Researchers at the National Institute for Nuclear Physics (INFN) and Sapienza University of Rome have recently launched an in-vivo study on patients to validate a radio-guided surgery technique using drugs that emit beta radiation which could help take a step forward in the fight against cancer.
Radio-guided surgery is an approach that makes it possible to identify tumour debris in real time. Specifically, the technique under investigation uses a probe to detect the radiation emitted by a radiopharmaceutical containing a specific molecule that is recognized and metabolized by the receptors of the tumour cells. This makes it possible to check directly during the operation whether the tissues being analysed are cancerous or not, thus guiding the surgeon to the parts that need to be removed.
The technique – the result of close interdisciplinary collaboration between physicists, chemists, radiopharmacists, nuclear physicians and surgeons – could become an additional tool to support surgeons during tumour removal.
“Being charged particles, the electrons that make up beta radiation quickly lose their energy as a result of interactions with other charged particles present in all the tissues of the human body,” explained Riccardo Faccini, Professor at the Physics Department of Sapienza University and Dean of the Faculty of Mathematical, Physical and Natural Sciences, one of the developers of the technique. “This results in the electrons being unable to leave the patient. This is what prompted us to devise an instrument that surgeons could use during operations, placing it directly on the tissues to be analysed.”
The project is based on an initial idea which envisaged the use of beta- radiation. The procedure – patented in 2013 by Sapienza, INFN and Museum of Physics and Fermi Research Centre – had proved effective but difficult to apply due to the limited availability of radiopharmaceuticals with this type of emission.
On the basis of subsequent studies carried out in collaboration with the Carlo Besta Neurological Institute, European Institute of Oncology (IEO), Leiden University Medical Centre and Agostino Gemelli University Hospital Foundation, the researchers chose to use beta+ radiation, characterized by the emission of a positron, or antielectron, and two photons, which is used daily in nuclear medicine departments for PET (Positron Emission Tomography) diagnostic tests.
“While beta- radiation, given its characteristics, is unsuitable for diagnostic investigations,” explained Francesco Collamati, a researcher at the INFN section in Rome and current Principal Investigator of the study, “the photons of beta+ radiation are able to pass through the patient’s tissues unhindered to be eventually detected by external diagnostic apparatus. That is why beta+ drugs are widely used in hospitals and can therefore also be partly used for our technique.”
Despite these advantages, beta+ emitting radiopharmaceuticals present difficulties due to the abundance of photons produced not only in diseased tissues but also in all areas of the body reached by the molecule after administration, which can disturb the signals detected by the probe. “For this reason, it is necessary to continue testing to understand and calibrate the device and to provide doctors with indications, for example, on the count levels associated with the actual presence of a tumour,” Collamati concluded.
The tests currently underway are being carried out – with the prototype developed by NUCLEOMED S.r.l. – at IEO in Milan and at the “Molinette della Città della Salute” Hospital in Turin on both gastroenteropancreatic neuroendocrine tumours (GEP-NET) and prostate tumours.
