Radiation dose reduction in paediatric cranial CT

Background. There is no consensus about the optimal milliamperage-second (mAs) settings for computed tomography (CT). Most operators follow the recommended settings of the manufacturers, but these may not be the most appropriate settings. Objective. To determine whether a lower radiation dose technique could be used in CT of the paediatric brain without jeopardising the diagnostic accuracy of the images. Materials and methods. A randomised prospective trial. A group of 53 children underwent CT using manufacturer's default levels of 200 or 250 mAs; 47 underwent scanning at 125 or 150 mAs. Anatomical details and the confidence level in reaching a diagnosis were evaluated by two radiologists in a double-blinded manner using a Lt-point scoring system. Results. For both readers there was no statistically significant difference in the confidence level for reaching a diagnosis between the two groups. The 95 % confidence intervals and P values were -0.9-1.1 and 0.13 treader 1) and -1.29-1.37 and 0.70 treader 2), respectively. Reliability tests showed the results were consistent. Conclusions. The recommended level may not be the optimum setting. Dose reduction of 40 % is possible on our system in paediatric brain CT without affecting the diagnostic quality of the images.