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Table 2 Population average dose levels for s-IMRT and IMAT treatments

From: Intensity modulated arc therapy implementation in a three phase adaptive 18F-FDG-PET voxel intensity-based planning strategy for head-and-neck cancer

Target/Organ-at-risk s-IMRT (Gy) IMAT (Gy) p-value
GTVT    
 D2% 80.4 (76.4 - 83.7) 81.0 (77.2 - 85.1) 0.175
 D98% 67.3 (63.8 – 71.0) 68.4 (64.8 - 73.6) 0.009
GTVN    
 D2% 73.3 (66.4 - 79.3) 74.8 (67.2 - 81.0) 0.014*
 D98% 64.8 (62.5 - 69.9) 66.3 (63.1 - 72.8) 0.043*
PTVHR    
 D2% 76.9 (74.5 - 79.6) 77.9 (75.8 - 79.3) 0.013
 D98% 57.5 (54.3 - 59.4) 56.9 (52.5 - 58.7) 0.160
PTVEN    
 D2% 66.0 (61.1 - 73.3) 67.0 (62.0 – 76.0) 0.005
 D98% 32.2 (21.2 - 42.2) 32.7 (20.2 - 40.8) 0.452
CTVHR    
 D2% 78.1 (75.6 - 81.2) 79.1 (76.6 - 81.3) 0.023
 D98% 60.9 (59.6 - 61.6) 60.3 (58.9 - 61.5) 0.025
CTVEN    
 D2% 66.5 (59.7 - 75.9) 67.8 (61.7 - 77.9) 0.001
 D98% 38.9 (35.2 - 44.5) 38.6 (34.1 - 42.2) 0.222
Spinal cord PRV    
 D5% 32.4 (29.5 - 34.7) 28.4 (23 - 35.3) 0.003
 D50% 21.4 (3.5 - 28.5) 13.6 (1.8 - 21.5) 0.001
Brainstem PRV    
 D5% 20.5 (12.4 - 28.4) 14.2 (6.1 - 23.6) <0.001
 D50% 2.3 (1.4 - 3.1) 2.1 (1.1 - 3.4) 0.019
Ipsilateral parotid    
 V27Gy 43.8 (34.8 - 52.5) 36.6 (24.6 - 48.1) 0.007
 Dmean 25.8 (18.7 - 31.8) 22.2 (14.9 - 29.4) 0.001
Contralateral parotid    
 V27Gy 40.0 (27.6 - 50.1) 33.0 (13.2 - 47.4) 0.003
 Dmean 24.4 (16.9 - 30.6) 21.3 (12.5 - 27.5) <0.001
PC    
 D2% 67.3 (63.9 - 73.3) 67.6 (63.5 – 74.0) 0.469
 D50% 57.0 (49.1 – 62.0) 53.4 (38.2 - 60.8) 0.021
 D98% 36.3 (19.4 - 51.3) 25.1 (11.1 - 43.7) <0.001
SS    
 D2% 68.0 (61.0 - 77.6) 68.0 (60.8 - 76.6) 0.903
 D50% 53.5 (40.5 - 63.8) 47.4 (32.5 - 63.2) 0.003
 D98% 34.3 (24.1 - 40.3) 23.3 (12.4 - 31.2) <0.001
Mandible    
 D2% 53.6 (34.4 - 68.1) 53.6 (35.0 - 66.9) 0.923
  1. The dose distributions of the 3 treatment phases were summed on the pretreatment CT. Reporting is done on manually delineated targets and organs-at-risk. Statistically significant differences are shown in bold
  2. Abbreviations: s-IMRT step-and-shoot IMRT, IMAT intensity modulated arc therapy, GTV T gross tumor volume of the primary tumor, GTV N GTV of the metastatic lymph nodes, CTV HR high-risk clinical target volume, PTV HR high-risk planning target volume, CTV EN elective neck CTV, PTV EN elective neck PTV, PRV planning organ-at-risk volume, SS swallowing structures include the superior, middle and inferior pharyngeal constrictor muscles, upper esophageal sphincter, supraglottic larynx and upper 2 cm of the cervical esophagus, PC pharyngeal constrictors include the superior, middle and inferior pharyngeal constrictor muscles, D x% dose received by x% of the volume, V 27Gy % of the volume that receives at least 27 Gy
  3. *Of 10 patients, 6 had metastatic lymph nodes