Particle Induced X-ray Emission Imaging of Gadolinium Distribution into Xenograft U87 Human Glioblastoma after AGuIX Nanoparticles Injection

In recent years, the use of high-Z nanoparticles (NPs) as potential tumor selective radiosensitizers has been proposed as a breakthrough in cancer radiotherapy (RT). NPs are capable of penetrating the cell and they lead to fewer adverse effects than conventional radiosensitizers [1]. Radiation sensitivity using NPs depends on cell line, irradiation energy, NPs type, size, concentration and distribution. High-Z metallic NPs (Au, Gd, Pt, Ag, Fe, etc.) have been predominantly used since they can generate shortrange photoelectrons or Auger electrons, which can enhance the therapeutic dose locally. It is of great interest to limit the diffusion of metallic NPs only to the tumor volume. So current investigations try to optimize the size of NPs and/or use chelating ligands of high affinity for tumor cells. Also the way that NPs are provided to the tumor, intravenously or by direct injection, will determine their distribution. Among those NPs, Gd-AGuIX (Activation and Guiding of Irradiation by X-ray) are 4 nm size polysiloxane GdNPs that have been proposed to be used for theragnostic as magnetic resonance imaging (MRI) contrast agents and radiotherapy sensitizers [2].