Table 2. Thorax Phantom.

AP and lateral dimensions, effective diameters calculated using phantom dimensions, and water equivalent diameters D_w calculated using CT images and CT localizer radiographs. Effective and water equivalent diameter values were normalized to D_w calculated from the CT images. The absolute value of D_w calculated using the CT image is shown in parentheses. (Adapted with permission from Wang et al. [8].)

Phantom	Phantom Size	Phantom Dimension (cm)		Effective Diameter (%)		Water Equivalent Diameter (%)
		AP	LAT	(AP + LAT)/2	$\sqrt{AP\times LAT}$	From CT Image**	From CT Localizer Radiograph
Tissue Equivalent Thorax Phantom	30 cm*	20	30	119.6	121.5	100 (20.9)	100.0
	35 cm*	25	35	109.9	112.5	100 (27.3)	100.7
	40 cm*	30	40	105.4	107.5	100 (33.2)	101.5
Anthro-pomorphic Phantom		21.6	31.8	104.3	112.1	100 (25.6)	100.0
Mean ± Standard Deviation				109.8 ±7.0%	113.4 ±5.9%	-	100.6 ±0.7%

AP = anteroposterior, LAT = lateral

^*Lateral width of the phantom

^**Absolute value in parenthesis (cm).