TABLE II.

Phase sorting of EPID images for four-dimensional dose reconstruction. EPID images acquired for the irradiation on the heterogeneous phantom were temporal-phase-sorted considering a single frame acquisition time of 0.0606 s, MLC travel duration of 0.85 s between segments, and phantom movement time of 4.5 s/cycle. Similar sorting was performed for the irradiation on the homogeneous phantom. Highlighted phases correspond to MLC travel duration.

Motion cycle	Phases (%)	Sorted image number	Subsum	Irradiation time (s)	Delivery timea (s)
1	10	7		0.42	0.42
	20	8	15	0.91	0.91
	30	7	22	1.33	1.33
	40	8	30	1.82	1.82
	50	7	37	2.24	2.24
	60	8	45	2.73	2.73
	70	7	52	3.15	3.15
	80	8	60	3.64	3.64
	90	7	67	4.06	4.06
	100	8	75	4.55	4.55
2	10	7	82	4.97	4.97
	20	8	90	5.45	5.45
	30				5.88
	40	1	91	5.52	6.36
	50	7	98	5.94	6.79
	60	8	106	6.42	7.27
	70	7	113	6.85	7.70
	80	8	121	7.33	8.18
	90	7	128	7.76	8.61
	100	8	136	8.24	9.09
3	10	7	143	8.67	9.52
	20	8	151	9.15	10.00
	30	7	158	9.58	10.42
	40	8	166	10.06	10.91
	50	7	173	10.48	11.33
	60	3	176	10.67	11.82
	70				12.24
	80	6	182	11.03	12.73
	90	7	189	11.45	13.15
	100	8	197	11.94	13.64
4	10	7	204	12.36	14.06
	20	8	212	12.85	14.55
	30	7	219	13.27	14.97
	40	8	227	13.76	15.45
	50	7	234	14.18	15.88
	60	8	242	14.67	16.36
	70	7	249	15.09	16.79
	80	8	257	15.58	17.27
	90	4	261	15.82	17.52
	100

^aDelivery time includes MLC travel time.