GE CT-9800

GE MEDICAL SYSTEMS CT 9800 QUICK SYSTEM
Rev. 12 ➤ Indicates Change Direction 18000
4-12-9
X
o
- Mean CT number for the outside of the phantom image derived by averaging the mean CT number
value for all of the specified outside coordinates (see data sheets).
AVX
o
- Average outside mean CT number for a minimum of 4 slices.
➤ AVσσ
c
- Average standard deviation (image noise) at the center of the phantom image for a minimum
14 slices.
AVσσ
o
- Average standard deviation for the outside of the phantom image for a minimum of 4 slices.
➤ Record each means data point to 2 decimal places (do not round off). However, when you average the slices, the
resultant mean shall be calculated by rounding off to the nearest tenth. For example:
AVX
c
= -2.66
AVX
c
(rounded) = -2.7
➤ Standard deviations shall be recorded on the data sheets to 2 decimal places. After averaging the slices, the
resultant value is determined by rounding off to the nearest tenth. For example:
AVσσ
o
= 3.79
➤ AVσσ
o
(rounded) =3.8