Heavy ion radiation is an advanced and effective radiotherapy method for tumor and cancer, which is determined by the unique physical and biological characteristics of heavy ion radiation. The physical property is that carbon ions, like other heavily charged particles, have the property of reversing dose distribution. When heavy ions penetrate matter, they mainly lose energy by colliding with electrons outside the target core. With the decrease of ion energy, the probability of this collision increases. In most areas where ions enter the human body, the huge initial energy makes ions pass through the tissue quickly, so the energy loss is small and a relatively low-energy platform is formed. At the end of the range, with the loss of energy, the movement speed of ions slows down, and the probability of collision with target electrons increases, eventually forming a steep high-dose (energy loss) peak at the end of the range, that is, Bragg peak, and then the dose drops rapidly. The depth of Bragg peak position can be adjusted by changing the initial energy of incident ions. During the treatment, the broadened Bragg peak is precisely adjusted and covers the whole tumor volume, so that the normal tissues around it are only irradiated with a small dose. Based on heavy ion electrification, the grid scanning technology is used to guide the beam to perform accurate tomographic "conformal therapy" on the tumor. In addition, the scattering of heavy ions is smaller than that of protons and photons, which is also very beneficial to accurate dose distribution.
The biological characteristics are as follows: heavy ion rays directly cause irreparable damage to DNA double strands. For hypoxic cancer cells that are insensitive to ordinary photon rays, heavy ion rays can also damage DNA double strands, leading to irretrievability.
Based on these two characteristics, it can be seen that heavy ion radiotherapy has great medical value and will become one of the main treatment methods for tumors and cancers in the future.