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Table 3 Dosimetric comparison and statistical analysis of dose to normal brain and substructures

From: Differential dosimetric benefit of proton beam therapy over intensity modulated radiotherapy for a variety of targets in patients with intracranial germ cell tumors

PTV location Item Median (range, min–max), Gy p value*
IMRT PSPT SSPT IMRT vs PSPT IMRT vs SSPT PSPT vs SSPT
WV Brain - Dmean 22.1 (21.2–23.3) 19.8 (18.4–21.3) 17.5 (15.9–18.7) <0.05 <0.05 <0.05
Brain - V10Gy (%) 88.5 (85.5–90.0) 77.9 (74.8–82.1) 62.7 (55.6–66.5) <0.05 <0.05 <0.05
Brain - V15Gy (%) 79.5 (75.9–83.6) 60.1 (54.0–64.8) 53.5 (45.5–57.0) <0.05 <0.05 <0.05
Rt. Temporal 22.5 (18.6–25.8) 22.5 (18.6–25.8) 19.6 (14.8–23.7) <0.05 <0.05 <0.05
Lt. Temporal 22.4 (18.9–27.2) 22.4 (18.9–27.2) 19.4 (15.4–25.6) <0.05 <0.05 <0.05
Rt. Hippocampus 31.3 (30.4–31.6) 31.3 (30.4–31.6) 31.1 (27.4–31.2) <0.05 NS <0.05
Lt. Hippocampus 31.4 (31.2–31.5) 31.4 (31.2–31.5) 31.1 (28.7–31.2) NS <0.05 <0.05
Pituitary Gland 31.8 (30.9–31.9) 31.8 (30.9–31.9) 31.0 (30.7–31.4) NS NS NS
PG Brain - Dmean 10.5 (6.5–14) 8.3 (4.4–12.2) 7.0 (3.3–10.4) <0.05 <0.05 <0.05
Brain - V10Gy (%) 47.8 (24.1–63.9) 25.4 (13.9–42.3) 21.1 (10.2–35.8) <0.05 <0.05 NS
Brain - V15Gy (%) 26.1 (10.9–41.0) 20.5 (10.5–34.7) 16.4 (7.5–27.8) <0.05 <0.05 <0.05
Rt. Temporal 15.0 (4.8–21.2) 2.8 (0.0–10.8) 2.0 (0.0–8.8) <0.05 <0.05 NS
Lt. Temporal 14.7 (4.8–20.5) 2.9 (0.1–8.5) 3.0 (0.0–7.4) <0.05 <0.05 NS
Rt. Hippocampus 28.0 (10.9–31.2) 25.1 (6.4–31.5) 21.8 (4.8–30.9) NS <0.05 NS
Lt. Hippocampus 25.8 (15.3–30.9) 23.0 (11.0–31.5) 22.3 (8.4–30.6) NS <0.05 <0.05
Pituitary Gland 6.8 (0.7–23.5) 5.0 (0.0–29.3) 3.2 (0.0–27.7) NS NS NS
SS Brain - Dmean 5.8 (4.9–11) 4.4 (3.6–7.9) 3.5 (2.9–6.7) <0.05 <0.05 <0.05
Brain - V10Gy (%) 23.0 (18.3–49.0) 12.7 (10.2–27.1) 9.4 (7.6–22.6) <0.05 <0.05 <0.05
Brain - V15Gy (%) 11.9 (9.8–25.9) 9.4 (7.6–21.8) 7.1 (5.6–17.2) <0.05 <0.05 <0.05
Rt. Temporal 12.9 (8.8–15.8) 6.6 (4.3–9.9) 5.1 (3.4–6.9) <0.05 <0.05 <0.05
Lt. Temporal 11.9 (9.1–15.4) 6.4 (3.0–9.5) 5.0 (2.4–6.7) <0.05 <0.05 <0.05
Rt. Hippocampus 15.9 (11.7–17.5) 10.1 (4.6–16.1) 7.2 (2.4–12.6) <0.05 <0.05 <0.05
Lt. Hippocampus 16.2 (12.7–17.5) 11.0 (6.2–15.3) 7.8 (3.7–13.5) <0.05 <0.05 <0.05
Pituitary Gland 31.4 (5.9–31.6) 31.2 (15–31.4) 31.4 (14.4–32.2) NS NS NS
BG Brain - Dmean 12.4 (11.6–14.2) 8.8 (7.5–9.9) 7.7 (6.3–8.4) <0.05 <0.05 <0.05
Brain - V10Gy (%) 56.5 (52.9–66.5) 29.1 (26.5–34.1) 25.2 (22.5–28.9) <0.05 <0.05 <0.05
Brain - V15Gy (%) 33.6 (28.8–39.9) 24.3 (21.7–28.0) 20.1 (17.7–23.2) <0.05 <0.05 <0.05
Ipsilat. Temp. 19.0 (13.2–22.6) 17.0 (13.8–23.1) 15.1 (10.4–20.3) NS <0.05 <0.05
Contralat. Temp. 10.3 (6.5–12.1) 0.0 (0.0–0.4) 0.0 (0.0–0.2) <0.05 <0.05 NS
Ipsilat. Hippoc. 29.1 (24.3–31) 30.4 (27.1–31.2) 29.7 (24.6–31.1) NS NS NS
Contralat. Hippoc. 15.6 (9.2–16.7) 0.2 (0.0–0.7) 0.1 (0.0–0.6) <0.05 <0.05 NS
Pituitary Gland 12.5 (1.4–29.9) 22.4 (0.0–30) 11.5 (0.0–29.3) NS NS NS
  1. WV whole ventricle, PG pineal gland, SS suprasellar, BG basal ganglia, PTV planning target volume, IMRT intensity-modulated radiation therapy, PSPT passively scattered proton therapy, SSPT spot scanning proton therapy, NS not significant
  2. * p -value by Wilcoxon’s signed rank test