Physics Bucharest 2017

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.