Means And Standard Deviations - GE CT-9800 Technical Publications

GE MEDICAL SYSTEMS
Rev. 12 Indicates Change

12-6 Means and Standard Deviations

Manipulate the ROI function at the console to determine the mean CT number and the standard deviation (i.e.,
image noise) using a box cursor with dimensions listed on the data sheets (rear of section). The statistical
parameters referenced on the data sheets are:
X c - Mean CT number at the center of the phantom image (X, Y coordinates are 256, 256 in pixels).
AVX c - Average mean CT number at the center of the phantom image (256,256) for a minimum of 4
slices.
ILLUSTRATION 4-12-2
PHANTOM CALIBRATION PROCEDURE
4-12-8
CT 9800 QUICK SYSTEM
Direction 18000