Table 1.

The intra‐fractional CTV displacement in PMRM‐IMRT for left‐sided breast cancer measured by 4D CT.

Paramaters	X (mm)	Y (mm)	Z (mm)
A1	0.2 ± 0.2	0.4 ± 0.1	0.4 ± 0.4
A2	0.3 ± 0.3	0.5 ± 0.1	0.5 ± 0.4
A3	0.3 ± 0.3	0.4 ± 0.8	0.7 ± 0.5
B1	0.2 ± 0.4	0.5 ± 0.1	0.6 ± 0.6
B2	0.4 ± 0.4	0.5 ± 1.0	0.6 ± 0.6
B3	0.4 ± 0.4	0.5 ± 1.0	0.6 ± 0.5
C1	0.2 ± 0.3	0.6 ± 1.1	0.7 ± 0.7
C2	0.5 ± 0.4	0.5 ± 1.0	0.3 ± 0.3
C3	0.4 ± 0.3	0.5 ± 0.9	0.5 ± 0.4

The intersection points (A1, A2, A3, B1, B2, B3, C1, C2, and C3) of the three lateral and the three longitudinal lines were marked with ink and radiopaque metal beads on the surface of the left chest wall. The displacement of the intersection points was measured to quantify the position change of the left‐sided chest wall. X, Y, and Z values indicated the displacement of the intersection points in x (laterally), in y (longitudinally), and in z coordinate axis (vertically), respectively. Data presented as mean ± standard deviation(mm). Abbreviations: PMRM‐IMRT = post modified radical mastectomy intensity‐modulated radiotherapy. 4D CT = four‐dimensional computed tomography.