17 research outputs found
Tomographic phase and attenuation extraction for a sample composed of unknown materials using X-ray propagation-based phase-contrast imaging
Propagation-based phase-contrast X-ray imaging (PB-PCXI) generates image
contrast by utilizing sample-imposed phase-shifts. This has proven useful when
imaging weakly-attenuating samples, as conventional attenuation-based imaging
does not always provide adequate contrast. We present a PB-PCXI algorithm
capable of extracting the X-ray attenuation, , and refraction, ,
components of the complex refractive index of distinct materials within an
unknown sample. The method involves curve-fitting an error-function-based model
to a phase-retrieved interface in a PB-PCXI tomographic reconstruction, which
is obtained when Paganin-type phase-retrieval is applied with incorrect values
of and . The fit parameters can then be used to calculate true
and values for composite materials. This approach requires no
a priori sample information, making it broadly applicable. Our PB-PCXI
reconstruction is single distance, requiring only one exposure per tomographic
angle, which is important for radiosensitive samples. We apply this approach to
a breast-tissue sample, recovering the refraction component, , with 0.6
- 2.4\% accuracy compared to theoretical values.Comment: 8 pages, 4 figures and 1 tabl
A synchrotron-based local computed tomography combined with data-constrained modelling approach for quantitative analysis of anthracite coal microstructure
Toward Improving Breast Cancer Imaging: Radiological Assessment of Propagation-Based Phase-Contrast CT Technology
Rationale and Objectives: This study employs clinical/radiological evaluation in establishing the optimum imaging conditions for breast cancer imaging using the X-ray propagation-based phase-contrast tomography. Materials and Methods: Two series of experiments were conducted and in total 161 synchrotron-based computed tomography (CT) reconstructions of one breast mastectomy specimen were produced at different imaging conditions. Imaging factors include sample-to-detector distance, X-ray energy, CT reconstruction method, phase retrieval algorithm applied to the CT projection images and maximum intensity projection. Observers including breast radiologists and medical imaging experts compared the quality of the reconstructed images with reference images approximating the conventional (absorption) CT. Various radiological image quality attributes in a visual grading analysis design were used for the radiological assessments. Results: The results show that the application of the longest achievable sample-to-detector distance (9.31 m), the lowest employed X-ray energy (32 keV), the full phase retrieval, and the maximum intensity projection can significantly improve the radiological quality of the image. Several combinations of imaging variables resulted in images with very high-quality scores. Conclusion: The results of the present study will support future experimental and clinical attempts to further optimize this innovative approach to breast cancer imaging