| 摘要 |
<p>WO 91/00048 PCT/US90/03722 1-TRANSMISSION/EMISSION REGISTERED IMAGE (TERI) COMPUTED TOMOGRAPHY SCANNERS AND SUMMARY OF INVENTION Reconstructed SPECT (Single Photon Emission Computed Tomography) images describe the intensity and location of sources of emitted photons in an attenuating medium, whereas transmission computed tomography (TCT) seeks to describe the distribution of different attenuation values within the attenuating medium. The photons emitted by inhaled, ingested or injected radionuclide sources in the body are attenuated by the amount and density of the attenuating material along a line between any emission source and the detector. The major problem in precise reconstruction of the SPECT image requires both the calculation of unknown activity in each part of the cross section as well as calculation of the unknown attenuation coefficients. The latter problem has been very poorly treated and is essentially unsolved by current methods which either make the (entirely incorrect) assumption of uniform gamma ray attenuation for all parts of the body or which grossly attempt to register CT images obtained by a different scanning device with different scanning geometry (and possibly different photon energy) for attenuation correction of a SPECT image. The present invention defines a system, a method, and several families of apparatus which make possible the WO 91/00048 PCT/US90/03722 1-1a acquisition of transmission and emission data from the same scanner. There has, until the present invention, been no simple, safe and reliable method of creating transmission and emission images in exact registry on a multihead SPECT scanner.</p> |
