The high precision of hadrons dose release in particle therapy is an improvement in treatment efficiency with respect to standard radiotherapy only if matched by precise patient positioning and accurate treatment planning. The Treatment Planning System (TPS) is the complex software that controls the accelerator parameters used during the treatment: intensity, energies, transverse positions, etc, needed to obtain the optimal dose deliver to the patient. Usually, the commercial TPS provided by the accelerator vendors are analytical code and are outperformed by Monte Carlo based TPS especially for those cases with very heterogeneous tissue. MC proton TPS is often performed using well-established packages such as GEANT 4, FLUKA, and MCNP X but the accuracy is achieved at the cost of large CPU time. Due to this limit, this method is applied only for recalculating analytic treatment plans only for specific patients. The advent of general programming Graphics Processing Units (GPU) has prompted the development of MC codes that can dramatically reduce the plan recalculation time with respect to full MC codes in Central Processing Unit (CPU) hardware. The impressive speed gain compared to CPU-based calculations is due to both algorithmic simplification and hardware acceleration. FRED code has been developed in this framework. It is a MC-based code that runs on GPU developed to recalculate and optimize ion beam treatment planning within minutes, opening the way to many clinical applications where the calculation time is important. As far as proton beams are concerned FRED is already used as a quality assurance tool and as research. Carbon ion beams have been introduced inside FRED to allow fast optimization of a treatment plan also in carbon ion therapy. Those implementations are under development and thanks to this work it will be possible to implement the complete interaction model of carbon ion with matter in FRED and published the results in an international paper.
In Particle Therapy (PT) treatment, high precision in dose delivery requires very accurate modelling of the interaction of the beam particles with the tissue. The high ballistic accuracy of hadrons is an improvement in treatment efficiency compared to radiotherapy only if accompanied by precise patient positioning and very accurate treatment planning. Treatment planning is carried out using TPS (Treatment Planning Software). Considering that TPS has to be done for each patient and each of his treatments and that on average about fifty patients are treated every day, the time required to make a treatment plan is crucial. For this reason, the TPSs used routinely are analytical TPSs that take a maximum of one hour per core. These treatment plans are based on a simplification of the human body that is brought back to a water equivalent representation. Their accuracy is therefore not always adequate and, for a small number of more difficult cases, some MCs are used to check the reliability of the analytical TPS. MCs, by taking into account all the details of the interactions of the particles with the human body, can achieve the accuracy that would allow for improved carbon treatment. Unfortunately, it currently takes days to run a MC, so it is not possible to introduce it as clinical practice. With the advent of GPUs, however, the idea has arisen of being able to make fast MCs deliver complete treatment plans in minutes instead of hours. FRED is a fast MC running on GPUs designed for this purpose. Currently, the proton implementation is finished and FRED is already being used with excellent results. By also implementing a model of interaction of carbon ions with the body, it will be possible to create treatment plans for carbon therapy as well, increasing the precision obtained and decreasing the time required for the calculation and control of this therapy.
Several centres, including the CNAO in Pavia, have already requested the possibility of using FRED for carbon therapy and we hope to soon have a validated model to make it available to research centres.