The use of ionizing radiation in medicine is the main source of radiation exposure to population, of which the greatest contribution has the use of diagnostic radiology methods that use X-rays. The most common methods use relatively low energy X-rays (20-150 keV), so the delivered dose for the patient is superficial, it is mostly absorbed by the skin where it is measured. Dosimetry represents one of the key steps of ensuring quality control in diagnostic radiology by measuring the patient's dose for the purpose of optimizing the entire process for obtaining accurate diagnostic information and reducing radiation exposure. Dosimetry is the primary responsibility of a medical physicist involved in optimizing radiation protection using standard quality control protocols consisting of checking functions of radiological devices (patient dose evaluation, measurements of physical parameters of radiation, etc.). To ensure the optimal delivered dose, due to the increasing use of CT devices for diagnostic purposes, in KBC Split was conducted an annual CT protocol of quality control to reduce the patient's dose in order to demonstrate the importance of quality assurance program.