From cyclotrons to Cancer Therapy: A Physics-Based Simulation of Proton Beam Interactions in Human Tissue

Since 1930, when Ernest Orlando Lawrence first conceived the device, the cyclotron has facilitated numerous achievements in nuclear and medical physics. This paper explores the physical principles behind the device, which uses a perpendicular magnetic field to deflect charged particles in a spiral trajectory and alternating electric fields across semicircular dees to increase their energy. The paper focuses on the applications of cyclotrons in proton beam therapy, where the Bragg Peak property makes protons highly effective at concentrating dose at the tumor and minimising damage to healthy tissue.

The paper presents a computationally light 3D python simulation modelling proton interactions with human tissue, with exploratory and optimising tracks. Fractionated treatment spread across multiple days, as well as one-time treatments can be modelled, helping discern the impact of various parameters such as beam energy, beam energy spread, and breathing motion on the beam range and the number of killed tumor and healthy cells. The optimiser found that 24 fractions, 1.6 Gy dose per fraction, 215 MeV beam energy, 1.2% beam energy spread, and 1.4 cm beam spot size results in maximum tumour cells killed (99.1%) and minimum healthy cells killed.