Novel approaches to produce radionuclides using hot atom chemistry principles

Abstract

Radionuclides are often used in the field of nuclear medicine. For some deceases the use of radionuclides is the best possible care, or even the only means of diagnosis or treatment. For these medical applications high specific activity (high activity per unit of mass) is required. Commonly, medical radionuclides are man-made. They can either be produced by neutron activation, charged particle or photon activation or by means of radionuclide generator. Furthermore, hospitals prefer an ‘on demand’ supply. A radionuclide generator is ideal. Radionuclide generators can also be used to produce high specific activity. Conventional radionuclide generators work with the principle that the mother and daughter radionuclide have different electrostatic interactions with the column material. This allows for easy elution of the daughter radionuclide. However, when working with chemical identical mother-daughter radionuclide pairs (e.g. 177mLu / 177Lu) another separation principle is required. Utilising ‘hot atom’ chemical principles such a mother-daughter pairs can be separated. ‘Hot atom’ principles describe the chemical effects that occur due to nuclear interactions or due to decay. An example of these effects is bond rupture. The effective range of those principles is rather limited, requiring thin layers. A possible technique to apply these thin layers is atomic layer deposition (ALD). ALD is commonly used in the semi-conductor industry, but can due to its versatility also be used in the field of catalysis or pharmaceutical. The advantage of using ALD is that this gas phase deposition technique allows for thin conformal coating of complex structured materials. Furthermore, the amount of material that can be deposited can easily be adapted to need because ALD is a self-limiting process. In this thesis the usefulness of ALD in combination with radionuclide production is explored. Because of the versatility of ALD it can also be used to create target materials for charged particle activation and enrichment experiments (Chapter 2). This versatility is illustrated by three case studies, namely this production of targets for 64Cu production, the production of 177Lu by means of a radionuclide generator and the production of 99Mo using three different routes. Also described is how ALD can be used to alter the surface chemistry of high surface area materials to increase their adsorption capacity for Mo (Chapter 3). The obtained particles with an alumina coating are then tested for their adsorption capacity and compared to acid activated alumina, the current used material in 99Mo/99mTc-radionuclide generators. The adsorption capacity of the obtained particles is twice that of acid activated alumina and has a 99mTc elution efficiency of 55%. Furthermore, the coating of nano-particles for the development of with Lu coated particles (Chapter 4) for the preparation of a radionuclide generator is described. ALD allows for a deposition of up to 15w% Lu. Furthermore, the gamma dose received during neutron activation has an influence on the specific activity produced (Chapter 5). Using Cu(II)-phthalocyanine as a target it is shown that an increase in gamma dose during neutron activation results in an increase in Cu release and hence a decrease in specific activity obtained.