ABSTRACT
The deposition of energy by ionizing radiation is a random process. Consequently, their use as therapeutic agents predicates the presence of high radionuclide concentrations within the targeted tissue and the traversal of several thousand electrons per mammalian cell nucleus. One of the simplest targeting agents is radioiodine, administered as iodide for treating functional cancer of the thyroid and, potentially, breast cancers that display the iodine transporter. Oxygen radiosensitizes mammalian cells to the damaging effects of radiation. Mammalian cells are generally capable of repairing some of the damage induced by radiation. To the extent that such animal data are relevant to human tumours, it is not surprising that dose fractionation favours tumour control and minimizes normal tissue damage. Bystander damage describes biological effects, originating from irradiated cells, in cells not directly affected by radiation-induced ionizations. The short range of Auger electrons requires their close proximity to radiosensitive targets for radiotherapeutic effectiveness.
