Importance

Loading Importance Indicators...

Abstract

An energy substraction medical imaging system which is used for imaging a body part impregnated with a radio-opaque dye such as iodine is provided. The system includes an electron beam target having a target surface which, when excited by a high-energy electron beam, generates radiation having strong K.sub..alpha. at energy levels slightly above and slightly below the K-edge energy level of the dye. The target surface is preferably formed of a compound containing lanthanum, such as lanthanum oxide. The target may also be formed of a compound containing a material having a K.sub..alpha. line at an energy level slightly above the dye K-edge and a material with K.sub..alpha. line slightly below the dye K-edge or with separate sections containing such materials which are alternately excited. The target is excited by a high-energy electron beam from a suitable source, the electron beam having sufficient energy to provide a high photon yield at the K.sub..alpha. line energy levels and sufficient power to produce the required photon fluences at such energy lines for the medical imaging application. One of the K.sub..alpha. lines in the radiation output from the excited target is selectively filtered and the output from the filter, both with the K.sub..alpha. line filter and with the line unfiltered, are passed through the body part being imaged to an x-ray detector. The output from the detector in response to the filtered and unfiltered outputs is processed to obtain an image of the body part. Continuum radiation from the target is reduced by filtering the continuum radiation at frequencies above the below the K.sub..alpha. line energy levels of the target compound, by viewing the radiation from the target in the backward direction to the beam, and by having the thickness of the target equal to a fraction of the electron range in the target compound material.

Loading the Abstract Image...

First Claim