Application of Energy-Weighting on Observer Performance Assessment in X-ray Phase-Contrast Imaging
Date Issued
2011
Date
2011
Author(s)
Lo, Chun-Wei
Abstract
The phase contrast imaging methods utilize phase information to improve image contrast. Many phase-contrast imaging formulas are based on monochromatic light as the light source. Because traditional X-ray tube output is polychromatic, it limits the usage in practical applications. Photon counting detectors can distinguish between different photon energies and their outputs are energy-bin intensity data. The energy-bin of each output channel can be determined by setting the energy threshold of the photon counting detector. The image quality can be enhanced by proper use of the information contained in polychromatic light. The objective of this study is to use energy-weighting technique on phase contrast images, and assess the performance of the observer.
The observer performance of the energy-weighted image, the averaged image and image with energy integrating detectors were compared. We used the weight derived from phase retrieval formulas for a particular energy-bin phase image to get the energy-weighted phase images. The weights of all energy-bin images were the same in the averaged image.
By calculating the observer performance of weighted and averaged images with photon counting detectors and the images with the energy integrating detectors, we could evaluate the observer performance of the signal detection. The energy-weighted image was better than the averaged image in observer performance, and was better than the images obtained with the energy integrating detectors.
Subjects
x-ray
phase contrast
energy-weighting
signal detection
Type
thesis
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