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Table 4 Comparison of NPC patients not fulfilling dose-volume histogram constraints for plans with pre-correction margins and for plans with post-correction margins

From: Dosimetric benefit to organs at risk following margin reductions in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy

Organ Objective Plan with pre-correction margins [ n (%)] Plan with post-correction margins [ n (%)] Reduction (%)
Targets Any PTV V93% ≥ 99% 0 (0) 0 (0) 0.0
   V100% ≥ 95% 0 (0) 0 (0) 0.0
  PTV_7000 V77Gy ≤ 20% 0 (0) 0 (0) 0.0
   V80.5Gy ≤ 5% 0 (0) 0 (0) 0.0
OARs BrainStem Dmax ≤ 54 Gy 23 (57.5) 22 (55.0) 4.3
  BrainStem_PRV D1% ≤ 60 Gy 12 (30.0) 8 (20.0) 33.3
  SpinalCord Dmax ≤ 45 Gy 0 (0) 0 (0) 0.0
  SpinalCord_PRV D1% ≤ 50 Gy 0 (0) 0 (0) 0.0
  OpticNerve_L Dmax ≤ 50 Gy 21 (52.5) 19 (47.5) 9.5
  OpticNerve_L_PRV D1% ≤ 54 Gy 21 (52.5) 17 (42.5) 19.0
  OpticNerve_R Dmax ≤ 50 Gy 22 (55.0) 19 (47.5) 13.6
  OpticNerve_R_PRV D1% ≤ 54 Gy 21 (52.5) 19 (47.5) 9.5
  Chiasm Dmax ≤ 50 Gy 26 (65.0) 26 (65.0) 0.0
  Chiasm_PRV D1% ≤ 54 Gy 27 (67.5) 27 (67.5) 0.0
  Lens Dmax < 25 Gy 0 (0) 0 (0) 0.0
  Parotids V20Gy > 20 cc (both glands) 40 (100) 40 (100) 0.0
   D50% < 30 Gy (at least one gland) 28 (70.0) 19 (47.5) 32.1
  Parotid_L Dmean < 26 Gy 40 (100) 40 (100) 0.0
  Parotid_R Dmean < 26 Gy 40 (100) 40 (100) 0.0
  TemporalLobe_L Dmax ≤ 60 Gy 39 (97.5) 38 (95.0) 2.6
   D1% ≤ 65 Gy 15 (37.5) 12 (30.0) 20.0
  TemporalLobe_R Dmax ≤ 60 Gy 39 (97.5) 38 (95.0) 2.6
   D1% ≤ 65 Gy 16 (40.0) 13 (32.5) 18.8
  Mandible/TM joint D1cc ≤ 75 Gy 0 (0) 0 (0) 0.0
  Ear_Inner_L V55Gy ≤ 5% 30 (75.0) 27 (67.5) 10.0
  Ear_Inner_R V55Gy ≤ 5% 34 (85.0) 26 (65.0) 23.5
  Larynx Dmean < 45 Gy 31 (77.5) 28 (70.0) 9.7
  1. OAR, organ at risk; PTV, planning target volume; PTV_7000, the PTV of gross tumor volume; PRV, planning risk volume; L, left; R, right; TM, temporomandibular; V93%, percentage volume receiving at least 93% of prescribed dose; V100%, percentage volume receiving at least 100% of prescribed dose; V77Gy, percentage volume receiving at least 77 Gy; V80.5Gy, percentage volume receiving at least 80.5 Gy; D1%, dose received by 1% of the volume; Dmax, maximum dose; V20Gy, volume receiving less than 20 Gy; cc, cubic centimeter; D50%, dose received by 50% of the volume; Dmean, mean dose; D1cc, dose received by 1 cc volume; V55Gy, percentage volume receiving at least 55 Gy.