Therapeutic interval and protection of normal tissues

Problems of increasing the therapeutic interval between the radiosensitivity of malignant and sane tissue are considered, as well as the problems of normal tissue protection in radiation oncology. Methods of increasing the therapeutic interval are shown, such as the application of high energy radiation, the method of nonuniform irradiation, the use of radiomodifiers, the increase in the sensitivity of tumour cells at the account of hyperbaric oxygenation and the introduction of halogenated bases in the DNA molecule, synchronization of tumour population, heat effects, etc. Methods of normal tissue protection are described. These are the method of tissue which takes into account the role of oxygen effect, the method of creating deep transit hypoxy of normal tissues with the aid of stached microparticles which block feeding vessels for a short time, the method of the general organism hypoxy, the use of chemical radioprotectors. The factors which accelerate tumour regression have been presented. The conclusion is made that the development of biological methods of normal tissue protection and the improvement of spatial distribution of radiation dose in case of new radiation types is of great importance