OBJECTIVE: The present study was aimed at developing a thermoluminescent dosimetric system capable of assessing the doses delivered to the rectum of patients submitted to high-dose-rate brachytherapy for uterine cervix cancer. MATERIALS AND METHODS: LiF:Mg,Ti,Na powder was the thermoluminescent material utilized for evaluating the rectal dose. The powder was divided into small portions (34 mg) which were accommodated in a capillary tube. This tube was placed into a rectal probe that was introduced into the patient's rectum. RESULTS: The doses delivered to the rectum of six patients submitted to high-dose-rate brachytherapy for uterine cervix cancer evaluated by means of thermoluminescent dosimeters presented a good agreement with the planned values based on two orthogonal (anteroposterior and lateral) radiographic images of the patients. CONCLUSION: The thermoluminescent dosimetric system developed in the present study is simple and easy to be utilized as compared to other rectal dosimetry methods. The system has shown to be effective in the evaluation of rectal doses in patients submitted to high-dose-rate brachytherapy for uterine cervix cancer.

Keywords: Rectum, Brachytherapy, HDR, Thermoluminescent dosimetry, Uterine cervix cancer

OBJECTIVE: To calculate spectra of cobalt-60 beam at water depth and correction factors for absorbed dose measurements obtained with lithium fluoride thermoluminescent dosimeters using Monte Carlo simulation. MATERIALS AND METHODS: The simulations of secondary spectra of clinical cobalt-60 sources were performed with the PENELOPE Monte Carlo code at different water depths. Experimental measurements of deep doses were obtained with thermoluminescent dosimeters and ionization chamber under reference conditions for radiotherapy. Correction factors for the thermoluminescent dosimeters detectors were obtained through the ratio between the relative energy absorption for the low energy spectrum and the total spectrum. RESULTS: Deep spectral analysis has demonstrated the presence of secondary low-energy spectra responsible for a significant portion of the dose deposition. Discrepancies of 3.2% were observed among the doses measured with ionization chamber and thermoluminescent dosimeters. The adoption of correction factors has allowed a reduction in the discrepancy among absorbed doses to a maximum of 0.3%. CONCLUSION: Simulated spectra allow the calculation of correction factors for reading of thermoluminescent dosimeters utilized in the measurement of deep doses, contributing for the reduction of uncertainties associated with quality control of clinical beams in radiotherapy.

Keywords: Monte Carlo simulation, Radiotherapy, Spectrometry, Quality control, Thermoluminescent dosimetry, TLD

OBJECTIVE: The present study evaluates the dose distribution received by physicians involved in hemodynamic procedures of coronary angiography and coronariography. The influence of some factors such as pulsed or continuous fluoroscopy mode and vein and/or artery access site was investigated. MATERIALS AND METHODS: Measurements have been performed with LiF:Mg,Ti thermoluminescent dosimeters placed on seven different sites of the practitioners' bodies: hands, left knee, neck, forehead and chest, under and over the lead apron. Radiation doses for each procedure were evaluated in physicians who had performed 60 coronariography and 30 angioplasty procedures. The thermoluminescent dosimeters were calibrated in the operational quantity personal dose equivalent, Hp(d), at depths of 0.07, 3 and 10 mm. RESULTS: The results of the present study demonstrate the significant role played by thyroid protectors and lead aprons for reducing radiation doses received by practitioners. Occupational doses in continuous mode fluoroscopy through brachial access were higher than with pulsed mode fluoroscopy through femoral access. CONCLUSION: The present study has demonstrated the necessity of implementing additional protective measures as well as a mechanism of training in radiation protection for physicians involved in interventional cardiological procedures.

Keywords: Interventional radiology, Fluoroscopy, Hemodynamic procedures, Radiation protection, Thermoluminescent dosimetry

OBJECTIVE: The present study was aimed at evaluating the accuracy of magnetic resonance cholangiography in the assessment of the biliary anatomy in living liver donors in correlation with surgical findings. MATERIALS AND METHODS: Fifty living liver donors were retrospectively evaluated at Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR, Brazil. Cholangiographic images were analyzed and results were compared with intraoperative findings. Only anatomical alterations that affected the surgical strategy and had not been previously observed at magnetic resonance cholangiography were considered as being in disagreement. RESULTS: Anatomical variations were found in 7 donors at magnetic resonance cholangiography, and in 14 during surgery. Agreement between imaging and surgical findings was observed in 41 of the 50 patients, and disagreement in 9. Magnetic resonance cholangiography sensitivity, specificity, positive and negative predictive values, and accuracy were respectively 43%, 97%, 86%, 81% and 81.6%. CONCLUSION: Magnetic resonance imaging is a safe and noninvase method for preoperative evaluation of the biliary tract in living liver donors. However some anatomical abnormalities are not detected by magnetic resonance cholangiography.

Keywords: Liver transplant, Living donors, Magnetic resonance imaging, Biliary tract

Energy and angular dependences of different thermoluminescent materials were studied with the objective to verify which type of detector would be the most appropriate for beta monitoring of workers. Three types of CaSO4:Dy + teflon pellets were studied. The energy dependence was evaluated using standard beta radiation sources (147Pm, 204Tl and 90Sr+90Y). For the angular dependence study, the pellets were exposed to beta radiation of the 90Sr+90Y source, varying the incidence angle between 0° and 90°. In relation to the studied characteristics, the CaSO4:Dy + 10% C dosimeters were the most adequate for use in beta monitoring of workers.

Keywords: Thermoluminescent dosimetry, Beta radiation, Angular dependence, Energetic dependence

OBJECTIVE: To present the solidly established traceability structure for ionometric standards and for thermoluminescent dosimetry system that ensures reliability of the Dosimetry Quality Assurance Program and is aimed to certify the highest level of accuracy of the measurements. MATERIALS AND METHODS: Thermoluminescent powder dosimeters (DTL 937) placed into plastic capsules and packed in specific kits for each intended application were mailed to the participant centers. RESULTS: The results of the intercomparisons performed between "Laboratório de Ciências Radiológicas da Universidade do Estado do Rio de Janeiro" and EQUAL-ESTRO for the beam of 60Co gamma rays, expressed for (1sigma), and the results of the dose absorbed measurements obtained with the chambers of the Program EQUAL and the chambers of the Dosimetry Quality Assurance Program were lower than 0.5%. CONCLUSION: Based on these results we concluded that the Dosimetry Quality Assurance Program reached the desired level of reliability to allow its implementation.

Keywords: Quality assurance, Radiotherapy, Dosimetric intercomparison, Thermoluminescent dosimetry, TLD

The dose area product was evaluated and the entrance skin dose was subsequently estimated by means of suitable calculations for pediatric examinations. Results showed values around 100% above the reference levels (0.070 mGy). The technical parameters of the X-ray tubes were periodically checked since a routine quality assurance program is implemented in the hospital. Results showed a good performance of the equipment complying with recommended limits according to Brazilian legislation. Therefore, the high doses can be attributed to the low kV techniques and the lack of appropriate training of the radiographers to perform pediatric examinations. Measurements of scattered radiation were performed in the gonads with the use of thermoluminescent dosimeters which proved to be inadequate for these measurements. Therefore an ionization chamber was used instead and the values obtained showed that the doses were far below the values that can cause permanent or transient sterility.

Keywords: Radiation doses, Pediatric radiology, Image quality

OBJECTIVE: To evaluate the precision of the absorbed radiation doses in bone marrow transplant therapy during whole body irradiation. MATERIALS AND METHODS: Two-hundred CaSO4:Dy + teflon tablets were calibrated in air and in "phantom". These tablets were randomly selected and divided in groups of five in the patients' body. The dosimetric readings were obtained using a Harshaw 4000A reader. Nine patients had their entire bodies irradiated in parallel and opposite laterals in a cobalt-60 Alcion II model, with a dose rate of 0.80 Gy/min at 80.5 cm, {(10 × 10) cm² field}. The dosimetry of this unit was performed using a Victoreen 500 dosimeter. For the determination of the mean dose at each point evaluated, the individual values of the tablets calibrated in air or "phantom" were used, resulting in a build up of 2 mm to superficialize the dose at a distance of 300 cm. RESULTS: In 70% of the patients a variation of less than 5% in the dose was obtained. In 30% of the patients this variation was less than 10%, when values obtained were compared to the values calculated at each point. A mean absorption of 14% was seen in the head, and an increase of 2% of the administered dose was seen in the lungs. In patients with latero-lateral distance greater than 35 cm the variation between the calculated doses and the measured doses reached 30% of the desired dose, without the use of compensation filters. CONCLUSION: The measured values of the absorbed doses at the various anatomic points compared to the desired doses (theoretic) presented a tolerance of ± 10%, considering the existent anatomical differences and when using the individual calibration factors of the tablets.

Keywords: Whole body irradiation, Dosimetry, Thermoluminescent dosimeters, Doses, Bone marrow transplantation

Objetivo: A principal utilidade da tomografia por emissão de pósitrons com 18-fluordeoxiglicose (FDG-PET) está no estadiamento do câncer de pulmão. Porém, ela também pode ser utilizada para diferenciar lesões pulmonares indeterminadas, mas seu impacto na ressecção cirúrgica de lesões benignas é desconhecido. O objetivo deste estudo foi comparar a prevalência de lesões benignas em toracotomias feitas por suspeição de câncer de pulmão, antes e após a introdução do FDG-PET, em um centro de referência de cirurgia torácica. Materiais e Métodos: Os autores analisaram, prospectivamente, uma base de dados cirúrgicos de todos os pacientes consecutivos submetidos a toracotomia por câncer de pulmão suspeito ou comprovado e compararam a prevalência de lesões benignas em dois grupos ao longo de dois anos consecutivos, respectivamente antes (grupo I) e depois (grupo II) da introdução da FDG-PET. Resultados: Ressecção cirúrgica foi feita em 1.233 pacientes durante o período do estudo. A prevalência de lesões benignas na cirurgia nos grupos I e II foi similar (44/626 e 41/607, ambas correspondendo a 7%), e também no grupo II, entre aqueles submetidos a FDG-PET e os restantes (21/301 e 20/306 respectivamente, ambos correspondendo a 7%). No grupo II, dos 21 pacientes com lesões benignas submetidos a FDG-PET, 19 tiveram um estudo falso-positivo (valor médio padrão de captação 5.3 [faixa 2.6–12.7]). Desses, respectivamente 13 e 4 pacientes tiveram broncoscopia não diagnóstica e biópsia transtorácica percutânea de pulmão antes da toracotomia. Não houve diferença na proporção de lesões benignas diferentes ressecadas entre o grupo I e aqueles submetidos a FDG-PET no grupo II. Conclusão: A introdução da FDG-PET não alterou a proporção de pacientes submetidos a toracotomia por lesões benignas, principalmente devido à avidez pelo isótopo de algumas lesões não malignas. Tais resultados falsos-positivos devem ser considerados nos casos em que se contempla a possibilidade de ressecção cirúrgica em pacientes com câncer de pulmão não confirmado.

Keywords: Tomografia por emissão de pósitrons; Tomografia computadorizada; Pulmão – lesões benignas ou congênitas; Câncer de pulmão – diagnóstico e estadiamento; Câncer de pulmão – cirurgia.

Objetivo: Avaliar a percepção de médicos residentes em radiologia de 4º ano sobre as melhores modalidades de imagem na investigação de neoplasias e trauma. Materiais e Métodos: Vinte e sete médicos residentes de 4º ano de quatro programas de residência em radiologia americanos participaram do estudo. Aos participantes foi perguntado sobre a melhor modalidade de imagem para se avaliar o cérebro e a coluna vertebral, pulmões, abdome e o sistema musculoesquelético. As modalidades de imagem disponíveis foram: RM, TC, ultrassonografia, PET e radiografia simples. Todos os achados foram comparados com os Critérios de Adequação de Exames de Imagem e Radioterapia do ACR. Resultados: A RM foi escolhida como melhor modalidade de imagem para se avaliar neoplasias encefálicas, espinhais, abdominais e musculoesqueléticas por 96,3%, 100%, 70,4% e 63% dos residentes, respectivamente. A TC foi escolhida por 88,9% dos residentes para avaliar neoplasias pulmonares. A modalidade de imagem ótima para se avaliar trauma foi a TC para lesões encefálicas (100%), espinhais (92,6%), pulmonares (96,3%), abdominais (92,6%) e grandes lesões traumáticas musculoesqueléticas (74,1%); a RM foi escolhida para lesões esportivas (96,3%). Observou-se concordância com os critérios de adequação do ACR. Conclusão: Houve concordância entre a percepção dos residentes sobre as melhores modalidades de imagem para avaliação de neoplasias e trauma e os critérios de adequação do ACR.

Keywords: Formação de residentes; Educação médica; Modalidades de imagem.

OBJETIVO: Este estudo teve por finalidade avaliar a perfusão miocárdica de pacientes com diabetes mellitus tipo 1 (DM1) e tipo 2 (DM2) assintomáticos, sem diagnóstico prévio de doença arterial coronariana (DAC) ou acidente vascular cerebral. MATERIAIS E MÉTODOS: Cinquenta e nove pacientes consecutivos (16 DM1, 43 DM2) foram submetidos a cintilografia de perfusão miocárdica com sestamibi-^99mTc (CPM). Foram avaliados quanto ao índice de massa corpórea, controle metabólico do diabetes, dislipidemia, terapia para o diabetes, hipertensão arterial sistêmica, nefropatia, retinopatia, neuropatia periférica, tabagismo e história familiar de DAC. RESULTADOS: CPM foi anormal em 25,4%: 12 (20,3%) com alterações de perfusão e 3 com disfunção ventricular esquerda isolada. Os mais fortes preditores de perfusão miocárdica anormal foram: idade igual ou maior a 60 anos (p = 0,017, odds ratio [OR] = 6,0), neuropatia periférica (p = 0,028, OR = 6,1), nefropatia (p = 0,031, OR = 5,6) e ECG de esforço positivo para isquemia (p = 0,049, OR = 4,08). CONCLUSÃO: A isquemia miocárdica silenciosa ocorre em mais de um em cada cinco diabéticos assintomáticos. Os mais fortes preditores de isquemia foram: idade avançada, neuropatia periférica, nefropatia, retinopatia e ECG de esforço positivo para isquemia.

Keywords: Diabetes mellitus; Cintilografia de perfusão miocárdica; Isquemia miocárdica silenciosa; Doença arterial coronariana.

OBJETIVO: Avaliar a completude das fissuras, resposta radiológica ao tratamento e análise quantitativa por TC (AQTC) em população de pacientes com enfisema grave submetidos ao implante de valvas endobrônquicas (VEB). MATERIAIS E MÉTODOS: Foram estudados exames de TC multidetectores de 29 pacientes, realizados com protocolo de baixo dose, cortes finos, sem contraste. Dois radiologistas revisaram, retrospectivamente, os exames em consenso. A completude das fissuras foi estimada em escala de 5% e a resposta radiológica (atelectasia/perda volumétrica do lobo alvo) foi avaliada. AQTC foi realizada nos exames pré e pós-tratamento utilizando programa completamente automático. RESULTADOS: Resposta radiológica positiva foi vista em 16/29 pacientes. Os 13 pacientes sem resposta à TC apresentavam fissuras incompletas e completude média das fissuras obliquas de 72,8%, contra 88,3% no outro grupo. Os resultados mais significativos da AQTC mostraram redução do volume pulmonar (VP) total (média de 542 ml), VP tratado (700 ml) e volume de enfisema (331,4 ml) no grupo com resposta positiva, que também apresentou melhora nos testes funcionais. CONCLUSÃO: O benefício das VEB é maior em pacientes com fissuras completas e que desenvolvem atelectasia lobar. Nos pacientes sem resposta radiológica encontramos maior prevalência de fissuras incompletas e grau de incompletude das fissuras. Nossa AQTC automática detectou as alterações pós-tratamento, principalmente considerado a análise do pulmão tratado.

Keywords: Enfisema; Terapia de colapso pulmonar; Tomografia computadorizada.

OBJECTIVE: To evaluate the level of ambient radiation in a PET/CT center. MATERIALS AND METHODS: Previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. RESULTS: In none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. CONCLUSION: In the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed.

Keywords: Dosimetry; Thermoluminescence dosimetry; PET/CT.

OBJECTIVE: To estimate the entrance surface air kerma (K_a,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 K_a,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 K_a,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.

Keywords: Radiometry; Radiography; Paranasal sinuses; Pediatrics; Thermoluminescent dosimetry..

OBJETIVO: Avaliar os padrões tomográficos relacionados aos agentes etiológicos da pneumonia em pacientes durante o primeiro ano após transplante renal. MATERIAIS E MÉTODOS: Foram analisados dados de prontuários de 956 pacientes submetidos a transplante renal, no período de 2013 a 2018, em um centro transplantador renal do nordeste do Brasil. Nos pacientes que desenvolveram pneumonia, os agentes etiológicos foram classificados em bactérias piogênicas, micobactérias, fungos, vírus e pneumonia polimicrobiana, enquanto os padrões tomográficos foram classificados em consolidação, broncopneumonia, pneumonia intersticial e nódulos e massas. Para verificar associação estatística entre micro-organismos e padrões tomográficos, foi utilizado o teste exato de Fisher, com p < 0,001. RESULTADOS: Foram encontrados 101 casos de pneumonia, dos quais 60 (59,4%) tiveram agente etiológico identificado, sendo as bactérias piogênicas as mais frequentes, detectadas em 22 (36,7%) dos casos. Entre os pacientes com agente causal identificado, o padrão tomográfico predominante foi o de nódulos e massas, identificado em 25 (41,7%) casos. Foi observada associação entre bactérias piogênicas e o padrão de consolidação, fungos com nódulos e massas, bem como entre agentes virais e padrão intersticial. CONCLUSÃO: Foi demonstrada associação estatística entre micro-organismos causadores de pneumonia e padrões tomográficos, informação que pode contribuir para o planejamento da terapia de pacientes transplantados renais.

Keywords: Pneumonia; Transplante de rim; Tomografia computadorizada.