Enhanced local tomography

摘要

Local tomography is enhanced to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. In a first method for evaluating the value of the discontinuity, the relative attenuation data is inputted to a local tomography function f LAMBDA to define the location S of the density discontinuity. The asymptotic behavior of f LAMBDA is determined in a neighborhood of S, and the value for the discontinuity is estimated from the asymptotic behavior of f LAMBDA . In a second method for evaluating the value of the discontinuity, a gradient value for a mollified local tomography function NABLA f LAMBDA epsilon (xij) is determined along the discontinuity; and the value of the jump of the density across the discontinuity curve (or surface) S is estimated from the gradient values.