A “depth-independent” collimator for use with 99mTc in both conventional and transverse section scanning

The design of a “depth independent” collimator for use with 99 m Tc is discussed. Since this is a novel design, not available commercially, experimental measurements of line spread function (L.S.F.), both in air and phantom material (Mix-D) and the modulation transfer function (M.T.F.) calculated from the L.S.F. are presented. The collimator is shown to have a good depth of focus and has been found to have an acceptable sensitivity for brain scanning. A pair of these collimators have been particularly useful for transverse section scanning of the brain.