Patent ID: 8213568

Claim:
A system for limiting radiation dose to a patient during a computed tomography scan, including: an X-ray source on a rotating gantry configured to move axially parallel to a volume of interest (VOI) on a stationary subject support as the X-ray source rotates around the VOI; a dynamic collimator positioned between the X-ray source and the VOI and moveable with the X-ray source; and an X-ray detector positioned opposite the X-ray source and collimator to receive X-rays that have passed through the VOI; wherein the X-ray source begins CT acquisition of the VOI at an X-ray initiation position, terminates CT acquisition of the VOI at an X-ray termination position; wherein the dynamic collimator begins to open at the X-ray initiation position to limit X-rays passing through the collimator to X-rays that will pass through the VOI, opens in coordination with axial movement to permit a full X-ray cone beam to pass through to scan the VOI, and closes in coordination with axial movement to reduce X-rays passing through the collimator as the collimator approaches the X-ray termination position.