Patent ID: 7756567

Claim:
A method in image guided radiosurgery for aligning the position of a treatment target relative to a radiosurgical beam generator during treatment, the method comprising: a. generating a pre-treatment 3D scan showing an initial position of said target at treatment planning time; b. generating a set of 2D reconstructed images from said 3D scan, wherein the set of 2D reconstructed images corresponds to perturbations from said initial position along fewer than six degrees of freedom; c. generating one or more 2D x-ray images of said target, wherein said x-ray images show a current position of said target at a current time during treatment; d. registering said reconstructed images that correspond to perturbations from the initial position along fewer than six degrees of freedom with said x-ray images by computing a set of 3D transformation parameters that represent the change in position of said target between said initial position of said 3D scan and said current position of said x-ray images along six degrees of freedom, wherein said 3D transformation parameters are 3D rigid body transformation parameters, and wherein said 3D transformation parameters are represented by three translations and three rotations (x, y, z, r, p, w); wherein x, y, z represent the translations of said target in the directions of three mutually orthogonal axes, respectively, and wherein r, p, w represent three rotations (roll, pitch, yaw) about said three orthogonal axes; and e. adjusting the relative position of said radiosurgical beam generator to said target by the amount prescribed by said 3D transformation parameters computed in step d, wherein said target is allowed six degrees of freedom of position.