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:
μ
obj
– μ
water
HU = –––––––– x 1000
μ
water
Luft ~ -1000 HU
Vand ~0 HU
Knogler >1000 HU