Curved Table Top Calibration Phantom for CT Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing table top calibration phantoms for CT scanners fail to capture various sources of bias and variation, such as spatially varying image warping and noise, which degrade the accuracy of scan measurements, and are costly to manufacture with precision objects at multiple radial positions.
Innovation Solution
A locally thin, curved table top calibration device with scanner-aligned cylinders and a diamond-shaped grid pattern, using less costly materials like high-density polystyrene and air, minimizes artifacts and effectively measures 3D point spread function, x-ray attenuation, and noise properties by exploiting radial symmetry in CT scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precision objects are placed at multiple radial positions in the calibration phantom, then measurement accuracy of spatially varying image warping and noise is improved, but manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent extracts only the essential calibration features needed for measuring spatially varying image warping and noise, eliminating unnecessary precision objects at multiple radial positions. The curved table top phantom with grid pattern and cylindrical reference objects provides the minimum necessary elements for accurate calibration without the complexity of multiple precision objects throughout the scan volume.
Solution Approach 2:
The patent uses cost-effective materials like high-density polystyrene and air instead of expensive precision-manufactured objects. The calibration phantom is designed to be simple and inexpensive while still providing accurate measurement capabilities for spatially varying image properties through its grid pattern and cylindrical reference objects.
2Measurement precision
If a comprehensive calibration phantom with multiple reference materials and objects is used, then image acquisition properties are measured accurately, but the phantom generates significant artifacts in patient scans
Solution Approach 1:
The patent applies local quality by placing reference materials and grid patterns only in the table top region where they are needed for calibration, rather than distributing them throughout the entire scan volume. This localized approach allows accurate measurement of image acquisition properties while minimizing the volume of material that could generate artifacts in patient scans.
Solution Approach 2:
The patent uses air as one of the reference materials in the calibration phantom. Air, being a gas with low density, generates minimal artifacts in CT scans compared to solid materials. The combination of high-density polystyrene and air creates contrast references that are effective for calibration while reducing overall artifact generation.
3Reliability
If traditional calibration phantoms are used without patient presence, then scanner performance is verified, but actual image quality of patient scans cannot be directly assessed
Solution Approach 1:
The patent designs the calibration phantom to serve multiple functions: it can be scanned alone to verify scanner performance and calibration, and it can also be scanned with patients to directly assess image quality in the actual scanning environment. The grid pattern and reference objects provide reference geometry that works for both phantom-only scans and patient scans, enabling the phantom to fulfill both calibration and quality assessment roles.
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 provides accurate and cost-effective measurement of image acquisition properties, reducing artifacts and maintaining high image quality, especially in clinical studies, by using cylindrical reference objects and a diamond grid pattern that aligns with the scanner's coordinate system, ensuring precise measurements without significant noise or deformation.
Implementation Method 1
x-ray attenuation measurement performance for a range of materials
Data Source
AI summary
A device for measuring image quality properties of an image acquisition device while the subject or object is being scanned contains an embedded grid pattern to measure spatial distortion along the length of the image acquisition table. The device also contains reference materials, which may run along the length of the device, for measuring fundamental imaging properties such as signal strength, noise, and resolution. Automated software can detect the device within an acquisition, measure its properties, and provide data and reports on the quality of the image acquisition.