Table 2. Summary of prostate motion per timestamp on log files, the worst-case motion during tracking irradiation simulated in this study in the SI, RL, and AP directions and the 3D vector length.

	Intra-fraction motion (mm)				Worst-case motion (mm)
	SI	RL	AP	3D vector length	SI	RL	AP	3D vector length
Mean	−0.15	−0.09	0.79	2.53	0.03	−0.01	−0.02	0.88
SD	2.06	0.81	1.99	1.77	0.91	0.35	1.04	1.25
Max	9.25	3.15	9.73	13.56	5.81	2.83	10.13	13.73
Min	−9.43	−3.73	−6.87	0.10	−9.48	−3.09	−8.68	0.00
RMSE	2.06	0.82	2.15	-	0.91	0.35	1.04	-

The sign of intra-fraction motion in the SI, RL, and AP directions is consistent with the coordinates in Fig 2.

SI, superior-inferior; RL, right-left; AP, anterior-superior; 3D, three-dimensional; SD, standard deviation; Max, maximum; Min, minimum; RMSE, root mean square error.