104 MI-42-0001 Rev. 19
SCANNING: Typical Scan Sequence: New Scan
When the dose caution appears on the
Please select 2D scout scan view
screen, the
selected scout scan and subsequent 3D scan may result in higher total dose than a
fixed mA 3D scan for the current protocol.
6.8.11 Positioning With Lasers
In Helical Scan
Mode
In Helical scan mode, start and end points set with lasers accurately represent the start and end of
the scan region.
In Axial Scan Mode
In Axial scan mode, the scan length will be a multiple of the axial scan step size (31 mm). The scan
region is centered between the start and end positions indicated by the lasers. What this means is:
• Coincident start and end points produce a single axial scan with the center slice indicated by
the laser line.
• Start and end points up to 31 mm apart produce a single axial scan centered around the
midpoint between the indicated start and end.
• Start and end points greater than 31 mm apart produce a sequential axial scan. A warning may
be displayed to inform the user that extension of the scan beyond the selected endpoints is
required to accommodate the axial step size. For example, start and end positions 50 mm apart
will produce a warning that the scan length has been increased by 12 mm. The scan region will
extend 6 mm beyond the lasers in each direction.
X-ray scan region overage is probable when using the Axial scan mode. When setting
the scan region close to areas sensitive to radiation, extra caution should be taken
when positioning the start and end points. Ensure that the extra scan length indicated
by the warning does not unintentionally cover these areas.
Steps
1. When the Select 2D scout scan screen shows the dose caution
a, review:
• kV and mA parameters of the 3D scan s
• kV and mA parameters of the 2D scout scan d
2. When the field of view optimization and, for Helical scans, the mA modulation possible with
a Scout scan are likely to:
• Benefit the patient, continue with either
A-P
or
Lateral
, and touch
Next
to set the End and
Start positions for the Scout scan.
Or
:
• Not benefit the patient, select
Skip Scout Scan
, and then touch
Next
to set the End and
Start positions for the 3D scan.
Options
To change the patient’s position settings, touch Back.
To proceed, touch Next.
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