METHOD AND APPARATUS FOR ACCURATELY CALIBRATING AN ATTENUATION MAP FOR EMISSION COMPUTED TOMOGRAPHY

摘要

The attenuation map is generated using a transmission scan of the object of interest (502). The map includes a number of attenuation coefficients for the object (501). A computer program for generating the attenuation map includes an instruction (503) for scaling the attenuation coefficients in the map from the transmission energy level to the emission energy level using a scaling factor. The scaling factor includes an effective attenuation coefficient for water, which is determined empirically. To determine the effective attenuation coefficient, the number of photons which pass from a transmission source through known depths of water using the emission energy level is counted. The effective attenuation coefficient is computed and the scaling factor used by the computer program is then set based on the effective attenuation coefficient.