The design of a treatment plan for intensity modulated radiation therapy a mathematical programming problem which is not yet satisfactorily solved. Current techniques include dividing the problem into several subproblems, which are then solved sequentially. My research addresses several of these subproblems, particularly, beam orientation optimization (BOO), fluence map optimization (FMO) and fractionation. The integration of the BOO and FMO subproblems is considered, as well as improved techniques to model the dose deposition of a beamlet.