Siemens ARCADIS Varic, Operator'S Manual, Page: 259 / 476

Image Processing
ARCADIS Varic
SPR2-310.620.30.02.02
57
of 78
Subtraction processing
0
Unlike bones for example, vessels do not show a considerably greater absorption
of X-rays compared to the surrounding tissue. In X-ray exposures vessels are not
especially highlighted.
When subtraction is performed, two X-ray exposures are acquired of the region
of interest, one with contrast medium and one without contrast medium. After-
wards both exposures are subtracted.
In the subtraction image, areas with the same attenuation and areas with a (slight-
ly) different attenuation, e.g. vessels that were filled with contrast medium during
the exposure, can be discerned clearly.
When the SUB/Roadmap option is installed, the following functions are available
to optimize subtraction images:
❏
Anatomical background
❏
Pixelshift
Loading and displaying images
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Native images from previous examinations acquired in the Subtraction mode (op-
tion) or Roadmap mode (option) are stored in the local database or in your archive
together with the subtraction images. Both image types can be displayed simul-
taneously on both monitors.
◆
Load the images of the requested patient into the Viewing task card by using
the Patient Browser .
◆
Select Sub > Sub/Native Display in the main menu of the Viewing task card.
— or —
◆
Click this button in the
Sub
subtask card.
– In the Viewing task card the subtraction images are displayed on the left
monitor.
– In the Native task card the corresponding native images are displayed on
the right monitor.