Patent ID: 7254215

Claim:
An imaging system comprising: a gantry comprising: a radiation source configured to generate a beam; a collimator configured to collimate the beam to generate a collimated beam; and a detector configured to detect the collimated beam, wherein the collimator is separate from said detector and comprises at least one radio opaque member having a curved contour proportional to a contour of the detector, wherein said at least one radio opaque member includes a first portion and a second portion spaced a distance from said first portion, wherein said first portion and said second portion are each configured to move along a direction substantially parallel to a rotational axis of said gantry, wherein each of said first portion and said second portion includes a first collimator point at a first collimator distance from said radiation source and a second collimator point at a second collimator distance from said radiation source, wherein said detector includes a first detector point at a first detector distance from the first collimator point and a second detector point at a second detector distance from the second collimator point, and wherein a sum of the first collimator distance and the first detector distance is equal to a sum of the second collimator distance and the second detector distance.