Recently, Chinese researchers have developed an automated system for simultaneous separation and purification of medical isotopes actinium-225 and radium-223. This study was published in Separation and Purification Technology.

The system was developed by a team led by Prof. QIN Zhi from the Institute of Modern Physics (IMP), Chinese Academy of Sciences. It is based on the medium and high-energy proton and nitrogen beams provided by the Heavy Ion Research Facility in Lanzhou (HIRFL).  

Actinium-225 (with a half-life of 10 days) and radium-223 (with a half-life of 11.4 days) are two alpha-emitting isotopes. Due to unique physicochemical properties, they have shown broad application prospects in the treatment of small-volume tumors and multi-site metastatic cancers. 

However, the traditional production methods for these two medical isotopes are complex and inefficient, making it difficult to meet the growing demand. Thus, there is an urgent need for a more efficient and automated preparation system.

The researchers at IMP used an improved tandem multi-column ion-exchange method, and established a complete preparation process route of "thorium target irradiation - separation and purification - drug labeling", significantly improving the separation and purification efficiency of actinium-225 and radium-223.

"The system has the advantages of high efficiency, stability and miniaturization. It can carry out  the separation and purification processes simultaneously and automatically," said TAN Cunmin, a researcher at IMP and the first author of this study.

Through automated experiments, the researchers achieved effective separation and purification of actinium-225 and radium-223 from hundreds of impurity nuclides. The separation recovery yield and the radionuclide purity of actinium-225 and radium-223 products were stabilized at 62% and 92%~96%, respectively.

Moreover, the researchers evaluated the radioactive levels of impurity nuclides actinium-226 and actinium-227 over time. By using the actinium-225 product prepared by the aforementioned process, the researchers successfully synthesized a labeled compound that meets the requirement of nuclear medicine. 

The research team has also obtained an invention patent for separating and purifying radium-223. "Based on these technological achievements, we will further carry out the preparation of actinium-225 and radium-223 at the level of millicuries," said Prof. QIN.

DOI: https://doi.org/10.1016/j.seppur.2024.129371

Figure. The experimental procedure for automatic preparation of the medical isotopes. (Image by TAN Cunmin)