Nicholas Benjamin Bevins PhD, Presenter: Nothing to Disclose

Joseph Zambelli PhD, Abstract Co-Author: Nothing to Disclose

Ke Li MS, Abstract Co-Author: Nothing to Disclose

Guang-Hong Chen PhD, Abstract Co-Author: Research funded, General Electric Company Research funded, Siemens AG Research funded, Varian Medical Systems, Inc Research funded, Hologic, Inc

Several methods have been recently proposed to achieve faster data acquisition in differential phase contrast CT (DPC-CT). The purpose of this work is to evaluate the performance of these methods and to determine their potential for clinical implementation.

A Talbot-Lau DPC CT system was used to obtain data. This system allows for both phase and absorption data to be acquired simultaneously. The alternative data acquisition techniques included interlaced phase stepping, moiré analysis, and a novel grating design which incorporates phase stepping without the need for mechanical movement during the acquisition. The common trait among all of the methods, except conventional phase stepping, is that none of them require multiple projections at each view angle, thus enabling faster data acquisition in DPC-CT. Physical phantom studies were conducted to study the reconstruction accuracy of the methods.

Interlaced phase stepping produces accurate reconstruction for smaller objects, but as the size of the object increases, blurring effects are produced with increasing radius from the center. Moiré analysis produces accurate reconstructions over the entire field of view, but inherently reduces through-plane spatial resolution. However, it does not require any movement of the gratings throughout the acquisition, drastically simplifying the setup. The novel grating design also produces accurate reconstructions and has the benefit of not requiring any grating movement, all with the addition of maintaining high interferometer efficiency.

All of the extraction techniques are capable of producing phase data that can be accurately reconstructed. Of the proposed methods, the novel grating design is the only one that allows for completely accurate reconstructions for any size object and maintains the efficiency of the interferometer.

Evaluating alternative means for phase signal extraction in place of phase stepping is an important step in moving DPC imaging to the clinic, where faster scanning performance is necessary.

Bevins, N, Zambelli, J, Li, K, Chen, G, Performance Evaluation of Fast Data Acquisition Methods in Differential Phase Contrast CT.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12027791.html