Authors: Kai Zhang Youli Hong Peiping Zhu Qingxi Yuan Wanxia Huang Zhili Wang Shengqi Chu Samuel A McDonald Federica Marone Marco Stampanoni Ziyu Wu
Publish Date: 2011/05/28
Volume: 401, Issue: 3, Pages: 837-844
Abstract
Impressive developments in Xray imaging are associated with Xray phase contrast computed tomography based on grating interferometry a technique that provides increased contrast compared with conventional absorptionbased imaging A new “singlestep” method capable of separating phase information from other contributions has been recently proposed This approach not only simplifies dataacquisition procedures but compared with the existing phase step approach significantly reduces the dose delivered to a sample However the image reconstruction procedure is more demanding than for traditional methods and new algorithms have to be developed to take advantage of the “singlestep” method In the work discussed in this paper a fast iterative image reconstruction method named OSEM ordered subsets expectation maximization was applied to experimental data to evaluate its performance and range of applicability The OSEM algorithm with different subsets was also characterized by comparison of reconstruction image quality and convergence speed Computer simulations and experimental results confirm the reliability of this new algorithm for phasecontrast computed tomography applications Compared with the traditional filtered back projection algorithm in particular in the presence of a noisy acquisition it furnishes better images at a higher spatial resolution and with lower noise We emphasize that the method is highly compatible with future Xray phase contrast imaging clinical applicationsWe would like to thank Professor Marcelli for many fruitful discussions This work was partially supported by the National Outstanding Youth Fund project no 10125523 to ZW the Knowledge Innovation Program of the Chinese Academy of Sciences KJCX2YWN42 the Key Important Project of the National Natural Science Foundation of China 10734070 the National Natural Science Foundation of China NSFC 10774144 and 10979055 and the National Basic Research Program of China 2009CB930804
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