Radiation collimator for use in x-ray systems

Claim 1

A radiation collimator comprising a casing, a thimble shutter at one end of the casing having a plurality of leaves of radiation absorbing material extending out through the casing, a ring encircling said leaves and operatively connected to each individual leaf for moving the leaves to effectively define a hollow cone, with the extent of movement of the ring determining the size of an aperture defined by the outer ends of the leaves whereby a beam of radiation directed into the casing will be intercepted and absorbed by said leaves except For the portion thereof which passes through the aperture, a first pair of plane shutters within the casing, first operating means for adjusting the spacing between the plane shutters so that the shutters will intercept opposed marginal portions of the beam passing therethrough from said thimble shutter, a second pair of plane shutters within the casing disposed respectively at the two sides of the beam not intercepted by the first plane shutters, second operating means for adjusting the spacing between the second plane shutters so that they will intercept opposed marginal portions of the beam passing therethrough from the thimble shutter and together with the first plane shutters providing the beam with a rectangular cross-sectional shape of desired size, connecting means including a whiffletree linkage between said first and second operating means and said ring for causing movement of the ring and consequent adjustment of the thimble shutter simultaneously with operation of both of said operating means to an extent where the thimble shutter will intercept radiation entering the casing from off-focus sources without intercepting radiation which contributes to the portion of the beam which is permitted to pass through said plane shutters in their adjusted positions.