A New Fiducial Marker for Gated Radiotherapy in the Lung – A Feasibility Study of Bronchoscopy Based Insertion and Removal in Göttingen Mini-Pig

To develop a new prototype fiducial marker (LS-1) that may be used for gated radiotherapy in the lung.  One LS-1 marker was inserted in the lung of each animal under sedation. Animals were kept under observation  for four weeks after insertion. After the observation period the marker was removed. Animals were  CT scanned after insertion and before removal of the LS-1 marker. After the last CT scan animals were  euthanized and lungs excised for pathology. The LS-1 marker was successfully inserted in all fourteen animals. Thirteen of fourteen LS-1 marker’s  were in situ after four weeks. Two cases of pneumothorax were seen in connection with insertion. The LS-1  marker could only be successfully removed from eleven of thirteen animals. Damage to the lung was mainly  local close to the LS-1 marker insertion site. The LS-1 marker has the potential to be a fiducial marker suitable for gated external beam radiotherapy in  the lung. The method still needs some refinement prior to application in humans.