Comparison of the physical and biological dose of oxygen ions and proton in hadron therapy

In radiation therapy, oxygen ions have more biological benefits than lighter ions such as proton. Oxygen has a higher Linear Energy Transfer (LET) and a larger Relative Biological Effectiveness (RBE). To design the Spread-Out Bragg Peak (SOBP) of biological doses, we have developed a functional approach with Monte Carlo calculations and matrix computations. We have used this method for both oxygen and proton beams. After obtaining the profiles of the Bragg Peak by Geant4 code, intensity weighing factors for each beam was calculated to create a uniform SOBP. Also, the RBE value was calculated according to the Linear-uQadratic model (LQ). Biological dose, physical dose, and cell survival levels were also obtained in the radiation of both ions. The designed biological SOBP has a good uniformity. Physical dose derived from proton and oxygen beams do not differ significantly, but for biological dose, there is a sharp difference between them. Even with the modulation of the intensity of the beams to produce the same biological dosage, the cell survival levels chart will vary greatly. The biological properties and effects of oxygen in respect to the proton can be a good choice to optimize the system to maximize damage to the tumor tissue and minimize damage to surrounding healthy tissues. The existence of richer tables of experimental values for the effective parameters on the amount of relative biological effectiveness greatly increases the accuracy of this optimization.