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The objective of the present study was to evaluate the intensity and spatial distribution of the scattered radiation caused by the use of hand-held x-ray equipment in the zone occupied by the operator, using the Monte Carlo simulation for radiographic views of the upper and lower incisor teeth, and the consequent evaluation of the equivalent dose in the lens. In order to carry out this evaluation, the geometry of a typical dental facility with plaster walls containing the scattering object was used for the computational scenario implemented for the Monte Carlo method simulation. The PENELOPE code for Monte Carlo simulation of electron and photon transport was used with the radiation beam represented by a 60 kV spectrum, 1.5 mm Al and tungsten target. The simulations were carried out with typical parameters for workload and the number of radiographs/week. The results showed that the exposure levels varied significantly according to the angle of the x-ray beam and with the distance to the scattering object. It is concluded that the incorporation of hand-held equipment in dental radiology must be accompanied by the surveillance of occupational exposure levels and a review of the training structure of professionals in dental radiology regarding aspects of radiological protection and the particularities of using this type of equipment.

Cone beam computed tomography (CBCT) has become essential for dental diagnoses in the last decade. This is supported by its low cost and low doses, when compared to medical CT. Following this increase in CBCT procedures, it is necessary to ensure the image quality within low radiation doses to the patients. This is an especially difficult challenge in CBCT, given the number of equipment models (more than 50), radiographic techniques that may be employed, and technical information not available to the users by the manufacturers. The objective of this study was to estimate the cancer risk, effective and absorbed doses in tissues and organs for CBCT protocols intended for dental use. Monte Carlo (MC) simulations were used to estimate these quantities in tissues and organs with radiological importance, as those suggested by the International Commission of Radiological Protection (ICPR) report ICRP 103. Five different fields of view (FOV) were simulated to i-Cat Classic CBCT, using the MCNPX code. The virtual anthropomorphic phantoms FASH3 (Female Adult MeSH) and MASH3 (Male Adult MeSH) were also used. The effective dose estimative was in the range 75.15–142.20 μSv. The largest contribution to the effective dose was from the salivary glands (17%), thyroid (27%) and remainder tissues (28%). The results of this work showed that the effective and absorbed doses in tissues/organs vary according to the FOV, exposure parameters, and the positioning of the beam, relative to the radiosensitive organs. Furthermore, for the same exposure conditions, women can exceed the total risk of cancer by 26–34%, when compared to men.

Este artigo tem por objetivo analisar a rede de coautoria formada a partir do número de publicações e interações entre os autores do Programa de Pós-Graduação Multi-institucional em Difusão do Conhecimento – (PPGDC) para verificar se a partir da entrada de novos docentes e discentes houve um aumento no número de produções acadêmicas e de coautorias no período de 2017-2019. A metodologia utilizada se caracteriza por uma abordagem exploratória, cujos métodos adotados são a análise de redes sociais e a revisão de literatura que investigou estudos sobre o conceito de ARS de coautoria e produção científica, utilizando os motores de busca: Science Direct e Google Scholar. A coleta dos dados ocorreu através da Plataforma Sucupira da CAPES. Os relatórios foram disponibilizados em formato “.xls”, com o uso do software Microsoft Excel, e a partir das análises, tornou-se possível a criação e composição da rede de produção intelectual e coautoria do PPGDC, através das ferramentas Pajek e Gephi. Como resultado principal, foi possível observar que, em virtude da introdução de novos participantes ao Programa, houve um acréscimo do número de autores e relações entre os mesmos. Apesar disso, nota-se que a rede é constituída por grandes grupos conectados, que publicam intensamente entre seus pares, mas com pouca conexão entre esses grupos, evidenciando a necessidade de uma maior cooperação e colaboração científica.

Systemic Arterial Hypertension (SAH) can generate complications such as stroke, myocardial infarction, kidney disease, arteriosclerosis, loss of vision, erectile dysfunction and cognitive dysfunction. Among people who know they suffer from hypertension, 50% use medication and of those only 45% have their blood pressure kept under control. SAH is a multifactorial clinical condition characterized by elevated and sustained blood pressure levels (BP, where systolic BP ≥ 140 mmHg and diastolic BP ≥ 90 mmHg). Faced with sparse investigative studies on the causes of SAH in individuals, the dictates of the pharmaceutical industry and the use of in vitro or inconclusive clinical studies, this paper presents the state of the art about the treatment of SAH based on a multifaceted view, including aspects about the physiology of SAH, food and PANC as alternatives for the prevention and control of SAH, as well as an approach on the importance of scientific rigor in the manufacture of medicines. La Hipertensión Arterial Sistémica (HSA) puede generar complicaciones como ictus, infarto de miocardio, enfermedad renal, arteriosclerosis, pérdida de visión, disfunción eréctil y disfunción cognitiva. De los que saben, el 50% usa medicación y, de estos, solo el 45% tiene la presión bajo control. La HSA es una condición clínica multifactorial, caracterizada por niveles elevados y sostenidos de presión arterial (PA, donde la PA sistólica ≥ 140 mmHg y la PA diastólica ≥ 90 mmHg). Ante los escasos estudios de investigación sobre las causas de la HAS en los individuos, los dictados de la industria farmacéutica y el uso de estudios clínicos in vitro o no concluyentes, este artículo propone presentar el estado del arte sobre el tratamiento de la HAS desde una mirada multifacética. , incluyendo aspectos sobre fisiología de la HAS, alimentos y PANC como alternativas para la prevención y control de la HAS, así como un abordaje sobre la importancia del rigor científico en la fabricación de medicamentos. A Hipertensão Arterial Sistêmica (HAS) pode gerar complicações tais como acidente vascular cerebral, infarto do miocárdio, doença renal, arteriosclerose, perda de visão, disfunção erétil e disfunção cognitiva. Das pessoas que têm conhecimento, 50% fazem uso de medicação e, dessas, apenas 45% têm a pressão controlada. A HAS é uma condição clínica de caráter multifatorial, caracterizada por níveis elevados e sustentados de pressão arterial (PA, onde PA sistólica ≥ 140 mmHg e PA diastólica ≥ 90 mmHg). Diante de parcos estudos investigativos sobre as causas da HAS nos indivíduos, dos ditames da indústria farmacêutica e do uso de estudo clínicos in vitro ou inconclusivos, este artigo se propõe a apresentar o estado da arte sobre o tratamento da HAS a partir de uma visão multifacetada, incluindo aspectos acerca da fisiologia da HAS, da alimentação e das PANC como alternativas para a prevenção e controle da HAS, como também uma abordagem sobre a importância do rigor científico na fabricação de medicamentos.

The aim of this study was to evaluate the kerma at the surface of the lens in TMJ CBCT and to derive the equivalent dose. An anthropomorphic phantom of the head and neck manufactured by Radiation Support Devices (model RS-230) was used. The dosimetric measurements were obtained by using fourteen thermoluminescent dosimetry (TLD) dosimeters (LiF: Mg, Ti), divided in two pairs (one pair for each eye) and positioned on the surface of the phantom, per scanner evaluated. The tomographic images were acquired in three types of CBCT equipment (CS 9000, Gendex GXCB 500 and i-CAT). Values of equivalent dose obtained were: 5.82 mSv (CS 9000); 5.38 mSv (Gendex GXCB 500) and 7.98 mSv (i-CAT), which varied in accordance with the scanner and the exposure factors used in the image acquisition. The Gendex GXCB 500 used larger FOV and higher kV, resulting in levels close to those obtained on the CS 9000, while larger doses were associated with the i-CAT. The dose values associated with TMJ radiological procedures should be performed with awareness and appropriateness due to sensitivity of the lens.

This study has the purpose of assessing the radiation absorbed dose in organs/tissues and estimating the effective dose using five different models of Cone Beam Computed Tomography equipment using protocols with similar purpose. For this purpose, 26 thermoluminescent dosimeters were inserted in the position of the organs/tissues of a female anthropomorphic phantom. From the measurements the contribution of wT×HT in the organs and tissues the effective dose were calculated. The measurements have shown the effective dose values within the range 9.3–111.5 µSv. The effective dose values by field of view (FOV) size are within the following ranges: 9.3–51.2 µSv, 17.6–52.0 µSv, and 43.1–111.5 µSv for small/located, medium and large FOV respectively. Protocols with same purpose, carried out with different models of equipment, presented significant differences in the values of the equivalent and effective doses. From the point of view of radiological protection, it is not enough to have knowledge about the dimensions of the FOV and the purpose of the examination. It is necessary to assess the dose using the different models of the equipment and protocols available. In this context, this study provides useful information for this assessment.

Objective The objective of this study was to assess and compare protocols with a single field of view and multiple stitched field of view with a similar clinical purpose by means of effective dose value. Materials and methods Measurements of absorbed dose were performed with thermoluminescent dosemeters inserted in the position of organs/tissues of a female anthropomorphic phantom and from these values the effective dose was calculated, utilizing weighting factor tissue-ICRP 103 (2007). Results The results obtained in this study for effective dose are within the range of 43.1 µSv and 111.5 µSv for equipment using protocols with single FOV and in the range of 44.5 µSv and 236.2 µSv for equipments that using protocols with stitched field of view. Conclusions In terms of the value of effective dose, stitched FOV protocols do not have any advantage over the single field of view protocols. This results suggest the necessity for knowledge of the exposure parameters and effective dose values associated with each image protocol.

Objective This study aimed to explore whether cone beam computed tomography (CBCT) and multislice computed tomography (MSCT) can be used to quantify tissue density and to determine if the Hounsfield unit scale is applicable. Study Design A clinical MSCT scanner and effective energy adjusted photon beam attenuation references were used to compare the gray scale of CBCT images of the mandible region. A phantom was scanned using axial cadaver slices and 4 different homogeneous reference objects. The consistency of the references' gray values and 12 linear profile lines from both scanner data sets were compared. Results The gray values of the 2 scans showed strong correlation with quantified position-dependent differences as an outcome of the validation process. Conclusions The introduced internal, in-scan validation is able to estimate and has a potential to compensate for the differences between MSCT and CBCT protocols. This validation serves as a guide in situations where the users can expect deviations.

We discuss some aspects related to the legal framework, international recommendations and training programs on radiological protection; image quality and equipment; the biological effects and risks of ionizing radiation; lesions in patients and operators; patient’s reference levels; occupational dose limit and preventive actions. The use of ionizing radiation involves risks that are justified in diagnostic and therapeutic procedures. The awareness and knowledge of these risks minimizes the damage, optimizing the quality of images and safe use of ionizing radiation. There is evidence of radiation induced cataracts in individuals who work in catheterization laboratories. Several studies suggest there may be a significant risk of lens opacity, if radiological protection devices are not properly used. Additionally, these interventional procedures are performed in Latin America, usually by medical specialists in collaboration with nurses, technologists and technicians, who often do not have adequate training in radiological protection.

This study aimed at the development and validation of the models of phantom: CQ-02-IFBA and CQ-01-IFBA, the first filled with water and the second fully with a solid structure in polymethylmethacrylate (PMMA). Both models allow its use in various models of cone beam computed tomography (CBCT), independent of the size of the field of view. The two phantoms are used to evaluate seven parameters of quality control: intensity or average value of pixels of five different plastics, signal to noise ratio, resolution, low contrast, spatial resolution, the accuracy of distances on the z axis, the geometric distortion and image uniformity. Spatial resolution is a critical parameter that differs significantly in the various imaging modalities in dental radiology, and in these two phantoms, it can be evaluated by two different methods: MTF obtained by Fourier transformation of the function LSF (line spread function) and/or by analysis visual image to a pattern of bars up to 16 lp/cm. Validation was performed in three models CBCT: CareStream CS 9000 3D, i-CAT Classical and Sirona Orthophos XG 3D. The two phantom models were viable and also complied with the specifications and data available in the literature. It is concluded that the two phantom models are viable for use in CBCT with different characteristics.

Objective: to evaluate the influence of FOV in air kerma-area product (KAP) and the constancy of exposure parameters on cone beam computed tomography equipments. Methodology: Two cone beam CT (GENDEX CBX 500 and i-CAT Classic) were used and seven exposures with the following FOVs were performed: (A) 14cm x 8,5cm, (B) 14cm x 6cm, (C) 8,5cm x 8.5cm e (D) 8,5cm x 6cm, for CBX 500; and (E) 14cm x 6.cm, (F) 14cm x 8cm e (G) 14cm x 13cm, for the i-CAT. The technical exposure factors (kV, mA, mAs and voxel), remained constant. The dosimetric evaluation was performed with air KAP meter manufactured by IBA dosimetry, model kerma X plus TinO, positioned at the output of the X-ray beam. To evaluate the constancy of the exposure parameters a semiconductor (Radcal, Rapidose) fixed in front of the tomography image receptor was used. Result: The KAP values obtained ranged between 360.1 mGy.cm² and 1031.2 mGy.cm². The FOV height had a substantial influence on the radiation dose. Repeatability and accuracy of the tube voltage varied less than 10%. Conclusion: The radiation dose is directly related to the height and inversely related with the FOV diameter; even within the recommended limits, the percentage variation of repeatability and accuracy of kV, for the tomography equipments tested, points to the regular equipment calibration, in order to reduce radiation dose to the patient to a minimum. Keywords: Cone beam computed tomography. Radiation. Dosimetry. Submitted by ROBERTO PAULO CORREIA DE ARAÚJO (ppgorgsistem@ufba.br) on 2017-06-20T13:30:04Z No. of bitstreams: 1 8_v.13_3.pdf: 667079 bytes, checksum: 4bb9cc9e39591f313692aa5eb8347146 (MD5) Made available in DSpace on 2017-06-20T13:30:04Z (GMT). No. of bitstreams: 1 8_v.13_3.pdf: 667079 bytes, checksum: 4bb9cc9e39591f313692aa5eb8347146 (MD5) Previous issue date: 2014-09 Objetivo: avaliar a influência do FOV no produto kerma-área (PKA) no ar e a constância dos parâmetros de exposição em equipamentos de tomografia computadorizada feixe cônico. Metodologia: Foram utilizados dois tomógrafos de feixe cônico (GENDEX CBX 500 e i-CAT Classic) e foram realizadas sete exposições com os seguintes FOVs: (A) 14cm x 8,5cm, (B) 14cm x 6cm, (C) 8,5cm x 8.5cm e (D) 8,5cm x 6cm, para o CBX 500; e (E) 14cm x 6.cm, (F) 14cm x 8cm e (G) 14cm x 13cm, para o i-CAT. Os fatores técnicos de exposição (kV, mA, mAs e voxel), permaneceram constantes. A avaliação dosimétrica foi realizada com um medidor do produto kerma-área no ar fabricado pela IBA dosimetry, modelo kerma X plus TinO, posicionado na saída do feixe de raios X. Para a avaliação da constância dos parâmetros de exposição foi utilizado um multimedidor do tipo semicondutor, Radcal, modelo Rapidose fixado na entrada do receptor de imagem do tomógrafo. Resultados: Os valores de PKA obtidos variaram entre 360,1 mGy.cm² e 1.031,2 mGy.cm². A altura do FOV teve influência substantiva na dose de radiação. A repetibilidade e exatidão da tensão do tubo variaram abaixo dos 10%. Conclusões: a dose de radiação tem relação direta com a altura e inversa com o diâmetro do FOV; embora dentro das margens recomendadas, a variação dos percentuais de repetibilidade e exatidão do kV, para os tomógrafos testados, aponta para a calibragem periódica dos equipamentos, com vistas a reduzir ao mínimo necessário a dose de radiação para o paciente. Salvador

This study aims to evaluate and compare protocols with similar purposes in a cone beam CT scanner using thermoluminescent dosimeter (TLD) and the air kerma-area product (PKA) as the kerma index. The measurements were performed on two protocols used to obtain an image of the maxilla–mandible using the equipment GENDEX GXCB 500: Protocol [GX1] extended diameter and asymmetric beam (14 cm×8.5 cm-maxilla/mandible) and protocol [GX2] symmetrical beam (8.5 cm×8.5 cm-maxillary/mandible). LiF dosimeters inserted into a female anthropomorphic phantom were used. For both protocols, the value of PKA was evaluated using a PTW Diamentor E2 meter and the multimeter Radcal Rapidose system. The results obtained for the effective dose/PKA were separated by protocol image. [GX1]: 44.5 µSv/478 mGy cm2; [GX2]: 54.8 µSv/507 mGy cm2. Although the ratio of the diameters (14 cm/8.5 cm)=1.65, the ratio of effective dose values (44.5 µSv/54.8 µSv)=0.81, that is, the effective dose of the protocol with extended diameter is 19% smaller. The PKA values reveal very similar results between the two protocols. For the cases where the scanner uses an asymmetric beam to obtain images with large diameters that cover the entire face, there are advantages from the point of view of reducing the exposure of patients when compared to the use of symmetrical beam and/or to FOV images with a smaller diameter.

Discutimos aqui aspectos vinculados ao enquadramento legal, a recomendações internacionais e a programas de formação em proteção radiológica; ao angiógrafo e à qualidade da imagem; aos efeitos biológicos e aos riscos das radiações ionizantes; às lesões em operadores e pacientes; aos níveis de referência do paciente; ao limite de dose ocupacional e a suas medidas de prevenção. O uso das radiações ionizantes acarreta riscos, que, contudo, justificam-se em procedimentos diagnósticos e terapêuticos. A consciência e o conhecimento desses riscos minimizam o dano, otimizando a qualidade da imagens e o uso seguro das radiações ionizantes. Tem-se demonstrado a ocorrência de cataratas radioinduzidas em trabalhadores de laboratórios de cateterismo. Diversos estudos sugerem que pode haver um risco significativo de opacidade do cristalino, caso não se utilizem adequadamente os dispositivos de proteção radiológica. Adicionalmente, esses tipos de procedimentos intervencionistas são realizados na América Latina, geralmente por médicos especialistas, com a colaboração de enfermeiros, tecnólogos e técnicos, que, muitas vezes, não têm formação adequada em proteção radiológica. We discuss some aspects related to the legal framework, international recommendations and training programs on radiological protection; image quality and equipment; the biological effects and risks of ionizing radiation; lesions in patients and operators; patient's reference levels; occupational dose limit and preventive actions. The use of ionizing radiation involves risks that are justified in diagnostic and therapeutic procedures. The awareness and knowledge of these risks minimizes the damage, optimizing the quality of images and safe use of ionizing radiation. There is evidence of radiation-induced cataracts in individuals who work in catheterization laboratories. Several studies suggest there may be a significant risk of lens opacity, if radiological protection devices are not properly used. Additionally, these interventional procedures are performed in Latin America, usually by medical specialists in collaboration with nurses, technologists and technicians, who often do not have adequate training in radiological protection.

Basically, all modalities of diagnostic radiology require phantoms suitable for dosimetric evaluations. New technologies frequently arise unaccompanied of tools for dosimetric evaluations and quality control. In this study, a low-cost phantom and a consequent proposed methodology for dosimetric evaluations in cone beam computed tomography (CBCT) were presented. The developed phantom has typical dimensions of the human face, was built in polymethyl methacrylate and filled with water. Three devices with different technological concepts were evaluated and a proposed index, kerma index-height product (PKIH), was defined as an option to the use of air kerma-area product. The results of this study show relatively uniform kerma profiles for scanners with field of views (FOVs) of large diameters and non-uniform for FOVs of small diameters. With regard to the values obtained for the kerma indexes, much higher values were found for the equipment FOVs with small diameter compared with the values of the two other equipment that have larger diameters. The results indicate that (1) there is a need for special phantoms for use in CBCT, (2) the use of P(KA) in the evaluation of protocols on different equipment can lead to false interpretations and (3) the new index is a suitable alternative for the use of P(KA) in CBCT.

A phantom for quality control in cone beam computed tomography (CBCT) scanners was designed and constructed, and a methodology for testing was developed. The phantom had a polymethyl methacrylate structure filled with water and plastic objects that allowed the assessment of parameters related to quality control. The phantom allowed the evaluation of essential parameters in CBCT as well as the evaluation of linear and angular dimensions. The plastics used in the phantom were chosen so that their density and linear attenuation coefficient were similar to those of human facial structures. Three types of CBCT equipment, with two different technological concepts, were evaluated. The results of the assessment of the accuracy of linear and angular dimensions agreed with the existing standards. However, other parameters such as computed tomography number accuracy, uniformity and high-contrast detail did not meet the tolerances established in current regulations or the manufacturer's specifications. The results demonstrate the importance of establishing specific protocols and phantoms, which meet the specificities of CBCT. The practicality of implementation, the quality control test results for the proposed phantom and the consistency of the results using different equipment demonstrate its adequacy.