Application of linear programming to dose optimization in intracavitary implant therapy.

Linear programming can be used to optimize intracavitary brachytherapy for carcinoma of the cervix. A method has been developed which gives meaningful output and is described. A set of reference points were necessary in addition to the standard reference points. Point A as well as an array of points for adjacent radiation sensitive normal structures were used in order to obtain isodose curves conforming to those commonly used for therapy. In addition, arbitrary upper and lower limits of dose at selected points were needed and were set to conform to systems commonly used clinically for intracavitary therapy. It was immediately evident that a wide variety of loadings can be used that deliver appropriate or improved doses to reference points while minimizing normal tissue dose. The loadings represent arrangements which are not commonly used in many clinics but offer potential for clinical use.