Pseudomonoenergetic x-ray diffraction measurements using balanced filters for coherent-scatter computed tomography

Area of Science:

• Medical Imaging
• Materials Science
• X-ray Physics

Background:

• Coherent-scatter computed tomography (CSCT) uses tissue diffraction patterns for composition imaging.
• X-ray spectral width limits angular resolution and material identification in CSCT.
• Improving spectral quality is crucial for accurate CSCT analysis.

Purpose of the Study:

• To describe the use of balanced Ross filters for generating pseudomonoenergetic scatter patterns in CSCT.
• To analyze angular blur mechanisms affecting CSCT resolution.
• To evaluate the feasibility of achieving high spectral and angular resolution.

Main Methods:

• Utilized balanced "Ross filters" with similar atomic numbers to create pseudomonoenergetic x-ray scatter patterns.
• Analyzed angular-blurring factors including focal spot size and beam width.
• Employed Er-Tm filters and calculated spectral and angular widths.

Main Results:

• Achieved a relative RMS spectral width of 1% in the difference spectrum.
• Attained a Bragg-peak RMS angular width of approximately 0.14 degrees.
• Demonstrated feasibility at an effective energy of 58 keV with a 3% relative width at 5 degrees scatter angle.

Conclusions:

• Balanced Ross filters effectively generate pseudomonoenergetic scatter patterns for CSCT.
• Focal spot size and beam width are critical for minimizing angular blur.
• The proposed method significantly enhances spectral and angular resolution in CSCT, improving material identification capabilities.