Image quality evaluation for a robot-driven C-arm CT system

Abstract

The aim of this study was an image quality evaluation for a state-of-the-art robot-driven C-arm CT system. CT values, noise and homogeneity as well as the spacial resolution in three dimensions were evaluated for different pixel binning and acquisition modes. A new feature for imaging large volumes (LV scans) which exceed the field of view of 24 cm in diameter was evaluated and compared in terms of image quality and resolution to standard FD-CT imaging with the same system. Standard FD-CT imaging achieved a maximum resolution of 3.5 lp/mm (10 % MTF value) for 1 × 1 pixel binning. Spacial resolution for LV scans was reduced by about 10%. Mean CT values in water (ideally corresponding to 0 HU) were 17 HU with a standard deviation of 22 HU. Homogeneity calculated to -11 and -8 HU for 220° partial scans and 360° full scans, respectively. Contrast evaluation showed a clear detectability of details of 30 HU contrast and 4 mm diameter (at CTDIW = 48.6 mGy, slice thickness of 0.48 mm). LV scans showed comparable homogeneity and low-contrast detectability. In conclusion, the robot-driven C-arm CT system offered the same performance as standard FD-CT. © 2009 Springer-Verlag.