1. A method of providing an optimal treatment plan for delivering a prescribed radiation dose to a predefined target volume within a patient using an external beam radiation delivery unit, comprising: a. receiving information related to (1) the prescribed radiation dose, (2) the predefined target volume, and (3) a plurality of parameters associated with the external beam delivery unit; b. developing a dose calculation optimization model based on a plurality of variables corresponding to the information which define a global system; and c. producing an optimal treatment plan based on the dose calculation optimization model and the information.