1. A radiation therapy optimization method for a multi-objective optimization problem comprising a planning-target-volume surrounded by organs-at-risk in a patient to be treated using radiation, the method comprising: representing computed tomography data of the patient as a three-dimensional grid of coordinates divided into voxels which contain the planning-target-volume and the organs-at-risk; using a multi-objective optimizer to search successive generations of trial solutions to generate a database of optimized solutions that form a Pareto non-dominated set of solutions, which sample an estimation of a Pareto front to the multi-objective optimization problem where all solutions on the Pareto front are regarded as equally optimal, each trial solution being specified by a set of parameters defining beam orientations and fluence patterns which together define the radiation; evaluating each generation of trial solutions by: estimating a radiation dose proxy to each voxel for each trial solution to the multi-objective optimization problem; associating a fitness function with each of the organs-at risk and the planning-target-volume; calculating a set of fitness values for each trial solution by evaluating the fitness functions associated with the trial solution using the respective radiation dose proxies of the respective voxels associated with the trial solution such that the fitness values are optimized with respect to Pareto-optimality of the trial solutions; and determining the Pareto non-dominated set of solutions to be optimized solutions by comparing the fitness values of the trial solutions to one another and to the fitness values of the optimized solutions of previous generations of the trial solutions; continuing to generate successive generations of the trial solutions according to a defined convergence criterion until the optimized solutions are determined according to prescribed criteria to be sufficiently approximate Pareto-optimal solutions to the multi-objective optimization problem; and displaying the Pareto non-dominated set of solutions to a user by means of an interactive graphical interface.