title: High sensitivity phase retrieval method in grating-based x-ray phase contrast imaging.
abstract: OBJECTIVE
  Grating-based x-ray phase contrast imaging is considered as one of the most promising techniques for future medical imaging. Many different methods have been developed to retrieve phase signal, among which the phase stepping (PS) method is widely used. However, further practical implementations are hindered, due to its complex scanning mode and high radiation dose. In contrast, the reverse projection (RP) method is a novel fast and low dose extraction approach. In this contribution, the authors present a quantitative analysis of the noise properties of the refraction signals retrieved by the two methods and compare their sensitivities.
  
  
  METHODS
  Using the error propagation formula, the authors analyze theoretically the signal-to-noise ratios (SNRs) of the refraction images retrieved by the two methods. Then, the sensitivities of the two extraction methods are compared under an identical exposure dose. Numerical experiments are performed to validate the theoretical results and provide some quantitative insight.
  
  
  RESULTS
  The SNRs of the two methods are both dependent on the system parameters, but in different ways. Comparison between their sensitivities reveals that for the refraction signal, the RP method possesses a higher sensitivity, especially in the case of high visibility and/or at the edge of the object.
  
  
  CONCLUSIONS
  Compared with the PS method, the RP method has a superior sensitivity and provides refraction images with a higher SNR. Therefore, one can obtain highly sensitive refraction images in grating-based phase contrast imaging. This is very important for future preclinical and clinical implementations.
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Zhao
authors: Z
authors: Wu
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Kun
authors: K
authors: Gao
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Jian
authors: J
authors: Chen
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Dajiang
authors: D
authors: Wang
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Shenghao
authors: S
authors: Wang
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Heng
authors: H
authors: Chen
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Yuan
authors: Y
authors: Bao
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Qigang
authors: Q
authors: Shao
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China.
authors: Zhili
authors: Z
authors: Wang
authors: Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors: Kai
authors: K
authors: Zhang
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China and Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors: Peiping
authors: P
authors: Zhu
authors: National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China and Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors: Ziyu
authors: Z
authors: Wu
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods*; D011859:Radiography / Q000379:methods*; D059629:Signal-To-Noise Ratio