GE LightSpeed 16 Product Data Sheet page 6

g
Product Data Sheet – rev 4.2
July 4th 2003
Page 6
next available recon. Available during or
after scanning.
Images annotated to indicate continuous
scan acquisition with table incrementation:
HE (helical) + Pitch
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.
Prospective Recon: Operator may initiate
full recons at any table location in
increments of 1/10 the image thickness;
image thickness remains constant.
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.
* Option
LightSpeed
With Xtream
CT Scanner System
Helical Scan Protocols
All protocols assume 120 kVp scans under
typical clinical conditions.
Single Helical Scans:
Scan Maximum
Time 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
Multiple Helical Scans
(contiguous helical coverage with 5-
second IGD):
Scan No.
Time IGD Scans
10 sec. 5 sec. 3
4
5
6
20 sec. 5 sec. 2
3
4
30 sec. 5 sec. 2
3
4
40 sec. 5 sec. 2
3
4
50 sec. 5 sec. 2
3
4
60 sec. 5 sec. 2
3
Contiguous Helical Coverage
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).
(The following chart assumes 120-second
helical with 5-sec IGD)
GE Medical Systems-America
Milwaukee, USA - Fax: 1 414 544 3384
GE Medical Systems-Asia:
16
Tokyo, Japan - Fax: 81 425 85 5490
Hong Kong - Fax: 852 2559 3588
GE Medical Systems-Europe
Total Scan
Time (sec.)
150
200
450
Helical Scan Image Quality
Volumetric Helical Scan Image Quality
With LightSpeed
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.
0.5mm
Max
mA
340-420
300-400
270-390
0.4mm
240-360
An Effective 0.5 mm voxel size is clearly
300-360
seen in coronal and sagittal views.
240-330
180-310
2. Statistic Measurement:
230-310
180-280
Volumetric MTF is computed from the X,Y
140-240
and Z axis of a 0.2mm bead using sagittal
190-290
and coronal images of the 8" Catphan,
140-230
MTF module with bead source #CTP445.
110-190
170-270
120-200
Detail Algorithm
90-160
140-240
MTF (z-axis) is 12.4 lp/cm @ 10%, 15
100-170
lp/cm @ 0% which is a 0.333 mm limiting
resolution
In Plane Helical Scan Image Quality
For details of scan technique please refer
to the technical reference manual.
High-Contrast Spatial Resolution
On GE Performance phantom:
Standard Algorithm
Total Elapsed Max
Time (sec.) mA
155 100-200
205 80-150
465 50-70
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being a sub-millimeter