CERN-MEDICIS: A Review Since Commissioning in 2017

Abstract

The CERN-MEDICIS (MEDical Isotopes Collected from ISolde) facility has delivered its first radioactive ion beam at CERN (Switzerland) in December 2017 to support the research and development in nuclear medicine using non-conventional radionuclides. Since then, fourteen institutes, including CERN, have joined the collaboration to drive the scientific program of this unique installation and evaluate the needs of the community to improve the research in imaging, diagnostics, radiation therapy and personalized medicine. The facility has been built as an extension of the ISOLDE (Isotope Separator On Line DEvice) facility at CERN. Handling of open radioisotope sources is made possible thanks to its Radiological Controlled Area and laboratory. Targets are being irradiated by the 1.4 GeV proton beam delivered by the CERN Proton Synchrotron Booster (PSB) on a station placed between the High Resolution Separator (HRS) ISOLDE target station and its beam dump. Irradiated target materials are also received from external institutes to undergo mass separation at CERN-MEDICIS. All targets are handled via a remote handling system and exploited on a dedicated isotope separator beamline. To allow for the release and collection of a specific radionuclide of medical interest, each target is heated to temperatures of up to 2,300°C. The created ions are extracted and accelerated to an energy up to 60 kV, and the beam steered through an off-line sector field magnet mass separator. This is followed by the extraction of the radionuclide of interest through mass separation and its subsequent implantation into a collection foil. In addition, the MELISSA (MEDICIS Laser Ion Source Setup At CERN) laser laboratory, in service since April 2019, helps to increase the separation efficiency and the selectivity. After collection, the implanted radionuclides are dispatched to the biomedical research centers, participating in the CERN-MEDICIS collaboration, for Research & Development in imaging or treatment. Since its commissioning, the CERN-MEDICIS facility has provided its partner institutes with non-conventional medical radionuclides such as Tb-149, Tb-152, Tb-155, Sm-153, Tm-165, Tm-167, Er-169, Yb-175, and Ac-225 with a high specific activity. This article provides a review of the achievements and milestones of CERN-MEDICIS since it has produced its first radioactive isotope in December 2017, with a special focus on its most recent operation in 2020.

Efficient Production of High Specific Activity Thulium-167 at Paul Scherrer Institute and CERN-MEDICIS

“…Figure 6B shows the activity at the implantation point for each of the foils from in-situ measurements, determined by the difference between the readout at a given point in time and the background value at the time when this foil was moved into the beam. In previous MEDICIS runs with different elements (from a few up to more than 100 MBq of 153 Sm, 155 Tb, 225 Ac) on identical collection foils ( 34 ), this value proved to be a reliable estimate for the gamma-spectrometry measurements that are performed on the foils afterwards by independent measurements in a dedicated, external setup. Yet, for the presented case this value obtained after recuperation of the foil, shown as star marker in Figure 6B with a 95% confidence interval error band, was significantly lower.…”

“…The CERN-MEDICIS (MEDical Isotopes Collected from ISolde) facility is dedicated to the production of non-conventional radionuclides for medical purposes ( 32 – 34 ). As schematically shown in Figure 1 , it comprises a 60 kV ion beam dipole sector field magnet mass separator, that uses either targets that are irradiated in a dedicated irradiation station at the adjacent CERN-ISOLDE radioactive ion beam facility ( 33 ) by a 1.4 GeV proton beam or, alternatively, radiogenic samples produced and delivered by partner institutes.…”

Terbium Medical Radioisotope Production: Laser Resonance Ionization Scheme Development

“…The obtained value of 53% ionization efficiency is comparable with previous studies of laser ionization on other lanthanides ( 23 , 35 ). This ionization scheme is currently in use at the CERN-MEDICIS facility to increase the production rate of Tb medical radioisotopes [the efficiency of surface ion source in case of Tb separation is estimated to be about 2% ( 2 )].…”

“…The novel CERN-MEDICIS facility aims for the production of non-conventional medical radioisotopes, being previously unavailable on the global market for biomedical research and development ( 1 , 2 ). It is based on the use of electromagnetic mass separation for extraction of a desired radionuclide from a pre-irradiated target material ( 3 ).…”

Production of Sm-153 With Very High Specific Activity for Targeted Radionuclide Therapy

“…The targets are heated to very high temperatures, typically up to 2,300 • C depending on the target material and radionuclide considered, to allow for the diffusion and effusion of the isotopes of interest out of the target to the ion source for subsequent ionization. The ions are then accelerated and sent through a mass separator which is a dipole magnet (24). The dipole magnet has been modified to allow its use with the MEDICIS Laser Ion Source for Separator Assembly (MELISSA) laser laboratory (25), resembling the Ti:sapphire laser setup of the ISOLDE Resonance Ionization Laser Ion Source (RILIS) (26).…”