g
Product Data Sheet – rev 4.2
July 4th 2003
Page 6
LightSpeed
With Xtream
CT Scanner System
GE Medical Systems-America
Milwaukee, USA - Fax: 1 414 544 3384
GE Medical Systems-Asia:
Tokyo, Japan - Fax: 81 425 85 5490
Hong Kong - Fax: 852 2559 3588
GE Medical Systems-Europe
next available recon. Available during or
after scanning.
Total Scan Total Elapsed Max
Time (sec.) Time (sec.) mA
Helical Scan Protocols
Images annotated to indicate continuous
scan acquisition with table incrementation:
150 155 100-200
200 205 80-150
450 465 50-70
All protocols assume 120 kVp scans under
typical clinical conditions.
HE (helical) + Pitch
Single Helical Scans:
Helical Scan Image Quality
Table speed
Prospective Multiple Reconstruction
(PMR): Up to 3 sets of reconstructions can
be pre-programmed as part of the scan
protocol prior to acquisition. The operator
can select different start/end location, slice
thickness, interval, reconstruction
algorithms and display fields of view for
each reconstruction. This frees the
operator from sitting at the console and
directly contributes to increased
productivity.
Scan
Time
Maximum
mA
10 sec. 440
20 390-440
30 330-380
40 290-350
50 260-320
60 230-310
70 210-300
80 180-280
90 170-270
100 160-260
110 150-250
120 140-230
Volumetric Helical Scan Image Quality
With LightSpeed
16
being a sub-millimeter
isotropic CT scanner, it is now possible to
specify coronal and sagittal image quality:
1. Visual Measurement:
Reformatted resolution is demonstrated on
the Nuclear Associates AAPM High
Contrast Resolution Insert #76-413.
Prospective Recon: Operator may initiate
full recons at any table location in
increments of 1/10 the image thickness;
image thickness remains constant.
0.5mm
Retrospective Recon: Operator may
initiate full recons at any table location in
0.1 mm increments; image thickness
remains constant.
Retrospective Image Decomposition:
The operator has the option to
retrospectively decompose the original
raw data set and reconstruct additional
images at any of the defined nominal
image thickness available for a given table
speed and scan mode.
Multiple Helical Scans
(contiguous helical coverage with 5-
second IGD):
Scan
Time IGD
No.
Scans
Max
mA
10 sec. 5 sec. 3 340-420
4 300-400
5 270-390
6 240-360
20 sec. 5 sec. 2 300-360
3 240-330
4 180-310
30 sec. 5 sec. 2 230-310
3 180-280
4 140-240
40 sec. 5 sec. 2 190-290
3 140-230
4 110-190
50 sec. 5 sec. 2 170-270
3 120-200
4 90-160
60 sec. 5 sec. 2 140-240
3 100-170
0.4mm
An Effective 0.5 mm voxel size is clearly
seen in coronal and sagittal views.
2. Statistic Measurement:
Volumetric MTF is computed from the X,Y
and Z axis of a 0.2mm bead using sagittal
and coronal images of the 8” Catphan,
MTF module with bead source #CTP445.
Detail Algorithm
MTF (z-axis) is 12.4 lp/cm @ 10%, 15
lp/cm @ 0% which is a 0.333 mm limiting
resolution
Contiguous Helical Coverage
In Plane Helical Scan Image Quality
Multiple helical scans can be performed in
succession with only 5-second delays
between helical scans, providing up to
2,881 contiguous rotations (with up to
1,500 images in one series).
For details of scan technique please refer
to the technical reference manual.
High-Contrast Spatial Resolution
On GE Performance phantom:
(The following chart assumes 120-second
helical with 5-sec IGD)
Standard Algorithm
* Option
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