Reference doses for paediatric computed tomography

Diagnostic reference levels appropriate to the peculiar conditions of exposure in CT have already been specified in relation to examinations on adult patients, utilising the dosimetric concepts of weighted computed tomography dose index (CTDIw) per slice in serial scanning or per rotation in helical scanning, and dose-length product (DLP) per complete examination. This methodology can also be applied to CT examinations on children, with reference dosimetry for all types of examination on children of all ages being based solely on measurements involving the smaller (16 cm diameter) of the two standard CT dosimetry phantoms. Some initial diagnostic reference levels for paediatric CT have been set on the basis of the rounded third quartiles of the dose distributions provided by a survey of typical practice at over 40 scanners from seven European countries. Values are presented in relation to three patient ages (<1 year, 5 y and 10 y) and five types of procedure.