To indicate that an image was generated within a scan region where ODM is enabled, an
asterisk is added after the Noise Index value.
4.3.3 Noise Index
Noise Index is an indication or index of the level of reconstructed image noise requested for the
diagnostic imaging task being performed. As the Noise Index increases, the required exposure
(mA and/or kV level) decreases and image noise increases; conversely overall image noise
levels decrease and the required patient exposure increases with a decrease in the prescribed
Noise Index. You can specify the Noise Index in the Noise Index field. The Noise Index field is
enabled only when you enable SmartmA or ODM. A change in prescribed Noise Index
necessarily adjusts dose to the patient, which is viewable at the bottom center of the
Dose
Display
area. Patient dose will be decreased or increased as the Noise Index is accordingly
increased or decreased.
You are unable to change the Noise Index after kV Assist is turned on. Set an appropriate Noise
Index prior to turning on kV Assist. kV Assist will adjust the Noise Index based on the clinical
task selected to maintain CNR.
The
Projected Noise Index
can be viewed from the
Image Quality
widget on the
Scan Settings
window.
Illustration 19: Image Quality widget
NOTE:
The
Image Quality
widget will not display if there are multiple scan groups. Select
individual scan groups to display the
Image Quality
widget.
The
Image Quality
widget will indicate if the prescribed Noise Index will be met. When the
projected noise is higher than the prescribed noise, the Projected Noise Index (PNI) will be
highlighted orange. When selected, [Adjust] will display recommended solutions to change scan
parameters to meet the prescribed Noise Index. The
Solutions
window displays the
recommended parameters, the change in noise and the change in DLP associated with the
change.
To make changes, click [Adjust] to view solutions for how to adjust the dose to achieve the
desired prescribed Noise Index.
Revolution CT User Manual
Direction 5480385-1EN, Revision 1
Chapter 11 Scan 275
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