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Dose Information
For spiral scan protocols, the indicated mAs is the
effective mAs per image. The correlation between tube
current and effective mAs of spiral scans on a Multi-
slice CT scanner is expressed by the following formula:
where Slice collimation refers to the collimation of one
detector row, and nrow is the number of used detector
rows.
Effective mAs = mA x RotTime
Pitch Factor
Pitch Factor = Feed per Rotation
nrow x Slice collimation
mA = effective mAs x Pitch Factor
RotTime