System Integration and Application of CdZnTe Detectors in a Compton Camera for Medical Use

Ion beams offer advantages over conventional treatment modalities, such as photons. Because of the way ions deposit their energy on their path through tissue they allow for an increased dose deposition in the tumor volume and reduce the collateral damage to the surrounding healthy tissue. However, the range of these particles is sensitive to small density changes in the irradiated volume. Deviations will lead to a misalignment of the deposited dose maximum and the tumor. It is therefore highly desirable to verify the particle range in-vivo and in realtime by means of a detector system independent from the treatment device. One approach is to monitor the prompt gamma-ray emissions from excited nuclei that originate in the interaction of projectile and target nuclei. A Compton camera could be one of the feasible technical solutions for such a monitoring system. To set up a clinical applicable device a comprehensive modelling of the creation of secondary radiation as well as of the detection process is required. Furthermore, a sophisticated reconstruction of the data is essential. This paper will present three different prototypes of such a detector system made of CdZnTe and scintillation detectors. Also we will show measurements on the detector performance as well as reconstructed images of the radiation sources.