Radiometals: Novel methods in production, radiochemistry and application

       The success and long-term viability of nuclear-based medical imaging relies on the availability of the isotopes used to produce radiopharmaceuticals. Two existing challenges for the use and development of metal-based radiopharmaceuticals include an ageing nuclear reactor infrastructure that threatens the global supply of ^99mTc, the world’s most prevalent medical isotope; while the second is the availability of alternative isotopes that have shown equal or enhanced promise as signal generators for novel molecular imaging agents.

      The nuclear medicine group at TRIUMF has been actively pursuing alternative, accelerator-based technology that will allow for the production of ^99mTc without the need for reactors or a feedstock of highly-enriched uranium. This alternative, based on bombarding targets of the stable isotope ¹⁰⁰Mo with protons on small medical cyclotrons, will enable regional hospitals to produce ^99mTc directly, daily and on demand. Details on the technology developed, as well as ensuing clinical implications will be presented.   

With the global supply of ^99mTc in question, cyclotron-based production of other radiometals (i.e. ⁶⁸Ga, ⁶⁴Cu, ⁸⁹Zr, ⁴⁴Sc) is possible, but requires facilities to purchase isotope generators or invest substantially in unique solid cyclotron target infrastructure; an expensive venture given that most medical cyclotron sites typically maintain only liquid or gas targets for the production of non-metallic isotopes ¹⁸F, ¹¹C, ¹⁵O, and ¹³N. These obstacles inhibit the development of novel tracers that may possess a better match between the physical half-life of a promising new radioisotope and the pharmacokinetic profile of the vector to which it is attached. At TRUIMF, an effort is underway to demonstrate the use of a modified liquid-target to enable irradiation of select metal-salt solutions for the production of research quantities (or higher) of various radioisotopes. This seminar will highlight progress toward solution-based production of various up and coming radiometals, such as ⁶⁸Ga, ⁸⁹Zr, ^94mTc and ⁴⁴Sc.