Patent ID: 8798228

Claim:
A method to reduce the radiation dose delivered by an imaging system, the method comprising: a user selecting a virtual mask representation based on the shape of an organ to be masked; displaying, the virtual mask representation on a scout image; manipulating radiation dose to be delivered so as to modify the virtual mask representation to obtain an optimum attenuation profile; and wherein the step of manipulating radiation dose comprises: acquiring a projection data set from each slice the virtual mask, the projection data set indicating patient attenuation of the radiation; calculating a relative attenuation function from the acquired projection data set, the relative attenuation function indicating the expected radiation attenuation at each slice location relative to the radiation attenuation of a known reference object; calculating a beam current command for each slice using the corresponding value of the relative attenuation function and a reference beam current command that produces the desired radiation dose in the known reference object; acquiring image data set for each slice using the radiation dose determined by the beam current command for that slice; and wherein the method allowing the user to treat a patient from multiple angles while varying the shape and dose of the radiation beam and thereby deliver radiation to a target while avoiding excess irradiation of the masked organ.