A computer method to model the dose distribution of high energy photon grid therapy in three dimensions

High energy photon grid therapy is the application of multiple circular divergent photon beams to the palliative care of patients. The photon beams are defined by cylindrical holes in a large attenuator placed in the path of an open radiation beam. We have developed a computer method to model the three-dimensional dose distribution of high energy photon grid therapy. The semiempirical method requires the measured data from a single cylindrical hole of the size to be modeled. For a given hole diameter, any arbitrary geometry can be calculated. This information is important when investigating the clinical implications of grid therapy for patient care.