Table 2.
Summary and comparison of the dosimetric parameters of centrally located tumors (50 CGE/4 fx = 4, 70 CGE/10 fx = 5, and 60 CGE/10 fx = 2).
| OARs | PBT | 3D-CRT | IMRT | VMAT | p-Value | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Median | Range | Median | Range | Median | Range | Median | Range | PBT vs.3D-CRT | PBT vs.IMRT | PBT vs.VMAT | ||
| Total lung (n = 11) | ||||||||||||
| V5 (%) | 13.17 | 6.7–18.7 | 21.31 | 19.0–28.7 | 20.63 | 14.5–31.2 | 20.72 | 17.9–27.8 | 0.001 | 0.001 | 0.001 | |
| V10 (%) | 11.5 | 6.1–16.2 | 15.63 | 10.7–18.9 | 13.79 | 9.5–19.2 | 14.19 | 9.4–19.8 | 0.001 | 0.001 | 0.001 | |
| V15 (%) | 9.95 | 5.4–12.8 | 11.66 | 8.0–15.7 | 9.58 | 6.1–16.2 | 10.14 | 7.5–14.2 | 0.003 | 0.067 | 0.054 | |
| V20 (%) | 8.1 | 4.8–10.7 | 9.01 | 5.5–12.4 | 7.93 | 4.7–12.7 | 7.56 | 5.1–12.3 | 0.024 | 0.898 | 1 | |
| V30 (%) | 5.66 | 2.9–6.8 | 5.13 | 2.9–8.2 | 5.12 | 2.6–7.7 | 4.38 | 2.4–8.7 | 0.519 | 0.966 | 0.278 | |
| V40 (%) | 2.96 | 1.8–4.5 | 3.04 | 1.6–4.2 | 2.62 | 1.4–4.2 | 2.55 | 1.4–3.85 | 0.578 | 0.376 | 0.016 | |
| Mean dose (Gy) | 4.2 | 0.1–5.4 | 5.75 | 4.3–7.3 | 5.38 | 3.8–6.8 | 5.14 | 4.0–7.4 | 0.006 | 0.001 | 0.001 | |
| Heart (n = 11) | ||||||||||||
| V5 (%) | 0.39 | 0–5.3 | 28.12 | 0–70.48 | 30.61 | 0–72.8 | 21.22 | 0–64.0 | 0.009 | 0.014 | 0.014 | |
| V10 (%) | 0.14 | 0–4.0 | 7.14 | 0–39.3 | 7.49 | 0–51.4 | 8.65 | 0–41.5 | 0.014 | 0.014 | 0.022 | |
| V15 (%) | 0.06 | 0–3.1 | 2.51 | 0–25.1 | 2.62 | 0–29.4 | 3.58 | 0–20.5 | 0.022 | 0.022 | 0.022 | |
| V20 (%) | 0.02 | 0–1.99 | 0.82 | 0–10.2 | 0.83 | 0–14.3 | 0.96 | 0–8.7 | 0.022 | 0.022 | 0.036 | |
| V30 (%) | 0 | 0–1.2 | 0 | 0–1.9 | 0 | 0–3.8 | 0 | 0–2.1 | 1 | 0.402 | 0.675 | |
| V40 (%) | 0 | 0–0.5 | 0 | 0–0.3 | 0 | 0–1.0 | 0 | 0–0.6 | 1 | 0.583 | 1 | |
| Mean dose (Gy) | 0.07 | 0–1.13 | 3.35 | 0.2–9.7 | 3.56 | 0.1–11.2 | 2.84 | 0.2–9.2 | 0.001 | 0.001 | 0.001 | |
| Dmax (Gy) | 23 | 0–65.98 | 25.7 | 0.8–54.8 | 29.23 | 0.7–63.8 | 28.81 | 0.8–64.4 | 0.206 | 0.147 | 0.175 | |
| Proximal bronchial tree (n = 9) | ||||||||||||
| Dmax (Gy) | 22.1 | 0.1–69.0 | 27.14 | 6.9–77.5 | 30.06 | 3.7–69.2 | 26.29 | 3.8–71.4 | 0.164 | 0.129 | 0.098 | |
| D1cc (Gy) | 12.37 | 0–65.3 | 15.71 | 1.9–61.7 | 17.33 | 1.7–60.5 | 18.45 | 1.8–62.5 | 0.164 | 0.164 | 0.074 | |
| Spinal cord (n = 11) | ||||||||||||
| Dmax (Gy) | 0.01 | 0–14.1 | 10.82 | 3.8–23.3 | 12.69 | 5.9–20.2 | 16.54 | 6.2–29.6 | 0.001 | 0.001 | 0.001 | |
| Esophagus (n = 11) | ||||||||||||
| Mean dose (Gy) | 0.02 | 0–0.9 | 4.88 | 1.6–16.0 | 5.87 | 1.6–16.9 | 6.38 | 1.7–17.6 | 0.001 | 0.001 | 0.001 | |
| Dmax (Gy) | 2.42 | 0–13.1 | 16 | 7.7–29.8 | 15.67 | 9.5–36.9 | 18.5 | 8.7–26.8 | 0.001 | 0.001 | 0.001 | |
| Chest wall (n = 7) | ||||||||||||
| Dmax (Gy) | 56.2 | 37.2–75.2 | 59.95 | 39.4–79.4 | 58.16 | 36.8–70.2 | 54.95 | 38.0–73.6 | 0.375 | 0.937 | 0.812 | |
| D30cc (Gy) | 27.21 | 18.1–44.0 | 31.95 | 22.8–39.6 | 33.86 | 22.9–41.6 | 27.71 | 21.9–39.7 | 0.375 | 0.297 | 0.469 | |
| Skin (n = 8) | ||||||||||||
| Dmax (Gy) | 21.48 | 9.9–54.8 | 28.46 | 15.1–35.9 | 32.46 | 18.2–40.6 | 24.84 | 17.6–37.8 | 0.641 | 0.359 | 0.496 | |
OARs, organs at risk; PBT, proton beam therapy; 3D-CRT, three-dimensional conformal radiotherapy; IMRT, intensity-modulated radiotherapy; VMAT, volumetric-modulated arc therapy, CGE, cobalt gray equivalent; fx, fractions; V5–40; percentage volume of tissue receiving 5–40 Gy; Dmax, maximum dose; D1cc, the dose delivered to 1 cubic centimeter volume; D30cc, the dose delivered to 30 cubic centimeter volume.