Tapered Collimator Design for X-ray Detector Motion Robustness
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Solution Overview
Problem
Focal spot motion in medical imaging systems introduces artifacts in reconstructed images, limiting visualization of small structures and features, and conventional skewed detector collimators reduce light collection and geometric efficiency while attempting to desensitize to this motion.
Innovation Solution
The use of tapered edge collimators between the object and radiation detectors increases the exposure to a range of focal spot positions, reducing sensitivity to focal spot motion without skewing the detectors, thereby enhancing geometric sharpness and spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If skewed detector collimators are used to desensitize to focal spot motion, then sensitivity to geometric tolerances and focal spot motion is reduced, but light collection and geometric efficiency are reduced
Solution Approach 1:
The collimator uses asymmetric tapered edges where one edge is tapered and the other is not, creating an asymmetric geometry that selectively accepts x-rays from a range of focal spot positions while maintaining optimal light collection geometry. This asymmetric design allows the collimator to be less sensitive to focal spot motion in one direction while preserving geometric efficiency.
Solution Approach 2:
Different edges of the collimator have different geometric properties - one edge is tapered to provide motion insensitivity while the other edge maintains sharp collimation. This local differentiation of geometric quality allows simultaneous achievement of motion robustness and high geometric efficiency in different spatial directions.
2Reliability
If the x-ray aperture is reduced by skewing the collimator, then sensitivity to focal spot motion is reduced, but geometric efficiency is reduced
Solution Approach 1:
The asymmetric tapered edge design allows the collimator to maintain a larger effective aperture by not skewing the overall geometry, while the tapered portion selectively filters x-rays to provide motion insensitivity. This preserves geometric efficiency while achieving the desired robustness to focal spot motion.
Solution Approach 2:
The tapered edge introduces a new geometric dimension (the taper angle) that provides an additional degree of freedom for controlling x-ray acceptance. This allows the collimator to achieve motion insensitivity through the taper geometry rather than through skewing, thereby maintaining high geometric efficiency.
3Reliability
If tapered edge collimators are used to increase exposure to focal spot positions, then sensitivity to focal spot motion is reduced, but device complexity increases
Solution Approach 1:
The tapered edge design modifies only the local geometry at the collimator edge rather than requiring a complete redesign of the entire collimator structure. This localized geometric modification achieves motion insensitivity while minimizing the overall device complexity.
Solution Approach 2:
The invention changes the geometric parameter of the collimator edge from a straight edge to a tapered edge with a specific angle. This parameter change provides the desired motion insensitivity while maintaining a simple structural form that is relatively easy to manufacture and integrate.
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
The tapered collimator design minimizes the impact of focal spot motion, reducing artifacts in images and maintaining high geometric efficiency by allowing a wider focal spot range and broader aperture, while rejecting scatter radiation.
Implementation Method 1
a plurality of collimators positioned between the object and the plurality of detectors, wherein the collimators have a tapered configuration
Data Source
AI summary
Methods and apparatus for collimation of detectors in an imaging system are provided. One an imaging system includes a radiation source configured to project radiation from a focal spot onto an object and a plurality of radiation detectors disposed around at least a portion of the object. The plurality of radiation detectors detect received radiation along a path projected from the focal spot to the plurality of detectors. The imaging system also includes a plurality of collimators positioned between the object and the plurality of detectors, wherein the collimators have a tapered configuration.