Abstract. Computed Tomography (CT), jointly with interventional radiology, is considered a high dose radiological procedure, so that optimization of the dose is necessary. Exposure to ionizing radiation in pediatric CT is of particular interest because the children are up to ten times more radiosensitive than adults to the late genetic and somatic effects of radiation. The exposure and risk associated with ionizing radiation in CT is best characterized by the absorbed dose to each organ. LiF: Mg, Ti TLD are best suited for this purpose due to its characteristics such as high sensitivity, small size and its tissue equivalence. Results of "in vivo" dose measurements for three types of CT studies (skull, thorax and abdomen) using LiF: Mg,Ti TLDs are presented. These results indicate that lowest doses were obtained in skull studies while the highest were in abdomen studies.