Multileaf collimator optimisation for column generation in radiotherapy

Radiation therapy is a form of therapy for cancer treatments, where ionizing radiation is used to eradicate malignant cells. The patient is treated with a device called a linear particle accelerator. It contains a source, from which photons are emitted. Constructing an optimal treatment plan for radiation therapy involves optimising the angles from which the patient is irradiated. Other degrees of freedom arise from the use of a multileaf collimator, allowing beam shaping. It is quite common that the tumour lies between other organs. With the multileaf collimator we can adjust the beam shape in such a way that we expose the healthy organs to a minimal amount of radiation. There are many shapes we cannotmake using the multileaf collimator. Column generation is a method for mathematical optimisation, that can be used to optimise treatment plans for radiation therapy. At some point during the column generation process, a suitable aperture must be found. This aperture is restricted because of the requirements of themultileaf collimator. In this project we have developed a algorithm that finds a suitable aperture for the column generation process. At first this algorithm creates an optimal aperture, while only taking some basic requirements of the multileaf collimator into account. Afterwards, the aperture found is adapted into an aperture that complies with all common requirements of multileaf collimators. The algorithmthatwe have developed, does not guarantee an optimal aperture. Even though better apertures might in the end deliver a better treatment plan, it is not a necessity. The column generation process can correct itself in the next step. How the column generation process responds to the apertures created during this research project, has not yet been tested.Applied mathematicsElectrical Engineering, Mathematics and Computer Scienc