Radionuclide production and separation techniques for radiopharmaceutical development and nuclear waste processing
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] With increasing cancer incident rates and advancements in nuclear medicine, the demand for optimizing pathways to produce radionuclides or investigating new radionuclides that improve current diagnostic and therapeutic methods are crucial. In this research, the production pathways and separation of radionuclides for diagnostic imaging and/or therapeutic purposes were evaluated and developed. Diagnostic Single Photon Emission Computed Tomography (SPECT) imaging with 99mTc, a well-established radionuclide applied in over 80% of nuclear medicine, supports the need for a therapeutic rhenium analogue. Both 186,189Re radionuclides have favorable decay properties for therapy, but their current production routes with reactors or few facilities with high energy particles limits their routine applicability. This research evaluated the production of 186,189Re using low-mid energy protons, which are more accessible worldwide, from bombardment of W and Os targets. Developing suitable production of 186,189Re would provide a 99mTc/186,189Re diagnostic/therapeutic matched pair. In this research, the 72As/77As diagnostic/therapeutic matched pair are also of interest. A positron-emitting radionuclide with applications for Positron Emission Tomography (PET), 72As has a longer half-life than most PET radionuclides, which matches the biological half-life of slower localizing biomolecules, such as antibodies or proteins. The University of Missouri Research Reactor (MURR) has demonstrated the therapeutic analogue, 77As, can be produced routinely from 76Ge targets, but the diagnostic analogue, 72As, can be made available from the decay of 72Se in the form of a 72Se/72As generator. This research evaluated the production and separation of 72Se from Ge and As targets and evaluated the integrity of 72Se/72As generators. Developing the production of 72Se and optimizing a 72Se/72As generator-based system would provide transportation of 72Se and on demand availability of 72As for PET imaging. A theranostic radionuclide with suitable decay properties for both SPECT and therapy is 105Rh, which has a favorable electronic configuration and has demonstrated high in vivo stability. Sufficient quantities of 105Rh can be produced from enriched 104Ru metal targets at MURR; however, no recycling method to recover 104Ru metal has been evaluated. In this research, a scheme to recycle and reuse 104Ru was developed for further production of 105Rh. These diagnostic/therapeutic matched pair and dual imaging/therapy radionuclides are critical for expanding the pool of available radionuclides and advancing the field of the nuclear medicine.
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