Scanning Information; Scan Parameters - Siemens SOMATOM Manual

Respiratory Gating

Scanning Information

The expected benefits in radiation treatment planning,
e.g. for lung and abdominal tumors are:
• Information about tumor motion in 3D coordinates
and over time
• More accurate tumor shape delineation and there-
fore a more precise RTP (radiation therapy planning)
• Potential for sparing of healthy tissue, minimization
of PTV (planned target volume) and less side effects
• Potential for dose acceleration and higher cure rate
To minimize motion artifacts, two requirements are
mandatory for a CT system:
– Fast gantry rotation to raise the temporal resolution
for artifact free images
– Prospective triggering of image acquisition in a
sequential mode or retrospective gating of image
reconstruction in a spiral mode based on the record-
ing of the respiratory curve in order to obtain images
during inspiration and expiration phases.

Scan Parameters

A respiratory gated lung spiral with cone correction
will be provided. To be able to work also with low
breathing rates, a fixed pitch factor of a min. of 0.1 is
needed. Slice widths and collimation are the same as
for cardio spiral.
In the Specials folder different scan protocols are pre-
defined for different breathing rates.
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