Table 4.

The computed tomography (CT) numbers and their variations in the centre and peripheral of the phantom

Scanners	Head scan			Neck scan
	CT number (HU)			CT number (HU)
	Centre of phantom	Mean of peripheral regions	Variation	Centre of phantom	Mean of peripheral regions	Variation
4-MDCT	2.6	0.5 ± 0.4	2.1 ± 0.4	–0.3	0.3 ± 0.6	0.6 ± 0.6
6-MDCT	0.9	0.3 ± 0.2	0.6 ± 0.2	1.2	1.6 ± 0.6	0.4 ± 0.6
16-MDCT	–0.4	0.6 ± 0.4	1.2 ± 0.4	–0.5	0.4 ± 0.3	0.9 ± 0.3
64-MDCT	0.1	0.4 ± 0.8	0.3 ± 0.8	–0.2	0.7 ± 0.5	0.9 ± 0.5