CT Collimator Reinforcing Layer for Centrifugal Deflection
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Solution Overview
Problem
Existing secondary collimators in CT detection systems deflect under centrifugal loads, allowing scattered radiation to reach the detector and compromising image accuracy due to non-perpendicular forces during gantry rotation.
Innovation Solution
A collimator assembly with a reinforcing layer made of X-ray transparent material, oriented perpendicular to the direction of X-ray travel, is coupled to the collimator grid to provide stiffness and prevent deflection, ensuring focused radiation reaches the detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the secondary collimator is constructed as an array of identical modules tiled side-by-side, then the ease of manufacture is improved, but the stability of the object's composition deteriorates under centrifugal loads
Solution Approach 1:
The collimator is divided into identical modular units that can be tiled side-by-side to form the complete array. Each module contains the essential collimator structure with absorbing walls and air gaps, allowing standardized manufacturing while maintaining overall system functionality through modular assembly.
Solution Approach 2:
The collimator modules are constructed using composite materials including high-density absorbing material (such as tungsten or lead) for the walls and low-density material (such as aluminum or polymer) for the supporting structure. This composite construction provides both the necessary radiation absorption properties and mechanical strength to resist centrifugal forces during rotation.
2Area of stationary object
If the collimator modules are tiled to form a large array, then the area of stationary object is improved, but the strength deteriorates under non-perpendicular forces
Solution Approach 1:
The collimator array is arranged in an arc configuration along the gantry rotation path rather than a straight line. This curved arrangement allows the collimator to better withstand centrifugal forces by distributing mechanical stresses along the arc, while maintaining the required large area coverage for the detector array.
Solution Approach 2:
The collimator structure incorporates reinforcing elements and support beams positioned to counteract the centrifugal forces generated during gantry rotation. These structural reinforcements are strategically placed to provide mechanical support against the outward forces, preventing deflection and maintaining alignment.
3Ease of operation
If the collimator is deflected under centrifugal loads, then the ease of operation is improved by allowing some flexibility, but the measurement precision deteriorates due to de-focusing
Solution Approach 1:
The collimator modules are pre-aligned and mechanically secured to the gantry structure before rotation begins. The modular design includes precision mounting features that ensure correct positioning and orientation of each module, establishing the proper geometric configuration for accurate X-ray collimation before the system enters operation.
Solution Approach 2:
The collimator structure serves multiple functions: it provides radiation absorption through high-density walls, mechanical support against centrifugal forces through reinforcing elements, and precise X-ray beam collimation through controlled air gaps. This multi-functionality allows the same structure to address both operational flexibility and measurement precision requirements.
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 solution effectively minimizes deflection of the collimator under centrifugal loads, maintaining focused radiation and improving image accuracy by preventing scattered radiation from reaching the detector, thus reducing false positives and enhancing detection precision.
Implementation Method 1
When such an array is subjected to centrifugal loads, each module is deflected by an unacceptable amount
Implementation Method 2
The reinforcing layer includes a substantially X-ray transparent material
Data Source
AI summary
A method for fabricating a collimator assembly is provided. The collimator assembly includes a first collimator grid having a first surface and an opposing second surface, wherein the first collimator grid defines a plurality of cells. Each cell of the plurality of cells is aligned in a first direction and extends between the first surface and the second surface. The method includes coupling a reinforcing layer to the first collimator grid such that the reinforcing layer extends substantially perpendicular to the first direction.