1. A collimator system rotatable about an axis of rotation for use in a radionuclide emission tomography camera for imaging a region of an object, comprising a collimator having a plurality of collimator elements for restricting and collimating radionuclide emissions within a field of view of said collimator, said collimator elements being disposed with their axes intersecting at least one line, parallel to the axis of rotation and within said collimator field of view, at at least two different angles, and said collimator elements comprising means for establishing a selected variation in imaging sensitivity across the imaging region.