Formation of a homogeneous dose field on a segment using 2 combined radiation sources

One of the most common methods of the arrangement of linear radiation sources during interstitial radiotherapy is their parallel position which results in a notable non-homogeneity of the dose field at the source edges. Terminal needles are necessary to alighn the dose field at the source edges through it is not always possible to introduce them. An active substance in active sources should be redistributed to form a homogeneous dose field without terminal needles. This is the first attempt to provide a theoretical basis for the solution of this kind of problems. Algorithms and programs have been worked out, and the results of the solution of concrete problems for optimal placement of an active substance in sources are presented. It is suggested that these sources should be referred to as combined linear radiation sources in contradistinction to those with a homogeneously distributed active substance