3.5.2 Coverage Speed
3.5.2.1 Detector Coverage (mm)
The detector coverage of the scan, or of the series of scans, is shown. To edit a value in a multi-
table position scan, first split the group into individual scans, then change the detector coverage
to the desired value. Note that this will disable the automatic determination of the detector
coverage based on your numerically or graphically specified end location.
3.5.2.2 Single Table Position
When Table Positions is set to “One”, the feature restricts the system to acquiring data at a
single axial location. When the system cannot fully cover the user-prescribed scan region, at the
field of view specified in the primary reconstruction, an alert will be displayed by the
Anatomy
Selection
scan start and end parameters, indicating that the scan range has been restricted by
the
Coverage Speed
:
Table Positions
:
One
. To allow a larger scan range with multiple table
positions, change the value to
One or More
.
3.5.2.3 Number of Passes
The number of times that the system runs the prescription defined in the
Anatomy Selection
and
ECG and Gating
settings. For example, changing the value from 1 to 2 will result in two passes,
and will double the patient dose.
This parameter is useful for generating multiple passes of a region, such as for viewing the
dynamic changes in contrast.
NOTE:
When Arrhythmia Retrigger is enabled, either by the user or by the Auto Gating
feature, the number of passes will be two. When Arrhythmia Retrigger is changed
from enabled to disabled, the
Number of Passes
will be one.
3.5.2.4 Minimum Time Between Passes
The system adds a delay between each pass so that generated images will be separated by this
amount of time. When the acquisitions are ECG-gated, the system attempts to generate images
that are within one-half of an R-wave to R-wave interval (half of a heart beat), or less, of the
specified time.
3.6 Display an ECG Trace on the operator console
The ECG Trace component is displayed near the top of the scan monitor. It shows the real-time
heart rate, recent min and max heart rates, the ECG Trace, the procedure duration, user-
selectable jump points to show the live ECG or one of up to three breath-hold ECG recordings.
The statistics of the last recording, indicated by a white dot, are used to set the Auto Gating
parameters. Click on
Live
to return to the live ECG.
Illustration 12: ECG Trace component
When Auto Gating is “On”, scan settings in the
ECG and Gating
collection are automatically
updated when a patient breath hold ECG is recorded. These settings are indicated by a white
dot, and are highlighted when an update occurs.
Revolution CT User Manual
Direction 5480385-1EN, Revision 1
Chapter 13 Cardiac 353
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