Effective doses to patients from paediatric cardiac catheterization.

The Council Directive of the European Communities 97/43/Euratom requires dose assessment, especially for X-ray examinations of children and if high doses to the patient are involved. Both these aspects apply in cardiac catheterization and angiocardiography of children. Effective doses are a good indicator of radiation risk, particularly for leukaemia. Effective doses have been determined for 2114 infants and children undergoing cardiac catheterization from 1984 to 1996 at the University Hospital in Essen. Conversion factors (effective dose/dose-area product) were calculated based on direct dose-area product measurements for posteroanterior (PA) and lateral (Lat) projections as well as on patient records and examination details. The factors are calculated for eight age groups of children, taking into account the X-ray tube voltage for fluoroscopy and cine-film sequences, with and without zoom mode. Frequency distributions are presented for 2114 patients, for dose-area product, number of angiographic examinations (each combined with one cine-film sequence both PA and Lat) and for calculated effective doses. Highest effective doses are found in newborns (18.0 mSv and 6.5 mSv 90th and 50th percentiles, respectively) compared with adolescents of 15-21 years (8.0 mSv and 3.0 mSv 90th and 50th percentiles, respectively). Effective dose for cardiac catheterization is highest for newborns, in spite of lowest measured dose-area products, because the decreased value of the conversion factors overcompensates for the increase of dose-area product with age. This is especially important because of the higher tumour risk for equal effective dose for young children compared with adults.