The GHOST in the machine

New software based on CERN's particle simulation toolkit Geant4 is being used to assess radiation doses in cancer treatment


New software based on CERN's particle simulation toolkit Geant4 is being used to assess radiation doses in the fight against cancer.

Geant4 was developed to model and visualize the passage of particles through matter. Now Frederic Brochu of the University of Cambridge is adapting the toolkit in a new programme called GHOST (Geant Human Oncology Simulation Tool) that simulates radiation deposition in a patient’s body over an entire course of radiotherapy treatment.

As the life expectancy of cancer survivors increases thanks to radiotherapy, so, unfortunately, does the risk of suffering a second cancer linked to the treatment of the first. Although rare, these second cancers occur many years after the initial treatment. As radiotherapy is still a relatively young discipline, the number of known cases of second cancers related to radiotherapy treatments is very low, and the body of knowledge is still limited.

The aim of the GHOST project is to improve the modelling of late toxicity and the risk of a second cancer by using an accurate distribution of both the treatment beams and imaging X-rays over an entire treatment, and to convert these into biological effects.

“If all goes to plan, we aim to develop a research tool in the coming three years, linking into a project funded by Cancer Research UK called VoxTox," says Brochu. "It would take another couple of years to produce a clinical tool which would help medical physicists to rethink a proposed treatment for an individual patient if their first option was found to provide a significant increase in the risk of getting a secondary cancer.”

For Brochu, the versatility of Geant4 is important. The collaboration can draw on the accumulated experience of many contributors to the field of Monte Carlo simulation of physics detectors and physical processes.

“It feels good that our curiosity-oriented research in particle physics has led to applications in other fields, especially medicine,” says John Allison of the University of Manchester, who leads one of the Geant4 working groups. Along with Geant4 colleagues, he has formed a company that offers radiation-modelling services to the space, medicine and industry sectors. All the company's profits support physicists to work on Geant4, attend conferences and undertake development work.

The GHOST project is funded by the Wellcome Trust.

Read a longer version of this article: "Particle physics to patients" - UK News from CERN, Issue 27