An Approach to Establishing Diagnostic Reference Levels in Interventional Pediatric Cardiology from Different Regions of Brazil.

Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma-area product-PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups.

Characterization of the imaging settings in screening mammography using a tracking and reporting system: A multi-center and multi-vendor analysis.

A tracking and reporting system was developed to monitor radiation dose in X-ray breast imaging. We used our tracking system to characterize and compare the mammographic practices of five breast imaging centers located in the United States and Brazil. Clinical data were acquired using eight mammography systems comprising three modalities: computed radiography (CR), full-field digital mammography (FFDM), and digital breast tomosynthesis (DBT). Our database consists of metadata extracted from 334,234 images. We analyzed distributions and correlations of compressed breast thickness (CBT), compression force, target-filter combinations, X-ray tube voltage, and average glandular dose (AGD). AGD reference curves were calculated based on AGD distributions as a function of CBT. These curves represent an AGD reference for a particular population and system. Differences in AGD and imaging settings were attributed to a combination of factors, such as improvements in technology, imaging protocol, and patient demographics. The tracking system allows the comparison of various imaging settings used in screening mammography, as well as the tracking of patient- and population-specific breast data collected from different populations.

Mammographic system performance using an image reading qualification method.

Our goal was to evaluate mammography systems based on microcalcifications and fiber detection using a statistical phantom (ALVIM, model TRM 18-209, Nuclear Associates) image readings. ALVIM phantom images were acquired under diverse exposure conditions with various equipments, and 5 radiologists with similar expertise reported their findings. The reading performance in the detection of microcalcifications and fibers of different sizes was measured by simulation of equivalent breast tissue with 4.5 and 6.5 cm thicknesses. We determined kappa values, ROC curves, and kappa probability density and detection rates with dedicated software developed locally. The statistical results generated three kappa (K) ranges that allowed quantification of the detection performance at three quality levels: unacceptable (K ≤ 0.64), achievable (K ≥ 0.70) and acceptable (0.64 < K < 0.70). An extensive database permitted a comparison of the reading performance with 99.5% reliability (p < 0.005). The comparison showed a larger dispersion of the kappa values for the images with low contrast generated with mammography equipment which was not properly calibrated, showing that the method is able to detect the performance changes associated with the loss of image quality.

Exposiçäo à radiaçäo no período pré-natal / Radiation exposure in the prenatal period

O conhecimento dos profissionais da saúde sobre os riscos da exposiçäo pré-natal é importante para a justificaçäo e uso correto da radiaçöes ionizantes em pacientes gestantes. O presente trabalho reúne dados recentes publicados na literatura científica e por organizaçöes internacionais sobre os efeitos, riscos, e limiares de dose nos diferentes estágios de desenvolvimento do embriäo e feto. A exposiçäo a radiaçäo no estágio da pré-implantaçäo normalmente induz a morte fetal ou completo reparo do dano causado. Durante o período da organogênese, o risco de morte fetal diminui substancialmente, ao passo que o risco de malformaçäo congênita aumenta a partir de um limiar de dose de 0,1 Gy. Durante o estágio de crescimento fetal, o risco de retardamento, anormalidades do sistema nervoso, e o risco de câncer infantil podem ser significantes. Doses fetais provenientes da maioria dos procedimentos de radiodiagnósticos säo abaixo dos limiares de dose para efeitos determinísticos, e näo têm demonstrado impactos no crescimento e desenvolvimento fetal, e raramente justifica o aborto terapêutico. Entretanto, cada caso deve ser avaliado individualmente e os riscos informados a paciente. Na terapia com radiaçäo, a dose fetal pode ultrapassar os limiares de dose, contudo, com o uso de proteçöes adicionais pode-se obter importante reduçäo na dose. Para o controle da exposiçäo ocupacional da gestante, controles adicionais têm sido estabelecidos para a proteçäo do concepto.

Processamento para simulaçäo da nitidez de imagens radiográficas para diversos sistemas de registro da imagem / Processing to clearness simulation of radiographic images to several image register system

Este trabalho descreve um método para prever a influência do sistema de registro sobre a nitidez de imagens radiográficas por simulação computacional, procurando apresentar previamente a imagem a ser obtida para cada tipo de filme ou combinação écran-filme usada durante a exposição.

This work describes a method aimed to predict the influence of the record system on radiographic images sharpness by computer simulation. This method is intended to previously show the image to be obtained for each type of film or screen-film combination used during the exposure. l