data from the Collaboration for Cancer Outcomes Research and Evaluation (CCORE) project decision trees for radiotherapy use. Optimal utilization rates were estimated by type of cancer and for the set of tumors, except for non-melanoma skin. Sensitivity analyzes were performed to assess the relevance of local data in estimating the need. The number of radiotherapy equipment needed to attend to cases that would benefit from treatment at some point in the course of the disease was calculated and the analysis of the offer coverage was performed. For Brazil, in 2018, 506,462 new cases of cancer were estimated, except for non-melanoma skin. Regional differences in I/M ratios and in the pattern of incident cases were identified, which may be related to socioeconomic factors. It was estimated that 53.55% of new cases in Brazil would need radiotherapy. The greatest need for radiotherapy was identified for the North: 55.32%, with an expressive weight of cervical cancer, both in terms of incidence and the number of cases in advanced stages, for which radiotherapy is considered the treatment of choice. To meet the need for radiotherapy in Brazil, 497 external radiotherapy equipment were estimated, with an estimated deficit of 114 for 2018 in the country. The greatest deficits were observed for the North and for the SUS care network. In conclusion, the use of international parameters was not adequate for the Brazilian reality. The planning of resources for cancer care in Brazil requires reliable estimates based on local needs so that inequities are not further aggravated.

Discussion on the Different Design Ideas of Medical Accelerator(I) / 中国医疗器械杂志

This discussion attempts to organize and analyze the clinical purpose of various technologies developed by medical electron accelerators from the development history and clinical needs of radiotherapy products, so as to avoid the troubles caused by specific technical details and summarize the development of medical accelerators. Directly, the study provides differentiated development ideas for the development of domestic medical accelerators and ways and means to determine the dimensions of differentiated development.

Viability of mobile applications for remote support of radiotherapy patients

SUMMARY BACKGROUND Technological advances of the 21st century have provided greater communication, regardless of socioeconomic class and age group. Actions to promote the development of health applications are emerging around the world. OBJECTIVE To provide a perspective on the viability and usability of mobile applications dedicated to radiotherapy patients for remote support to health professionals proposing solutions to encourage Brasil in the development of these digital tools. METHODS Cross-sectional exploratory study by systematic review and literature review. We searched the PubMed, BVS, IBGE, and WHO databases, from 2014 to 2018. RESULTS 6 articles were found with topics related to the use of mobile applications in the health area, two of which were published in Portuguese and four in the English, on oncology, from 2014 to 2018. CONCLUSIONS We did not find an expressive number of works on this subject in Brasil. Mobile applications have the potential to assist in the remote support of radiotherapy patients. The latest studies suggest the need for a regulation of data protection protocols to be deployed.

RESUMO INTRODUÇÃO O avanço tecnológico no século XXI tem proporcionado maior comunicação entre todos, independentemente da classe socioeconômica e da faixa etária. Ações de fomento ao desenvolvimento de aplicativos para a área da saúde estão surgindo ao redor do mundo. OBJETIVO Oferecer uma perspectiva sobre a viabilidade e usabilidade dos aplicativos móveis dedicados aos pacientes radioterápicos para suporte remoto aos profissionais da saúde propondo soluções a fim de incentivar, no Brasil, o desenvolvimento dessas ferramentas digitais. MÉTODOS Estudo transversal de caráter exploratório por revisão sistemática e análise da literatura. Foram utilizadas buscas nas bases de dados: PubMed, BVS, IBGE, OMS, por publicações citadas de 2014 a 2018. RESULTADOS Foram encontrados cinco artigos com temas relacionados ao uso de aplicativos móveis na área da saúde, sendo dois nacionais, publicados em língua portuguesa, e três internacionais, no idioma inglês, dos quais esses últimos aplicados à oncologia no período de 2014 a 2018. CONCLUSÕES Não foi encontrado um número expressivo de trabalhos com este tema no Brasil. Aplicativos móveis têm potencial para ajudar no suporte remoto de pacientes radioterápicos. Os últimos estudos sugerem a necessidade de uma regulamentação de protocolos de proteção de dados transmitidos a ser implantada.

An experimental study on the determination of gantry angle and SSD dependencies of TLD and MOSFET dosimeter systems

Background: The purpose of this study was to investigate the various gantry angle and SSD dependencies of TLD and MOSFET dosimeters

Materials and Methods: LiF [Mg] TLD and MOSFET were used in this study. Dosimeter systems were calibrated and then irradiated at various gantry angle and SSD by applying 6 MV photon energy

Results: Based on the results, MOSFET changes were found to be in 2% range between +/-50[9] gantry angles and the rate of dose change was found to be increasing as gantry angle was at the extremes of graph. This increase was especially obvious in tail end of the asymmetric axes. Change in the gantry angle dependency of TLD was -2% till +/- 609 gantry angle and -5% between 60 to 90. Dependency of SSD was +/-1% for TLD and MOSFET

Conclusion: Results indicate that properties of dosimeters must be well known by users for accurate determination of the entire doses on the patient. These observations may lead to better treatment quality and prevention of probable dose errors

Caracterização dosimétrica de feixes de fótons com detector de diamante / Dosimetric characterization of photon beams using a diamond detector

OBJETIVO: Este trabalho foi realizado com o objetivo de caracterizar o detector de diamante, bem como observar seu comportamento. MATERIAIS E MÉTODOS: As características dosimétricas de feixes de fótons de 6 MV de energia foram medidas utilizando o sistema automático de varredura MP3 da PTW com um detector de diamante e foram comparadas com medidas usando uma câmara de ionização 31010 da PTW. RESULTADOS: As características dosimétricas do detector de diamante foram observadas por meio de medidas de linearidade com a dose, dependência com a taxa de dose e distribuições de dose em profundidade, bem como perfis. CONCLUSÃO: Algumas medidas com diamante e câmara de ionização foram validadas com resultados publicados na literatura, o que demonstrou um bom comportamento do detector de diamante na comparação com a câmara de ionização, muito utilizada para dosimetria em radioterapia, evidenciando que o diamante é uma boa escolha de detector para dosimetria de campos pequenos.

OBJECTIVE: The present study was aimed at characterizing a diamond detector and observing its behavior. MATERIALS AND METHODS: The dosimetric characteristics of 6 MV photon beams were measured by utilizing an automatic PTW MP3 scanning system with a diamond detector, and compared with measurements performed with a PTW 31010 ion chamber. RESULTS: Measurements of dose linearity, dose rate dependence and depth dose distribution as well as dose profiles demonstrated the dosimetric characteristics of the diamond detector. CONCLUSION: Some measurements with diamond detector and ion chamber were validated with results published in the literature, demonstrating a good behavior of the diamond detector as compared with the ionization chamber that is widely utilized for dosimetry in radiotherapy, indicating that the diamond detector is a good choice for small field dosimetry.

Arterial Occlusive Disease Complicating Radiation Therapy of Cervical Cancer

Radiation-induced arterial disease is caused by significant atherosclerosis in the circumjacent vessels being irradiated. Even though this has been recognized as survival of cancer patients treated with radiotherapy improves, it is a problem that is often under-reported. We present a case of chronic thromboembolic occlusion of right common iliac artery in a 53-year-old woman who was treated with radiation therapy for cervical cancer 13 years ago. We initially performed percutaneous transluminal angioplasty with thrombolytic therapy, but had to cease thrombolytic therapy due to upper gastrointestinal bleeding of Dieulafoy's lesion, nevertheless, achieved good results after revascularization by Fogarty embolectomy.

Describen la utilidad de la resonancia magnética en el diagnóstico del cáncer de cerviz: [revisión] / Advances in imaging diagnosis, scheduling and radiotherapy for cervical cancer: [review]

La resonancia magnética (RM) es una herramienta de gran ayuda para la evaluación del cáncer de cérvix. Cuando se integra junto a los hallazgos clínicos, permite optimizar el plan de tratamiento. En el cáncer de cérvix la RM es superior a otras modalidades de diagnóstico por imágenes, tanto para la estadificación local como para la identificación de recurrencias locales. Esta preferencia se debe al desarrollo de nuevas secuencias y antenas, la introducción de nuevos agentes de contraste y la evidencia acumulada durante los últimos años de la gran eficacia de la RM en la evaluación y manejo del cáncer de cérvix. Las principales limitaciones de la estadificación clínica son la evaluación del parametrio, la invasión de la pared pélvica, la extensión proximal del tumor y la evaluación de las metástasis línfáticas. La RM es la técnica más precisa para el estudio de estas estructuras, ya que tiene un importante papel para determinar el volumen tumoral, la localización, el estadio y la extensión proximal con vistas a una posible cirugía con preservación de la fertilidad. En un futuro cercano, el desarrollo de nuevas técnicas incrementará su potencial en el diagnóstico y seguimiento de estas pacientes. La secuencia ponderada en difusión es una técnica recientemente introducida basada en difusión molecular, muy útil para discriminar entre lesiones benignas y malignas y para el estudio de diseminación peritoneal.

Evaluation of the physical characteristic of Cerrobend blocks used for radiation therapy

In Radiation Therapy, the sparing of normal tissues can be performed using either multi-leaf collimators or Cerrobend blocks. The current work focuses on the physical characteristics of Cerrobend blocks including attenuation coefficient, effective penumbra width and isodose curves undulation in penumbral regions. All measurements were performed using a dual energy linac and the Cerrobend blocks designed and fabricated using a commercial Cerrobend material. Data were collected using a calibrated ionization chamber as well as EDR2 films. The results showed that the attenuation coefficient was found to be 0.4475 and 0.4276 cm[-1] for photon beams 6MV and 15 MV, respectively, and a potential air bubble with a diameter greater than 3 mm affects beam attenuation significantly. The optimum Cerrobend block width was found to be around 16 mm. The isodose curves scalloping achieved for secondary collimator jaws, were also similar. If Cerrobend blocks are used as a basic method to protect normal tissues, its physical characteristics will be recommended to be taken into account comprehensively

Multileaf collimator transmission from the first Hi-Art II helical tomotherapy machine in India.

The purpose of this study was to measure the multileaf collimator (MLC) transmission from the first Hi-Art II tomotherapy machine installed at the Advanced Center for Treatment, Research, and Education in Cancer (ACTREC). The MLC transmission was measured with an A1SL ion chamber and the radiographic extended dose range (EDR2) film in virtual water slabs at 1.5-cm depth with a source-to-surface distance of 85 cm. The MLC transmission was measured for 30 s with all leaves open and for 360 s with all leaves closed. The movable jaws were set to the calibration field size of 5 x 40 cm at isocenter. The MLC transmission was found to be 0.3% with the ion chamber and 0.32% with the film. Thus, the MLC transmission value was found well within the manufacturer tolerance of 0.5%. MLC can safely be used for the beam modulation during intensity-modulated radiotherapy (IMRT) to deliver accurate doses to the patients.

Execution of mantle field with multileaf collimator: a simple approach.

BACKGROUND: Until very recently mantle field radiotherapy remained the gold standard for the treatment of favorable early-stage Hodgkin's lymphoma. The classic mantle includes all the major lymph nodes above the diaphragm and extends from the inferior portion of the mandible to the level of the insertion of the diaphragm. AIMS: To describe a simple technique that has been devised to treat the mantle field with the help of multileaf collimator and using computed tomography (CT)-based treatment planning. MATERIALS AND METHODS: CT scan was performed with the patient in the supine position and the datasets were transferred to the Eclipse treatment planning system. Elekta Precise linear accelerator equipped with 40 pairs of multileaf collimator (MLC) was used for the execution of the mantle field. The MLC's shapes were designed to take the shape of the conventional customized blocks used for treatment of mantle field. The anterior mantle field was divided into three separate MLC segments with the collimator kept at 0 degrees. The first MLC segment was shaped to cover the neck, clavicular regions, and mediastinum. The second and the third MLC segments covered the right and left axilla, respectively. The posterior fields were opposed to the anterior subfields in a similar fashion. The dose was prescribed at the midplane, using reference points. RESULTS AND CONCLUSION: The technique described in this study is very simple, easy to implement, and avoids unnecessary delay in the execution of the mantle field. The mantle field can be easily shaped with the multileaf collimators, without any collimator rotation.

Campos neutrónicos producidos por un acelerador lineal para radioterapia / Neutron fields produced by linear accelerator for radiotherapy

Mediante una serie de medidas y cálculos Monte Carlo se han determinado las características dosimétricas y los espectros de los fotoneutrones que se producen en torno a un acelerador lineal para radioterapia de 18 MV. Las medidas se realizaron con dosímetros termoluminiscentes TLD 600 y TLD 700 que se expusieron desnudos y emparedados con Cd, así como dentro de una esfera de parafina y dentro de esferas Bonner.

Measurements and Monte Carlo calculations has been utilized to determine the dosimetric features as well as the neutron spectra of photoneutrons produced around an 18 MV linear accelerator for radiotherapy. Measurementes were carried out with bare and Cd covered thermolumiscent dosimeters, TLD600 and TLD700, as well as inside a paraffine moderator. TLD pairs were also utilized as thermal neutrons inside a Bonner sphere spectrometer.

Cálculo independente de dose para tratamentos de arco dinâmico com colimador micromultilâminas / Independent dose calculation for dynamic arc treatments delivered with micromultileaf collimator

OBJETIVO: Em técnicas de tratamento como o arco dinâmico, a verificação manual dos cálculos do sistema de planejamento é muito difícil. Assim, a utilização de ferramentas computacionais é de utilidade e torna-se componente essencial do programa de controle de qualidade. MATERIAIS E MÉTODOS: Foi criado um programa computacional de tipo planilha eletrônica para realizar cálculo independente da dose, ou equivalente das unidades monitoras, nos tratamentos realizados pela técnica de arco dinâmico com micromultilâminas. Os valores de dose calculados, por arco e por tratamento completo, foram comparados aos valores obtidos do sistema de planejamento BrainScan v5.3. O programa desenvolvido foi testado com 229 campos de arco dinâmico que representam 42 tratamentos de crânio. Desses, 109 campos foram calculados em reconstrução tridimensional feita a partir das imagens de tomografia dos pacientes, 109 na reconstrução de um objeto simulador de polimetilmetacrilato e 21 na de um objeto simulador sólido equivalente à água. RESULTADOS: A diferença média de doses totais encontrada nos 42 tratamentos (compostos de um ou mais arcos dinâmicos), entre o programa de verificação e o sistema de planejamento, foi de +1,73 por cento, com desvio-padrão de 0,76 por cento. A diferença máxima encontrada foi de 3,32 por cento e a mínima, de -0,20 por cento. No caso dos 229 arcos testados um a um, a diferença média encontrada foi de 1,61 por cento, com desvio-padrão de 1,04 por cento. Os valores máximos e mínimos das diferenças foram de 4,01 por cento e -2,04 por cento, respectivamente. Em 80,35 por cento dos arcos testados, as doses calculadas acham-se na faixa de ± 2,5 por cento de diferença com relação às doses geradas pelo sistema de planejamento. CONCLUSÃO: O programa apresentado é recomendado para a verificação da dose pontual dos planos de tratamento, como parte do procedimento de garantia de qualidade em radioterapia e radiocirurgia estereotáxica quando se...

OBJECTIVE: In treatment techniques such as dynamic arc, the manual verification of treatment planning system calculations is very difficult. In these cases, the use of computational tools is useful and becomes an essential component of the quality assurance program. MATERIALS AND METHODS: A worksheet-based software has been created to perform an independent dose or monitor unit calculation in treatments applying the dynamic arc technique delivered with micromultileaf collimator. The dose values calculated per arc and per complete treatment, are compared with values obtained from BrainScan v5.3 treatment planning system. The software has been tested with 229 dynamic arc fields representing 42 skull treatments. From these 229 fields, 109 have been calculated in 3D reconstruction of patients CT images, 109 in reconstruction of polymethylmetacrylate phantom images, and 21 in reconstruction of images from a water equivalent phantom. RESULTS: The mean difference of total doses found in the 42 treatments (composites of one or more dynamic arcs), between the verification software and the treatment planning system, was of +1.73 percent with a 0.76 percent standard deviation. The maximum difference was 3.32 percent and the minimum -0.20 percent. When the 229 dynamic arcs were tested one by one, the average difference found was 1.61 percent with a 1.04 percent standard deviation. Maximum and minimum differences were, respectively 4.01 percent and -2.04 percent. As a result of the test, in 80.35 percent the doses calculated have presented a ± 2.5 percent difference in relation to the doses generated by the planning system. CONCLUSION: The software presented in this study is recommended for checking point dose included in treatment plans as an integral part of the process of quality assurance in radiotherapy and stereotactic radiosurgery when the dynamic arc technique is utilized in treatment with micromultileaf collimator, where a manual calculation...

[Study of wedge factor dependence with depth, field size and SSD in [60] Co units]

In radiotherapy, wedge filters are used to modify iso-dose curves and hence optimize tumor dose distribution in patient. To deliver prescribed dose, timer or monitor unit should be involved the dose with no wedged field and wedge factor. Therefore, any variation of wedge factor due to treatment parameters will affect the deliver dose to patients. Effects of field size, SSD and depth of treatment on wedge factor were studied, using universal wedge filters with nominal angles of 30°, 45° and 60°, a hand made water phantom 21x21x10 Cm and a 0.6 cc Farmer ionizing chamber, at different SSD and depth from the water surface. Wedge factors were calculated as the ratio of charge [nC] of the wedge to open beam, measured by and an electrometer model NE2571, while the dosimeter was irradiated for 60s with Picker ATC9 [60]Co unit. Except for 60° wedge filter, with 95% certainty, there is no meaningful relation between wfs with field size and depth. For 60° wedge filter, variation of wf for situation used in this study is about 0.55% per Cm'Cm variation in field size and 0.28% per Cm variation in depth. An inverse linear relation between wf and SSD approved with 95% certainty. Variations of wf for 30°, 45° and 60° wedge filters, for situation used in this study are 0.11%, 0.18% and 0.33% per Cm variation in SSD respectively. Dependence of wfs to FS, depth and SSD for 60o wedge filter were formulated and shows that the field size and depth of treatment has a negligible effect on wedge factor. Correction of wf for SSD, which has a large domain of variation, is appreciable in clinical usage [more than 5%] and for 60o wedge filter can be calculated as: wfc=wf [1- 0.0033[SSD-80]] 65

Estudo das propriedades físicas do filtro dinâmico: modulação unidimensional - 2005

O presente trabalho apresenta uma caracterização das propriedades físicas do filtro dinâmico em varredura do acelerador linear Clinac 2300CD, da Varian Medical Systems, por meio de determinações experimentais, comparando-as com cálculos feitos pelo sistema de planejamento de tratamento CadPlan, sob as mesmas condições.Os parâmetros determinados foram: o fator filtro dinâmico para campos quadrados e retangulares no eixo central e fora dele, a dependência do fator filtro dinâmico com o colimador estático, o percentual de dose em profundidade, a dependência do fator filtro dinâmico com a profundidade no eixo central e fora dele, os ângulos dos filtros dinâmicos, e os perfis de campo em diversas profundidades. Foi retificado que o fator filtro dinâmico diminui com o aumento do tamanho decampo e com o aumento do ângulo nominal do filtro, e que aumenta com o incremento da energia. O fator filtro dinâmico é independente do colimador X e do colimador dinâmico, exceto para campos pequenos. Não varia com a profundidade no eixo central, mas fora dele apresenta variações. Foi encontrada uma diferença entre o ângulo nominal dos filtros e os obtidosexperimentalmente. Porém, tal diferença não interfere no resultado do tratamento.Ao final é sugerido um conjunto de parâmetros físicos a ser determinado para o comissionamento, para a implementação clínica e para o controle de qualidade do filtro dinâmico