GE Revolution CT User Manual page 663

Revolution CT User Manual
Direction 5480385-1EN, Revision 1
Illustration 15: Torso Phantom shown with overlay indicating: Left - Water Equivalent Diameter
= 25.6cm (OR=1) and Right - Ellipse based on Dw and OR (OR=1.24)
Unlike SmartmA where there is mA modulation over the scan range in the z-direction based on
patient size, applications like Auto Gating and kV Assist set parameters that do not modulate
during the scan acquisition. Auto Gating calculates a median Dw from the specified scan range
to translate it to a scout-attenuation BMI estimate based on the conversion detailed in Menke,
Radiology 2005.
Chapter 21 General Information 663