Dose Distributions and Image Quality in Paediatric Colon Examinations: Assessment of Effective Dose and Conversion Coefficients

Abstract

Measurement of kerma-area product (KAP) can be part of a quality assurance programme aiming at optimisation of image quality with respec to radiation risk to the patient for examinations involvin both fluoroscopy and fluorography Effective dose (E) is often used as an indicator of radiatior risk. In this work evaluation of conversion coefficients from KAP to effective dose for pediatric double-contrast colon examinations has been performed. Two anthropomorphic phantoms corresponding to a 1 year and a 5 year old child were used. Complete examinations were performed with and without an added filter of 0.3 mm Cu. Effective dose was calculated using measurement results from TLDs inserted in the phantoms with simultaneous recording of the KAP values. Conversion coefficients are strongly dependent on radiation quality and patient size. The dependence on radiation quality is particularly strong for the small children. Effective dose can be reduced by about 50% with added filtration without impairing clinical image quality.