Nuclear physics applied to the production of innovative radiopharmaceuticals

Abstract

In this work, we review the theory of nuclear reactions induced by charged particles at cyclotrons and we show in a pedagogical way how to perform a reaction yield calculation in a realistic irradiation case. The topic is currently of great interest in the field of radioisotope production for medical applications, in which an international effort is underway to find efficient production routes of novel radiopharmaceuticals that could be used in theranostics or for multimodal imaging: Particular interest is devoted to the reaction channels that allow the production of a given isotope with high yield and high purity. In part I, the nuclear reaction theory is reviewed, with a discussion on the main reaction mechanisms that are important for the calculation of the cross sections: direct reactions, compound nucleus formation and decay and pre-equilibrium emission. The role of modern nuclear reaction codes, such as Talys, for the calculation of nuclear cross sections is also shown with examples. In part II, a tutorial demonstrates how calculate the production yield of the isotope $$^{52g}$$ Mn starting from the Talys cross section for the specific reaction $$^{52}$$ Cr(p,n) $$^{52g}$$ Mn: This is a real and up-to-date research case motivated by the search of a $$\beta ^+$$ emitting radioisotope with paramagnetic properties that could be used for a combined PET–MRI imaging. In the exercise, all the steps to calculate the yield and activities of the reaction are shown in great detail and the result is compared with the reference values. The calculation is performed both in Excel and in Python, and the input files are provided as supplementary material.