GE LightSpeed 16 Product Data Sheet page 8

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Product Data Sheet – rev 4.2
July 4th 2003
Page 8
Reconstruction Matrix: 512
Display Matrix: 1024.
Display FOV: Freely variable center/off-center,
prospective/retrospective target selection.
CT Number Scale: -1024 to 3071 HU
Axial Image Reconstruction:
• Reconstruction time as fast as 6 images
per second.
• Typical 0.167 sec. image-to-image recon in
16 slice recon mode.
• Maximum image-to-image cycle time is
± 10% for prospective and retrospective
image-to-image display. This applies for
512 matrix; any display FOV; in
AutoView (all layouts); with concurrent
filming and image archival for all scan
modes.
• Iterative bone processing increases time by
250 milliseconds.
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 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.
The operator has the option to reconstruct
the original raw data set at any of the
defined nominal slice thicknesses.
Reconstructions can be prescribed down
to 1/16 the original acquisition image
thickness for images acquired in the 1i
scan mode, down to 1/8 the original
thickness for 2i mode, and down to 1/4 the
original thickness for 4i mode.
Similarly, additional reconstruction
supports partial-volume artifact reduction
by reconstructing images with 4, 8, or 16
times the acquisition image thickness.
These reconstruction features effectively
facilitate later, more detailed image
analysis without additional patient scans
and subsequent dose and image
registration concerns.
The following table illustrates the
retrospective reconstruction image
thicknesses available for each acquisition
thickness and mode:
* Option
LightSpeed
With Xtream
CT Scanner System
Prospective Perscription
Slice
Scan M ode Thickness Slice Thicknesses
16i - 0.625m m
8i - 1.25mm
16 row 0.625
16i - 1.25m m
16row 1.25
8i - 1.25mm
8 row 1.25
8row 2.5
Axial Scan Protocols
All protocols assume 120 kVp scans under
typical clinical conditions.
Standard Scans:
Scan
Time ISD mA Scans
1 sec. 1 sec. 440 18-45 0:35-1:27
1 1 400 24-55 0:47-1:49
1 1 360 32-68 1:03-2:15
1 1 340 37-76 1:13-2:31
1 1 320 43-86 1:25-2:49
1 1 300 50-97 1:37-3:11
1 1 280 58-110 1:45-3:37
1 1 260 66-122 1:55-3:59
1 1 240 74-135 2:07-4:21
1 1 220 84-152 2:21-4:49
1 1 200 94-168 2:37-5:21
2 1 200 37-77 1:13-2:33
2 1 180 42-86 1:23-2:51
• Cluster Scans (All cluster protocols assume
9-second clusters of five slices, 1-second
scans with 1-second interscan delays and 7
seconds between clusters).
16
Recon
mA
440
400
4i - 2.5m m
340
2i - 5.0m m
320
300
8i - 2.5m m
280
4i - 5.0m m
260
2i - 10m m
240
4i - 2.5m m
220
2i - 5.0m m
200
1i - 10m m
180
8i - 2.5m m
4i - 5.0m m
Axial Scan Image Quality
2i - 10m m
For details of scan technique parameters,
please refer to the technical reference
manual.
High Contrast Spatial Resolution:
On GE Performance phantom:
Standard Algorithm
Acquisition
Time •
•
•
•
Hi-Res Algorithm
•
•
•
•
Line pair values decrease with larger focal
spot (by 5% with Standard and by 7% with
Hi-Res); limiting resolution is unaffected.
Low-Contrast Detectability
On 8 inch (20 cm) CATPHAN phantom:
5mm @ .3% at 13.3 mGy
3mm @ .3% at 37.2 mGy
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
# Scans Acquisition
(Clusters) Time
15-45 (3-11) 0:41-2:49
25-55 (5-13) 1:13-3:21
35-75 (7-18) 1:45-4:41
45-85 (9-20) 2:17-5:13
50-95 (10-22) 2:33-5:45
60-110 (12-25) 3:05-6:33
75-125 (13-28) 3:21-7:21
85-145 (14-31) 3:37-8:09
100-170 (16-34) 4:09-8:57
115-185 (18-38) 4:41-10:01
135-250 (22-43) 5:45-11:21
0.584 mm limiting resolution
4.0 lp/cm @ 50% MTF
6.5 lp/cm @ 10% MTF
8.5 lp/cm @ 0% MTF
0.324 mm limiting resolution
8.5 lp/cm @ 50% MTF
13.0 lp/cm @ 10% MTF
15.4 lp/cm @ 0% MTF