In this study the PAGAT polymer gel dosimeter was used for measurement and image analysis with MRI to investigate slice width dose profiles (SWDP), Computer Tomography Dose Index (CTDI100) and z-efficiency on multislice x-ray CT scanners. The measurements obtained using the polymer gel dosimeters were compared to conventional integrating dosimeters; a dedicated CT ionisation chamber and TLD for phantoms of various diameters.