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Detectability Index and Its Variation in Differential Phase Contrast CT Compared with the Conventional CT - A Channelized Hotelling Observer Study

X Tang

X Tang*, Y Yang, S Tang, Emory Univ, Johns Creek, GA

SU-C-144-6 Sunday 1:00PM - 1:55PM Room: 144

Purpose: As an emerging imaging method for preclinical and eventually clinical applications, the grating-based x-ray differential phase contrast (DPC) CT has drawn increasing interest. It has been hoped that the potential detectability index d' in the DPC-CT can be significantly larger than its counterpart in the conventional attenuation-based CT. In this study, with the channelized Hotelling (CHO) model observer, we investigate the detectability d' and its variation in the DPC-CT and compare it with that of the conventional CT.

Methods: The CHO study of the DPC-CT's detectability index d' and its comparison with that of the conventional CT are carried out under the framework of signal and background exactly known (SKE/BKE). Using the Gabor channel template, we investigate the detectability index d' and its variation over dimension of the target to be detected and the detector cells used for data acquisition, while the x-ray exposure is kept constant between the DPC-CT and conventional CT over all the cases. In addition, the internal noise, through which the CHO model deals with the psychological uncertainty existing in a human observer, is assumed identical in both the DPC-CT and conventional CT.

Results: Preliminary data show that, the DPC-CT outperforms the conventional CT significantly in detectability while both the object to be detected and the cell of detector used for data acquisition are relatively small. However, the DPC-CT's dominance in the detectability diminishes with increasing dimension of either object or detector cell, and virtually disappears while the dimension of object or detector cell approaches a threshold, respectively.

Conclusion: Based on the CHO study, the potential imaging performance of the grating-based DPC-CT in comparison to the conventional CT can be further understood and appreciated, providing insightful guidelines on the design and performance optimization of DPC-CT as a new imaging technology.

Funding Support, Disclosures, and Conflict of Interest: Department of Defense Grant: U.S. Army Medical Research and Material Command (USAMRMC) via the award under contract number: W81XWH-12-1-0138 (PI: Xiangyang Tang)

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