Table 1.

Comparison of CTDI₁₀₀ (mGy∕100 mA s) obtained from measurements and simulations for head and body CTDI phantoms and 10 mm collimation for the tube potentials of 80, 100, and 120 kVp.

Collimation width (mm)	Phantoms	Measurement position in CTDI phantoms	Measured CTDI100 (mGy∕100 mA s)	Simulated CTDI100 (mGy∕100 mA s)	Percent error (%)
80 kVp	Head phantom	Center	5.3	5.1	−4.1
		12 o’clock	6.9	6.6	−3.3
		3 o’clock	6.5	6.3	−3.4
		6 o’clock	5.7	5.7	−0.3
	Body phantom	Center	1.0	0.9	−5.7
		12 o’clock	2.7	2.5	−6.2
		3 o’clock	2.4	2.4	1.1
		6 o’clock	2.1	2.1	0.4
100 kVp	Head phantom	Center	9.7	9.2	−5.2
		12 o’clock	11.8	11.4	−3.7
		3 o’clock	11.3	10.8	−4.3
		6 o’clock	9.9	9.9	−0.3
	Body phantom	Center	2.1	2.0	−6.5
		12 o’clock	5.0	4.6	−7.2
		3 o’clock	4.6	4.6	0.1
		6 o’clock	4.0	4.0	0.0
120 kVp	Head phantom	Center	13.8	13.1	−5.2
		12 o’clock	16.8	15.6	−7.2
		3 o’clock	15.6	14.9	−4.6
		6 o’clock	13.6	13.6	0.1
	Body phantom	Center	3.4	3.2	−7.9
		12 o’clock	7.4	6.7	−8.6
		3 o’clock	6.8	6.7	−2.0
		6 o’clock	6.0	5.9	−1.0