g 
Product Data Sheet – rev 4.2 
July 4th 2003  
Page 4 
 
 
 
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 
Helical Multi-slice Modes:  Prospective Multiple-
Thickness Reconstruction: 
efficient cooling for high throughput and 
superior helical performance. 
•  Wide range of technique factors (10 to 440 
mA, in 5 mA increments) gives the operator 
and physician flexibility to tailor technique to 
specific needs, optimizing patient dose, and 
providing the power needed to perform a 
broad spectrum of axial and helical 
examinations. 
Simplified scan prescriptions and easy-to-use 
default protocols make the  LightSpeed
16 
 fast 
and efficient in patient set up. 
For all helical scan modes, the operator can 
choose to reconstruct images prospectively in 
any of the defined nominal slice thicknesses.  
Multi-slice acquisitions and short intergroup 
delays significantly reduce potential mis-
registration between scans by increasing the 
number of scans possible in a patient breath 
hold. Contrast agents may be better utilized 
as well due to significantly faster scan 
acquisition. 
In addition to the initial reconstructed slice 
thickness, the operator has the option to 
prospectively specify additional images to be 
reconstructed from a single raw data set. 
These images can be reconstructed at any of 
the defined nominal slice thicknesses 
available for a given table speed and scan 
mode. 
System Specifications 
Scan Modes: 
Helical protocols are almost identical to 
“classical” axial scan protocols. At the 
beginning of a study, the operator selects the 
type of exam with the anatomical programmer, 
and indicates the desired scan range - either 
manually, or from a Scout. 
The  LightSpeed
16 
CT  system can perform 
virtually any clinical application due to its wide 
variety of scan modes. With the LightSpeed
16 
,  
body CT studies are easier to perform and 
more productive than ever before. 
This effectively facilitates later, more detailed 
image analysis without additional patient 
scans and subsequent dose and image 
registration concerns. 
After completing the prescribed exam, the 
system remains ready to continue with 
additional helical scans or a set of axial scans. 
Helical:
 
 
8-SLICE HELICAL MODES 
Table Speed (mm/rotation) 
Slice
Thick
-ness 
(mm) 
Pitch 
0.625:1 
 
 
0.875:1
 
 
1.35:1
 
 
1.675:1
 
1.25 6.25  8.75   13.5 16.75 
2.5 6.25 
12.5 
8.75 
17.5 
13.5 
27.0 
16.75 
33.5 
3.75 6.25 
12.5 
8.75 
17.5 
13.5 
27.0 
16.75 
33.5 
5 6.25 
12.5 
8.75 
17.5 
13.5 
27.0 
16.75 
33.5 
7.5 6.25 
12.5 
8.75 
17.5 
13.5 
27.0 
16.75 
33.5 
10 6.25 
12.5 
8.75 
17.5 
13.5 
27.0 
16.75 
33.5 
•  Continuous 360° scanning with table 
incrementation and no interscan delay. 
The operator may reconstruct helical scans 
prospectively with up to 90% overlap, and 
retrospectively, at any arbitrary table location 
in 0.1 mm increments. 
•  Scans can be acquired in a wide variety of 
speeds. 
Axial:
 
Helical Multi-slice Modes 
•  Up to 16 contiguous axial slices acquired 
simultaneously with each 360° rotation, with 
the time between scans set by the user-
selected interscan delay (ISD) or intergroup 
delay (IGD). 
The complex nature of helical multi-slice 
scanning has been simplified by grouping 
all critical acquisition parameters within 8 
basic scan modes, all optimized for image 
quality and speed. For eight-slice 
acquisition: 0.625: 1; 0.875: 1; 1.35: 1 and 
1.675: 1. For sixteenslice acquisition: 
0.5625: 1; 0.9375: 1; 1.375: 1 and 1.75: 1. 
These clinically derived multi-slice scan 
modes offer a wide range of selections 
that carefully balance acquisition speed, 
image thickness, artifact level and 
retrospective image reconstruction 
flexibility. 
•  Scans may be easily clustered in groups to 
allow multiple scans in a single breath hold. 
•  Minimum scan-to-scan cycle time of only 1.5 
sec with table moves of  ≤ 10 mm (any scan 
time). 
Scout™:
 
•  Single radiographic plane for scan 
localization and graphical prescription of 
prospective reconstruction; 
 
This simplified user interface guides the 
user in the choice of scan parameters. 
The user selects a pitch mode, a desired 
image slice thickness and table travel per 
rotation. The user interface also displays 
the resulting choice of retrospective image 
thicknesses available for each choice of 
acquisition parameters. 
•  Extended range matches helical scannable 
range. 
Helical Scans 
Slip ring technology has advanced axial 
scanning by enabling scans with zero 
interscan delay and simultaneous table 
movement. 
The 16 slice helical acquisition modes 
provide table speeds from 5.625 
mm/rotation up to 35 mm per rotation, 
enabling scan speeds that are up to 12 
times faster than 4-slice helical scanners. 
* Option