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Table 1 Mean volume, coefficient of variance, and mean OAR ratio per observer and organ at risk

From: 3D Variation in delineation of head and neck organs at risk

OAR Mean volume CV Mean OAR ratio*
  [cm3] (SE)   obs. 1 obs. 2 obs. 3 obs. 4 obs. 5
Spinal cord 17.6 (1.1) 16% 0.98 0.98 0.91 0.92 1.17
Parotid gland left 28.4 (2.6) 15% 0.92 0.85 1.10 1.08 1.03
Parotid gland right 29.6 (3.9) 12% 0.88 0.90 1.06 1.04 1.02
Submandibular gland left 10.6 (0.9) 16% 1.06 0.86 1.12 1.06 0.95
Submandibular gland right 10.4 (0.9) 16% 1.09 0.88 1.06 1.03 0.90
Thyroid cartilage 11.4 (1.5) 14% 0.96 1.11 1.11 0.97 0.93
Glottic larynx 10.3 (2.8) 56% 0.45 0.60 1.13 1.38 1.66
  1. OAR = organ at risk, SE = standard error of the mean, CV = coefficient of variance, obs. = observer
  2. SE and CV were determined by the results of ANOVA, the CV represents variability due to observers
  3. *OAR ratio = the volume of the OAR as determined by each observer divided by the mean volume of all five observers