Patrik Rogalla MD, Presenter: Nothing to Disclose

Noga Emilie Rogalla MD, Abstract Co-Author: Nothing to Disclose

Alexander Lembcke MD, Abstract Co-Author: Nothing to Disclose

Thomas Elgeti MD, Abstract Co-Author: Nothing to Disclose

Brigitte Stoever, Abstract Co-Author: Nothing to Disclose

Bernd K. Hamm MD, Abstract Co-Author: Nothing to Disclose

The development of a simple formula to calculate the tube current setting in multislice CT and evaluation of the formula in a pediatric patient population.

Images from 67 multislice CT examinations (Toshiba Aquilion) through the abdomen (n=21), chest (n=37), and head (n=9) on patients with an age younger than 14 years of age (group I) were retrospectively analysed with regard to the selected mAs setting at 120 kV, body weight, and image noise impression. The results were used to create a formula that calculates the mAs setting based on the child’s body weight and body area to be scanned. 47 children were subsequently imaged with mAs settings calculated by the new formula (group II), and the resulting images were judged with respect to image noise: too high, acceptable, so low that mAs could have been dropped further.

There was no difference in average body weight between group I (15,4 kg) and II (15,6 kg, p>0.9). The derived formula was mAs = (body weight [kg] + 5) * f, with f = 1 for scans of the chest, 1.5 for the abdomen and 5 for the head. The image noise in the subsequent CT scans using mAs values calculated by the formula was judged adequate in 13/14 studies of the abdomen, 26/26 of the chest, and 7/7 of the head. In only one abdominal study, the image noise level was slightly too high without influencing the correct diagnosis.

The formula for mAs calculation seems to be suitable in multislice CT and may help in preventing accidental unnecessary radiation exposure in pediatric patients.

Rogalla, P, Rogalla, N, Lembcke, A, Elgeti, T, Stoever, B, Hamm, B, Calculation of Tube Current in Pediatric Multislice CT.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4416401.html