A Monte Carlo code for ion beam therapy
Initially developed for applications in detector and accelerator physics, the modern Fluka Monte Carlo code is now used in many different areas of nuclear science. Over the last 25 years, the code has evolved to include new features, such as ion beam simulations. Given the growing use of these beams in cancer treatment, Fluka simulations are being used to design treatment plans in several hadron-therapy centres in Europe.
Fluka calculates the dose distribution for a patient treated at CNAO with proton beams. The colour-bar displays the normalized dose values.
Fluka is a Monte Carlo code that very accurately simulates electromagnetic and nuclear interactions in matter. In the 1990s, in collaboration with NASA, the code was developed to predict potential radiation hazards received by space crews during possible future trips to Mars. Over the years, it has become the standard tool to investigate beam-machine interactions, radiation damage and radioprotection issues in the CERN accelerator complex.
Recently, the medical community has shown great interest in Fluka for a different type of application: ion beam therapy for cancer treatment. As this type of intervention uses particle beams to target tumour cells, it is very important to predict accurately how they will interact with the patient’s body. “Currently, we are working in collaboration with the National Institute for Nuclear Physics (INFN) in Italy, the Heidelberg Ion-beam Therapy Center (HIT) in Germany and the National Hadrontherapy Center for Cancer Treatment (CNAO) in Italy to develop and adapt Fluka for various applications in ion beam therapy, which exploits proton and carbon ions beams,” says Alfredo Ferrari, one of the main authors of the code. “Indeed, medical physicists and radiation oncologists have quickly realized how useful Fluka can be to help them choose the best beam configuration to use during treatment.”
Fluka computes physics data – ion types, beam models, different energies, etc. – to generate a database. This database is then used in conjunction with individual patient data to optimize the treatment plan. “Fluka is a valuable tool to compute doses for patient treatment very accurately,” explains Till Böhlen from CERN, who is currently working on developing Fluka for ion beam therapy in the framework of the PARTNER European network. “This is especially useful in critical situations - for example, if the patient has a metal implant in the target area of the intervention.”
Future developments of Fluka include the improvement of physics models for new ions, such as oxygen and helium, with a view to their possible use in hadrontherapy. The code is also increasingly employed to simulate the secondary radiation produced during treatment by the beam interacting with the patient. This feature is crucial as secondary radiation is being studied as a very powerful tool to perform in-vivo monitoring during treatment.
