Performance of longitudinal and volumetric tube current modulation in a 64-slice CT with different choices of acquisition and reconstruction parameters.

Aim of the study was to evaluate the performance of a tube current modulation (TCM) system ((SURE)Exposure 3D). On a 64 detector-row CT scanner (Aquilion 64, Toshiba), performance of fixed tube current, longitudinal TCM, and volumetric TCM acquisitions were assessed. A homogeneous cone-shaped phantom and an anthropomorphic phantom were used. Tube current and noise profiles were quantitatively analysed by box and whisker plots when phantom size, acquisition, and reconstruction parameters were varied. At similar median noise, fixed tube current scanning showed a noise range of 16.8-38.3 HU, while longitudinal TCM showed a range of 19.4-31.4 HU and volumetric TCM showed an even lower range of 20.7-28.7 HU. When acquisitions resulting in similar image quality (noise) were compared, the use of volumetric compared to longitudinal TCM resulted in a variable radiation dose reduction up to 6.6%. In conclusion, (SURE)Exposure 3D resulted in more uniform image quality at a lower dose. Volumetric TCM shows improved results over longitudinal TCM.