OBJECTIVE: The objective of the present study is to analyze the optimization of fluoroscopic image quality and patient entrance surface air kerma rate in interventional radiology procedures, utilizing a phantom adapted for fluoroscopy. MATERIALS AND METHODS: The authors utilized a phantom developed for evaluating conventional radiological images adapted for fluoroscopy through the addition of two catheters with different diameters, both of them utilized in interventional radiology. The patient entrance surface air kerma rate was determined with the aid of this phantom. RESULTS: The evaluation of technical parameters for different exposure modes of a digital fluoroscopic imaging system has allowed the determination of the air kerma rate, enabling the optimization of the image quality in interventional procedures. The decrease in the patient entrance surface air kerma rate may achieve 67%. CONCLUSION: The optimization of fluoroscopic image quality achieved with a phantom allows reducing the patient entrance surface air kerma with no significant loss of diagnostic performance.

Keywords: Images optimization, Fluoroscopy, Phantom, Dose reduction

OBJECTIVE: The purpose of thys study was to investigate the effect of the addition of aluminum (1 mm) and copper (0.4 mm) filters on effective radiation doses and image quality in videofluoroscopy. MATERIALS AND METHODS: An ionization chamber coupled with an electrometer was added to x-ray tube to measure the kerma area product with 65 kV and 0.7 mA technique, without and with additional filtration. Low contrast, gray scale and spatial resolution were measured utilizing Leeds test objects. Fifteen volunteers underwent pharynx study, ten without and five with aluminum and cooper filters associated, and had the kerma area product/minute compared. RESULTS: The specified filters addition, either separated or associated, allowed an expressive decrease in kerma area product besides an actual improvement in the videofluoroscopic images quality determined by a better gray tones differentiation and increased brightness contrast ratio in the gray curve. CONCLUSION: Additional aluminum and copper filters interposition, especially when associated, results in improved image quality with expressive reduction in the required radiation doses.

Keywords: Videofluoroscopy, Kerma area product, X-ray, Radiological image, Radiation dose

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.

Keywords: Pediatric radiology, Patient dose, Organ dose

OBJECTIVE: To compare radiological techniques used in Brazil and in Australia, and to evaluate radiation doses of the most common x-ray procedures. MATERIALS AND METHODS: The entrance skin dose (ESD) and the effective dose (ED) were obtained with the software DoseCal. In both countries the study was conducted in large public hospitals. Four distinct procedures were evaluated: chest, abdomen, pelvis and thoracic spine in three views (anterior-posterior, posterior-anterior and lateral) In Australia, all x-ray equipment are digital and linked with PACS whereas in Brazil conventional equipment is used. RESULTS: The mean values of ESD and ED were consistently higher in Brazil, except for chest x-rays. The higher differences were seen in pelvis (26 fold higher in Brazil) and thoracic spine (43 fold higher in Brazil) radiographs. CONCLUSION: All Australian hospitals have quality assurance programs (QAP) implemented on a permanent basis, the most advanced digital equipment and count with an effective medical physics service. These factors are determinant for high quality images, low rejection rates and low doses imparted to patients when compared to Brazilian standards. Theses results reinforce the need of implementation of quality assurance programs in Brazil. However, when analyzing the results of ESD for chest x-rays, we concluded that low doses can also be achieved in Brazil with the use of appropriate x-ray techniques.

Keywords: Entrance skin dose, Radiodiagnosis, Effective dose, Dosimetry

High-dose rate brachytherapy was first introduced in Brazil in January 1991. Significant changes in the management of malignant neoplasms were observed since utilization of high-dose rate brachytherapy. The high number of gynecological patients awaiting for brachytherapy also decreased during this period. In the first ten years 26,436 patients were treated with high-dose rate brachytherapy. More than 50% of these patients presented neoplasms of the uterine cervix. In this study we present the number and profile of the patients treated with high-dose rate brachytherapy as well as the distribution of these patients in the Brazilian territory, proving the benefit of the use of high-dose rate brachytherapy in Brazil.

Keywords: High-dose rate brachytherapy, Cancer, Neoplasms

We analyzed the dose area product (DAP) of 12 patients submitted to videofluoroscopic swallowing studies. The aim of this study was to establish, in a preliminary manner, the values of radiation exposure for patients submitted to this type of examination. A Diamentor equipment was used to register the cumulative radiation doses emitted by the x-ray tubes. Two different rooms with identical radiological equipment were used to collect the data. The protocol used was rigorously the same and the same experienced professional performed the examinations. DAP's values for the three phases (oral, pharyngeal and esophagogastric) of the videofluoroscopic swallowing study were, for the room A (7 patients), 4,101 cGy.cm², DAP/min. = 577 cGy.cm²/min., and for the room B (5 patients), 804 cGy.cm², DAP/min = 119 cGy.cm²/min. These different results were obtained from patients of the same height and weight, using the same examination time (around 7 minutes) for all patients. We concluded that the data showing doses five times lower in room B are more reliable that those obtained for room A and that DAP and DAP/min. are good elements to inform patient doses imparted by videofluoroscopic swallowing examination. We believe that the high dose differences observed between the two groups are due to lack of calibration of the x-ray equipment, since unfortunately "quality assurance programs" are not routinely implemented.

Keywords: Dosimetry, Videofluoroscopy, Dose area product (DAP), Swallowing

OBJECTIVE: The aim of this work is to discuss the effects of the main parameters that influence image quality and the entrance skin dose. MATERIALS AND METHODS: The pediatric chest radiographs of three different Institutions were evaluated. Tests on all x-ray equipment were performed. The skin entrance dose was assessed using thermoluminescent dosimeters. RESULTS: Only one of all x-ray equipments tested was in good operation condition. The average skin entrance dose was: (0.222 ± 0.088) mGy for children under 1 year, (0.28 ± 0.11) mGy for 1.1 to 4 years, (0.26 ± 0.13) mGy for 4.1 to 6 years, (0.23 ± 0.13) mGy for 6.1 to 10 years and (0.26 ± 0.25) mGy for older than 10 years. CONCLUSION: The results showed that the average skin entrance doses are higher than the European Community Commission reference levels and other values reported in the literature. We recommend the implantation of quality assurance programs to reduce skin entrance doses and for obtaining good quality images.

Keywords: Pediatric radiology, Skin dose, Reference levels

The authors report a case of a patient with an extensive angiosarcoma of the scalp that was submitted only to radiotherapy with a combination of orthovoltage roentgentherapy and high-dose rate brachytherapy, using a mould. The clinical and technical features as well as the therapeutic outcome are presented, and the usefulness and peculiarities of high-dose rate brachytherapy for this particular indication is discussed. A comparative analysis of the difficulties and limitations of employing low-dose rate brachytherapy is also presented. The authors concluded that high-dose rate brachytherapy might be an useful, practical and safe option to treat neoplastic lesions of the scalp, and an alternative treatment to electrontherapy.

Keywords: High-dose rate brachytherapy, Mould, Scalp angiosarcoma

Human mistakes are an important source of errors in radiotherapy and may occur at every step of the radiotherapeutic planning and treatment. To reduce this level of uncertainties, several specialized organizations have recommended a comprehensive quality assurance program. In Brazil, the requirement for these programs has been strongly stressed, and most radiotherapy services have pursued this goal regarding radiation units and dosimetry equipment, as well as the verification of the calculations of the patient's dose and the revision of the plan charts. As a contribution to the improvement of quality control, we present some recommendations to avoid failure of treatment due to error in the delivered dose, such as redundant check of the manual or computer calculations, weekly check of the total dose for each patient, and prevention of inadvertent access to any safety system of the equipment by any staff member that is only supposed to operate the machine. Moreover, the use of a computerized treatment record and verification system should be considered in order to eliminate errors due to incorrect selection of the treatment parameters, in a daily basis. We report four radioactive incidents with patient injuries occurred throughout the world and some gross errors of dose.

Keywords: Radiotherapy. Treatment. Dose errors. Quality assurance.

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.

OBJECTIVE: To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. MATERIALS AND METHODS: Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. RESULTS: Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. CONCLUSION: The present study contributes to verify the equipment conformity as regards dose values and image quality.

Keywords: Mean glandular dose; Image; Direct radiography.

OBJECTIVE: In the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231) cells line and radiosensitive peripheral blood mononuclear cells (PBMC), as a function of different radiation doses, dose rates and post-irradiation time kinetics, with a view to the interest of clinical radiotherapy. MATERIALS AND METHODS: The cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min^-1 and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. RESULTS: Radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDA-MB-231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48-72 hours post-radiation. CONCLUSION: Low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer.

Keywords: Radiation; MDA-MB-231; PBMC; LET; Dose; Dose rate.

OBJECTIVE: To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters. MATERIALS AND METHODS: Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A - 551 studies) and three months after (group B - 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDI_vol per phase, mean DLP per phase, and mean DLP per scan. RESULTS: A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDI_vol per phase, DLP per phase and DLP per scan (p < 0.001). CONCLUSION: The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.

Keywords: Computed tomography; Abdomen; Contrast media; Radiation dose; Radiation protection.

OBJECTIVE: To determine whether dual-energy computed tomography (DECT) of the chest can be performed at a reduced radiation dose, with an emphasis on images generated with post-processing techniques. MATERIALS AND METHODS: In 21 patients undergoing DECT of the chest in a dual-source scanner, an additional image series was acquired at a reduced radiation dose. Four thoracic radiologists assessed both image series for image quality, normal thoracic structures, as well as pulmonary and mediastinal abnormalities, on virtual monochromatic images at 40 keV and 60 keV. Data were analyzed with Student’s t-test, kappa statistics, analysis of variance, and the Wilcoxon signed-rank test. RESULTS: The overall image quality of 60 keV virtual monochromatic images at a reduced radiation dose was considered optimal in all patients, and no abnormalities were missed. Contrast enhancement and lesion detection performance were comparable between reduced-dose images at 40 keV and standard-of-care images at 60 keV. The intraobserver and interobserver agreement were both good. The mean volumetric CT dose index (CTDIvol), size-specific dose estimate (SSDE), dose-length product (DLP), and effective dose (ED) for reduced-dose DECT were 3.0 ± 0.6 mGy, 4.0 ± 0.6 mGy, 107 ± 30 mGy.cm, and 1.5 ± 0.4 mSv, respectively. CONCLUSION: DECT of the chest can be performed at a reduced radiation dose (CTDIvol < 3 mGy) without loss of diagnostic information.

Keywords: Radiation dose reduction; Dual energy computed tomography; Monochromatic images.

Os nervos cranianos representam extensões das estruturas funcionais do cérebro que cruzam a cabeça e o pescoço. Eles estão ligados a diferentes estruturas cranianas e se relacionam com diversas doenças. Uma compreensão profunda de sua complexa anatomia e aparência normal de imagem permite ao examinador identificar e caracterizar com mais precisão as anormalidades. A ressonância magnética com contraste é uma importante ferramenta para avaliar essas estruturas, especialmente as sequências tridimensionais de precessão livre de estado estacionário, que proporcionam alta resolução espacial e de partes moles, apesar da fina espessura dos nervos cranianos. Na maioria dos casos, os achados de imagem são inespecíficos, e uma anamnese completa, exame físico dirigido e testes laboratoriais são necessários para estreitar o diagnóstico diferencial. Este ensaio iconográfico ilustra e discute doenças congênitas, traumáticas e vasculares dos nervos cranianos, mostrando imagens em uma abordagem fisiopatológica.

Keywords: Neuroimagem/métodos; Radiologia/métodos; Ressonância magnética/métodos; Nervos cranianos/diagnóstico por imagem.