Fast IMRT by increasing the beam number and reducing the number of segments

Radiation Oncology

Table 1 Quality parameters COV and S_D

Technique	MU_eff	Field	Segment	norm. COV	S_D/n	T (old)	T (new)	MU_eff	field	Segment	norm. COV	S_D/n	T (old)	T (new)	MU_eff	field	Segment	norm. COV	S_D/n	T (old)	T (new)
		#	#			[min]	[min]		#	#			[min]	[min]		#	#			[min]	[min]
	Patient Cases
	Prostate							Spine							Breast
DMPO 9	591	9	50	1.00	0	11.8	7.8 [7.4]	888	9	50	1.00	0	12.3	8.2 [8.8]	821	10	38	1.00	0	10.9 [10.4]	6.5
2-Step IMRT 9	466	9	38	1.02	0.1	10.2	6.1	755	9	44	1.05	0.4	11.9	7.2	898	10	30	1.03	0.8	10.1	6.2
2-Step IMRT 15	492	15	47	0.53	0	12.9	7.2	711	15	64	1.00	0.2	17.2	9.7	927	15	41	0.69	0.3	13.2	7.5
2-Step Fast								901	34	34	1.07	0.3	14.4	7.5 [7.1]	672	25	25	0.81	0.7	10.3 [10.5]	5.3
2-Step Fast*	468	23	23	0.73	0	9.3	4.7 [5.0]
DMPO Fast	378	23	23	1.31	0.8	5.7	4.5	565	36	36	1.46	1.1	8.9	7.1	377	25	25	3.49	5.3	9.7	4.9
	Phantom Case
	Quasimodo S4							Quasimodo S10							Quasimodo P10
DMPO 9	525	9	54	1.00	0.9	13.6	8.1 [8.0]	501	9	54	1.00	1.0	13.5	8.1	493	9	54	1.00	1.5	13.4 [13.3]	8.1
2-Step IMRT 9	507	9	40	1.01	0.9	13.6	8.1	526	9	45	0.76	0.8	11.8	7.1	508	9	40	0.82	1.0	10.7	6.5
2-Step IMRT 15	511	15	75	0.48	0	18.6	10.5	538	15	73	0.36	0	18.3	10.3	520	15	67	0.34	0	17.0	9.6
2-Step Fast	802	30	30	1.10	0.6	12.8	6.7 [6.6]	863	30	30	1.02	1.0	13.0	6.8	816	30	30	0.59	0.8	12.9 [12.9]	6.7
2-Step Fast*	504	30	30	1.14	0.6	11.8	6.0 [6.0]	581	30	30	0.74	0.7	12.0	6.1	554	30	30	0.54	0.5	12.1 [12.2]	6.2
DMPO Fast	401	30	30	9.1	6.0	11.5	5.7	397	30	30	21.3	7.9	11.5	5.7	393	30	30	28.2	8.0	11.5	5.7

Overview of the resulting quality parameters COV and SD of all plans used in the study (lower values correspond to better plans). n: number of objectives used to calculate the normalized quality index S_D /n. For prostate, spine, and breast cases, the reference achieves S_D = 0 by definition. T: delivery time calculated using Eq. (1), for an old linac with slow data handling and a new linac with fast data handling. Values in brackets: measured values.
S4: Elekta Synergy™ with 4 mm leaves (BeamModulator™), S10: Elekta Synergy™ with 10 mm leaves. P10: Siemens Primus™ with 10 mm leaves. The techniques are presented in detail in the text.

ISSN: 1748-717X