MRI-based Radiation Detection

Within this project we theoretically and experimentally investigate if ionizing radiation can be detected in a standard clinical MRI system.

As moving electrons, which are emitted during the interaction between ionizing radiation and matter, represent small currents, they emit themselves magnetic fields. These additional fields interfere with the external and internal (subject specific) magnetic fields. As such, they might potentially influence the signal of a standard MR gradient echo sequence. If such a contribution can be detected, it might provide direct information about the position of a radioactive tracer in a hybrid MR/PET system or about the distribution of energy absorbed from the incident beams, e.g. when combining MR systems with an external linear accelerator for the treatment of malignant diseases.

In initial experiments, we have indeed observed a small change of the MR phase signal inside an area that was hit by highly-ionising alpha particles. However, a simple theoretical model for the calculation of the strength of the additional magnetic field contribution is in contradiction with the experimentally observed phase changes. We therefore currently investigate possible reasons for this discrepancy by developing refined theoretical models that are compared to new, independently designed experiments.