Effect of Low Tube Voltage on Image Quality, Radiation Dose, and Low-Contrast Detectability at Abdominal Multidetector CT: Phantom Study

Table 3

The subjective scores of LCD.

Tube voltage/tube current-time product	Subjective score of LCD		Mean	𝑃 value*
	Observer A	Observer B
80 kV/150 mAs	3.0 (1.0, 1.0, 1.0)	3.0 (1.0, 1.0, 1.0)	1.00±0.00	0.001
80 kV/200 mAs	3.0 (1.0, 1.0, 1.0)	3.0 (1.0, 1.0, 1.0)	1.00±0.00	0.001
80 kV/250 mAs	3.0 (1.0, 1.0, 1.0)	3.0 (1.0, 1.0, 1.0)	1.00±0.00	0.001
80 kV/300 mAs	5.0 (1.0, 2.0, 2.0)	6.0 (2.0, 2.0, 2.0)	1.83±0.41	0.001
80 kV/350 mAs	6.0 (2.0, 2.0, 2.0)	6.0 (2.0, 2.0, 2.0)	2.00±0.00	0.001
80 kV/400 mAs	7.0 (2.0, 3.0, 2.0)	7.0 (2.0, 3.0, 2.0)	2.33±0.52	0.019
80 kV/450 mAs	7.0 (3.0, 2.0, 2.0)	7.0 (2.0, 2.0, 3.0)	2.33±0.52	0.019
80 kV/500 mAs	8.0 (2.0, 3.0, 3.0)	6.0 (2.0, 2.0, 2.0)	2.33±0.52	0.019
80 kV/550 mAs	8.0 (3.0, 3.0, 2.0)	8.0 (3.0, 2.0,3.0)	2.67±0.52	0.138
80 kV/600 mAs	9.0 (3.0, 3.0, 3.0)	8.0 (2.0, 3.0, 3.0)	2.83±0.41	0.317
80 kV/650 mAs	9.0 (3.0, 3.0, 3.0)	9.0 (3.0, 3.0, 3.0)	3.00±0.00	1.000
120 kV/300 mAs	9.0 (3.0, 3.0, 3.0)	9.0 (3.0, 3.0, 3.0)	3.00±0.00	—

*The 𝑃 values are those obtained with 80 kV at the 150–650 mAs settings compared with the values obtained with 120 kV and 300 mAs. There was good agreement between observer A and observer B in regard to subjective assessment of LCD (𝜅=0.67).