Irradiation Fractional

Fractional or fractionated irradiation is a method of radiation therapy in which radiation is carried out in several stages, while the dose rate at all stages of treatment is constant (equal), and the irradiation time in each dose is different.

Fractionated dose irradiations can be given to any patient after clinical response to a higher dose of one fraction; high fractional doses (8-25 Gy) allow irradiation to be performed daily over long periods of time (6-8 weeks). However, when prescribing high fractional doses, it was not possible to reduce the tumor response caused by leukopenia. Therefore, along with daily irradiation in large fractions, small fractions (2-4 Gy) are used, which make it possible to treat patients almost every day and reduce the number of breaks between fractions to 3-4 with a total dose of 50-70 Gy. However, the longer the break in the treatment regimen, the less effective the treatment is under the influence of lower absorbed doses. Low dose exposure should be preferred in cases where high ROD values ​​can be achieved. This irradiation technique is especially important for the rapid restoration of normal hematopoiesis after high fractionated dose therapy. Unlike old methods of X-ray irradiation, which have radiobiological flexibility, the method of daily irradiation of a patient with large doses of ionizing radiation has a certain radiobiological fixity. When a large volume of additional irradiation is required to eliminate the residual population, the dose can be divided into shorter doses.