The Production and Application of Radionuclides for the Targeted Radiotherapy

Tara Mastren, Assistant Professor, University of Utah

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The Production and Application of Radionuclides for the Targeted Radiotherapy

Clinicians rely on nuclear medicine for the treatment of numerous diseases impacting millions of patients annually. Recently, targeted radiotherapy (TR) has been successfully advanced with the US FDA approval of several radionuclide-based drugs. Several types of radioactive emissions are of interest to therapy such as alpha, beta and auger electrons. The linear energy transfer (LET) of these particles to the surrounding tissue results in free radical production and direct damage to the DNA in cancer cells resulting in cell death.

We are currently working on producing Tb-161 (β-, 6.9 d), an isotope of interest due to its decay via the emission of both Auger and Beta particles, in the University of Utah TRIGA reactor using the indirect method: 160Gd(n,γ)161Gd(β-, 3.66m)161Tb reaction. As neighboring lanthanides are notoriously difficult to separate, we are investigating the feasibility of an in situ Szilard-Chalmers method employing a column in the center of the reactor to perform the initial separation of 161Tb from the target material. Furthermore, we are investigating the application of synergistic extraction ligands to enhance the separation factor for Gd and Tb.

Finally, we are working with alpha emitting radionuclides for the treatment of cancer and Alzheimer’s disease. The two main radionuclides of interest are 225Ac and 211At. One of the main challenges when working with alpha emitters is its release from the molecule after decay. In the case of 225Ac, there are multiple alpha emitting daughters in the decay chain. This is problematic as the daughters are free to circulate throughout the body depositing dose to healthy tissue. We are looking into the use of nanoparticles to help trap these daughter radionuclides at the cancer site; increasing the dose to the diseased site while minimizing dose to healthy tissues