140 / 1542
Surrogates of target position
• Used when the target object cannot be seen directly using the
imaging technologies available, commonly MV portal imaging or kV
planar imaging.
• Implanted markers in, or close, to the structure of interest may be
used as surrogates.
•
Surgical clips
may be placed in the tumour cavity of a breast
patient at the time of surgery.
•
Gold markers
are used in prostate patients with EPI or CBCT.
• The BrainLab and Cyberknife systems use
implanted markers
to
track tumour movement.
• Small
wireless transmitters
have been used in both prostate and
lung.