Table 2.

Phantom Pb concentrations calculated using the background subtraction method.

Standard phantom ppm	Lucite thickness
	0 mm	1 mm	2 mm	3 mm
0	−0.38 ± 0.8	−0.1 ± 1.3	−2.22 ± 2.1	3.31 ± 3.31
5	4.83 ± 0.86	3.57 ± 1.34	9.61 ± 2.19	7.37 ± 3.37
10	10.23 ± 0.9	10.5 ± 1.39	11.23 ± 2.19	17.83 ± 3.42
15	14.9 ± 0.94	13.3 ± 1.4	20.37 ± 2.27	13.39 ± 3.41
20	19.52 ± 0.97	19.17 ± 1.46	21.25 ± 2.27	17.37 ± 3.46
30	31.32 ± 1.06	30.09 ± 1.53	30.35 ± 2.36	32.34 ± 3.56
50	47.45 ± 1.17	52.76 ± 1.7	49.43 ± 2.48	48.54 ± 3.7
75	75.56 ± 1.33	77.44 ± 1.85	74.49 ± 2.65	74.34 ± 3.82
100	96.96 ± 1.44	108.65 ± 2.02	105.26 ± 2.84	101.73 ± 4.06