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

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

ParameterObjectiveHalcyon (H)Helical Tomotherapy (HT)Difference (H-HT)p
Node Positive
 PTV45
  V95% [%]≥9599.1 ± 1.298.3 ± 0.90.8 ± 0.90.02
  D1% [%]≤130b122.9 ± 1.7123.2 ± 3.8−0.3 ± 2.80.73
  Homog [%]a2.8 ± 3.13.3 ± 2.1−0.5 ± 2.60.002
 ITV45
 D99% [%]≥95100.1 ± 1.297.6 ± 1.32.5 ± 1.1< 0.001
 D50% [Gy]45.045.0 ± 0.445.8 ± 0.5−0.7 ± 0.60.002
 PTV_N1
  D1% [Gy]≤58.956.2 ± 0.258.0 ± 0.6−1.8 ± 0.6< 0.01
  D98% [Gy]≥49.553.8 ± 0.351.2 ± 1.22.6 ± 1.1< 0.01
  Homog [%]a3.8 ± 2.78.9 ± 3.5−5.1 ± 3.3< 0.001
 PTV_N2
  D1% [Gy]≤58.956.3 ± 0.258.1 ± 0.7−1.2 ± 1.0< 0.001
  D98% [Gy]≥49.553.6 ± 0.351.0 ± 1.21.8 ± 1.5< 0.001
  Homog [%]a3.9 ± 3.19.1 ± 4.05.2 ± 4.0< 0.001
 CTV_N1
  D98% [Gy]≥55.055.5 ± 0.156.0 ± 0.8−0.5 ± 0.90.10
  D50% [Gy]55.054.5 ± 0.957.1 ± 0.5− 2.5 ± 1.2< 0.001
 CTV_N2
  D98% [Gy]≥55.055.5 ± 0.255.5 ± 0.4−0.1 ± 0.30.63
  D50% [Gy]55.054.4 ± 1.157.1 ± 0.5−2.7 ± 1.2< 0.001
Node Negative
 PTV45
  V95% [%]≥9597.2 ± 1.196.5 ± 1.90.7 ± 1.90.27
  D1% [%]≤107104.2 ± 0.9103.1 ± 0.70.1 ± 0.10.003
  Homog [%]a4.5 ± 1.53.2 ± 2.11.3 ± 0.90.007
 ITV45
  D99% [%]≥95100.0 ± 0.896.5 ± 1.53.3< 0.001
  D50% [Gy]45.045.4 ± 0.145.1 ± 0.20.3 ± 20.23
  1. a: not included as optimisation constraint
  2. b: due to the simultaneous irradiation of the boost volumes. Vx%: volume receiving at least x% of the dose. Dx%: dose received by at least x% of the volume. Homog = (D5-D95)/Dmean