Estimating the effective dose to children undergoing heart investigations--a phantom study.

The aim of the investigation was to assess the conversion factor (F) for derivation of effective dose from measured dose-area product (DAP) during radiological examination of congenital heart diseases. Two anthropomorphic phantoms corresponding to a 1-year-old and a 5-year-old child were irradiated at several projections to imitate irradiation conditions at heart examinations. Organ doses were measured using thermoluminescent dosimeters for calculation of mean organ doses and effective dose according to ICRP. DAP values were measured simultaneously. The conversion factor (F) was calculated from the ratio of effective dose (mSv) to DAP value (Gy cm2). The conversion factor (F) correlated strongly to the size of the phantom but less to the irradiation projection. However, at major beam angulation and at lateral projection F deviated note-worthily from that obtained at true or slightly angulated frontal views. Effective dose can therefore be estimated from the DAP values at heart investigation using two different F values. The following values are recommended for PA and lateral view respectively: for children weighing 7-11 kg, 1.8 and 1.4; for children weighing 15-26 kg 0.9 and 0.7.