Nanoparticles for Enhanced Radiotherapy and Imaging Applications

The unique physical properties of nanomaterials have been increasingly applied in many aspects of medical therapy, and oncology is no exception. In particular, high atomic mass nanoparticles, such as scintillating nanoparticles, have exhibited unique properties under excitation which can be exploited to provide antineoplastic effects. With the application of external energy, internal energy transfers occur within these nanoparticles, resulting in the generation of reactive oxygen species (ROS) and free electrons. These disrupt cellular membranes and cause damage to the genetic material of cancerous cells. Interestingly, internal energy transfers within these materials may also result in the generation of photons, which allow these nanoparticles to provide additional antineoplastic effects by using these photons to trigger conjugated photosensitizers, producing even more ROS. The activation of these nanoparticles using radiotherapy techniques has resulted in the creation of a new treatment technique—Radiodynamic therapy (RDT). In radiotherapy, external energy in the form of X-rays, protons, and heavy ions are used to treat cancer by causing damage to the cellular genetic material, thereby causing cellular death. In RDT, these ROS generating nanoparticles are also delivered to the tumour sites and the applied external energy for radiotherapy also generates additional antineoplastic effects. Nanoparticles can also enhance radiotherapies, where nanoparticles have demonstrated radioisotope retention properties, allowing radionucleotides to confer longer-term radio-cytotoxicity to tumours when retained at diseased sites. Importantly, nanoparticles can be modified to provide increased uptake in tumour cells, not only allowing the focusing of their cytotoxic effects during RDT, but also to unique imaging applications for diagnosis or for the monitoring of the progress of treatment. The use of these nanoparticles thus presents great potential in the development of next-generation radiotherapies. In this chapter, we will discuss the role these nanoparticle technologies play in the evolution of radiotherapeutic treatments for cancer, along with the strategies used to deliver these nanoparticles and their concurrent use in imaging and for treatment monitoring. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.