The Studies On Radiobiological Effects Of Heavy Ion Beams In Tissue And Organ Level

Radiation therapy has become one of the most important modalities in the treatment of cancer. Ideally, the objective of any cancer treatment method is to remove or destroy the tumor while preserving at the same time the healthy tissue as much as possible. This requires a high dose targeted at the tumor while exposing the surrounding tissue to as little dose as possible. The key to successful treatment is the precision of the dose delivered to the tumor. Compared to conventional radiation treatment with photons, radiation therapy using heavy ion delivers the highest dose directly to the target volume. The tissue in front of the tumor is exposed to far less radiation and the tissue behind the tumor remains virtually damage-free. Heavy ion therapy uses the inverse depth dose profile of carbon ions to treat tumors with the highest accuracy. Unlike photon beams, whose dose increases just after penetrating the tissue and declines exponentially at greater depths, heavy ion beams release their highest dose near the end of their path, at the Bragg Peak. The Bragg Peak can be precisely positioned by adjusting the energy of the accelerated particles. The linear energy transfer (LET) or the rate of energy deposition along the path of a particle is higher for heavy ions than it is for conventional radiation, including protons; the relative biological effectiveness (RBE) tends to be higher if LET values are higher. The relative biological effectiveness (RBE) for carbon ions varies typically between 2 - 5 where the particle path ends (Bragg Peak), whereas the RBE of protons is...