Siemens SOMATOM Emotion 6 Application Manual page 31

Children
The special kernels are mostly used for "physical"
measurements with phantoms, e. g. for adjustment
procedures (S80s), for constancy and acceptance
tests (S80s, U90s), or for specification purposes (U90s).
For special patient protocols, S80s and U90s are
chosen, e. g. for osteo (S80s) and for high resolution
bone studies (U90s).
We recommend to use the high resolution specifi-
cation kernel U90s only with "small" objects, like the
wrist, otherwise artifacts will occur in the images.
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