Table 4.
Planning target volume (PTV) margins reported by different studies.
| Study | Imaging | Correction protocol | Margin (range) in mm | Largest margin direction | |
|---|---|---|---|---|---|
| van Kranen et al.10 (2009) | CBCT | SAL | Skull (occiput) | 4.6–7 | ML |
| C1–C3 spine | 3.8–4.7 | ML | |||
| C5–C7 spine | 5.4–6 | AP | |||
| Kapanen et al.7 (2013) | Orthogonal | Weekly | Skull (occiput) | 6.1(SI), 8.3(AP) | AP |
| kV image | C1–C2 spine | 4.8–7 | AP | ||
| C5–C7 spine | 4.9–5.7 | AP | |||
| Djordjevic et al.9 (2014) | Orthogonal | No | Skull (maxilla) | 5.2–5.9 | SI |
| kV image | ‘ | C2 spine | 4.5(SI), 6.5(AP) | AP | |
| C5 spine | 5–9.3 | AP | |||
| Daily | Skull (maxilla) | 4.2–5.9 | AP | ||
| C2 spine | 2.3(SI),2.6(AP) | AP | |||
| C5 spine | 2.6–5 | AP | |||
| Cheo et al.8 (2015) | CBCT | No | Skull (clivus) | 1.75–2.33 | SI |
| C4 spine | 2.61–4.33 | ML | |||
| C7 spine | 2.72–6.52 | ML | |||
| Weekly | Skull (clivus) | 0.51–1.2 | AP | ||
| C4 spine | 0.97–3.72 | ML | |||
| C7 spine | 1.2–6.08 | ML | |||
| Present study | Orthogonal | No | Skull(clivus) | 3.2–4.4 | AP |
| kV image | C3 spine | 4.4–5.5 | AP | ||
| C6 spine | 4.4–6.9 | ML | |||
CBCT, cone beam CT; SAL, shrinking action level; AP, antero-posterior; ML, medio-lateral; SI, supero-inferior.