Cardiologist's exposure to radiation in cath lab measured with InstadoseTMdosimeter.

INTRODUCTION: complex fluoroscopy-guided interventional procedures in cardiology are known to result in higher radiation doses for patients and staff. PURPOSE: to estimate the equivalent dose received in different regions of the cardiologist's body in catheterism (CATH) and percutaneous coronary intervention (PCI) procedures, as well as to evaluate the effectiveness of monitoring the doses in the catheritization laboratory (cath lab) using a direct ion storage dosimeter. MATERIALS AND METHODS: the InstadoseTMand the thermoluminescent dosimeters (TLD-100) were fixed simultaneously in the following regions of the cardiologist's body: near the eyes (left and right), the trunk region (over the lead apron) and the left ankle. Occupational doses were recorded during 86 procedures (60% CATH). RESULTS: catheterization procedures showed third quartile dose values near to the left eye region equal to 0.10 mSv (TLD-100) and 0.12 (InstadoseTM) and for intervention 0.15 mSv (TLD-100 and InstadoseTM). The doses measured in the trunk region, over the lead apron, were about 13% higher for catheterization procedures and 20% higher for intervention procedures compared to left eye region measurements. The Wilcoxon-Mann-Whitney test was applied for unpaired data for all body regions, comparing the data obtained between the TLD-100 and InstadoseTMdosimeters. For CATH and PCI, the responses of the TLD-100 and InstadoseTMdosimeters are considered equal for all analysed regions (p> 0.05) with the exception of the right eye region. CONCLUSION: the InstadoseTMpassive dosimeter can be useful as a complementary assessment in the monitoring of a cardiologist's personal occupational doses in the cath lab.

CHEST CT USAGE IN COVID-19 PNEUMONIA: MULTICENTER STUDY ON RADIATION DOSES AND DIAGNOSTIC QUALITY IN BRAZIL.

We assessed variations in chest CT usage, radiation dose and image quality in COVID-19 pneumonia. Our study included all chest CT exams performed in 533 patients from 6 healthcare sites from Brazil. We recorded patients' age, gender and body weight and the information number of CT exams per patient, scan parameters and radiation doses (volume CT dose index-CTDIvol and dose length product-DLP). Six radiologists assessed all chest CT exams for the type of pulmonary findings and classified CT appearance of COVID-19 pneumonia as typical, indeterminate, atypical or negative. In addition, each CT was assessed for diagnostic quality (optimal or suboptimal) and presence of artefacts. Artefacts were frequent (367/841), often related to respiratory motion (344/367 chest CT exams with artefacts) and resulted in suboptimal evaluation in mid-to-lower lungs (176/344) or the entire lung (31/344). There were substantial differences in CT usage, patient weight, CTDIvol and DLP across the participating sites.

PRACTICAL CHALLENGES WITH IMAGING COVID-19 IN BRAZIL: MITIGATION IN AND BEYOND THE PANDEMIC.

Computed tomography (CT) provides useful information in patients with known or suspected COVID-19 infection. However, there are substantial variations and challenges in scanner technologies and scan practices that have negative effect on the image quality and can increase radiation dose associated with CT. OBJECTIVE: In this article, we present major issues and challenges with use of CT at five Brazilian CT facilities for imaging patients with known or suspected COVID-19 infection and offer specific mitigating strategies. METHODS: Observational, retrospective and prospective study of five CT facilities from different states and regions of Brazil, with approval of research and ethics committees. RESULTS: The most important issues include frequent use of CT, lack of up-to-date and efficient scanner technologies, over-scanning and patient off-centring. Mitigating strategies can include updating scanner technology and improving scan practices.

An overview of acquisition parameters, dose measurements and organ doses in abdominal CT scans in Brazil.

The aim of this multi-centre study was to evaluate the irradiation parameters and the radiation dose of abdomen CT exams without contrast, performed in adults In Brazil, in order to provide an overview of the CT installed base in the country and contribute for the establishment of optimization programs. Equipment of seven different models, with 16 and 64 channels, installed in 17 Brazilian states, plus the Federal District, were analyzed. The results show that the mean CTDIvol ranged from 6.60 mGy to 34.64 mGy. The results also showed that different irradiation parameters are used in equipment of the same model, resulting, in some cases, in three times higher CTDIvol values. These characteristics are not restricted to a given region of the country but distributed throughout the national territory. Repetitions of acquisitions and topograms with scan length larger than the region of interest were found in 13.5% of abdomen examinations, resulting in considerably higher absorbed doses than expected. This survey of the abdomen tomography exams, performed in about 74% of the Brazilian states, showed that in many clinics the procedures are not optimized. This study can be used for the planning of dose optimization programs and will contribute to the establishment of local diagnostic reference levels (DRL) for CT.

Estimating brain radiation dose to the main operator in interventional radiology.

The aim of this study was to estimate brain radiation dose to the main operator during interventional radiology procedures. Occupational brain doses from 19 interventional procedures were measured using thermoluminiscent dosimeters and an anthropomorphic RANDO woman phantom simulating a main operator. Results show that, interventional radiologists may receive minimum and maximum brain doses per procedure of 0.01 mGy (left temporal cortex) and 0.08 mGy (temporal lobe cortex), respectively. A radiologist who works without movable shielding devices during procedures and has a typical workload (for example 500 procedures per year), might exceed the new dose threshold of 0.5 Gy for circulatory disease in the brain working 12.6 years of his career.

Image evaluation and breast density categories as a function of mammary positioning in full-field digital mammography.

BACKGROUND: Appropriate mammary positioning is an important factor in optimizing image quality in mammography (MMG). PURPOSE: To study the correlation of quality criteria and breast density classification proposed by the American College of Radiology (ACR) and European Guidelines and its influence to achieve a proper positioning, therefore an adequate MMG. MATERIAL AND METHODS: A total of 128 routine MMG examinations were reviewed for the definition of breast composition parenchyma and assessment of several quality criteria proposed by the ACR and European Guidelines to achieve an adequate MMG. Adequate MMG was defined as a difference between the posterior nipple line (PNL), difference of the mediolateral oblique (MLO) and craniocaudal (CC) incidences > 1 cm. The quality criteria were analyzed as a function of correlation coefficient in order to evaluate the individual impact of each factor and analysis of variance (ANOVA) for all criteria. Receiver operating characteristic (ROC) curves were plotted to evaluate the performance of the criteria on each type of parenchyma. RESULTS: Negative correlation of fatty breasts and visibility of the mammary angle, a greater number of skin folds and PNL > 1 cm (r < 0). Dense MMG presented less visibility of the lateral tissue compared with other categories. Area under the curve of ROC analysis revealed values of 53.1% and 54.7% for the right and left breasts, respectively. CONCLUSION: Several factors influenced in the MMG process, but we find that breast parenchyma has a substantial role in affecting these criteria and therefore a correct position for diagnosis, which could compromise MMG diagnostic performance.

Study on patient dosimetry and image quality in digital mammography

Abstract Introduction Digital mammography present many advantages in comparison to conventional mammography, such as high dynamic range and the post-processing of acquired images. One problem is that protocols may not be optimized, resulting in higher absorbed doses to patients. The objective of this work is to evaluate image quality and to estimate mean glandular doses (MGD) in patients submitted to mammography examinations with three digital systems and one screen-film system in Recife, Brazil. Methods To estimate the MGD, the parameters used to acquire images of 5475 patients, with ages between 40 and 64 years and compressed breasts between 2 and 9 cm, were registered. The MGD was calculated by multiplying the incident air kerma with conversion coefficients depending on the anode/filter, breast glandularity and half-value layer. The image quality evaluation of the digital systems was made using objective and subjective European criteria. Results The results showed MGDs in the range of 0.4-10.3 mGy and the higher values were observed with digital systems. It was also observed that in the digital systems the use of compression force is not adequate and the irradiation parameters are not optimized. The images failed to reproduce the pectoral muscle and the contrast-to-noise ratio was not adequate for one system, indicating the need to improve the patient's positioning and the exposure parameters. Conclusion It can be concluded that the use of non-optimized irradiation parameters is causing the higher doses with digital systems, highlighting the insufficient compression force.

Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients.

OBJECTIVE: To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. MATERIALS AND METHODS: Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. RESULTS: The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. CONCLUSION: The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses.

OBJETIVO: Estimar o kerma no ar na superfície de entrada (Ka,e) e o kerma no ar na região de órgãos radiossensíveis em radiografias pediátricas dos seios paranasais. MATERIAIS E MÉTODOS: Foram coletados os dados dos pacientes e parâmetros de irradiação em exames de seios paranasais de crianças com 0 a 15 anos, em dois hospitais infantis na cidade do Recife, PE. O Ka,e foi estimado utilizando os rendimentos dos tubos de raios X e os parâmetros selecionados. Os valores de kerma no ar nas regiões dos olhos e tireoide foram estimados utilizando dosímetros termoluminescentes. RESULTADOS: Os valores de Ka,e variaram de 0,065 a 1,446 mGy para radiografias cavum, 0,104 a 7,298 mGy para Caldwell e 0,113 a 7,824 mGy para Waters. Os valores de kerma no ar na região dos olhos variaram de 0,001 a 0,968 mGy para cavum e 0,011 a 0,422 mGy para Caldwell e Waters. Na região tireóidea, os valores de kerma no ar variaram de 0,005 a 0,932 mGy para cavum e 0,002 a 0,972 mGy para Caldwell e Waters. CONCLUSÃO: Os parâmetros de irradiação utilizados pelas instituições foram mais elevados do que os recomendados em protocolos britânicos. Ações de otimização são recomendadas de modo a contribuir para a redução da radiação nos pacientes e, portanto, os riscos.

Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients / Avaliação dosimétrica de pacientes pediátricos submetidos a exames radiográficos de seios paranasais

Abstract Objective: To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and Methods: Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results: The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion: The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses.

Resumo Objetivo: Estimar o kerma no ar na superfície de entrada (Ka,e) e o kerma no ar na região de órgãos radiossensíveis em radiografias pediátricas dos seios paranasais. Materiais e Métodos: Foram coletados os dados dos pacientes e parâmetros de irradiação em exames de seios paranasais de crianças com 0 a 15 anos, em dois hospitais infantis na cidade do Recife, PE. O Ka,e foi estimado utilizando os rendimentos dos tubos de raios X e os parâmetros selecionados. Os valores de kerma no ar nas regiões dos olhos e tireoide foram estimados utilizando dosímetros termoluminescentes. Resultados: Os valores de Ka,e variaram de 0,065 a 1,446 mGy para radiografias cavum, 0,104 a 7,298 mGy para Caldwell e 0,113 a 7,824 mGy para Waters. Os valores de kerma no ar na região dos olhos variaram de 0,001 a 0,968 mGy para cavum e 0,011 a 0,422 mGy para Caldwell e Waters. Na região tireóidea, os valores de kerma no ar variaram de 0,005 a 0,932 mGy para cavum e 0,002 a 0,972 mGy para Caldwell e Waters. Conclusão: Os parâmetros de irradiação utilizados pelas instituições foram mais elevados do que os recomendados em protocolos britânicos. Ações de otimização são recomendadas de modo a contribuir para a redução da radiação nos pacientes e, portanto, os riscos.

Evaluation of occupational and patient dose in cerebral angiography procedures / Avaliação da dose ocupacional e de pacientes adultos em procedimentos de angiografia cerebral

Objective The present study was aimed at estimating the doses received by physicians and patients during cerebral angiography procedures in a public hospital of Recife, PE, Brazil. Materials and Methods The study sample included 158 adult patients, and during the procedures the following parameters were evaluated: exposure parameters (kV, mAs), number of acquired images, reference air kerma value (Ka,r) and air kerma-area product (PKA). Additionally, the physicians involved in the procedures were evaluated as for absorbed dose in the eyes, thyroid, chest, hands and feet. Results The results demonstrated that the doses to the patients' eyes region were relatively close to the threshold for cataract occurrence. As regards the physicians, the average effective dose was 2.6 µSv, and the highest effective dose recorded was 16 µSv. Conclusion Depending on the number of procedures, the doses received by the physicians may exceed the annual dose limit for the crystalline lenses (20 mSv) established by national and international standards. It is important to note that the high doses received by the physicians are due to the lack of radiation protection equipment and accessories, such as leaded curtains, screens and protective goggles. .

Determination of diagnostic reference levels in general radiography in Latin America.

The International Atomic Energy Agency (IAEA) through the International Action Plan on Radiation Protection of Patients and the International Commission on Radiological Protection have for some time carried out important efforts to assure that in the medical applications of the ionising radiations, the optimisation of radiological protection of patients is fundamental, to such a point that the IAEA includes it directly as a requirement for these practices (in its International Basic Safety Standards for Protection against Ionising Radiation and for the Safety of Radiation Sources (BSS)-GSR Part 1, 2011). For this reason, among the objectives of Regional Project RLA/9/057 and Regional Project RLA/9/067, the intention was to establish the dose references in conventional radiology for Latin America, for the purposes of determining whether these doses comply with the requirements of the BSS and to tend to improve practices, in order to minimise the dose received by the patients.

Doses extracranianas em pacientes submetidos a radiocirurgia estereotáxica para tumores cerebrais / Extracranial doses in patients submitted to stereotactic radiosurgery for brain tumors

OBJETIVO: Estimar a dose extracraniana nos olhos, tireoide, tórax e pelve em pacientes submetidos a radiocirurgia com acelerador linear de 6 MV. MATERIAIS E MÉTODOS: Foram avaliados 11 pacientes com tumores cerebrais primários (7 pacientes) e secundários (4 pacientes), sendo que dois destes apresentavam duas lesões. Para a estimativa da dose extracraniana, foram utilizados dosímetros termoluminescentes. Foram utilizados cones de 1,50 a 3,75 cm e as doses de radiação variaram de 1300 a 2000 cGy. RESULTADOS: A idade média dos pacientes foi de 52 anos, sendo 63,6% do sexo feminino e 36,4% do sexo masculino. As localizações das lesões foram: nervo acústico direito (1), frontal (2), parietal (5), occipital direito (1), cerebelar (2) e parassagitais (2). Os valores médios das doses recebidas na região entre os olhos foram de 5,1 cGy; no olho direito, de 4,8 cGy; no olho esquerdo, de 6,5 cGy; na tireoide, de 4,2 cGy; no tórax, de 1,65 cGy; e na pelve, de 0,45 cGy. CONCLUSÃO: Estes resultados mostram que embora as doses não ultrapassem os limites de tolerância para ocorrência da opacidade do cristalino, é importante que os médicos radioterapeutas considerem os riscos de dose de radiação nessas regiões durante o planejamento de procedimentos de radiocirurgia craniana.

OBJECTIVE: To estimate extracranial doses on eyes, thyroid, chest and pelvis in patients submitted to radiosurgery with 6 MV linear accelerator. MATERIALS AND METHODS: The present study evaluated 11 patients, 7 of them with primary, and 4 with secondary brain tumors. In the latter group, 2 patients had two lesions. Thermoluminescent dosimeters were utilized to estimate the extracranial dose. Radiosurgery cones ranges between 1.50 and 3.75 cm and doses between 1300 and 2000 cGy. RESULTS: Mean patients' age was 52 years, and 63.6% of them were women and 36.4%, men. Lesion locations were the following: right acoustic nerve (1), frontal (2), parietal (5), right occipital (1), cerebellum (2) and parasagittal (2). Mean received doses were the following: 5.1 cGy between the eyes; 4.8 cGy in the right eye; 6.5 cGy in the left eye; 4.2 cGy in the thyroid; 1.65 cGy in the chest; and 0.45 cGy in the pelvis. CONCLUSION: The results demonstrate that that although the eye doses do not exceed the tolerance limits for occurrence of lens opacity, it is important that the risks associated with radiation doses are taken into consideration by radiotherapists in the planning of cranial radiosurgery procedures.

Dosimetria de pacientes e médicos em intervenções coronárias percutâneas em Recife, Pernambuco, Brasil / Radiation dosimetry in patients and physicians during percutaneous coronary angioplasty in Recife, Pernambuco, Brazil

OBJETIVO: Este trabalho teve como objetivo estimar os valores de doses de radiação recebidas por médicos e pacientes em procedimentos intervencionistas cardíacos realizados em um hospital público na cidade de Recife, Pernambuco. MATERIAIS E MÉTODOS: As medidas foram determinadas em 31 pacientes adultos, dos quais 22 tiveram acompanhamento clínico após o procedimento, e em dois cardiologistas com mais de dez anos de experiência. Parâmetros de irradiação para cada procedimento foram registrados. RESULTADOS: Os valores obtidos para a dose absorvida máxima na pele do paciente variaram entre 612 e 8.642 mGy, sendo que 53 por cento foram maiores que 2.000 mGy, valores estes que podem causar efeitos determinísticos. Com relação aos médicos, a dose efetiva média por procedimento foi de 11 µSv e os valores médios do equivalente de dose nas extremidades, mais altos, foram: 923 µSv no pé esquerdo, 514 µSv no pé direito, 382 µSv na mão esquerda e 150 µSv no olho esquerdo. Dependendo do número de procedimentos, as doses recebidas pelos médicos podem exceder os valores limites de doses estabelecidos pelas normas nacionais e internacionais. CONCLUSÃO: Os resultados obtidos sinalizam a necessidade de adoção de estratégias para otimização da proteção radiológica tanto de pacientes quanto de médicos.

OBJECTIVE: The present study was aimed at estimating the values of radiation doses received by physicians and patients during interventional cardiology procedures performed at a public hospital in the city of Recife, Pernambuco, Brazil. MATERIALS AND METHODS: Measurements were made in two cardiologists with more than ten years of experience and in 31 adult patients, with 22 of them being clinically followed-up after the procedure. The individual irradiation parameters were documented. RESULTS: The values for maximum patients skin dose ranged between 612 and 8,642 mGy, achieving more than 2,000 mGy in 53 percent of the patients; such dose values may cause deterministic effects. As regards the physicians, the mean effective dose per procedure was 11 µSv, and the highest mean equivalent doses in the limbs were 923 µSv in the left foot, 514 µSv in the right foot, 382 µSv in the left hand, and 150 µSv in the left eye. Depending on the number of procedures, the doses received by the physician may exceed the dose limits established by the Brazilian and international standards. CONCLUSION: The obtained results indicate the necessity of adopting strategies for optimizing the radiological protection for both patients and physicians.

A radiopacidade de cimentos endodônticos variando-se tempo de exposição e filmes / Endodontics sealers radiopacity with different exposure times and films

Objetivo: Avaliar a radiopacidade dos cimentos endônticos Fillcanal, Apexit, Vidrion Endo e Endométhasone, variandose filmes radiográficos periapicais D-Speed, E-Speed e Agfa Dentus M2 Comfort e dois tempos de exposição. Material e Métodos: Foram confeccionados 5 corpos de prova para cada material estudado, os quais foram radiografados, juntamente com um dente, nos tempos de exposição e filmes estudados. Em cada imagem do corpo de prova e do dente, foram obtidas medidas da densidade óptica. Foram utilizados os testes de Kruskal-Wallis e de Mann-Whitney, com o nível de significância de 0,05. Resultados: Os valores da densidade óptica do dente e dos cimentos mostraram-se diferentes quando se variou filme e/ou tempo de exposição. Em todas as condições estudadas, o dente apresentou valores da densidade óptica maiores que os dos cimentos. O cimento Vidrion Endo mostrou-se mais radiopaco seguido, em ordem decrescente, pelo Fillcanal, Endométhasone e Apexit na maioria das condições estudadas. Com exceção do cimento Vidrion Endo, por não ter demonstrado alteração da radiopacidade variando-se o tipo de filme utilizando-se menor tempo de exposição, houve diferenças nos resultados quanto ao tipo de filme e tempo de exposição em todos os casos. Conclusão: Os fatores tempo de exposição e filme influenciam na radiopacidade dos materiais.

Objective: The radiopacity of the endodontic sealers Fillcanal, Apexit, Vidrion Endo and Endométhasone, was assessed, with three periapical radiographic films: D-Speed, E-Speed and Agfa Dentus M2 Comfort and two exposure times. Material and Methods: Five test specimens were made for each material studied, which were radiographed together with a teeth, at the exposure times and with the films studied. In each test specimen and tooth image, optic density measurements were obtained. The Kruskal-Wallis test and the Mann-Whitney test was used, with level of significance of 0.05. Results: The optic density values of the tooth and the cements were shown to differ with the film and/or exposure time that was varied. Under all the studied conditions, the tooth presented higher optical density values than those of the sealers. The Vidrion Endo sealer was shown to be the most radiopaque, followed by Fillcanal, Endométhasone and Apexit in decreasing order, under the majority of the studied conditions. With exception of the Vidrion Endo cement, since it showed no alteration in radiopacity when varying the type of radiographic film and using a shorter exposure time, there were differences in the results regardings the type of film and exposure time in all cases. Conclusion: The factors exposure time and film influence the radiopacity of the materials.

Riscos dos exames radiográficos em recém-nascidos internados em um hospital público de Belo Horizonte, MG / Risks of radiographic procedures for neonates admitted to a public hospital in Belo Horizonte, MG, Brazil

OBJETIVO: Os objetivos deste trabalho são: a) avaliar os procedimentos radiográficos e estimar o valor do kerma no ar na superfície de entrada nos recém-nascidos prematuros submetidos a exames de tórax e abdome, realizados no setor de neonatologia de um hospital público de Belo Horizonte; b) estimar as doses nos órgãos e os respectivos riscos de ocorrência de câncer nesses órgãos em decorrência das exposições à radiação. MATERIAIS E MÉTODOS: Foram analisados os prontuários dos pacientes internados no setor de neonatologia desse hospital durante o período de maio a setembro de 2004, anotando-se os dados antropométricos, data de internação/alta, exames de raios X realizados. O kerma no ar na superfície de entrada foi determinado a partir do rendimento do tubo de raios X e dos parâmetros de irradiação utilizados nos exames. As doses nos órgãos foram estimadas com o software PCXMC e o risco, durante o restante da expectativa de vida, com o software IREP. RESULTADOS: O valor médio do kerma no ar na superfície de entrada por exame foi abaixo do nível de referência da publicação da Comunidade Européia. Para o paciente mais severamente irradiado, os órgãos mais suscetíveis à ocorrência de câncer foram fígado, mama e estômago, com valores máximos de excess relative risk, respectivamente, de 3,4 por cento, 2,3 por cento e 1,7 por cento. CONCLUSÃO: Foi constatada a necessidade de otimização dos procedimentos radiográficos com vista à diminuição do risco para os recém-nascidos, que apesar de ser considerado baixo (comparativamente ao benefício), deve ser sempre diminuído para valores tão baixos quanto razoavelmente exeqüíveis.

OBJECTIVE: The present study was aimed at: a) evaluating radiographic procedures and estimating entrance surface air kerma in preterm neonates submitted to chest and abdominal radiography at the unit of neonatology in a public hospital of Belo Horizonte, MG, Brazil; b) estimating the dose to organs and respective risks for cancer as a result from radiation exposure. MATERIALS AND METHODS: Records of patients admitted to the unit of neonatology of this hospital in the period between May and September 2004 were reviewed. Anthropometric data, admission/discharge dates and radiographic studies performed were recorded for each of the patients. The calculation of the entrance surface air kerma was based on the x-ray tube output and irradiation parameters adopted for examinations. Dose to organs was calculated with the aid of the software PCXMC, and the lifetime risk for cancer, with the software IREP. RESULTS: Mean entrance surface air kerma per examination was below the diagnostic reference levels recommended by the European Community. In the most severely irradiated patients, liver, breast and stomach were the organs at highest risk for cancer, with maximum excess relative risk of respectively 3.4 percent, 2.3 percent, and 1.7 percent. CONCLUSION: The present study demonstrated the need for optimization of radiographic procedures in order to reduce the risks for neonates that, in spite of being considered to be low as compared with the benefits, should be reduced to values as low as reasonably achievable.

Assessment of dosimetric quantities for patients undergoing X-ray examinations in a large public hospital in Brazil--a preliminary study.

The introduction of routine patient dosimetry to Brazilian radiological institutions is very necessary in order to meet national and international standard requirements for radiation protection. This work presents a survey of the air kerma-area product (P(KA)), the entrance surface air kerma (K(e)) and the effective dose (E) in common radiographic examinations during the routine of a large public hospital in the city of Belo Horizonte, Brazil. Results draw attention to the use of field sizes larger than the cassette dimension, the lack of both the collimation X-ray beam and the standardisation of the exposure parameters by radiology technicians.

Influência do tempo de exposiçãoe da kVp na radiopacidade de cimentos endodônticos / Influence of time exposure and kVp on endodontics sealers radiopacity

Este estudo avaliou a radiopacidade dos cimentos endodônticos FillCanal®, Apexit®, Vidrion Endo® e Endométhasone®, variando o tempo de exposição (0,3 e 0,4s) e quilovoltagem (50 e 70 kVp). Para cada material estudado foram confeccionados cinco corpos-de-prova, os quais foram radiografados, juntamente com um dente, nos tempos de exposição e quilovoltagens determinados. Em cada imagem do corpo-de-prova e do dente foram realizadas cinco medidas da densidade óptica. Foram utilizados os testes de Kruskal-Wallis, para avaliar a influência dos fatores quilovoltagem, tempo de exposição e cimento, e de Mann-Whitney, para comparações múltiplas (p,0,05). Nas condições avaliadas, todos os materiais foram mais radiopacos que o dente. Com exceção do Endométhasone®®, que apresentou radiopacidade inferior em relação aos demais materiais nos dois tempos de exposição estudados, não houve diferença significativa entre os outros cimentos endodônticos avaliados quando a quilovoltagem empregada foi de 50 kVp. Quando os materiais foram expostos utilizando-se a quilovoltagem de 70 kVp, houve maior densidade óptica para o tempo 0,4 s e, nos dois tempos de exposição empregados, os valores de densidade apresentados pelos cimentos Vidrion Endo® e FillCanal® e Endométhasone® e Apexit® foram semelhantes. Concluiu-se que o fator quilovoltagem apresentou maior influência na radiopacidade dos materiais do que o tempo de exposição. Da mesma forma, pode-se dizer que a quilovoltagem de 70 kVp permite que a radiopacidade do material se diferencie pela densidade e composição deste.

Radioproteção, dose e risco em exames radiográficos nos seios da face de crianças, em hospitais de Belo Horizonte, MG / Radioprotection, doses and risks in the radiological assessment of paranasal sinuses in children, in hospitals of Belo Horizonte, MG

OBJETIVO: Avaliar a freqüência das incidências radiográficas realizadas nos seios da face de pacientes pediátricos em hospitais de Belo Horizonte, MG, as condições de radioproteção, as técnicas radiográficas empregadas, o kerma no ar de entrada e as doses nos órgãos mais expostos. MATERIAIS E MÉTODOS: Foram coletados os dados dos pacientes e parâmetros de técnica radiográfica empregados em exames de crianças de 1 a 16 anos de idade, em cinco salas de quatro hospitais da cidade, observando, também, aspectos de proteção radiológica. O kerma no ar de entrada foi estimado a partir dos rendimentos dos tubos de raios-x e as doses nos órgãos utilizando o software PCXMC. RESULTADOS: Os valores médios do kerma no ar de entrada para as cinco salas foram, respectivamente, 1.398 µGy, 829 µGy, 877 µGy, 1.168 µGy e 3.886 µGy para pacientes entre 1 e 5 anos de idade. CONCLUSÃO: Foi constatado que as incidências mento-naso e fronto-naso são comumente solicitadas em conjunto, na maioria dos hospitais, o que confere dose significativa para os pacientes. Os riscos para os pacientes podem ser diminuídos mediante a utilização de cilindros de colimação, a não-utilização de grades antiespalhamento, o emprego de altos valores de tensão e baixos valores de tempo.

OBJECTIVE: The present study was aimed at evaluating the frequency of radiographic assessment of paranasal sinuses in pediatric patients in hospitals of Belo Horizonte, MG, Brazil. Additionally, aspects regarding radiation protection conditions and radiographic parameters were evaluated, and entrance air kerma and organ doses were estimated. MATERIALS AND METHODS: Patients' data and parameters of radiographic technique employed in the assessment of children in the age range between 1 and 16 years were collected in five examination rooms of four hospitals in Belo Horizonte, also taking into consideration the radiation protection aspects. Entrance air kerma calculation was based on the x-ray tubes output, and organ doses were estimated with the PCXMC software. RESULTS: Mean entrance air kerma values found in the five rooms were, respectively, 1398 µGy, 829 µGy, 877 µGy, 1168 µGy and 3886 µGy for patients with ages between 1 and 5 years. CONCLUSION: Most frequently, mento-naso and fronto-naso views are requested in conjunction in the majority of hospitals, which increases the radiation dose to the patients. It may be concluded that the risks for patients can be reduced by means of the utilization of an appropriate x-ray field, non-utilization of antiscattering grids, selection of high voltages and lower exposure times.

Desenvolvimento de um sistema não invasivo para o controle de qualidade de equipamentos mamográficos / Development of a non-invasive system for quality control in mammography equipment

A mamografia é atualmente o método de diagnóstico mais eficaz para detecção de patologias nas mamas. Contudo, o uso de radiação ionizante está associado a um risco de indução de câncer nos pacientes, o que torna imprescindível a implantação de programas de conotrole de qualidade para a otimização do procedimento e a obtenção de imagens de qualidade para o diagnóstico com a menor dose ao paciente. Este trabalho tem como objetivo a avaliação da resposta de um distema dosimétrico desenvolvido para auxiliar nos programas de controle de qualidade em mamografia, através de medidas simultâneas da tensão do tudo de raios-X, do tempo de irradiação e do kerma ar na entrada da pele do paciente. Este sistema dosimétrico consiste de três sensores semicondutores (fotodiodos comerciais), acoplados a um sistema eletrônico e associados a um conjunto de filtros de Al e Cu. Um dos fotodiodos é usado para o controle do processo de leitura e medição do tempo de irradiação. A razão entre as leituras dos outros dois é utilizada para a determinação da tensão dotubo de raios-X através do método não invasivo baseado na diferença de atenuação com diferentes absorvedores. O sinal do semicondutor sem filtro também é usado para obter o valor do kerma no ar na entrada da pele do paciente. Todo processo de medição é controlado por um dispositivo microcontrolador e os valores obtidos são visualizados em um display. O instrumento foi testado em um equipamento de raios-X mamográfico. Os resultados obtidos mostraram uma resposta linear e uma repetibilidade de 2 por cento para as medidas do kerma ar na entrada da pele do paciente. A estabilidade na resposta da medida de tensão se mostrou reprodutível dentro de mais ou menos 1,5 por cento. O teste das medids do tempo de irradiação indicou uma variação inferior a 0,5 por cento.