Table 2.
Dosimetric and treatment parameters in comparison between CyberKnife and single-isocenter volumetric modulated arc therapy (SI-VMAT).
| CyberKnife | SI-VMAT | p (Wilcoxon SR) | |
|---|---|---|---|
| Median (Q1–Q3) | Median (Q1–Q3) | ||
| Dose to the healthy brain | |||
| Mean dose (Gy) | 0.123 (0.109–0.154) | 0.413 (0.359–0.445) | <0.001 |
| V3GyPlan (ml) | 97.3 (68.8–128.9) | 760.0 (665.2–922.1) | <0.001 |
| V5GyPlan (ml) | 33.0 (23.8–39.6) | 351.5 (294.1–429.7) | <0.001 |
| V8GyPlan (ml) | 6.1 (10.1–17.4) | 109.1 (95.4–133.8) | <0.001 |
| V10GyPlan (ml) | 9.5 (6.7–12.0) | 61.8 (54.1–67.4) | <0.001 |
| V12GyPlan (ml) | 6.5 (4.6–8.3) | 37.0 (32.6–41.0) | <0.001 |
| V3GyTarget (ml) | 14.9 (10.5–21.1) | 133.0 (100.9–154.5) | <0.001 |
| V5GyTarget (ml) | 5.2 (3.1–7.6) | 59.6 (47.5–80.5) | <0.001 |
| V8GyTarget (ml) | 2.4 (1.3–3.3) | 19.8 (15.1–22.1) | <0.001 |
| V10GyTarget (ml) | 1.6 (0.9–2.2) | 10.6 (8.9–12.5) | <0.001 |
| V12GyTarget (ml) | 1.1 (0.6–1.5) | 6.2 (5.4–7.3) | <0.001 |
| Gradients and conformity | |||
| GIhigh | 3.1 (2.9–3.1) | 5.0 (4.3–5.5) | <0.001 |
| GIlow | 3.0 (2.9–3.2) | 5.6 (5.0–6.5) | <0.001 |
| CI | 1.2 (1.1–1.2) | 1.5 (1.4–1.7) | <0.001 |
| nCI | 1.2 (1.2–1.3) | 1.6 (1.5–1.8) | <0.001 |
| Treatment time | |||
| Estimated treatment time (minutes) | 130 (114.5–154.5) | 13.7 (13.5–14.0) | <0.001 |
Numbers in bold indicate statistical significance.
Wilcoxon SR, Wilcoxon signed-rank test; VXGy, volume of healthy brain receiving X Gy; GIhigh, gradient index for high-dose range; GIlow, gradient index for low-dose range; CI, RTOG conformity index; nCI, new conformity index.