The diffusion of water into PDTFI solution in acetone was measured by PGSE-NMR, showing the expected linear attenuation functions.
The quantitative method first involved conversion of the CT data into an energy-dependent linear attenuation map, or µ-map.
A lecture key for the interpretation of the tomographic images is proposed, based on the relationship between the linear attenuation coefficient μ-function of the density and elemental composition of each mineral phase- and the corresponding grey tone experimentally observed.
b CT scan of the phantom after conversion to linear attenuation coefficient map (μ-map).
As the depth increased, the radial dose function decreased more slowly for lung than for water due to the linear attenuation coefficient being small in lung tissue, whereas the function decreased faster in bone than in water due to the linear attenuation efficient being higher in bone than in water.
Furthermore, a map of linear attenuation coefficients was segmented (soft tissue and air) from this image for scatter and attenuation correction.
This method uses the photon x-ray spectrum, the linear attenuation coefficients of water, CA1, and CA2 together with the spectral detector response function [7, 9].
Unlike the Hounsfield units of CT data that are directly related to the linear attenuation coefficients (LACs) of the 511 keV photons in PET, MRI is a function of proton density and tissue relaxation times that have no direct relation to the LACs.
Generally, attenuation correction is made by incorporating a linear attenuation coefficient, which is based on the attenuation coefficient map (mu-map) created from a computed tomography scan, into the ordered subsets-expectation maximization reconstruction method in non-uniform domains.
Briefly, the CT attenuation map was generated using a bilinear conversion for HU to linear attenuation coefficient values, and collimator correction was based on the Gaussian convolution.
