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Table 2 Absolute dose parameters of organs at risk for different cranial PTVs of rectal cancer

From: Dosimetric analysis and comparison of reduced longitudinal cranial margins of VMAT-IMRT of rectal cancer

Structure Parameter PTV0 PTV-1 p-value PTV-2 p-value PTV-3 p-value
  Dose (Gy)
Rectum Median 50.5 50.4 0.170 49.9 0.220 49.6 0.185
Max 53.4 53.2 0.110 53.3 0.687 53.3 0.624
Sigmoid colon Median 38.8 37.4 0.362 33.1 0.126 29.8 0.093
Max 51.9 52.0 0.575 51.7 0.444 52.0 0.221
Femoral head Median 23.4 23.6 0.646 23.9 0.241 23.8 0.646
Max 37.9 38.2 0.441 38.8 0.203 38.6 0.114
Bladder Median 28.0 27.8 0.153 27.0 0.110 25.7 0.013
Max 52.5 52.5 0.575 52.7 0.314 52.7 0.221
Bone Median 27.6 26.6 0.007 24.9 0.005 21.9 0.005
Max 53.8 53.8 0.959 53.7 0.594 53.8 0.959
Small bowel loops Median 2.7 1.1 0.005 0.6 0.005 0.4 0.005
Max 45.5 45.5 0.508 42.8 0.441 41.1 0.445
Peritoneal space Median 20.9 15.5 0.005 9.9 0.005 5.0 0.005
Max 53.6 53.6 0.721 53.8 0.386 53.4 0.214
65 cc 50.9 50.4 0.475 48.5 0.083 46.1 0.007
100 cc 49.3 48.5 0.153 46.2 0.028 44.4 0.005
180 cc 46.2 44.2 0.038 42.8 0.009 41.6 0.005
830 cc 18.0 14.9 0.012 9.6 0.012 7.5 0.012
  1. Bold values: statistic significant to PTV0. PTV-1 = PTV minus 1 cm on cranial site. p-value = PTV1,2,3 vs. PTV0