IMRT is a widely used therapy technique to treat cancer. The main goal of IMRT is to eliminate cancer cells while minimizing the damage to vulnerable organs. To this end, it is essential to identify the best possible set of beam angles, called BAC, from which to irradiate cancerous cells.

The authors propose a reduced Variable Neighbourhood Search (rVNS) algorithm that explores the search space with two different local search movements at each iteration of the algorithm. In order to improve the current BAC at each iteration, the algorithm solves the so-called FMO problem which is a complex mixed-integer nonlinear problem (MINLP).

Artelys Knitro is leveraged for the resolution of each FMO allowing the authors to determine a good and stable beam angle configuration within fewer iterations when compared to other local search algorithms proposed in the literature.