Computed Tomography Collimator Shield Slit Scanning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial computed tomography systems face challenges in reducing scatter, particularly in digital detector array (DDA) systems, which results in unusable data due to cross-scatter, and existing solutions like algorithmic compensation have limitations, especially with the increasing complexity of additively manufactured parts with intricate internal geometries.
Innovation Solution
A computed tomography system that includes a collimator shield with a slit between the object holder and the detector, allowing only a portion of the cone of illumination to reach the photodetector array, and moving the slit across the array to acquire two-dimensional images, reducing scatter and enabling faster scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If digital detector array (DDA) systems use a cone shaped illumination source with a two-dimensional array of detectors to record a single exposure of the whole part at each rotational position, then scan time is reduced and productivity is improved, but cross-scatter increases and measurement precision deteriorates
Solution Approach 1:
The patent divides the continuous cone-shaped illumination into discrete segments by introducing a collimator with a narrow slit that allows only specific portions of the x-ray cone to reach the detector at any given time. This segmentation of the illumination path enables the system to maintain fast scanning while reducing cross-scatter by limiting the angular spread of x-rays reaching the detector
Solution Approach 2:
The collimator shield acts as an intermediary element positioned between the DDA system components (illumination source and detector array). This intermediary device modifies the x-ray path by blocking scattered radiation while allowing primary radiation through the slit, thereby improving data quality without sacrificing the fast scan capability of the DDA system
2Measurement precision
If algorithmic compensation is used to resolve DDA system data, then measurement precision is improved, but device complexity increases and reliability may still be insufficient
Solution Approach 1:
The patent converts the harmful cross-scatter effect into a manageable condition by using the collimator's slit to define a controlled beam path. Instead of relying on complex algorithms to compensate for scattered radiation, the physical collimator structure pre-filters the radiation before it reaches the detector, turning the scatter problem into a solved condition through physical means
3Measurement precision
If linear detector array (LDA) systems use a planar illumination source with a linear detector array sensor to record thousands of exposures at each level, then scatter is reduced and measurement precision is improved, but scan time increases and productivity deteriorates
Solution Approach 1:
The patent merges the advantages of both LDA and DDA systems by combining the collimator-based scatter reduction technique (from LDA) with the two-dimensional detector array and cone-shaped illumination (from DDA). This hybrid approach achieves the scatter reduction of LDA systems while maintaining the fast single-rotation scanning capability of DDA systems
Solution Approach 2:
The invention transitions from the traditional one-dimensional linear detector array to a two-dimensional detector array, adding a spatial dimension to the detection capability. This dimensional change allows simultaneous capture of multiple projection angles while the collimator maintains precision by controlling the x-ray path in the angular dimension
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 system achieves reduced scattering and faster scan times, combining the speed of DDA systems with the reduced scatter of LDA systems, producing reliable and usable data for complex internal geometries without requiring new software or acquisition algorithms.
Implementation Method 1
A collimator shield is positioned between the rotational platform and the photodetector array. The collimator shield defines a slit therethrough for exposure of the photodetector array to the cone of illumination only through the slit of the collimator shield.
Implementation Method 2
A two-dimensional photodetector array faces the illuminator, opposite the illuminator from the rotational platform for imaging an object on the rotational platform with illumination from the illuminator.
Data Source
Figure 1
Figure 2
AI summary
A method of computed tomography includes illuminating an object (108) with a cone of illumination (104), such as X-ray, wherein the object (108) is between a source (102) of the cone of illumination (104) and a two-dimensional photo-detector array (110). The method includes shielding the photodetector array (110) from the collimator shield (112) that includes a slit (114) defined therethrough and moving the slit (114) of the collimator shield (112) across the photodetector array (110) in a direction perpendicular to the slit (114) to expose the photodetector array (110) to the cone of illumination (104) through the slit (114) as the slit (114) scans across the photodetector array (110) to acquire a two-dimensional image of the object (108). The method includes rotating the object (108) to a new rotational position and repeating movement of the slit (114) to expose the photodetector (110) and rotating the object (108) along the axis until the object (108) has been imaged from multiple rotational positions to form a three-dimensional model of the object (108).