Table 2.
Dosimetric parameters of the target volumes in the nasopharynx
| Parameters | GTV-P | PTV-G |
|---|---|---|
| Volume (cm3) | 48.7 (5.1–166.9) | 83.9 (24.3–252.0) |
| V95 (%) | 95.3 (62.9–100) | 94.9 (64.5–100) |
| V90 (%) | 97.4 (76.3–100) | 97.7 (76.8–100) |
| D98 (Gy) | 63.8 (51.4–71.3) | 64.6 (54.0–69.8) |
| D95 (Gy) | 65.4 (52.4–71.8) | 66.6 (56.9–70.8) |
| Dmed (Gy) | 72.1 (67.4–75.0) | 72.3 (67.3–74.1) |
| D2 (Gy) | 75.5 (69.1–77.7) | 75.5 (69.1–77.7) |
| HI | 0.16 (0.03–0.35) | 0.15 (0.05–0.32) |
Abbreviations: GTV-P, primary gross tumor volume; PTV-G, planning target volume of the primary tumor; V95, percent target volume covered by the 95% prescribed dose line; V90, percent target volume covered by the 90% prescribed dose line; D98, dose to 98% of the target volume; D95, dose to 95% of the target volume; Dmed, median dose; D2, dose to 2% of the target volume; HI, homogeneity index.