Isotope factory and experimental arena
Bern cyclotron combines medical applications with fundamental research
For cancer patients, every day counts. Imagine one could skip one step in the cancer diagnosis and treatment process and do both at the same time: finding out where the tumor is and attacking it right away. A team at the University of Bern, which runs its own medical cyclotron laboratory, is currently working on exactly that. Their cyclotron is a proper workhorse for science. During the night, it produces medical isotopes for cancer diagnostics. During the day, it sidelines as a test facility for particle physics and multi-disciplinary scientific activities.
“Our cyclotron is a really versatile machine,” says Prof. Saverio Braccini, the project leader. “We can use the beam for whatever we want.” A particle physicist by training, he is used to pushing concepts and equipment to their limit, and when discussions for building a medical cyclotron in Bern began, it was his idea to open the facility up for other areas of research. The cyclotron, a type of particle accelerator, is only one of three in operation in hospitals in Switzerland. It is located in Bern University Hospital (Inselspital) and is run by the spin-off company SWAN Isotopen AG for the production of radiopharmaceuticals and by the University of Bern for research activities.
The machine’s primary goal – producing radio isotopes for cancer diagnostics – obviously always has priority over everything else. Whenever possible, though, particle physicists test new types of detectors, for example for the ATLAS experiment at the LHC at CERN, or radiation protection experts try new hardware for better shielding against radiation. Even space scientists put their equipment in the beam to check whether it can withstand the harsh conditions in space, like the European Space Agency’s JUICE space mission to Jupiter. “We have proved that we can simulate twelve years of irradiation on Jupiter in 30 minutes!” Braccini says.
It therefore suits very well that medical isotopes are produced during the night because the radiopharmaceuticals have a half-life of a few hours and need to be transported to patients quickly the very next day. The spin-off company produces F-18 for Fluorodeoxyglucose (a glucose analogue) and other compounds by shooting the 18-MeV proton beam onto a liquid target of stable isotopes, turning them into radioactive isotopes. When injected into a cancer patient through a liquid, these radioisotopes gather in areas in the body with high metabolic activity – a near-sure sign of a tumor – and can be made visible with the help of a PET scan, another spin-off from particle physics to medical research.
During the day, the cyclotron would have stood still unused if it hadn’t been for Braccini and his team of scientists, engineers and students. “It’s a win-win-win situation,” he explains. “We can alert the company if somethings is wrong with the cyclotron so no production time is lost, and the students have to learn all the aspects of running such a machine – the ion source, the high-precision beam handling, the beam diagnostics, the experiments and their advanced imaging. It’s an excellent place to train new generations of physicists.” Since its start in 2013, some 50 theses have been written about working on the cyclotron, including five PhD theses and also a couple of scientific reports by high-school students.
Braccini finds the aspect of deeply understanding and being able to handle all aspects of the experiments particularly important. When he was building muon chambers for the ATLAS experiment, he didn’t really feel at home in the huge science collaborations of several thousands of people. He noticed that he was more interested in the application side of particle physics. His former professor from the University of Florence, Ugo Amaldi, convinced him to switch to the field of hadron therapy, which Amaldi had been promoting for a long time, to translate what they knew from particle physics into medical applications. Joining the Laboratory for High-Energy Physics (LHEP) at the University of Bern and setting up a dual-use accelerator was the next logical step.
And what about this idea of combining therapy and diagnostics into one (to become “theranostics”)? It is still at the testing stage, but it’s a big topic in nuclear medicine around the world and if proven to work, it could revolutionise cancer therapy. In close collaboration with other labs like PSI or CERN his group and together with groups of other departments at Bern University, Braccini and his team are developing methodologies for this new process. The idea sounds convincing: medical isotopes are already attached to biomarkers to be transported to those high-metabolism areas in the body where tumors and metastases are. These days, they can pinpoint the locations of the cancer cells very precisely, which is important when you want to treat them: healthy tissue should receive as little damage as possible from the therapy. “If we can produce isotopes that bring radiation into the body to see the cancer cells, why not produce isotopes that introduce radiation to cure the cancer?”, Braccini explains. Ideally, these two isotopes should be of the same element so that they can both be attached to the same biomarkers with the same chemical procedure. The team is currently working on theranostic radionuclides, in particular on combining scandium-44 (a beta+ emitter for diagnostics) and scandium-47 (a beta- emitter for cell destruction). The researchers have proven that they can produce the isotopes both in quality and in quantity, and their hope is that the method will find its way to human patients in hospitals in the next years.