Magnetic nanoparticles dynamics investigated by X-ray photon correlation spectroscopy

Magnetomotive ultrasound (MMUS) is a novel diagnostic imaging technique which enables more precise cancer staging than other clinically-established diagnostic tools. MMUS relies on magnetic nanoparticles (MNPs) acting as contrast agent while stimulated by time-varying magnetic fields generated by a rotating permanent magnet. The magnet is fitted inside the same probe which is used for ultrasound imaging. We propose to run an XPCS experiment aimed at investigating the dynamics of MNPs in conditions modelling those of human tissue – i.e. suspended in a polyvinyl alcohol (PVA) gel matrix – while operating the MMUS probe. We aim to characterise the periodic dynamics of MNPs in a 25 Hz magnetic field generated by the MMUS probe. These dynamics will be investigated as a function of the distance between the X-ray beam spot on the sample and the MMUS probe centre. Knowledge of this distance dependency is critical for an accurate diagnosis.