Radiation Detector Collimator Wedge Retention
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Solution Overview
Problem
In radiation detection apparatuses, the collimator, made of heavy metal, experiences centrifugal force during rotation and thermal expansion mismatch with detector elements, leading to adhesive failure and potential collimator detachment.
Innovation Solution
A radiation detection apparatus design featuring a collimator with tapered outer end surfaces and a pair of blocks with tapered inner end surfaces, creating a wedge effect to securely sandwich the collimator, preventing detachment even if adhesive delamination occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the collimator is adhesively bonded to the detector element array, then the assembly is simple and easy to manufacture, but the adhesive layer may fail due to centrifugal force and thermal expansion mismatch during rotation and temperature changes
Solution Approach 1:
The collimator is divided into multiple collimator modules that can be independently assembled to the detector element array, allowing for better distribution of mechanical and thermal stresses across multiple bonding interfaces rather than a single large adhesive joint
Solution Approach 2:
A recess is formed in the detector element array at the position where the collimator will be bonded, creating a mechanical interlock that provides beforehand cushioning against centrifugal force and thermal expansion, preventing the collimator from detaching even if adhesive fails
2Reliability
If the collimator is made of heavy metal such as tungsten, then the collimator has sufficient density for radiation shielding and detection, but it experiences large centrifugal force during rotation causing adhesive failure
Solution Approach 1:
The collimator is segmented into multiple modules, reducing the moment of inertia and centrifugal force on each individual module while maintaining sufficient heavy metal density for radiation shielding in each segment
Solution Approach 2:
The recess in the detector element array provides beforehand cushioning against centrifugal force, creating a mechanical stop that prevents the heavy metal collimator from detaching during rotation even though it experiences large centrifugal force
3Ease of manufacture
If the collimator and detector elements are bonded with adhesive, then the bonding process is simple, but thermal expansion mismatch causes stress in the adhesive layer leading to collimator detachment
Solution Approach 1:
The collimator is segmented into multiple modules, distributing thermal expansion stress across multiple bonding interfaces and reducing the stress concentration in any single adhesive layer
Solution Approach 2:
The recess in the detector element array provides beforehand cushioning against thermal expansion stress, creating a mechanical accommodation space that absorbs dimensional changes and prevents adhesive layer failure due to thermal mismatch
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 wedge effect ensures the collimator remains securely attached, preventing falling off and reducing stress due to thermal expansion, enhancing the apparatus's stability and reliability.
Implementation Method 1
a collimator adhesively bonded to a side of said detector element array on which the radiation impinges, and having outer end surfaces on both sides in the cone-angle direction tapered to align with a direction of emission from a radiation source; and a pair of blocks disposed to sandwich said collimator in the cone-angle direction, and having inner end surfaces on both sides in the cone-angle direction tapered to align with said direction of emission
Implementation Method 2
the collimator and detector elements have significantly different coefficients of linear expansion, so that their adhesive layer suffers from stress due to a change in ambient temperature
Implementation Method 3
The collimator, however, is constructed of heavy metal such as tungsten, and therefore, it experiences a large centrifugal force by a rotation during a scan
Data Source
AI summary
A collimator, which is adhesively bonded to a detector element array, is prevented from falling off from the radiation detection apparatus even in case that a failure of the adhesive joint occurs in the collimator. There is provided a radiation detection apparatus comprising: a detector element array in which a plurality of detector elements are arranged substantially in a fan-angle direction and in a cone-angle direction of a radiation; a collimator adhesively bonded to a side of the detector element array on which the radiation impinges, and having outer end surfaces on both sides in the slice direction tapered to align with a direction of emission from a radiation source; and a pair of blocks disposed to sandwich the collimator in the cone-angle direction, and having inner end surfaces on both sides in the cone-angle direction tapered to align with the direction of emission.