Those who have to fight a powerful enemy must look for allies. This is why physicists from different scientific fields have decided to cooperate with biomedical physicians in order to place the fight against cancer through heat treatment by means of magnetic nanoparticles on a solid, scientific basis. It is the objective of the cooperation to improve the success of the therapy. Within the scope of a joint project funded by the Deutsche Forschungsgemeinschaft, Melanie Kettering from the Institut für Diagnostische und Interventionelle Radiologie (IDIR), University Hospital Jena, and Heike Richter from the Physikalisch-Technische Bundesanstalt (PTB) are responsible for the task of detecting where many magnetic nanoparticles can be found in the body of the patient. They are injected into the tumour - but do they really remain there or are they distributed throughout the body? Knowing how many are in the tumour is important for the success of the heat treatment. Now the scientists have been able to successfully demonstrate on mice that magnetic relaxometry is suited to be applied together with the heat treatment. It furnishes information about the whereabouts of the nanoparticles in the body – completely without contact to the patient.