Asymmetric Tiled Detector for Differential Phase Contrast CT
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Solution Overview
Problem
Tiled detector systems in phase contrast and dark-field computed tomography scanners face challenges in image quality due to gaps between detector tiles, particularly when acquiring differential data, which requires critical interpolation and increases the depth of the tiles, leading to ring artifacts in reconstructed images.
Innovation Solution
A rotating radiation source and detector arrangement where detector tiles are arranged asymmetrically along a circular arc, allowing complementary rays to fill data gaps by positioning the radiation source on the opposite side of the object, ensuring that radiation hits a tile rather than a gap, thereby utilizing complementary data for image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If detector tiles are arranged symmetrically along a circular arc, then the detector structure is simple and easy to manufacture, but gaps between tiles cause data loss and ring artifacts in reconstructed images
Solution Approach 1:
The patent applies asymmetry by offsetting the detector tiles from symmetric positions along the circular arc. Specifically, the detector tiles are positioned at asymmetric angles relative to the radiation source, ensuring that complementary rays from opposite sides of the object fall on different tiles. This asymmetric arrangement eliminates data gaps and prevents ring artifacts in the reconstructed images, resolving the contradiction between manufacturing simplicity and data completeness.
2Measurement precision
If detector tiles are placed to cover the entire field of view, then measurement precision is improved, but the depth of each tile increases leading to more significant gap issues
Solution Approach 1:
The patent resolves this contradiction by transitioning from a two-dimensional detector plane to a three-dimensional asymmetric arrangement. By positioning detector tiles at different angular positions and depths along the circular arc, the system achieves complete spatial coverage without requiring excessively deep individual tiles. The asymmetric offset in the angular dimension allows complementary rays to be captured, maintaining measurement precision while controlling tile depth.
3Device complexity
If symmetric detector arrangement is used, then device complexity is reduced, but interpolation of data across gaps becomes critical and difficult
Solution Approach 1:
The patent eliminates the need for complex data interpolation by implementing an asymmetric detector arrangement. The asymmetric positioning ensures that every ray path, including complementary rays from opposite sides, intersects with a detector tile. This removes data gaps entirely, making interpolation unnecessary and significantly reducing the difficulty of data acquisition and image reconstruction while maintaining manageable device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances image quality by effectively closing data gaps and reducing ring artifacts in reconstructed images, making it suitable for both medical and industrial applications, including non-destructive testing and security scanning.
Implementation Method 1
an interferometer (e.g. a grating) is placed behind the object to generate an interference pattern of intensity maxima and minima when the object is irradiated with (coherent) X-rays
Implementation Method 2
a radiation source emits a first beam of electromagnetic radiation along a first path in a first direction towards a detector
Data Source
AI summary
Radiation source and detector arrangement for a differential phase contrast CT scanner, in which the detector tiles are placed asymmetrically such that direct rays, which hit gaps between tiles are sampled by tile centers for the complementary rays. This may provide for good image quality without any approximate processing.