Key points are not available for this paper at this time.
To investigate the effects of tube voltage and phantom diameter on noise inhomogeneity of computed tomography (CT) image. This study used a step-wedge water cylindrical phantom with four diameters (i.e., 8, 16, 24, and 32 cm). The phantom was scanned with GE 128- Slice CT scanner with tube voltage variation of 80, 100, 120, and 140 kV. Noise inhomogeneity was measured using IndoQCT software. The noise inhomogeneity measurement was started with creating noise maps on the image with kernel size of 11 pixels. After that, multiple region of interests (ROIs) with size of 15 pixels were placed at 85% of image area. The noise inhomogeneity was determined as difference between the highest and the lowest noises from each ROI. : It was found that the highest noise inhomogeneity is at phantom diameter of 32 cm and tube voltage of 80 kV (14.00 ± 0.93 HU), and the lowest noise inhomogeneity is at phantom diameter of 8 cm and tube voltage of 140 kV (0.40 ± 0.02 HU). The trends of the tube voltage and phantom diameter on noise inhomogeneity were similar to the trends of the noise level, i.e., noise inhomogeneity increases with increasing phantom diameter and with decreasing tube voltage. Effects of variations of tube voltage and phantom diameter on the noise inhomogeneity has been investigated. Trends of the noise inhomogeneity due to tube voltage and phantom diameter are the same as trends of the noise level.
Kharisma et al. (Tue,) studied this question.