Proton Beam Range Verification with Secondary Radiation from Titanium Implants

Several methods of proton beam range verification have been evaluated during the last decades. Since so-called in-room solutions require the space in the treatment room and offline imaging methods, e.g. positron emission tomography (PET), is limited by the wash out of biological molecules, another method is evaluated during this experimental study on the potential for PET imaging. A possible solution for the biological wash out is that, four out of five brain tumor patients at the West German Proton Therapy Centre Essen (WPE) have titanium clips from surgical resection. This requires a precise knowledge of the produced radionuclides from titanium after the irradiation with protons and the corresponding activation cross sections. For the determination of the activation cross section a pure, thin titanium sheet is irradiated. A titanium alloy, which is called grade 5 and used for implants and clips, is also irradiated and compared with the pure one. Furthermore, a first simplified titanium based phantom is irradiated and afterwards a PET scan is taken to determine the activity with the sample. The first studies show the potential of titanium for proton beam range verification.