Dosimetric evaluation of a 256-slice computed tomography scanner

Purpose This study evaluated the effectiveness of patient dose reduction tools on a 256-slice computed tomography scanner (Brilliance iCT, Philips). Materials and methods The performance of the Brilliance iCT scanner was described in terms of cumulative dose and dose-normalised contrast-to-noise ratio (CNRD). The efficiency of automatic tube current modulation (Z-Dom and D-Dom), shaping filters (SmartShape and IntelliBeam) and asymmetric collimator (Eclipse) was evaluated using appropriate phantoms. Results The scattered radiation contribution from the peripheral regions to the cumulative dose is not negligible. The CNRD is 20 % better compared to a traditional 16-slice scanner, with a dose reduction of 40 %. The application of shaping filters decreases the dose in the peripheral regions. The application of D-Dom and Z-Dom modulations reduces the current–time product (mAs) values by 23 and 18 %, respectively, but they are not yet integrated. The over-ranging effect is not negligible, despite the use of an Eclipse asymmetric collimator. Conclusions Brilliance iCT dose reduction tools are efficient, but should be analysed carefully and used correctly.