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PAROTID GLANDS –
shrinkage and CT density
84 pts, (Fiorino
et al
, RO,2012), parotid reduced during IMRT
parotid deformation and average Hounsfield number changes
evaluated through MVCT or kVCT diagnostic at treatment start
individual
∆
HU highly correlated with degree of local
deformation in terms of volume change and with neck thickness
variation
individual assessment of
density changes reliable
with kVCT
density changes
to score toxicity?
Risk of density variation <-11 HU
(kVCT data)
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
4 4,5 5 5,5 6 6,5 7 7,5 8 8,5 9 9,5
Initial neck half-thickness (cm)
% risk
Largely deforming parotids
no or moderately deforming parotids