Abstract: The disclosure relates to methods for treating tumors. In particular, the disclosure relates to a method of treating a tumor by magnetic resonance image-guided radiation therapy in a subject in need thereof, said method comprising the steps of: (i) administering an efficient amount of high-Z element containing nanoparticles having, contrast enhancement for magnetic resonance imaging and/or radiosensitizing properties for radiation therapy, in a subject in need thereof, and, (ii) exposing said subject to magnetic resonance image-guided radiation therapy by means of a Magnetic Resonance Imaging Guided Linear Accelerator (MR-Linac), wherein said high-Z element containing nanoparticles are nanoparticles containing an element with an atomic Z number higher than 40, preferably higher than 50, and said nanoparticles have a mean hydrodynamic diameter below 20 nm, for example between 1 and 10 nm, preferably between 2 and 8 nm.

Abstract: Gold nanoparticles are conjugated to phosphatidylserine-specific ligands for targeting and binding to surface-exposed phosphatidylserine on tumor cells and tumor vasculature. The ligand may be an annexin (e.g., annexin V). Tumor contrast is significantly increased using the targeted gold nanoparticles. Breast cancer tumors as small as 4 mm, for example, were detectable via computed tomography (CT) within 4 hours after injection of the conjugates, demonstrating usefulness of the conjugates as imaging agents. The targeted gold nanoparticle conjugate may further have a drug conjugated thereto that can be used therapeutically, for example, for cancer treatment. The gold nanoparticle conjugates can also be used for photothermal therapy and can be used in concert with an X-ray radiation treatment for cancer treatment.