A Fast dose recalculation tool for hadrontherapy and its clinical application.

In hadrontherapy, it is important to obtain accurate physical and biological quantities for both clinical and research activities. Currently, there are two major systems used at Centro Nazionale di Adroterapia Oncologica (CNAO) for the purpose: one is the Monte-Carlo (MC) simulation tool FLUKA and the other is a commercial treatment planning system Siemens Syngo. FLUKA is a robust MC simulation with long calculation time often taking several hours and Syngo is less accurate albeit with shorter calculation time. In this thesis we have realized a Fast Recalculation code on GPU (FRoG), an accurate and fast dose calculation tool, and achieved the accuracy of the MC simulation within minutes. FRoG employs pencil beam (PB) and PB splitting algorithm with triple Gaussian distribution database, implemented on modern computing architecture, general-purpose computing on graphics processing units (GPGPU). FRoG is able to predict physical and biological quantities for clinical (H and C) and research (He and O) ions in hadrontherapy. The differences between FRoG and FLUKA predictions in terms of DRBE values have been found to be 1% and 2.5% for protons and carbon ions, respectively. FRoG was used to convert current MKM based rectum constraints into new LEM based rectum constraints for future Gastrointestinal (GI) patients, who will be treated with carbon ions at CNAO. CNAO employs Japanese (MKM) rectal constraints but the treatment plans have been optimized with European biological model (LEM). However, because the biological dose predictions between Japanese (MKM) and European (LEM) are different, the MKM constraints need to be converted into LEM constraints. FRoG recalculated plans of representative patients whose rectums were irradiated, and then successfully converted MKM constraints into LEM constraints. FRoG has proven its accuracy and calculation capability in this research. As a conclusion, FRoG is able to provide accurate physical and biological quantities in a reasonable time to support clinical and research activities.