Asymmetric Gamma Detector Array for Pipeline Scanning
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Solution Overview
Problem
Existing gamma radiation scanning apparatuses for structures, particularly subsea pipelines, face limitations in resolution due to space constraints and detector size, leading to reduced signal-to-noise ratio and increased scan time, with symmetric detector arrays duplicating information and not effectively improving resolution.
Innovation Solution
The apparatus employs an asymmetric arrangement of detectors with offset positions, allowing additional detection paths during a single 360° scan, effectively reducing detector spacing and improving resolution without increasing scan time or detector size, by positioning first and second detectors at angles A + n·S and A + (n+f)S respectively, where 0<f<1, to provide unique information between paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of detectors is increased to improve resolution, then measurement precision is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent applies asymmetry by offsetting the second array of detectors relative to the first array by a fraction f of the detector spacing S. This asymmetric arrangement ensures that the detection paths from the two arrays are not redundant, allowing effective utilization of all detectors to improve image resolution without simply doubling the number of detectors in a symmetric configuration.
2Device complexity
If detector size is reduced to accommodate more detectors in limited space, then device complexity is reduced, but measurement precision deteriorates due to reduced signal-to-noise ratio
Solution Approach 1:
The patent transitions from a single array of detectors to two arrays arranged in two dimensions, with the second array offset from the first. This dimensional expansion allows the system to collect radiation data from multiple angular perspectives simultaneously, improving measurement precision without requiring each individual detector to be larger.
3Measurement precision
If detectors are closely spaced to improve resolution, then measurement precision is improved, but device complexity increases due to space constraints and pressure requirements
Solution Approach 1:
The patent segments the detector system into two distinct arrays, each with its own spacing configuration. The first array has detectors spaced at intervals of S, while the second array has detectors spaced at intervals of fS relative to the first array. This segmentation allows the system to achieve effective finer spacing for improved resolution while maintaining manageable individual detector sizes and spacing.
4Device complexity
If symmetric detector array is used, then device complexity is reduced, but measurement precision is limited due to information duplication
Solution Approach 1:
The patent deliberately introduces asymmetry by offsetting the second detector array by a fraction f of the spacing S relative to the first array. This asymmetric configuration ensures that each detector in both arrays samples unique radiation paths through the structure, eliminating the information duplication that occurs in symmetric arrangements and thereby improving measurement precision.
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 resolution without reducing detector size or increasing scan time, simplifying the apparatus and reducing calibration errors, while maintaining a high count rate and efficient scanning.
Implementation Method 1
Gamma rays entering the scintillation crystal interact with the scintillating material to produce photons in the visible and/or ultraviolet region
Implementation Method 2
These scintillation photons are detected using a photodetector, for example a photomultiplier tube, which outputs an electrical pulse
Implementation Method 3
Counting the number gamma photons transmitted from the source to the detectors, through the structure being scanned, enables differences in the density of different parts of the structure to be detected
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
An apparatus (10), collimator and method for scanning a structure (100) to detect differences in density between different parts of the structure (100) is described. The apparatus (10) comprises a source of gamma radiation (20). A plurality of first detectors (30) are arranged to detect radiation emitted by the source (20) along a plurality of respective first paths (32). A plurality of second detectors (40) are arranged to detect radiation emitted by the source (20) along a plurality of respective second paths (42). Each first and second path (32, 42) is substantially aligned with a respective radius of a circle centred on the source (20), and an angular separation between at least two neighbouring first paths is S. The first and second detectors (30, 40) and the source (20) are arranged for rotation in a fixed relationship with respect to each other, about an axis of rotation (60) located between the source (20) and detectors (30, 40), wherein the axis of rotation (60) is substantially orthogonal to said circle. At least one first path (32) is located on a first side of a plane (70) containing the source (20) and said axis of rotation (50), at an angle of A + n S to the plane (70), where A is an arbitrary offset angle and n is an integer, and at least one second path (42) is located on a second side of the plane (70), at an angle of A + (n+f) S to the plane (70), where 0<f<1. An asymmetric collimator block (50) is provided for directing the gamma radiation from the gamma source (20) to the plurality of detectors (30, 40).