Treatment planning comparison of volumetric modulated arc therapy employing a dual-layer stacked multi-leaf collimator and helical tomotherapy for cervix uteri

Table 1 Summary of the dose volume histogram analysis for the target volumes. Data are presented for the node positive and node negative patients

Parameter	Objective	Halcyon (H)	Helical Tomotherapy (HT)	Difference (H-HT)	p
Node Positive
PTV45
V_95% [%]	≥95	99.1 ± 1.2	98.3 ± 0.9	0.8 ± 0.9	0.02
D_1% [%]	≤130^b	122.9 ± 1.7	123.2 ± 3.8	−0.3 ± 2.8	0.73
Homog [%]	^a	2.8 ± 3.1	3.3 ± 2.1	−0.5 ± 2.6	0.002
ITV45
D_99% [%]	≥95	100.1 ± 1.2	97.6 ± 1.3	2.5 ± 1.1	< 0.001
D_50% [Gy]	45.0	45.0 ± 0.4	45.8 ± 0.5	−0.7 ± 0.6	0.002
PTV_N1
D_1% [Gy]	≤58.9	56.2 ± 0.2	58.0 ± 0.6	−1.8 ± 0.6	< 0.01
D_98% [Gy]	≥49.5	53.8 ± 0.3	51.2 ± 1.2	2.6 ± 1.1	< 0.01
Homog [%]	^a	3.8 ± 2.7	8.9 ± 3.5	−5.1 ± 3.3	< 0.001
PTV_N2
D_1% [Gy]	≤58.9	56.3 ± 0.2	58.1 ± 0.7	−1.2 ± 1.0	< 0.001
D_98% [Gy]	≥49.5	53.6 ± 0.3	51.0 ± 1.2	1.8 ± 1.5	< 0.001
Homog [%]	^a	3.9 ± 3.1	9.1 ± 4.0	5.2 ± 4.0	< 0.001
CTV_N1
D_98% [Gy]	≥55.0	55.5 ± 0.1	56.0 ± 0.8	−0.5 ± 0.9	0.10
D_50% [Gy]	55.0	54.5 ± 0.9	57.1 ± 0.5	− 2.5 ± 1.2	< 0.001
CTV_N2
D_98% [Gy]	≥55.0	55.5 ± 0.2	55.5 ± 0.4	−0.1 ± 0.3	0.63
D_50% [Gy]	55.0	54.4 ± 1.1	57.1 ± 0.5	−2.7 ± 1.2	< 0.001
Node Negative
PTV45
V_95% [%]	≥95	97.2 ± 1.1	96.5 ± 1.9	0.7 ± 1.9	0.27
D_1% [%]	≤107	104.2 ± 0.9	103.1 ± 0.7	0.1 ± 0.1	0.003
Homog [%]	^a	4.5 ± 1.5	3.2 ± 2.1	1.3 ± 0.9	0.007
ITV45
D_99% [%]	≥95	100.0 ± 0.8	96.5 ± 1.5	3.3	< 0.001
D_50% [Gy]	45.0	45.4 ± 0.1	45.1 ± 0.2	0.3 ± 2	0.23

^a: not included as optimisation constraint
^b: due to the simultaneous irradiation of the boost volumes. V_x%: volume receiving at least x% of the dose. D_x%: dose received by at least x% of the volume. Homog = (D5-D₉₅)/D_mean

ISSN: 1748-717X