Table 2.

Comparison of the ICRP 60-based age-specific k-factors between the EG based on stylised phantoms and the current study (NCI) based on the ICRP reference phantoms. The k-factors for adult head and neck and paediatric scans assume use of the head CTDI phantom (16 cm). All other k-factors assume use of the body CTDI phantom (32 cm). The percent difference (% diff) was calculated as (NCI − EG)/EG × 100.

Scan type	0-y-old			1-y-old			5-y-old			10-y-old			Adult
	NCI	EG	% diff	NCI	EG	% diff	NCI	EG	% diff	NCI	EG	% diff	NCI	EG	% diff
Head and neck	0.012	0.013	−6.2	0.008	0.009	−5.7	0.006	0.006	12.1	0.005	0.004	9.1	0.003	0.003	−1.9
Head	0.009	0.011	−16.5	0.006	0.007	−10.6	0.004	0.004	6.4	0.003	0.003	−8.7	0.002	0.002	−26.7
Neck	0.021	0.017	23.3	0.012	0.012	0.3	0.009	0.011	−19.3	0.006	0.008	−19.5	0.004	0.006	−26.3
Chest	0.045	0.039	14.5	0.029	0.026	12.0	0.021	0.018	16.7	0.015	0.013	12.3	0.018	0.014	27.8
AP	0.046	0.049	−5.2	0.031	0.030	4.2	0.022	0.020	10.9	0.015	0.015	−0.5	0.018	0.015	22.4
CAP	0.043	0.044	−2.3	0.029	0.028	3.6	0.021	0.019	10.3	0.014	0.014	2.6	0.018	0.015	17.2