Radiographic Phantom for Deformation Verification
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Solution Overview
Problem
Current methods for verifying the accuracy of deformation algorithms in radiation treatment are limited by their inability to effectively measure tangential deformation errors and represent the deformation of the entire volume, leading to inconsistencies and noise issues.
Innovation Solution
A two-dimensional radiographic phantom system using transparent plates and non-radiopaque markers allows for the measurement of complete deformation fields without perturbing the deformation algorithms, enabling direct comparison of measured and predicted deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contour comparison methods are used to verify deformation algorithms, then surface deformation can be measured, but tangential deformation errors cannot be detected and internal point deformation accuracy cannot be determined
Solution Approach 1:
The patent transitions from two-dimensional contour comparison to three-dimensional volumetric verification using phantom objects with embedded markers throughout the volume. This dimensional expansion enables detection of tangential errors and internal deformation that were invisible in surface-only methods.
Solution Approach 2:
The patent introduces radiopaque markers as intermediary objects embedded within the phantom volume. These markers serve as mediators that make internal deformation visible to imaging systems, allowing precise measurement of three-dimensional displacement fields without directly observing the deformation itself.
2Measurement precision
If visible landmarks or radiopaque markers are used for landmark tracking, then deformation can be measured at specific points, but prominent landmarks may not be representative of overall volume deformation and processing remnants can affect algorithm predictions
Solution Approach 1:
The patent segments the phantom volume into numerous small regions, each containing radiopaque markers. This segmentation distributes measurement points throughout the entire volume, ensuring that the collected deformation data represents overall volume deformation rather than being biased toward prominent surface landmarks.
Solution Approach 2:
The patent changes the parameter of marker distribution from sparse prominent landmarks to dense uniformly distributed markers throughout the volume. This parameter change ensures statistical representativeness of the deformation measurements across the entire phantom volume.
3Measurement precision
If deformations are applied digitally to images for verification, then direct comparison with algorithm predictions is possible, but noise variations in the original image affect the determined deformation and additional noise does not represent discrepancies between distinct images
Solution Approach 1:
The patent creates physical copies (phantoms) that replicate the deformation characteristics of interest, rather than working with digital copies of images. The phantoms are imaged under identical conditions to generate comparable images, eliminating noise-related artifacts that plague digital deformation application methods.
4Ease of operation
If traditional verification methods are used, then some deformation aspects can be tested, but the methods have shortcomings including inability to measure complete deformation fields and reduce anatomy to a measurable system
Solution Approach 1:
The patent reduces three-dimensional anatomical deformation verification to a two-dimensional measurable system by using planar phantoms with marker arrays. This dimensional reduction maintains essential deformation characteristics while enabling precise optical measurement without the complexity of full three-dimensional marker tracking.
Data Source
AI summary
There is provided a radiographic phantom for inter alia mimicking specific anatomical parts in a computerized tomography scan. Methods are provided for a variety of purposes including detecting a difference between a measured optical deformation of a radiographic phantom pair and a theoretical deformation of the radiographic phantom pair.