Material decomposition and identification method based on phase CT

Abstract

The invention discloses a material decomposition and identification method based on phase CT, and the method comprises the steps: 1, enabling m to be equal to 0, and initializing a first substrate image f (m) and a second substrate image g (m); 2, according to a formula (6), calculating an estimated value and a corresponding residual error of the discretized absorption projection data in the mth iteration and an estimated value and a corresponding residual error of the discretized differential phase projection data in the mth iteration; 3, according to a formula (5), iteratively solving a value f (m + 1) of a first base material image f (m) in the (m + 1) th iteration and a value g (m + 1) of a second base material image g (m) in the (m + 1) th iteration; 4, performing regularization operation on f (m + 1) and g (m + 1); 5, if the stop condition is not met, enabling m to be equal to m + 1, and executing the step 2 again. The absorption projection information and the differential phase projection information are combined for base material decomposition, the noise of the obtained base material image is smaller, and the noise of the equivalent atomic number image calculated subsequently is smaller than that of a conventional method.

Description

technical field [0001] The invention relates to the technical field of material identification, in particular to a material decomposition and identification method based on phase CT. Background technique [0002] X-ray imaging technology is widely used in many fields, such as biomedicine, industry and security inspection, etc. Traditional X-ray absorption CT is based on the differences in the absorption of radiation between different substances or tissues, which is not ideal for imaging materials composed of light elements (such as muscle, blood vessels, and breasts, etc.). The X-ray phase contrast CT is based on the change of the phase of the passing X-rays by the matter, and generally has a greater advantage in imaging light matter than the absorption CT. Commonly used in X-ray phase contrast imaging methods are grating phase contrast method and diffraction enhanced method, both of which can provide absorption and phase information at the same time. Material decompositio...

AI Technical Summary

Problems solved by technology

[0005] However, performing a one-shot decomposition in the image domain has the problem of noise amplification

The result of the decomposition will be affected by the reconstructed image, and the quality of the reconstructed image is mainly determined by the noise level of the initial projection data and the selection of the reconstruction algorithm. Without joint absorption and phase information for reconstruction and decomposition, the obtained results are not good

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