Study of the capabilities of the Timepix detector for Ion Beam radiotherapy applications

The finite range of ion beams in matter and the presence of the Bragg-peak at the end of their range enable to create highly localized dose distributions. This advantage represents at the same time a challenge - namely to control all factors influencing the dose distribution with high precision. To ensure the required quality of the dose distribution applied to the patient, a number of measurement procedures is conducted. Many of these techniques were adopted from photon beam radiotherapy. Improvements in terms of the information amount gained are expected from new generations of dedicated ion detection techniques. One of the possible research directions is given by semiconductor-based detectors, which are at present rarely used in ion beam radiotherapy. In this contribution we report on the studies of the capabilities of the Timepix detector. This hybrid semiconductor pixelated detector was developed by the Medipix Collaboration at CERN. Its high spatial resolution allows an online registration of single ions. Experiments were performed at the Heidelberg Ion Beam Therapy Center in Germany using carbon ion beams. The signal pattern of single ions in the detector signal was shown to provide separation of the primary and different types of secondary ions. The direction of the secondary ions emerging from different irradiated phantoms were measured using 3D voxel detector containing several Timepix layers. The analysis of the recorded ion tracks shows a correlation with the beam range, position and width, which are all of high interest for monitoring of the beam within the patient during the therapy delivery. The results of the discussed studies show that the Timepix detector offers attractive capabilities for the needs of carbon ion beam therapy.