Patent ID: 8135111

Claim:
A method of calibrating a radiation therapy system that comprises: 1) a cone beam computed tomography image system that includes a flat panel imager and a keV x-ray source that generates x-ray beams in a cone-beam form towards the flat panel imager and 2) a radiation therapy source system comprising: a radiation therapy source that generates radiation, a collimating structure and an imager that is located opposite said radiation therapy source that generates therapeutic radiation, the method comprising: calibrating said radiation therapy source system, said calibrating said radiation therapy source system comprising: providing a reference marker embedded in an object located at a known location with respect to an isocenter of rotation of said radiation therapy source and said imager; directing said therapeutic radiation towards said object and said imager; generating images of said reference marker by said therapeutic radiation at angular increments of positions of said radiation therapy source and said imager; and calibrating said collimating structure based on said generated images; calibrating said cone beam computed tomography image system, said calibrating of said cone beam computed tomography image system comprises: directing said x-ray beams towards said object and said flat panel imager; generating images of said reference marker by said x-ray beams at angular increments of positions of said keV x-ray source and said flat panel imager; determining residuals based on said generated images; and subsequently generating cone beam computed images of a second object, wherein said generated cone beam computed images are generated based on calibrating back-projection trajectories in a reconstruction process involving said generated cone beam computed images.