Over 120,000 new cases of cancer are diagnosed in Australia every year, impacting the lives of millions of people. Often, these are treated with a combination of chemotherapy, radiation therapy and surgery.

In Australia, the most common kind of radiation therapy for cancer uses X-rays. They are a well-understood tool for cancer treatment, and are effective with many kinds of cancers. Most people are aware, however, of the side effects of cancer treatments: the damage they cause to functioning organs and the eventual collateral effects in the healthy tissues surrounding the tumour.

A combination of computational and clinical research is working to improve the way that radiation therapy works, making it more targeted and effective than current solutions. Dr Susanna Guatelli from the Centre for Medical Radiation Physics (CMRP) at the University of Wollongong is part of a worldwide collaboration developing a piece of simulation software named GEANT4, ideally suited for studying how radiation interacts in matter, including human tissues of interest for medical physics applications.

Within the GEANT4 international collaboration, Dr Guatelli is developing software models to study the radioenhancement of gold nanoparticles during X-ray radiotherapy. A gold nanoparticle hit with X-rays will release an enhanced number of electrons, increasing the probability of killing the cells around them. Therefore, if gold nanoparticles the right size, shape and concentration are placed inside a tumour, targeted radiation can trigger their electron release, improving the cancer treatment outcome.

For research like this, the combination of experiments and computer modelling is extremely powerful. The GEANT4 model allows researchers to learn about the gold-X-ray interactions, which helps design the nanoparticles. Dr Guatelli says "The computational methods we use are extremely helpful for learning about the composition, size and shape of the ideal nanoparticles. That side of the work deals with the fundamental physics mechanism at the basis of the treatment, and then radiobiological experiments bring out the chemical and biological factors going on as well." The radiobiological research, working in tandem with the computational research, is led by CMRP researchers Dr Moeava Tehei, A/Prof Michael Lerch and Prof. Anatoly Rozenfeld (Director of the CMRP), and Dr. St├ęphanie Corde of the Prince of Wales Hospital, Sydney.

Supported by an Australian Research Council grant, Dr Guatelli and her collaborators Dr. Sebastien Incerti (CENBG, France), A/Prof Dimitris Emfietzoglou and Dr. Ioanna Kyriakou (University of Ioannina, Greece), and Dr. Stephen McMahon (Queen's University Belfast, Northern Ireland) are working to improve the existing physics models of nanoscale particle interactions in the GEANT4 software. Those improvements feed into the work of medical researchers around the world, and make possible the future treatments being developed right now.