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

Table 2

The CT numbers, image noise, and CNR obtained at each set of acquisition conditions.

Tube current-time product (mAs)	CT number		𝑃 value	Image noise		𝑃 value*	CNR		𝑃 value*
	120 kV	80 kV		120 kV	80 kV		120 kV	80 kV
150	56.12	27.56	<0.001	5.10	9.60	<0.001	0.89	0.62	<0.001
200	56.34	27.73	<0.001	4.45	8.20	<0.001	1.20	0.79	<0.001
250	56.21	28.17	<0.001	4.09	7.61	<0.001	1.46	0.87	0.006
300	56.76	28.35	<0.001	3.61	6.50	<0.001	1.73	1.04	0.029
350	56.93	28.21	<0.001	3.37	5.88	<0.001	1.95	1.00	0.025
400	56.77	28.41	<0.001	3.15	5.70	<0.001	1.97	1.04	0.028
450	56.69	28.43	<0.001	2.91	4.96	<0.001	2.11	1.07	0.031
500	57.00	28.36	<0.001	2.77	4.82	<0.001	2.29	1.19	0.042
550	56.78	28.68	<0.001	2.75	4.97	<0.001	2.21	1.38	0.224
600	57.14	28.78	<0.001	2.65	4.76	<0.001	2.33	1.40	0.272
650	57.14	28.86	<0.001	2.48	4.27	<0.001	2.47	1.53	0.501

*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.