4D in-beam PET Datenauswertung für bewegte Phantome bei Bestrahlung mit einem getrackten 12C6+-Strahl

In-beam PET has become a quality assurance tool providing valuable clinical feedback for static tumor entities and shall be extended to monitor the treatment of intra-fractional moving tumors like in the lung or
liver which are subjected to respiratory motion. The potential of 4D in-beam PET for the detection of possible malfunction of the motion compensated beam delivery has been investigated by means of systematic phantom experiments at the clinical in-beam PET installation at GSI Darmstadt. The new system for tracking moving targets with the scanned ion beam at GSI Darmstadt was used to adapt the Bragg peak positions laterally and in depth. The pencil beam has been rescanned on a horizontal line in a phantom placed at the central plane of the double head PET scanner with an energy corresponding to 60mm penetration depth while the target was performing a one dimensional periodic motion perpendicular to the beam direction. 4D PET data were compared with an appropriate 3D PET measurement which followed immediately after the dynamic acquisition. It is shown for different irradiation scenarios that in-beam PET is capable for detecting treatment errors for moving target irradiation.