Related Experiment Video
Updated: Jun 22, 2026

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Pseudomonoenergetic x-ray diffraction measurements using balanced filters for coherent-scatter computed tomography
1Department of Medical Biophysics, Robarts Research Institute, The University of Western Ontario, 100 Perth Drive, London, Ontario N6A 5K8, Canada. sbeath@imaging.robarts.ca
Abstract:
Coherent-scatter computed tomography (CSCT) is a method of "composition" imaging based on measurements of diffraction patterns from tissues. Use of an x-ray tube degrades scatter pattern angular resolution due to the x-ray spectral width, making it difficult to uniquely identify some materials. The use of two transmission filters with similar atomic numbers (balanced "Ross filters") to generate pseudomonoenergetic scatter patterns is described as it applies to CSCT. An analysis of angular-blur mechanisms reveals that focal spot size and beam width are the most important factors determining Bragg-peak width when Er-Tm filters are used. A relative RMS spectral width of 1% can be achieved in the difference spectrum and a Bragg-peak RMS angular width of approximately 0.14 degree (relative width of 3% at 5 degrees scatter angle) can be achieved with an effective energy of 58 keV.
Related Concept Videos
Computed Tomography
The technique was invented in the 1970s and is based on the principle that as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates...
X-ray Diffraction of Biological Samples
According to Bragg's law, when X-rays strike the sample positioned on a stage, the rays are scattered by the electron clouds around the sample atoms. The X-ray diffraction or scattering is caused by constructive interference of the X-ray waves that reflect off the internal crystal...
Electron Microscope Tomography and Single-particle Reconstruction
Electron Tomography
Electron tomography can be performed either in TEM or STEM (scanning transmission...
X-ray Imaging
Imaging Studies III: Computed Tomography
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...

