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 | |||||
| V95% [%] | ≥95 | 99.1 ± 1.2 | 98.3 ± 0.9 | 0.8 ± 0.9 | 0.02 |
| D1% [%] | ≤130b | 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 | |||||
| D99% [%] | ≥95 | 100.1 ± 1.2 | 97.6 ± 1.3 | 2.5 ± 1.1 | < 0.001 |
| D50% [Gy] | 45.0 | 45.0 ± 0.4 | 45.8 ± 0.5 | −0.7 ± 0.6 | 0.002 |
| PTV_N1 | |||||
| D1% [Gy] | ≤58.9 | 56.2 ± 0.2 | 58.0 ± 0.6 | −1.8 ± 0.6 | < 0.01 |
| D98% [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 | |||||
| D1% [Gy] | ≤58.9 | 56.3 ± 0.2 | 58.1 ± 0.7 | −1.2 ± 1.0 | < 0.001 |
| D98% [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 | |||||
| D98% [Gy] | ≥55.0 | 55.5 ± 0.1 | 56.0 ± 0.8 | −0.5 ± 0.9 | 0.10 |
| D50% [Gy] | 55.0 | 54.5 ± 0.9 | 57.1 ± 0.5 | − 2.5 ± 1.2 | < 0.001 |
| CTV_N2 | |||||
| D98% [Gy] | ≥55.0 | 55.5 ± 0.2 | 55.5 ± 0.4 | −0.1 ± 0.3 | 0.63 |
| D50% [Gy] | 55.0 | 54.4 ± 1.1 | 57.1 ± 0.5 | −2.7 ± 1.2 | < 0.001 |
| Node Negative | |||||
| PTV45 | |||||
| V95% [%] | ≥95 | 97.2 ± 1.1 | 96.5 ± 1.9 | 0.7 ± 1.9 | 0.27 |
| D1% [%] | ≤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 | |||||
| D99% [%] | ≥95 | 100.0 ± 0.8 | 96.5 ± 1.5 | 3.3 | < 0.001 |
| D50% [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. Vx%: volume receiving at least x% of the dose. Dx%: dose received by at least x% of the volume. Homog = (D5-D95)/Dmean