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CT numbers = Hounsfield units
The grey tones on the CT image represent the
attenuation in every pixel/voxel
The grey tones are expressed in Hounsfield units (HU)
– CT numbers:
μobj – μ water
HU = –––––––– x 1000
μ water Luft ~ -1000 HU
Vand ~0 HU
Knogler >1000 HU