Programação linear no planejamento do tratamento de câncer por radiocirurgia

Medical Physics has been reaching an important role among several lines in Science, providing means for the improvement of several theories and procedures. Currently, its main application is related with the use of ionizing radiations, specially, in treatment procedures such as Radiotherapy. Radiosurgery is a Radiotherapy technique which consists in administering a single tumoricidal dose of radiation exclusively to the tumorous lesion. It becomes then an interesting alternative to surgical treatment, mainly in cerebral metastases, which are the most frequent cerebral tumors in the central nervous system. The radio neurosurgical team works out a planning for the Radiosurgery treatment, aiming for obtaining an appropriate ideal treatment for each case. For the working out of this treatment planning, Computed Tomography images of the region to be treated are obtained, digitalized and later, fused with nuclear magnetic resonance images. Through these images, critical structures, organs at risk and lesions are localized. After this, calculations are made to determine three-dimensional positions of isocenters, isodose curves, prescribed dose, collimators sizes, position, numbers and respective weight of isocentric conformal fields, and others. The treatment planning is commonly based in desired levels of dose for specific types of tumors and organs at risk concerning the irradiated region. Theses levels of dose are chosen in a way that a high probability of cure may be achieved and meanwhile, that the probability of complications, in whichever organ at risk, may be minimal. Thus, many researches have been carried out, showing that mathematical techniques may help to obtain an optimal planning for the treatment of cerebral metastases. Among the methods of optimization in the study...(Complete abstract click electronic access below)

Análise quantitativa dos parâmetros físicos e radiométricos de procedimetnos radioterapicos em tumores de mama

The paper presents the radiometric parameters determined by the medical physicist during routine radiotherapy planning service in cases of breast cancer . The contours of the breast volume in patients undergoing radiation breast tumors at the Hospital das Clinicas, Faculty of Medicine , UNESP, Botucatu ( HCFMB ) during the year 2012 were analyzed . In order to analyze the influence of physical and radiometric parameters for the determination of the dose distribution of irradiated breast volume , four measurements of isodose curves were prepared in four different heights breast , and compared with the isodose curves plotted computationally . In the routine of planning , the medical physicist must determine the isodose curve that gives the best dose distribution homogeneity in the irradiated volume . The choice of the treatment plan can be done by dedicated computer systems , which require significantly costly investments available services having better financial support . In the Service of Medical Physics , Department of Radiotherapy , HC FMB , we use a two-dimensional software for determination of isodose curves , however , this software is out of date and frequently becomes inoperable due to the lack of maintenance and it is a closed system without feasibility of interference from computer professionals . This fact requires manual preparation of isodose curves , which are subject to uncertainties due to the subjectivity in the clinical interpretation of medical radiation oncologist and medical physicist responsible for planning , plus dispendiar significant calculation time . The choice of the optimal isodose curve depends on the energy of the radiation beam , the geometry and dimensions of the irradiated area . The contours of the breast studied in this work evaluations showed that , for a given energy input , such as the energy of 1.25 MeV of gamma radiation Unit Telecobaltoterapia , the determination of the percentage depth dose ( PDP ) ...

Braquiterapia com sementes de iodo-125: manufatura e tratamento

According to the National Institute of Cancer – INCA, 466.730 new cancer cases will occur in Brazil in 2009. Prostate and Lung cancer in man are the most incident types (in exception of the non-melanoma cancer). The brachytherapy with 125-iodine sources is an important method of prostate cancer treatment. The implant with iodine-125 seeds uses aproximately 100 seeds that are imported impossibilitating the treatment in large scale. For this reason, a multidisciplinary group was created at the Energetic and Nuclear Research Institute – Radiation Technology Center (IPEN –CTR / SP) to develop a national 125-iodine source and established a facility for local production. The seeds manufacture in Brazil will diminish the cost of treatment and prostate brachytherapy will be offered to more patients. This work aim is to observe and discuss the methods used in seeds manufacture there are being developed in Brazil and to present an prostate cancer case folloied in A.C. Camargo Hospital. The 125-iodine is adsorbed in an silver wire, then deposited at titanium coat. The weld is made by an process of plasm sealing. The seeds goes through several test to guarantee that there is no leakage. The result is an high quality and cheaper product. The implant tecnique is an fast and save procedure. The medical physicst preplan the case to stipulate the quantity of seeds there will be used. At the dat of the implant the medical physicst replan the procedure due to changes of volume in the organ. That assure the correct dose distribution in the target. Besides, the 125-iodine low energy is absorbed at the volume of interrest saving sourronding healthy tissues such as the rectum and the urethra

Análise dosimétrica de aplicadores de Betaterapia

Betatherapy is a special medical technique using a radioactive source of strontium-90 for the treatment of superficial lesions, especially in dermatology and ophthalmology. Strontium-90 sources emit β radiation, which possesses high ionization power, but a very short distance propagation into matter. This work presents a method of dosimetric analysis of betatherapy using strontium- 90-based instrumentation, commonly used against superficial diseases, such as keloid and pterygium, aiming the description of the dosimetry analysis procedures, which can be easily implemented on tradiotherapy services that offers the betatherapy treatment. IBF-MEDIX radiographic films (conventional films) were exposed to betatherapy applicators during different time intervals according to the activity of the source, and afterwards the optical densities (O. D.) of the radiographic images were measured using an optical densitometer MACBETH. Therefore, the parameters used to make the dosimetric analysis in betatherapy were standardized, as the exposure time depended on the geometry and size of the source, providing an efficient and fast method of dosimetric analysis of the betatherapy equipment of the services, the majority of which do not have the scientific structure to perform this study

Análise da viabilidade de simulações com feixes de prótons de 100, 150, 200 e 250 MeV em alvos heterogêneos

In the recent years, the use of proton beams in radiotherapy has been an outstanding progress (SMITH, 2006). Up to now, computed tomography (CT) is a prerequisite for treatment planning in this kind of therapy because it provides the electron density distribution required for calculation of dose and the interval of doses. However, the use of CT images for proton treatment planning ignores fundamental differences in physical interaction processes between photons and protons and is, therefore, potentially inaccurate (SADROZINSKI, 2004). Proton CT (pCT) can in principle directly measure the density distribution needed in a patient for the dose distribution (SCHULTE, et al, 2004). One important problem that should be solved is the implementation of image reconstruction algorithms. In this sense, it is necessary to know how the presence of materials with different density and composition interfere in the energy deposition by ionization and coulomb excitation, during its trajectory. The study was conducted in two stages, was used in both the program SRIM (The Stopping and Range of Ions in Matter) to perform simulations of the interaction of proton beams with pencil beam type. In the first step we used the energies in the range of 100-250 MeV (ZIEGLER, 1999). The targets were set to 50 mm in length for the beam of 100 MeV, due to its interaction with the target, and short-range, and 70 mm for 150, 200 and 250 MeV The target was composed of liquid water and a layer of 6 mm cortical bone (ICRP). It were made 9 simulations varying the position of the heterogeneity of 5 mm. In the second step the energy of 250 MeV was taken out from the simulations, due to its greater energy and less interaction. The targets were diminished to 50 mm thick to standardize the simulations. The layer of bone was divided into two equal parts and both were put in the ends of the target... (Complete abstract click electronic access below)

Efeitos genéticos tardios de terapias para linfomas

O tratamento dos Linfomas de Hodgkin e Não - Hodgkin é baseado, atualmente, na combinação de drogas antineoplásicas, associadas ou não à radioterapia. Embora as taxas de cura sejam elevadas, sabe-se que tais terapias podem induzir mutações gênicas e cromossômicas que, mais tarde, podem ser responsáveis pela iniciação de novos processos carcinogênicos ou de doenças degenerativas relacionadas a danos genéticos. Sendo assim, o presente estudo teve por objetivo avaliar o efeito toxicogenético tardio (sobre os níveis de danos no DNA) das terapias antineoplásicas para linfomas. Para isso, foram incluídos no estudo 10 pacientes recém diagnosticados com linfoma (Grupo 1- Pré-terapia), 10 pacientes com história de linfoma e que finalizaram o tratamento antineoplásico há no mínimo dois anos (Grupo 2- Pós-terapia) e 10 indivíduos saudáveis (Grupo 3- Controles). Os linfócitos de sangue periférico foram utilizados para se avaliar os níveis de danos no DNA pelo teste do cometa. Além disso, foi avaliada a eficiência do sistema de reparo do DNA frente às lesões induzidas in vitro pelo peróxido de hidrogênio (H2O2). Os dados mostraram que não houve diferença estatisticamente significativa nos níveis de danos no DNA entre os três grupos. No entanto, foram observadas diferenças estatisticamente significativas no reparo das lesões induzidas pelo (H2O2), com o grupo controle apresentado maior indução de danos em comparação com aos demais grupos (p <0,05). Concluindo, os resultados não evidenciaram efeitos toxicogenéticos tardios decorrentes da exposição às terapias antineoplásicas para linfomas

Estudo da deposição de energia das radiofrequências através do método das diferenças finitas dependentes do tempo Monografia

Radiotherapy in veterinary practice is already known and widely distributed in large specialized centers of developed countries. In early 2000, there were about 30 radiotherapy equipment specifically designed for the veterinary clinic in the United States. In Brazil, the veterinary radiotherapy is still confined to research in universities, where most of the procedures is radiation therapy performed with superficial x-ray machines, with a voltage between 50 and 150 kVp, focus-distance surface (DFS) between 20,0cm and 40,0cm. As that occurs in human medicine, new research strengthens the development and prospects for the use of radiotherapy as a safe option for treating cancer in animals. This paper presents a methodology for calculating the exposure time for superficial radiotherapy procedures in veterinary medicine for small animals (dogs and cats). The dosimetric parameters of X-rays are determined using a spreadsheet tool for Microsoft Office Excel, developed in this paper for a device Dermopan 2, Veterinary Hospital of UNESP in Araçatuba. Using the worksheet helps the veterinarian to determine the time of exposure to radiation determined for each clinical case, optimize the workflow for professionals in veterinary radiotherapy procedures, which often lack the medical physics in team and at the time of radiotherapy. The correct use of spreadsheet decreases the chances of errors in dose rates of radiation, providing a higher quality of care

Métodos de Calibração e Dosimetria de Aplicadores de Betaterapia

The sources of betatherapy for clinical use in Brazil are, the vast majority of strontium-90, radioactive element that is not produced in the country, and therefore requires importation of international laboratories accredited by the International Atomic Energy Agency (IAEA).The use of these resources is always limited the crediting of characteristic values supplied by the manufacturer tables that provide the nominal value of activity and dose distribution to determine the irradiation time of the injury. The Institute of Nuclear Energy Research (IPEN / CNEN-SP) has recently researching the emission profile of these types of radiation sources, and some jobs are being developed with ionization chambers extrapolation for the purpose of standardizing a systematic calibration sources betatherapy. Other studies using parallel measures dosimeters (TLD's) and simulations with the Monte Carlo method. Radiological films have also been used in studies of applicators dosimetric analysis of strontium-90. This paper seeks to analyze the different methods for calibration of applicators betatherapy, already consolidated in studies by examining the advantages and disadvantages of each procedure

Aplicações práticas de proteção radiológica nas áreas de medicina nuclear e radiodiagnóstico em instalações hospitalares

After the discovery of ionizing radiation, its applications in various fields of science began to take significant proportions. In the case of medicine, there are the application areas in radiotherapy, diagnostic radiology and nuclear medicine. It was then necessary to create the field of radiological protection to establish the conditions necessary for the safe use of such ionizing radiation. Apply knowledge obtained during the graduation stage and in the practice of radiological protection in the areas of nuclear medicine and diagnostic radiology. In the area of nuclear medicine, tests were made in the Geiger-Muller counters (GM) and the dose calibrator (curiometer), the monitoring tests of radiation, waste management, clean of the Therapeutic room and testing the quality control of gamma-chambers. In the area of radiology, were performed tests of quality control equipment for conventional X-ray equipment and x-ray fluoroscopy, all following the rules of the National Health Surveillance Agency (ANVISA), and reporting of tests. The routine developed in the fields of nuclear medicine in hospitals has proved very useful, since the quality control of GM counters contribute to the values of possible contamination are more reliable. The control of dose calibrator enables the patient not to receive different doses of the recommended amounts, which prevents the repetition of tests and unnecessary exposure to radiation. The management of waste following the rules and laws established and required for its management. Tests for quality control of gamma chambers help to evaluate its medical performance through image. In part of diagnostic radiology, tests for quality control are performed in order to verify that the equipment is acceptable for usage or if repairs are needed. The knowledge acquired at the internship consolidated the learning of graduation course

Determinação de genes potencialmente responsivos à radiação ionizante através de aprendizado de máquina

A predição da resposta do tumor a radioterapia e a questão mais importante durante o tratamento de pacientes com câncer. Como consequência, a predição de genes que sejam responsivos a radiação ionizante e uma possibilidade para a melhoria dos resultados clínicos e a otimização das doses as quais os pacientes são submetidos ao longo do tratamento. Juntamente com esses dados, é possível obter respostas sobre os mecanismos de resistência a radiação dos tumores e até mesmo a identificação de biomarcadores responsáveis pela resistência a radiação ionizante que podem ser potenciais para o desenvolvimento de novas drogas visando a proteção de tecidos saudáveis. A determinação experimental dos genes que sejam responsivos à radiação ionizante é algo caro e que demanda muito tempo e trabalho; porém, se utilizarmos uma forma computacional de direcionar os estudos experimentais diretamente aos genes que têm mais potencial para serem responsivos à radiação ionizante, as pesquisas podem ser mais direcionadas e específicas. Para determinar essa característica, construímos, analisamos e determinamos os dados da topologia da rede integrada de interações moleculares entre genes humanos, contendo interações físicas entre proteínas, interações metabólicas e interações de regulação transcricional. Os dados topológicos foram utilizados como atributos de treinamento para o aprendizado de máquina, no qual os genes conhecidamente responsivos à radiação ionizante foram apresentados a um algoritmo de árvore de decisão que gerou modelos de predição com índices de sensibilidade e precisão de 5% e 72%, respectivamente. Os índices de acerto obtidos para os conjuntos de teste foram satisfatórios, retornando 91% dos genes conhecidos como responsiveis à radiação ionizante utilizados para o treinamento da árvore de decisão. Nós aplicamos o modelo de predição na rede integrada e atribuímos probabilidades ...

Terapia fotodinâmica - Aplicações em lesões cutâneas

Photodynamic therapy is a method of healing skin lesions , in addition to radiotherapy and brachytherapy are commonly used in the treatment of skin cancers , but it is still little known in Brazil , consisting of the application to the skin of a drug in the form of cream or lotion ( photosensitizer ) . It is absorbed by tumor cells and subsequently activated by light device , that wavelength of light in the order of 630 nanometers , promoting the selective destruction of cancer cells while preserving healthy cells around the lesion . It can be considered highly effective for treatment of skin cancer types of non-melanoma ( basal cell carcinoma , 85-100 % success in curing [ 3 ] , and Bowen's disease), actinic keratoses , which are precancerous lesions and still no studies that prove also action in the treatment of acne and aging caused by the sun . And the advantage of this treatment is that , when indicated , replace the surgical procedure , selectively treating the diseased cells . Thus, it offers better cosmetic results, reducing the risk of scarring [ 4 ]

Efeitos do metotrexate subaracnoideo sobre a medula espinal e as meninges de coelhos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Plasmacytoma in the oral cavity: a case report

The plasma cell neoplasms may present in soft tissue as extramedullary plasmacytoma (EMP), in bone as a solitary plasmacytoma of bone (SPB), or as part of the multifocal disseminated disease multiple myeloma (MM). The EMP is rare, comprising around 3% of all plasma cell neoplasm. The majority (80%) occurs in the head and neck region. In this study we report a case of a man, 70 years old, melanoderm, with a lesion of the oral cavity. Upon physical examination, a lesion was found that extended throughout the posterior upper alveolar ridge, as far as the maxillary tuber on the left side, extending towards the palate. Radiographic examination, complementary laboratory exams were performed. Based on the conclusive symptoms of plasmacytoma, the patient was referred to the hematology service for treatment with local radiotherapy. The patient responded satisfactorily to the treatment, and after 15 months, all clinical symptoms of the lesion in the oral cavity had disappeared.

Revisão sistemática: Eficácia da quimioterapia e associações no tratamento do carcinoma espinocelular em gatos

O carcinoma espinocelular é uma das quatro neoplasias malignas que mais acomete gatos, principalmente os de pele clara e que residem em países tropicais onde a incidência de raios solares é intensa. O tratamento cirúrgico é o mais indicado, mas nem sempre é possível de ser realizado seja pelo estágio avançado do tumor, pela sua localização ou por opção do proprietário que não quer ver seu animal mutilado. O objetivo desta revisão sistemática foi verificar a eficácia da quimioterapia com ou sem associações terapêuticas para o tratamento do carcinoma espinocelular superficial, multicêntrico e de cabeça e pescoço em gatos. Os melhores resultados para o tratamento do carcinoma espinocelular superficial foram observados com a aplicação intralesional do quimioterápico associado à radioterapia ou à eletroterapia, para o tipo multicêntrico faltam trabalhos sobre o assunto e o único encontrado não apresentou resultados satisfatórios. No caso do carcinoma espinocelular de cabeça e pescoço que alberga o pior prognóstico, a terapia multimodal com associação de quimioterapia, radioterapia e excisão cirúrgica demonstrou ser eficiente. Mais estudos sobre o assunto devem ser realizados utilizando um número maior de animais e com um tempo de seguimento mais longo

Oral changes in individuals undergoing hematopoietic stem cell transplantation

INTRODUCTION: Patients undergoing hematopoietic stem cell transplantation receive high doses of chemotherapy and radiotherapy, which cause severe immunosuppression. OBJECTIVE: To report an oral disease management protocol before and after hematopoietic stem cell transplantation. METHODS: A prospective study was carried out with 65 patients aged > 18 years, with hematological diseases, who were allocated into two groups: A (allogeneic transplant, 34 patients); B (autologous transplant, 31 patients). A total of three dental status assessments were performed: in the pre-transplantation period (moment 1), one week after stem cell infusion (moment 2), and 100 days after transplantation (moment 3). In each moment, oral changes were assigned scores and classified as mild, moderate, and severe risks. RESULTS: The most frequent pathological conditions were gingivitis, pericoronitis in the third molar region, and ulcers at the third moment assessments. However, at moments 2 and 3, the most common disease was mucositis associated with toxicity from the drugs used in the immunosuppression. CONCLUSION: Mucositis accounted for the increased score and potential risk of clinical complications. Gingivitis, ulcers, and pericoronitis were other changes identified as potential risk factors for clinical complications.