Table 3.

REF (relative ESD factors). The factors are the averages of the ratios of the ESDs measured on different phantoms based on Table 1.

		Relative ESD factors
(a) Alderson Rando phantom Examination	ALD/CHE	ALD/SKU	ALD/UNI	ALD/A31
AP abdomen	N/A	N/A	0.95	1.03
PA chest	1.09	N/A	0.96	1.04
AP chest	1.15	N/A	0.92	1.03
LAT chest	1.19	N/A	1	1.02
AP lumbar spine	N/A	N/A	1.09	0.96
LAT lumbar spine	N/A	N/A	1.56	1.44
LAT lumbo‐sacral joint	N/A	N/A	1.15	1.08
AP pelvis	N/A	N/A	1.20	1.02
PA skull	N/A	1.01	0.85	0.92
LAT skull	N/A	1.01	0.89	0.97
AP urinary tract	N/A	N/A	1.20	1.02

(b) Chest phantom Examination	CHE/ALD	Relative ESD factors CHE/UNI	CHE/A31
PA chest	0.92	0.83	0.95
AP chest	0.87	0.67	0.88
LAT chest	1.10	0.90	0.87

(c) Skull phantom Examination	SKU/ALD	Relative ESD factors SKU/UNI	SKU/A31
PA skull	0.99	0.83	0.92
LAT skull	0.99	0.88	0.95

		Relative ESD factors
(d) Uniform phantom Examination	UNI/ALD	UNI/CHE	UNI/SKU	UNI/A31
AP abdomen	1.05	N/A	N/A	0.94
PA chest	1.04	1.22	N/A	1.09
AP chest	1.09	1.58	N/A	0.87
LAT chest	1.22	1.12	N/A	1.02
AP lumbar spine	0.94	N/A	N/A	0.90
LAT lumbar spine	0.74	N/A	N/A	0.95
LAT lumbo‐sacral joint	0.89	N/A	N/A	0.95
AP pelvis	0.90	N/A	N/A	1.02
PA skull	1.18	N/A	1.21	1.09
LAT skull	1.12	N/A	1.14	1.08
AP urinary tract	0.90	N/A	N/A	0.92

		Relative ESD factors
(e) AAPM31 phantom Examination	A31/ALD	A31/CHE	A31/SKU	A31/UNI
AP abdomen	1	N/A	N/A	1.12
PA chest	0.96	1.05	N/A	0.92
AP chest	0.97	1.15	N/A	1.25
LAT chest	0.98	1.15	N/A	0.98
AP lumbar spine	1.04	N/A	N/A	1.14
LAT lumbar spine	0.77	N/A	N/A	1.07
LAT lumbo‐sacral joint	0.94	N/A	N/A	1.07
AP pelvis	1.01	N/A	N/A	1.06
PA skull	1.10	N/A	1.09	0.92
LAT skull	1.03	N/A	1.05	0.92
AP urinary tract	1.01	N/A	N/A	1.13

N/A means that the phantom in the denominator is not appropriate for that examination.