Table 3.
Dose–volume metrics and univariate analysis of factors related to symptomatic radiation pneumonitis (RP)
| Metrics | All patients (n = 56) | RP < Grade 2 (n = 50) | RP ≥ Grade 2 (n = 6) | p-value |
|---|---|---|---|---|
| MTD (mm) | ||||
| Mean (range) | 22.0 (5–42) | 21.2 (5–37) | 28.8 (15–42) | 0.019 |
| GTV (cm3) | ||||
| Median (range) | 5.8 (0.4–29) | 5.35 (0.4–21.4) | 13.35 (3–29) | 0.016 |
| PTV (cm3) | ||||
| Median (range) | 23.8 (2.2–59.8) | 22.05 (2.2–55.0) | 56.7 (15–59.8) | 0.003 |
| Total dose | ||||
| Median (range) | 56 (48–56) | 56 (48–56) | 56 (48–56) | 0.816 |
| Maximum dose (Gy) | ||||
| Mean (range) | 66.5 (57.8–77.8) | 66.5 (57.8–77.8) | 66.6 (59.9–70.7) | 0.967 |
| Normal lung volume (ml) | ||||
| Median (range) | 2651 (1230–5383) | 2655 (1612–5383) | 2480.5 (1230–3825) | 0.375 |
| MLD (Gy) | ||||
| Median (range) | 3.2 (1.1–8.0) | 2.95 (1.1–5.6) | 5.05 (3.8–8.0) | 0.001 |
|
V50 (%) | ||||
| Median (range) | 0.4 (0.1–1.2) | 0.4 (0.1–1.2) | 0.9 (0.4–0.8) | 0.006 |
|
V45 (%) | ||||
| Median (range) | 0.7 (0.1–1.8) | 0.6 (0.1–1.8) | 1.4 (0.7–1.6) | 0.003 |
|
V40 (%) | ||||
| Median (range) | 0.9 (0.2–2.4) | 0.9 (0.2–2.4) | 1.75 (1.1–2.2) | 0.001 |
|
V35 (%) | ||||
| Median (range) | 1.2 (0.3–3.1) | 1.1 (0.3–3.1) | 2.35 (1.4–3.1) | 0.001 |
|
V30 (%) | ||||
| Median (range) | 1.55 (0.4–4.3) | 1.35 (0.4–3.9) | 3.15 (1.9–4.3) | <0.001 |
|
V25 (%) | ||||
| Median (range) | 2.05 (0.6–5.8) | 1.80 (0.6–5.1) | 4.45 (2.6–5.8) | <0.001 |
|
V20 (%) | ||||
| Median (range) | 2.85 (0.8–8.2) | 2.55 (0.8–6.9) | 6.75 (3.6–8.2) | 0.001 |
|
V15 (%) | ||||
| Median (range) | 4.45 (1.1–14.3) | 4.05 (1.1–11.0) | 10.55 (5.3–14.3) | 0.001 |
|
V10 (%) | ||||
| Median (range) | 8.25 (1.5–31.8) | 7.95 (1.5–19.7) | 16.25 (9.3–31.8) | 0.002 |
|
V5 (%) | ||||
| Median (range) | 18.1 (2.6–32.6) | 17.3 (2.6–32.6) | 26.95 (17.0–32.2) | 0.008 |
GTV, gross tumour volume; MLD, mean lung dose; MTD, maximum tumour diameter; PTV, planning target volume; Vx, normal lung volume receiving x Gy of radiation.