High-Z gold nanoparticles (AuNPs) conjugated to a targeting antibody can help to improve tumor control in radiotherapy while simultaneously minimizing radiotoxicity to adjacent healthy tissue. This paper summarizes the main findings of a joint research program which applied AuNP-conjugates in preclinical modeling of radiotherapy at the Klinikum rechts der Isar, Technical University of Munich and Helmholtz Zentrum München. A pharmacokinetic model of superparamagnetic iron oxide nanoparticles was developed in preparation for a model simulating the uptake and distribution of AuNPs in mice. Multi-scale Monte Carlo simulations were performed on a single AuNP and multiple AuNPs in tumor cells at cellular and molecular levels to determine enhancements in the radiation dose and generation of chemical radicals in close proximity to AuNPs. A biologically based mathematical model was developed to predict the biological response of AuNPs in radiation enhancement. Although simulations of a single AuNP demonstrated a clear dose enhancement, simulations relating to the generation of chemical radicals and the induction of DNA strand breaks induced by multiple AuNPs showed only a minor dose enhancement. The differences in the simulated enhancements at molecular and cellular levels indicate that further investigations are necessary to better understand the impact of the physical, chemical, and biological parameters in preclinical experimental settings prior to a translation of these AuNPs models into targeted cancer radiotherapy.

High amounts of precipitation are temporarily stored in high-alpine snow covers and play an important role for the hydrological balance. Stable isotopes of hydrogen (δ2H) and oxygen (δ ¹⁸ O) in water samples have been proven to be useful for tracing transport processes in snow and meltwater since their isotopic ratio alters due to fractionation. In 18 snow profiles of two snowfall seasons, the temporal and spatial variation of isotopic composition was analysed on Mt. Zugspitze. The δ ¹⁸ O and δ2H ranged between -26.7‰ to -9.3‰ and -193.4‰ to -62.5‰ in 2014/2015 and between -26.5‰ to -10.5‰ and -205.0‰ to -68.0‰ in 2015/2016, respectively. Depth-integrated samples of entire 10 cm layers and point measurements in the same layers showed comparable isotopic compositions. Isotopic composition of the snowpack at the same sampling time in spatially distributed snow profiles was isotopically more similar than that analysed at the same place at different times. Melting and refreezing were clearly identified as processes causing isotope fractionation in surficial, initial base or refrozen snow layers. For the future, a higher sampling frequency with detailed isotopic composition measurements during melt periods are recommended to improve the understanding of mass transport associated with snowmelt.

In the last decades, new technologies and new radiopharmaceuticals for diagnosis and therapy have continuously grown, and that growth was accompanied by an increasing use in clinical practice, but, as with any other application involving radiation, the extent to which they may contribute to increasing the radiation dose to the operator must be studied. For that reason, EURADOS (European Radiation Dosimetry Group) decided to evaluate the exposure of medical staff in nuclear medicine to new possible radiopharmaceuticals labelled with Sc-47 and Cu-67. Modified ICRP voxel model were employed to determine the exposure of the eye lens and of the thyroid of operators administrating radiopharmaceuticals in a typical Peptide Receptor Radionuclide Therapy scenario. The simulations were validated comparing Monte Carlo results with TLD measurements performed in hospital with Lu-177 labelled compounds. Doses to the eye lens and thyroid are derived from the photon emissions (the beta contribution is three order of magnitude lower). The agreement obtained for Lu-177 provides confidence that, notwithstanding the limits of the simulations, the robustness of the followed approach can be extended also to the evaluation performed for Sc-47 and Cu-67. The dose to the lens of the eye is of the order of 2 µSv/GBq per patient for Lu-177 compounds and, due to the different energies and yields, about 8 µSv/GBq for both Sc-47 and Cu-67. These evaluations can be useful to optimize the radiation protection of medical staff in the nuclear medicine environment and assess the correct personnel workload in these kinds of practices.