Recoil Analysis for Heavy Ion Beams

Given that there are 94 clinics and more than 200,000 patients treated worldwide, proton and carbon are the most used heavily charged particles in heavy-ion (HI) therapy. However, there is a recent increasing trend in using new ion beams. Each HI has a different effect on the target. As each HI moves through the tissue, they lose enormous energy in collisions, so their range is not long. Ionization accounts for the majority of this loss in energy. During this interaction of the heavily charged particles with the target, the particles do not only ionize but also lose energy with the recoil. Recoil occurs by atom-to-atom collisions. With these collisions, crystalline atoms react with different combinations and form cascades in accordance with their energies. Thus, secondary particles create ionization and recoil. In this study, recoil values of Boron(B), Carbon(C), Nitrogen(N), and Oxygen(O) beams in the water phantom were computed in the energy range of 2.0-2.5 GeV using Monte Carlo simulation and the results were compared with carbon. Our findings have shown that C beams have 35.3% more recoil range than B beams, while it has 14.5% and 118.7% less recoil range than N and O beams, respectively. The recoil peak amplitude of C beams is 68.1% more than B beams, while it is 13.1% less than N and 22.9% less than O beams. It was observed that there is a regular increase in the recoil peak amplitude for C and B ions, unlike O and N where such a regularity could not be seen. Moreover, the gaps in the crystal structure increased as the energy increases.