Brainlab EXACTRAC INFRARED MONITORING Clinical User Manual page 100

Reasons for Ambiguities may occur due to symmetrical marker positioning as shown in figure 41:
Remaining
Ambiguities
Ambiguities may occur due to marker shift, caused by any of the following:
• Inaccurate reapplication of markers.
• Skin shift causing a different interrelationship between the markers.
• Inaccurate patient (re)positioning.
100
No. Description
a
Exact rotation not uniquely defined
Avoid symmetrical marker positioning.
No. Description
a
No alignment possible
Place markers accurately and carefully. Select relatively immobile skin areas for mark-
er placement.
a
Figure 41
a
Figure 42
Clinical User Guide Rev. 1.1, ExacTrac Infrared Monitoring Ver. 1.0