Anatomy Selection; Considerations; Graphic Prescription (Graphic Rx) - GE Revolution CT User Manual

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Cardiac Axial imaging is used for non-contrast calcium score scans.
Recommended setting for calcium scoring, including Agatston (AJ-130), calcium volume and
calcium mass: GE CACS Auto Gating Profile, 120 kV, 0.28 s/rotation, 2.5 mm slice
thickness, 160 mm coverage, 25 cm DFOV, Noise Index = 20, with an ASiR-V level of 50%.
A manual mA of 300 for a medium-sized patient may be used in place of specifying a Noise
Index.
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The system will support heart rates from 30–200 beats per minute, but imaging cardiac
patients with arrhythmias, mechanical dysfunction, or higher heart rates may lead to images
that are degraded because of motion, which may compromise diagnostic quality.

3.4.1 Anatomy Selection

The user sets the start and end location of the cardiac scan, either graphically or using a
numerical entry. The system determines the minimum number of exposures and the smallest
collimation or collimations that will cover the prescribed region to minimize both scan time and
dose.
Hearts can typically be acquired using a single exposure. Scans that require the aortic arch or
scans of coronary artery bypass graft (CABG) patients will typically require two exposures. In
this case, the system also optimizes to place the entire heart within a large inferior-sided scan
with a smaller superior-sided scan.
The user inputs the top and bottom of the region where imaging is required. The system
generates scan prescription parameters that will cover these top and bottom locations out to the
edge of the DFOV specified for the primary reconstruction. Additional image slices will also be
reconstructed above and below these locations to the extent allowed by the geometry of the
system. The first and last image locations are displayed, and these values can be indirectly
changed by specifying where full field of view images are required.

3.4.1.1 Considerations

The advanced, wide coverage system is able to generate high temporal-resolution images
throughout most of the imaged volume. Additionally, the system generates images with
excellent spatial resolution but with increased susceptibility to motion artifact in the outer radial
portions of several of the first and last images. For this reason, we recommend that the scanned
region extend at least 1 cm beyond the heart in all directions.

3.4.1.2 Graphic Prescription (Graphic Rx)

With the Graphic Rx feature, the user can use the scout to specify the required scan range, as
well as the lateral extent of the primary reconstruction. When two orthogonal (e.g. A/P and
Lateral) scouts are acquired, the graphic prescription remains synchronized.
Right-click on the Graphic Rx to adjust the display options.
Detailed View Off:
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A blue Graphic Rx box indicates the approximate location of the image region that will have
optimal temporal resolution across the full DFOV for the primary image reconstruction.
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The first and last few images may have a reduced field of view. The system will generate full
DFOV images at or beyond the location of the user specified scan ranges indicated by a
blue line.
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Revolution CT User Manual
Direction 5480385-1EN, Revision 1
3 Cardiac Scan Parameters