GE LightSpeed 16 Product Data Sheet page 7

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Product Data Sheet – rev 4.2
July 4th 2003
Page 7
•
0.584 mm limiting resolution
•
4.0 lp/cm @ 50% MTF
•
6.5 lp/cm @ 10% MTF
•
8.5 lp/cm @ 0% MTF
Hi-Res Algorithm (Edge).
•
0.324 mm limiting resolution
•
8.5 lp/cm @ 50% MTF
•
13.0 lp/cm @ 10% MTF
•
15.4 lp/cm @ 0% MTF
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:
5 mm @ .3% at 13.3 mGy
3 mm @ .3% at 37.2 mGy
Noise:
On either an AAPM water phantom or GE
Quality Assurance phantom:
0.32% +/- 0.03% at 28.5 mGy (2.85 Rad)
CTDI:
On CTDI Head and Body Dose Reference
Phantoms:
CTDI expressed in mGy/100 mAs for
vol
IEC pitch 1: (normalized to a pitch of 1).
Head 20.9 mGy/100 mAs
Body 10.6 mGy/100 mAs
* Option
LightSpeed
With Xtream
CT Scanner System
Axial Scans
Multi-slice acquisitions and short interscan
delays significantly reduce potential missed
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 scans.
Axial Multi-slice Prescription
Simplified scan prescriptions and easy-to-use
default protocols make the Lightspeed
Scanner fast and efficient in patient set-up.
Axial protocols are nearly identical to helical
scan protocols.
Axial Multi-slice Modes
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The LightSpeed acquires axial scans in
sets of 8 or 16 contiguous images in one 360°
rotation.
For each rotation of the gantry, the
16
LightSpeed collects 16 rows of scan
data. There are five reconstruction modes
available for creating images from the
multi-slice scan data (1i, 2i, 4i, 8i, and 16i).
By using 1i, 2i, 4i, and 8i reconstruction
modes, scan data can be combined prior
to image reconstruction to create slices
with reduced partial-volume artifacts. This
is particularly useful for posterior-fossa
imaging.
1i Mode:
• Produces 1 image per rotation
• Nominal Thickness: 1.25, 5, 10 mm
2i Mode:
• Produces 2 images per rotation
• Nominal Thickness: 0.625, 2.5, 5, 7.5, 10
mm
4i Mode:
• Produces 4 images per rotation
• Nominal Thickness: 2.5, 3.75, 5 mm
8i Mode:
• Produces 8 images per rotation
• Nominal Thickness: 1.25, 2.5 mm
16i Mode:
• Produces 16 images per rotation
GE Medical Systems-America
Milwaukee, USA - Fax: 1 414 544 3384
GE Medical Systems-Asia:
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Tokyo, Japan - Fax: 81 425 85 5490
Hong Kong - Fax: 852 2559 3588
GE Medical Systems-Europe
• Nominal Thickness: 0.625, 1.25 mm
Axial Scan Parameters
Scan Time:
• 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0 and 4.0
second full scans (360° acquisition)
Scan Technique:
• kVp: 80, 100, 120, 140
• mA: 10 to 440, in 5 mA increments
• Power: 0.8 to 53.2 kW
16
CT
• Focal Spot Selection:
• Small spot for up to 24 kW
• Large spot for greater than 24 kW
Scan Plane Geometry:
• +/- 30° gantry tilt, in 0.5° increments
• Longitudinal positioning in 0.01 mm per slice
increment. Gantry display in 0.5 mm
increments.
Interscan Delay (ISD):
• Minimum ISD with table movements of
0 - 10 mm: 1.0 sec.
• Minimum ISD with table movements of more
than 10 mm and up to 20 mm: 1.3 sec
• User-selectable.
Inter Group Delay (IGD):
• Minimum IGD is the same as minimum ISD;
also user-selectable.
Scan-to-Scan Cycle:
• Minimum scan-to-scan cycle of 1.5 seconds
possible for 0.5 sec. scan speed with
minimum ISD's.
Scan Fields of View:
• 25 cm for adult head
• 25, 50 cm for body
• 25 cm for pediatric head
Scan with no table incrementation,
contiguous image location, or skipped
image location are possible. Overlapped
axial scans are not possible.
Axial Image Reconstruction
Reconstruction Algorithms: Soft Tissue,
Standard, Detail, Bone, Bone Plus, Lung and
Edge.