Table 2. Regression coefficients for relation of grey level variation to MAR, position and peak kilovoltage.

		Regression coefficient (SE)
Reference (peripheral without MAR)		Profile AB	Profile BC	Profile CA
	Level (kVp=70)	47.61 (1.50) *	83.63 (2.09) *	64.40 (2.06) *
	Slope	−0.40 (0.09) *	−0.83 (0.12) *	−0.57 (0.10) *
Factor	Effect
MAR	Change in level (kVp=70)	−26.63 (1.73) *	−9.40 (2.41) **	−43.80 (2.92) *
Central position	Change in level (kVp=70)	−2.05 (1.73)	1.82 (2.41)	−11.90 (2.92) **
	Change in slope	0.30 (0.12) ***	0.39 (0.17) ***	0.59 (0.15) **
MAR and central position	Change in level (kVp=70)			15.30 (4.12) **
R2		0.95	0.84	0.96

MAR, metal artefact reduction; SE, standard error.

* p≤0.001.

** p≤0.01.

*** p≤0.05.