Build A Protocol With Kv Assist - GE Revolution CT User Manual

scan. Because of the interaction between tube voltage and tube current, however, the scanner
output at a fixed mA value is very different between kV stations. This is especially important for
kV Assist, since the scan kV may be different from the baseline kV in the protocol. This could
result in very different behavior if the same mA limits are used.
For example, if you select a maximum mA limit of 440 mA at 120 kV, and then perform a scan at
80 kV (with the same 440 mA limit), the maximum X-ray output during the scan (at the
maximum mA limit) could be 2-3 times lower than expected. This is equivalent in terms of
maximum output to a scan at 120 kV with a mA limit of ~150-220 mA, which may not be the
desired behavior. To prevent you from having to perform this type of calculation manually to
update mA limits when a new kV is used, kV Assist automatically updates the mA limits for the
kV selected. The mA limits are set to achieve the same minimum / maximum scanner radiation
output as at the baseline kV (up to the system limits).

4.5 Build a protocol with kV Assist

Use this procedure to build a kV Assist enabled protocol and define the baseline Manual kV,
Noise Index, or Manual mA values in the protocol.
1. From the image monitor, click
Protocol Management , then click Protocol Management again.
2. Click
CT Login authentication window, enter your Log On Name and Password.
3. From the
Protocol Selection window, create a new protocol or select a protocol to edit.
4. From the
5. Click [Edit] if you are making changes to an existing protocol.
6. Set the Scout parameters.
7. Set the Axial scan parameters.
a. From the
Slice Thickness , Rotation Time , Pitch and SFOV .
NOTE:
b. From the
[kV] and set the baseline
c. From the
d. Select a
e. Select a minimum and maximum kV value to define the kV range.
This selection allows the user to avoid using too low or too high of tube voltages.
f. Select [Auto Adjust].
8. Continue with specifying the parameters for the series.
9. Verify the remaining parameters for the subsequent series in the protocol.
10. Save the protocol.
Chapter 18 Protocols
.
Scan Settings window, set the baseline parameters for Noise Index , Mode ,
Once kV Assist is selected, you are not able to change these settings until kV
Assist is turned off.
Scan Settings window, open the kV and mA Control collection and then click
Manual kV value.
kV Mode area, select [kV Assist].
Clinical Task .
Revolution CT User Manual
Direction 5480385-1EN, Revision 1
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