The study's primary goal was to compare radiation exposure in two different positions during chest x rays in children. It was conducted from June/2014 to July/2015, and included children from 0 to12 years old staying at the Pediatric Intensive Care Unit at the Instituto de Cardiologia de Porto Alegre, Brazil, with chest x ray requests during ICU stay. They were randomized to two groups: during the x ray, one group was positioned with the thyroid facing the anode end, and the other group was positioned with the thyroid facing the cathode end.