Method and apparatus for forming multi-dimensional attenuation

Abstract

A method and apparatus for producing radioactive transmission measurements to form multi-dimensional attenuation correction data with a point source of radiation, such as required in positron emission tomography applications. This involves the passing of the point source proximate the face of each of the tomograph units for the formation of a 3-D image, or a selected portion of the tomograph units for a 2-D image. As such, attenuation data, transmission data, detector performance data, etc., can be obtained. This point source of radiation, in one embodiment, is rapidly circulated through a conduit that passes across each detector face under the influence of a transport fluid in, for example, an oscillatory motion to achieve a selected radiation field whereby calculation of transmission measurements within a body positioned within the tomograph scanner is achieved. When not being circulated, the radiation source is held within a shield. In another embodiment, the point source is a CT device. In a further embodiment, a single photon source is used in association with an ECAT ART having two oppositely disposed detector banks. One point source is provided for association with each detector bank. Each point source is capable of axial movement with respect to the detector banks, with the entire apparatus including the detector banks and the point sources being rotatable. Collimators are provided for each point source, the collimators and the point source being fixed with respect to each other, thus reducing the effects of dead-time during a transmission scan typically caused by the point source moving behind a collimator.