Dosimetric Quantities for Computed Tomography Examinations of Paediatric Patients on the Thoracic and Abdominal Regions

Abstract

Computed Tomography (CT) is a high dose X ray imaging procedure and its use has rapidly increased in the last two decades fueled by the development of helical CT. The aim of this study is to present values of the dosimetric quantities for CT paediatric examinations of thoracic and abdominal regions. The protocols studied were those of chest, lung‐mediastine, chest‐abdomen, pulmonary high resolution and mediastine‐abdomen, which are the more common examinations performed at “Hospital Infantil de México Federico Gómez” in the thoracic‐abdominal region. The measurements were performed on a Siemens SOMATOM Sensation 16 CT Scanner and the equipment used was a CT pencil ionization chamber, connected to an electrometer. This system was calibrated for RQT9 CT beam quality. A PMMA head phantom with diameter of 16 cm and length of 15 cm was also used. The dosimetric quantities measured were the weighted air kerma index (Cw), the volumetric dose index (Cvol) and the CT air kerma–length product. It was found that the pulmonary high resolution examination presented the highest values for the Cw (31.1 mGy) and Cvol (11.1 mGy). The examination with the lowest values of these two quantities was the chest‐abdomen protocol with 10.5 mGy for Cw and 5.5 mGy for Cvol. However, this protocol presented the highest value for PKL,CT (282.2 mGy cm) when considering the average clinical length of the examinations.