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Table 1 Dosimetric comparison of IMRT with 3DCRT: median value (range)

From: Intensity modulated radiation therapy (IMRT): differences in target volumes and improvement in clinically relevant doses to small bowel in rectal carcinoma

Volume Parameter IMRT 3FBB 3DCRT
PTV Dmean (Gy) 46.6 (46.4 - 46.9) 46.0 (45.6 - 47.0)* 46.6 (46.3 - 48.3)
1547 cm3 V45Gy 99.5% (98.7% - 99.8%) 87.2% (80.0% - 93.4%) 98.4% (97.7% - 99.6%)*
(1459 - D99% (Gy) 45.3 (44.8 - 45.8) 35.2 (10.7 - 40.3) 44.9 (44.2 - 45.2)*
1968 cm3) D1% (Gy) 47.6 (47.2 - 47.9) 48.3 (47.7 - 50.5) 47.5 (47.1 - 48.2)
  HI 3.2% (2.5% - 3.6%) N/A 4.2% (3.0% - 5.3%)
  CI 1.16 (1.09 - 1.23) N/A 1.35 (1.27 - 1.38)
Bladder Dmean (Gy) 38.6 (31.1 - 42.4) 37.9 (27.5 - 44.2) 41.8 (31.0 - 45.0)
72 cm3 V30Gy 74.7% (40.8% - 90.0%) 72.6% (36.7% -96.6%) 85.8% (47.2% - 100%)
(32-652 cm3) V40Gy 56.8% (26.2% - 76.6%) 58.5% (27.6% - 84.0%) 75.4% (38.0% - 100%)
Femoral heads Dmean (Gy) 27.1 (20.8 - 29.6) 24.9 (22.4 - 30.7) 28.5 (21.9 - 31.8)*
211 cm3 V30Gy 28.0% (17.8% - 44.2%) 22.6% (12.0% - 33.3%) 31.9% (13.2% - 57.4%)
(151-393 cm3) V40Gy 3.4% (1.1% - 7.0%) 6.3% (1.9% - 13.2%)* 9.1% (3.5% - 14.6%)
Pelvic bones Dmean (Gy) 34.2 (30.5 - 36.2) 34.7 (31.9 - 36.8)* 36.7 (32.3 - 38.4)
914 cm3 V30Gy 69.8% (55.6% - 76.3%) 66.7% (61.8% - 72.3%) 74.9% (63.4% - 81.0%)
(725-1338 cm3) V40Gy 47.0% (35.2% - 52.8%) 53.9% (46.5% - 59.2%) 56.9% (41.3% - 63.6%)
Sigmoid/Colon Dmean (Gy) 18.9 (10.4 - 27.9) 17.5 (9.8 - 23.6) 25.5 (13.7 - 31.1)
outside PTV V20Gy 41.6% (13.2% - 72.6%) 38.0% (11.5% - 54.0%) 60.6% (24.9% - 75.2%)
162 cm3 V30Gy 17.6% (5.1% - 48.1%) 10.4% (3.0% - 36.9%) 36.9% (10.8% - 63.2%)
(23 - 389 cm3) V40Gy 4.0% (0.7% - 19.2%) 2.4% (0.4% - 30.3%) 18.3% (5.1% - 38.5%)
Small bowel Dmean (Gy) 18.6 (11.2 - 34.0) 21.0 (8.6 - 34.2) 25.2 (15.9 - 40.0)
251 cm3 V5Gy (cc) 224 (2.5 - 526) 225 (2.2 - 525) 234 (2.5 - 530)
(3 - 537 cm3) V15Gy (cc) 138 (0.1 - 257) 144 (0.4 - 413)* 157 (2.2 - 428)
  V25Gy (cc) 81 (0.0 - 142) 79 (0.0 - 149) 123 (0.5 - 183)
  V40Gy (cc) 45 (0.0 - 111) 50 (0.0 - 118) 76 (0.0 - 156)
  V45Gy (cc) 37 (0.0 - 100) 33 (0.0 - 74) 53 (0.0 - 121)
Normal tissues Dmean (Gy) 19.5 (12.0 - 21.6) 17.5 (12.8 - 20.6)* 20.5 (17.4 - 22.4)
10.3*103 cm3 V10Gy 69.5% (58.0% - 76.9%) 64.9% (53.3% - 75.6%)* 73.8% (62.2% - 80.7%)
(7.7*103 - V20Gy 48.3% (39.5% - 52.7%) 42.0% (32.6% - 52.7%)* 50.5% (40.0% - 58.3%)*
   18.9*103 cm3) V30Gy 20.3% (16.5% - 27.4%) 17.3% (12.6% - 20.2%)* 23.5% (16.8% - 27.8%)
  V40Gy 6.7% (4.0% - 9.2%) 8.3% (4.2% - 10.9%)* 11.0% (6.7% - 15.7%)
  V45Gy 2.3% (1.2% - 5.1%) 4.4% (2.1% - 6.0%) 5.2% (2.8% - 6.4%)
  1. Abbreviations: PTV = planning target volume; IMRT = intensity modulated radiation therapy; 3FBB = 3 field belly board; 3DCRT = 3 dimensional conformal radiation therapy; HI = homogeneity index; CI = conformality index; for definitions of dosimetric parameters, refer to text; denotes statistically significant difference with IMRT as comparator, p < 0.05 (*) or p < 0.01 (); otherwise, not statistically significant.