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Table 2 Lower neck target dose changes (cm3) due to important shifts.

From: Assessment of shoulder position variation and its impact on IMRT and VMAT doses for head and neck cancer

Shift   Patient 1 Patient 2 Patient 3
   V100% V98% V95% V100% V98% V95% V100% V98% V95%
IMRT           
3 mm superior Target 1 -4 0 0 -4 0 0 0 0 0
  Target 2 0 0 0 -1 0 0 -1 0 0
5 mm superior Target 1 -19 -1 0 -14 -2 0 -2 0 0
  Target 2 -3 0 0 -9 -1 0 -7 0 0
15 mm superior Target 1 -132 -73 -9 -53 -31 -4 -58 -20 -2
  Target 2 -29 -5 -1 -64 -35 -12 -77 -25 -7
15 mm posterior Target 1 -12 0 0 -8 0 0 -4 -1 0
  Target 2 -5 -1 0 -7 -2 -1 -25 -4 -1
VMAT       
3 mm superior Target 1 -4 0 0 -2 -2 0 0 0 0
  Target 2 -2 0 0 0 0 0 -1 0 0
5 mm superior Target 1 -24 -3 0 -7 -4 0 0 0 0
  Target 2 -10 -1 0 -5 0 0 -6 -1 0
15 mm superior Target 1 -152 -102 -41 -36 -13 -1 -49 -7 0
  Target 2 -43 -22 -10 -36 -11 0 -65 -29 -7
15 mm posterior Target 1 -1 0 0 -1 -1 0 0 0 0
  Target 2 0 0 0 -1 -1 -1 -3 -2 -1
  1. Target 1 = higher dose clinical target volume (CTV); target 2 = lower dose CTV; V100%, V98% and V95% are the volumes covered by the 100%, 98%, and 95% isodose lines, respectively; 15 mm superior shifts show greatest loss of coverage for both IMRT and VMAT, and 15 mm posterior shifts show loss of coverage greater than 4 cm3 for IMRT plans only.