Variable Thickness Filter for Radiation Imaging Calibration
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Solution Overview
Problem
Current normalization filters for high energy imaging systems, such as step wedges, add bulk, weight, and expense due to their solid construction and limited flexibility, requiring additional shielding and encroaching on imaging lanes, while offering no flexibility in thickness selection.
Innovation Solution
A variable thickness filter system using multiple movable plates that can be positioned to attenuate radiation in increments, allowing for flexible calibration of radiation imaging devices, including a collimator subassembly with a beam flattening filter, primary collimator, and a variable thickness normalization filter with actuators to adjust plate thickness and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a solid step wedge filter is used for calibration, then the imaging system can be calibrated, but the system size and weight increase
Solution Approach 1:
The solid step wedge filter is segmented into multiple individual plates of different thicknesses. These plates can be selectively positioned in the beam path independently, replacing the single monolithic step wedge structure. This segmentation reduces the overall weight while maintaining calibration functionality across the full range of thicknesses.
Solution Approach 2:
The filter system transitions from a static solid step wedge to a dynamic configuration where individual plates can be moved in and out of the beam path. This dynamic arrangement allows the system to achieve variable attenuation levels without requiring a solid structure that accommodates all thicknesses simultaneously, thereby reducing weight.
2Measurement precision
If a solid step wedge filter is used for calibration, then the imaging system can be calibrated, but the system bulk and size increase
Solution Approach 1:
The filter is divided into multiple thin plates that can be stacked or positioned separately. This segmentation allows the system to achieve the same calibration range with significantly reduced volume compared to a solid step wedge that must accommodate all thicknesses in a single block.
Solution Approach 2:
Instead of achieving variable thickness through a single dimension (height of solid blocks), the system uses multiple thin plates arranged in a stackable configuration. This transforms the problem from a 1D height variation to a 3D stacking arrangement, reducing the volume occupied by the filter assembly.
3Measurement precision
If a solid step wedge filter is used for calibration, then the imaging system can be calibrated, but additional shielding is required
Solution Approach 1:
By segmenting the filter into individual plates, the system reduces the total amount of attenuating material required. Each plate can be optimized for its specific thickness requirement, eliminating the need for excessive shielding material that would be required in a solid step wedge design to achieve the same calibration range.
4Adaptability or versatility
If a solid step wedge filter is used for calibration, then the imaging system can be calibrated, but flexibility in thickness selection is limited
Solution Approach 1:
The solid step wedge is divided into multiple independent plates, each representing a discrete thickness option. This segmentation transforms the filter from a fixed structure with predetermined steps to a modular system where plates can be selectively combined and positioned, dramatically increasing flexibility in thickness selection.
Solution Approach 2:
The filter system becomes dynamic with movable plates that can be positioned in or out of the beam path as needed. This dynamic configuration allows the system to adapt to different calibration requirements and imaging scenarios, providing flexibility that a static solid step wedge cannot offer.
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 reduces the overall size and weight of the radiation source configuration, allowing for more compact shielding and increased flexibility in imaging capabilities, enabling accurate calibration and imaging without the need for additional components, thus enhancing imaging quality and efficiency.
Implementation Method 1
a variable thickness filter consisting of multiple movable plates for attenuating radiation
Data Source
AI summary
A system and method for calibrating a radiation imaging system include a dual use variable thickness radiation filter having a slit in one part thereof such that in a first position a radiation beam passing through is not attenuated and in a second position the radiation beam is attenuated according to the total filter thickness in the path of the radiation beam. The filter may be formed of multiple movable plates or a single piece of stepped high density material.