Doran Wood: The Value of a Multistage Dynamic Approach for Radiation Therapy Planning

The goal of intensity modulated radiation therapy is to distribute a prescribed dose of radiation to cancerous tumors while sparing the surrounding healthy tissue. Current approaches implement a radiation plan such that the prescribed tumor dosage is divided equally and delivered through several treatment sessions. This equally distributed (uniform) approach involves solving an optimization problem at each treatment session without consideration of the future sessions or tumor evolution. Herein, we develop a generalization of the uniform formulation that does not automatically assume equal session tumor prescriptions (nonuniform) and also takes future decisions into consideration. This nonuniform multistage framework allows for a natural connection between treatment sessions as well as consideration for sources of uncertainty due to tumor evolution. For the proposed formulation, a sequence of prostate cancer scans provide numerical results revealing drastic improvement in tumor delivery precision while using a total dosage no more than the current practice methods.