Nonrigid Registration of Lung CT Images Based on Tissue Features

Table 3

Errors of 15 representative points using the proposed and conventional SIFT.

Point index	Point coordinates in template image (mm)	Point coordinates in target image (mm)	Errors of conventional SIFT (mm)	Errors of proposed method (mm)
1	191.6, 224.7, 21.0	191.6, 219.8, 40.5	7.1, −1.9, 10.5	2.2, 2.4, 3.0
2	294.6, 234.3, 21.0	299.5, 227.3, 51.0	4.2, −4.2, 18.0	0.7, 1.4, 3.0
3	287.6, 265.1, 45.0	288.3, 260.9, 64.5	1.6, 1.4, 0.0	0.7, 0.0, 0.0
4	189.4, 246.9, 55.5	186.0, 242.0, 72.0	−0.1, −2.1, 1.5	0.6, 0.0, 0.0
5	309.2, 299.1, 54.0	305.7, 299.8, 70.5	−1.4, 0.7, 1.5	−0.7, −0.7, 0.0
6	284.1, 353.3, 82.5	280.7, 351.2, 82.5	−0.6, 0.6, −1.5	−1.0, −0.4, −1.5
7	188.8, 297.0, 81.0	184.7, 295.6, 90.0	1.4, 2.1, 0.0	0.0, −0.7, 0.0
8	280.7, 266.4, 73.5	279.3, 265.0, 90.0	−0.7, 3.5, 3.0	0.0, 0.0, 1.5
9	289.7, 306.0, 93.0	286.2, 303.9, 100.5	−0.7, −0.7, 0.0	0.0, −0.7, 0.0
10	188.8, 236.5, 96.0	186.1, 233.7, 106.5	−2.7, −2.1, 6.0	−0.7, −0.7, 1.5
11	309.9, 303.3, 106.5	305.7, 304.0, 111.0	−3.5, 1.4, 0.0	−0.7, −0.6, 0.0
12	191.6, 279.6, 109.5	187.5, 278.9, 114.0	0.1, 1.4, 0.0	0.1, 0.7, 0.0
13	262.6, 346.4, 117.0	257.7, 341.5, 117.0	0.0, −3.4, 0.0	2.1, 0.0, 0.0
14	190.9, 271.9, 123.0	190.2, 269.9, 123.0	0.0, −0.7, 0.0	0.0, −0.7, 0.0
15	319.6, 263.6, 135.0	318.9, 269.9, 139.5	0.0, 2.1, 0.0	0.0, −1.4, 0.0