Radiometals - production methods optimized for small medical cyclotron
Warsaw Medical Physics Meeting 2015
The development of biological targeting agents such as proteins, peptides, antibodies and nanoparticles contributing in vivo processes lasting many hours and days demands the production of radionuclides with radioactive half-lives complementary to these biological properties. Potentially useful radiometals include nuclides such as Zirconium 89 (89Zr), Yttrium 86 (86Y) and Copper 64 (64Cu). In the presented project, optimal methods of cyclotron target production for these radiometals were investigated.
89Zr is a promising radionuclide in the development of new immuno-PET agents (in vivo positron emission tomography imaging of cancerous tumors and radioimmunotherapy planning). In addition to the convenient half-life of 78.4 h, Zirconium 89 has a b+ emission rate of 23% and with a low maximum energy of 0.9 MeV, delivering good spatial resolution as a result of positrons short range in tissue (around 1 mm).
86Y is also an attractive radionuclide for positron emission tomography (PET) studies of patient specific dosimetry for 90Y-based radiotherapy. Yttrium 90 (90Y) is a pure beta minus emitter and as such is not applicable for imaging studies. 86Y with its 14.7 h half-life, 33% positron emission rate and 1.2 MeV maximum energy, linked to the same targeting molecule in combination with PET, can provide the necessary information on biodistribution and kinetics required for dose planning.
64Cu is one of the most useful radionuclides for PET as well as systemic and targeted radioimmunotherapy of tumors. 64Cu has an intermediate half-life (12.7 h) and a multiple decay mode that involves b-, electron capture, and positron decay (b+).
Our aim is to develop novel imaging agents for early and effective diagnosis of cancer and treatment targeting for individual patients, thus realizing some of the goals of personalized medicine. Successful treatment outcomes for many disease states rely upon early diagnosis for which modern imaging techniques have become essential.
Optimization of basic parameters for nuclear reactions (in which 89Zr, 86Y and 64Cu are produced) and for further separation and purification steps, will lead to increase in production yields and purities of isotopes dedicated to form anti-cancer drugs and to label imaging agents with long biological half-lives (e.g. monoclonal antibodies).
Future perspective for some other radiometals will be also presented.
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