[en] Acute lower respiratory tract infection (ALRI), primarily pneumonia, is the leading cause of childhood death in developing countries. The increasing incidence of antimicrobial resistance and the high cost of vaccines lead to considering the first strategy to reduce pneumonia deaths the early detection of the disease. Case management begins with the clinical examination and may continue with the prescription of a chest x-ray. Consequently, the radiograph should meet quality standards, and radiologists and paediatricians must know how to interpret the images. Special attention should be paid on patient dose due to children radiosensitivity, high frequency and chest x rays rejection rate. This paper is a retrospective study of chest radiographs performed in 5731 children with clinical diagnosis of ALRI assisted in three Uruguayan hospitals during the three year investigation supported by the Division of Vaccines and Immunization of the Pan American Health Organization (PAHO) that had the aim of estimating the burden of pneumonia (from 2001 to 2004). It is analyzed the prescription of radiographs during the diagnosis and in later controls (2220 children assisted in two of the three hospitals). Patient doses are estimated from technical parameters and equipment specifications. The investigation also analyzes patient doses that could have been avoided if paediatricians had managed the disease according to the established protocols. Results show that 82.4 % of chest X-rays diagnosed pneumonia and that some children underwent up to ten radiographs. Significant differences were found in patient dose in the three hospitals, concluding that education on image quality on chest radiographs of radiologists, paediatricians and radiological technologists is the first and best tool for the earlier diagnosis of pneumonia in children and for the application of Radiation Protection (RP) principles in medical exposures. (author)