4.3.1.2 kV Assist kV Mode
When
kV Assist
Mode is selected, the system will adjust kV and NI / minimum and maximum
mA based on the patient attenuation from the scout, and the protocol’s clinical task, baseline kV,
kV range, mA mode, and mA setting or mA range and Noise Index.
See the
Protocol
chapter for additional details on setting up kV Assist in protocols.
4.3.2 mA Mode
From the
kV and mA Control
collection, select
mA Mode
.
The mA value determines the focal spot size that can be used to limit the system to a small
focal spot. You need to enter the correct mA value for the focal spot you wish to use based on
Table 17 and Table 18. The system minimum is 10 mA. The system maximum for SmartPrep
scans is 140 mA. The system maximum for scout scans is 250 mA. The system maximum for
pediatric scans is kV dependent based on a limit of 42 kW. For Helical scans, the mA may be
further constrained by the duration of the scan.
Table 17: Maximum permissible mA values for single 0.3 second exposure
Single Scan mA Ratings: 0.3s Focal Spot
Scan Mode kV Extra Large Large Small
Normal
70
375 375 250
80 580 580 580
100 720 720 490
120 740 665 405
140 635 570 350
Hi-Res
70
N/A 375 250
80 N/A 580 425
100 N/A 545 340
120 N/A 455 280
140 N/A 390 240
Table 18: Maximum permissible mA values for single 4 second exposure
Single Scan mA Ratings: 4s
Focal Spot
Scan Mode kV Extra Large Large Small
Normal
70
375 375 250
80 580 580 550
100 720 660 440
120 605 550 365
140 520 470 310
Hi-Res
70
N/A 375 250
80 N/A 580 385
100 N/A 475 310
120 N/A 395 255
Revolution CT User Manual
Direction 5480385-1EN, Revision 1
Chapter 11 Scan 271
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