one of the few laboratories in Europe for investigating fuel rods in commercial reactors. The division works closely with ETH Zurich, EPFL and the University of Bern, using, for example, their high-performance computers or the CROCUS research reactor at EPFL. Human health PSI is one of the leading institutions worldwide in the research and application of proton therapy for the treatment of cancer. Since 1984, the Center for Proton Therapy has been successfully treating cancer patients with a special form of radiation therapy. To date, more than 7500 patients with ocular tumours have been irradiated (status 2020). The success rate for eye therapy using the OPTIS facility is over 98 percent. In 1996, an irradiation unit (Gantry 1) was equipped for the first time to use the so-called spot-scanning proton technique developed at PSI. With this technique, tumours deep inside the body are scanned three-dimensionally with a proton beam about 5 to 7 mm in width. By superimposing many individual proton spots – about 10,000 spots per litre volume – the tumour is evenly exposed to the necessary radiation dose, which is monitored individually for each spot. This allows an extremely precise, homogeneous irradiation that is optimally adapted to the usually irregular shape of the tumour. The technique enables as much as possible of the surrounding healthy tissue to be spared. The first gantry was in operation for patients from 1996 to the end of 2018. In 2013, the second Gantry 2, developed at PSI, went into operation, and in mid-2018 another treatment station, Gantry 3, was opened. In the field of radiopharmacy, PSI's infrastructure covers the entire spectrum. In particular, PSI researchers are tackling very small tumours distributed throughout the body. These cannot be treated with the usual radiotherapy techniques. New medically applicable radionuclides have, however, been produced with the help of the proton accelerators and the neutron source SINQ at PSI. When combined for therapy with special biomolecules – so-called antibodies, therapeutic molecules can be formed to selectively and specifically detect tumour cells. These are then labelled with a radioactive isotope. Its radiation can be localized with imaging techniques such as SPECT or PET, which enables the diagnosis of tumours and their metastases. Moreover, it can be dosed so that it also destroys the tumour cells. Several such radioactive substances have been developed at PSI. They are currently being tested in clinical trials, in close cooperation with universities,