Novel medical radioisotopes, hopes for healthcare, challenges for nuclear physics

The evolution of patient care, in the UK and Europe, pushes towards a more tailored approach, often referred to as personalised healthcare. The idea is to be able to obtain more accurate information about a patient’s condition and be able to provide a treatment that reflects the individual needs, instead of a one-size-fits-all magic pill that does not exist. Molecular imaging and targeted radiotherapy have been identified as very promising approaches in that respect. In particular, the concept of theranostics has emerged, where a single isotope can be used for either imaging or treatment, or where several isotopes of a single element can be interchanged to alternate between imaging and treatment. While the concept of theranostics is highly praised and its prospect might be exciting, numerous challenges are still ahead of us before these can become routinely available in our local medical practices. First and foremost, extensive pre-clinical and clinical trials need to be performed to assert the action of these isotopes, their combination to different biological delivery mechanisms, etc. However, the nuclear physics community also has its responsibilities as part of this research field. In order to guarantee access to these isotopes, research on the production mechanisms are necessary. Reaction cross sections for the production of these isotopes, as well as potential contaminants, have to be known in order to determine the most viable production route. In that respect, one of the most promising theranostic set of isotopes are the terbium isotopes, going across A=149, 152, 155, and 161. However, the most crucial isotope of the set, 149Tb and its alpha decay, is one of the most elusive isotopes. A full area of research is therefore dedicated to exploring its production, either from fusion-evaporation reactions from gadolinium targets or from the spallation of tantalum. The characterisation of these isotopes are also essential. While some basic understanding of all of the potentially interesting isotopes exist from legacy nuclear structure studies, the knowledge is sometimes insufficient to accurately predict the dose a patient would be exposed to, or the most appropriate settings to use for SPECT imaging. Dedicated studies are therefore required to validate the existing knowledge and eventually develop standards against which medical radioisotope batches can be evaluated. The purity of the samples is also of great importance and extensive work is ongoing to either improve the quality of the radioisotope batches at the production level, or to improve the radiochemical separation and treatment for delivering the highest quality final product.invited contributionstatus: publishe