Phase contrast imaging technique has been improved promptly in recent years. Among these techniques in-line phase contrast imaging is widely used. Various algorithms for in-line phase retrieval have been proposed so far such as TIE (transport of intensity equation), CTF (contrast transfer function), first Born-approximations, GSF (Gerchberg-Saxton-Fienup) and etc. Bronnikov’s algorithm (BA) is a type of linear algorithm that is simple and efficient. But it can only be used for no absorption situations. In this paper an improved algorithm based on BA is presented. The approach adds a Δϕ(x,y) to the phase map ϕ b (x,y) retrieved by BA to make the reconstructed phase map more precise. Further, the approach is evaluated on simulated images and confirmed to be accurate at higher absorption rates.

The invention provides a coaxial phase-contrast imaging method. The coaxial phase-contrast imaging method is characterized in that rays with spatial coherence are generated by a micro-focal-spot X-ray source and penetrate through an imaging object with fixed position on a rotary platform; images after the rays penetrate through the imaging object are received by a detector, and specifically, exposure imaging is carried out respectively on the images which are generated by the micro-focal-spot X-ray source working under two voltages and are formed by different rays penetrating through the imaging object so as to obtain a double-energy-spectrum image; the light-intensity distribution and the spectrum-density distribution at the incident plane position of the imaging object under the two voltages are respectively tested; according to the double-energy-spectrum image, the light-intensity distribution and the spectrum-intensity distribution, phase retrieval is carried out. The coaxial phase-contrast imaging method provided by the invention has the advantages that highly-difficult and accurate registration of multiple images is not needed and the cost is low. In addition, the invention also provides a coaxial phase-contrast imaging system. Meanwhile, on the basis of the coaxial phase-contrast imaging method, the invention provides a phase-contrast CT method which can be used for restoring multiple information of the imaging object. In addition, the invention also provides a phase-contrast CT system.

An improved phase retrieval algorithm for X-ray in-line phase-contrast imaging

Citations

Coaxial phase-contrast imaging method and system as well as phase-contrast CT method and system

Coaxial phase-contrast imaging method and system as well as phase-contrast CT method and system

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