Setting up regional diagnostic reference levels for pediatric computed tomography in Latin America: preliminary results, challenges and the work ahead.

We established a framework for collecting radiation doses for head, chest and abdomen-pelvis computed tomography (CT) in children scanned at multiple imaging sites across Latin America with an aim towards establishing diagnostic reference levels (DRLs) and achievable doses (ADs) in pediatric CT in Latin America. Our study included 12 Latin American sites (in Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Honduras and Panama) contributing data on the four most common pediatric CT examinations (non-contrast head, non-contrast chest, post-contrast chest and post-contrast abdomen-pelvis). Sites contributed data on patients' age, sex and weight, scan factors (tube current and potential), volume CT dose index (CTDIvol) and dose length product (DLP). Data were verified, leading to the exclusion of two sites with missing or incorrect data entries. We estimated overall and site-specific 50th (AD) and 75th (diagnostic reference level [DRL]) percentile CTDIvol and DLP for each CT protocol. Non-normal data were compared using the Kruskal-Wallis test. Sites contributed data from 3,934 children (1,834 females) for different CT exams (head CT 1,568/3,934, 40%; non-contrast chest CT 945/3,934, 24%; post-contrast chest CT 581/3,934, 15%; abdomen-pelvis CT 840/3,934, 21%). There were significant statistical differences in 50th and 75th percentile CTDIvol and DLP values across the participating sites (P<0.001). The 50th and 75th percentile doses for most CT protocols were substantially higher than the corresponding doses reported from the United States of America. Our study demonstrates substantial disparities and variations in pediatric CT examinations performed in multiple sites in Latin America. We will use the collected data to improve scan protocols and perform a follow-up CT study to establish DRLs and ADs based on clinical indications.

Pulmonary imaging in coronavirus disease 2019 (COVID-19): a series of 140 Latin American children.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which resulted in the worldwide coronavirus disease 2019 (COVID-19) pandemic of 2020, has particularly affected Latin America. OBJECTIVE: The purpose of the study was to analyze the imaging findings of pulmonary COVID-19 in a large pediatric series. MATERIALS AND METHODS: Children with SARS-CoV-2 infection confirmed by either quantitative reverse transcription-polymerase chain reaction from nasopharyngeal swabs or presence of circulating immunoglobulin M (IgM) antibodies and who underwent chest radiograph or CT or both were included in this retrospective multicenter study. Three pediatric radiologists independently reviewed radiographs and CTs to identify the presence, localization, distribution and extension of pulmonary lesions. RESULTS: We included 140 children (71 female; median age 6.3 years, interquartile range 1.6-12.1 years) in the study. Peribronchial thickening (93%), ground-glass opacities (79%) and vascular engorgement (63%) were the most frequent findings on 131 radiographs. Ground-glass opacities (91%), vascular engorgement (84%) and peribronchial thickening (72%) were the most frequent findings on 32 CTs. Peribronchial thickening (100%), ground-glass opacities (83%) and pulmonary vascular engorgement (79%) were common radiograph findings in asymptomatic children (n=25). Ground-glass opacity and consolidation were significantly higher in children who needed intensive care admission or died (92% and 48%), in contrast with children with a favorable outcome (71% and 24%, respectively; P<0.05). CONCLUSION: Asymptomatic children and those with mild symptoms of COVID-19 showed mainly peribronchial thickening, ground-glass opacities and pulmonary vascular engorgement on radiographs. Ground-glass opacity and consolidation were more common in children who required intensive care admission or died.

Educacion y sociedad. Historia y diversidad cultural en la educacion boliviana

Contiene: Historia de la educacion y diversidad cultural pueblos prehispanicos - Cultura y educacion en la epoca colonial - Cultura independentista y educacion en el siglo XIX - Diversidad cultural y procesos educativos en el siglo XX.

Educacion y sociedad. Sociedad, educacion y politicas educativas

Contiene: Sociedad, economia, politica y educacion - Indicadores de desarrollo humano en Bolivia - Politicas educativas en el cotexto de la reforma educativa - Politicas educativas especificas.

Levitador magnetico / sss

Este trabajo presenta herramientas de diseño e implementacion de un Levitador magnetico cuyo proposito es servir como ayuda en la enseñanza del control automatico y la ilustracion del fenomeno de la levitacion magnetica, se ha diseñado un levitador magnetico de bola, el control este sistema se ha implementado analogicamente con circuitos basados en amplificadores operacionales. Este equipos puede servir como banco de pruebas la experimentacion de tecnicas de modelo de control...