1. A method of generating a virtual collision map for use in optimizing planning of a radiation treatment by a radiation beam to be delivered from an associated treatment device on a gantry to a patient target volume (PTV) within a treatment volume of an associated patient disposed on a couch operatively coupled with the associated treatment device, the method comprising: acquiring segmented data, the segmented data being representative of a characteristic of the PTV, and representative of a non-treatment volume comprising an organ at risk (OAR) of the associated patient; modeling the PTV of the segmented data as a source of simulated rays projecting outwardly relative to the PTV and having a predetermined initial value; modeling the OAR of the segmented data as having an assigned ray attenuation feature to reduce an intensity of a selected one or more of the simulated rays passing through the OAR; defining a virtual map surface surrounding the PTV and the OAR; calculating an accumulated intensity value for points on the virtual map surface having the simulated rays passing through the points, the accumulated intensity value of each point being i) the predetermined initial value for areas of the virtual map surface having simulated rays passing directly from the PTV to the virtual map surface, and ii) the predetermined initial value attenuated by the assigned ray attenuation feature of the OAR for areas of the virtual map surface having the OAR disposed between the PTV and the virtual map surface; generating an intensity distribution on the virtual map surface in accordance with the calculated accumulated intensity values; and determining, in accordance with the intensity distribution, the virtual collision map defining a relationship between the associated patient disposed on the couch and plural positions of the treatment device on the gantry relative to the associated patient for delivering the radiation beam to the PTV.