Computed Tomography Correction for Scattered Radiation
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Solution Overview
Problem
Computed tomography methods face challenges in accurately determining dimensional features due to physical effects like scattered radiation, beam hardening, and sensor errors, which lead to measurement deviations and artifacts in imaging quality.
Innovation Solution
The method involves simulating physical effects to generate correction data, which are then used to correct measured data, utilizing a comparison between simulation data with and without physical effects to refine voxel volume and surface point calculations, often referencing ideal models like CAD data for accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction data are determined by comparing simulation data with and without physical effects, then measurement precision is improved, but device complexity increases due to the need for multiple simulations and data processing
Solution Approach 1:
The patent applies preliminary action by performing simulations of physical effects (scattered radiation, beam hardening, cone beam artifacts) before the actual measurement correction. Correction data are determined by comparing simulation results with and without physical effects, and this correction data is then applied to measured data. This preliminary preparation of correction data through simulation eliminates the need for complex real-time correction during measurement, thereby improving measurement precision while managing device complexity.
2Measurement precision
If correction is made later in the processing chain, then measurement precision is improved by recording deviations more completely, but loss of time increases due to extended processing
Solution Approach 1:
The patent resolves this contradiction by performing the computationally intensive simulation and correction data determination in advance, before actual measurements are processed. The correction data obtained from simulations are stored and then quickly applied to measured data in a final correction step. This approach allows complete deviation recording for high precision while minimizing time loss during actual measurement processing.
3Device complexity
If analytical correction methods are used for physical effects, then device complexity is reduced, but measurement precision deteriorates due to inability to account for scattered radiation and other random influences
Solution Approach 1:
The patent applies the copying principle by creating simulated copies of the measurement process that include physical effects. Instead of using simple analytical corrections, the patent generates synthetic radiographs through simulation that replicate the actual measurement conditions including scattered radiation, beam hardening, and cone beam artifacts. These simulated copies are then compared with actual measurements to determine accurate correction data, thereby achieving high measurement precision without excessive device complexity.
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 effectively reduces inaccuracies in computed tomography measurements by correcting for physical effects as late as possible in the processing chain, ensuring more accurate dimensional determinations and surface point calculations.
Implementation Method 1
Due to the interaction of the X-ray radiation, which is mostly used in computed tomography, with the object to be measured, there are physical effects that negatively influence the imaging quality
Implementation Method 2
Among other things, influences from beam hardening, scattered radiation and afterglow effects are known
Implementation Method 3
Among other things, influences from beam hardening, scattered radiation and afterglow effects are known
Data Source
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AI summary
The invention relates to a computer tomography method for dimensionally determining features of a measurement object, through which a radiation is passed in several rotational positions, wherein measurement deviations due to the scattered radiation or other physical effects are corrected. In order to avoid or correct measurement deviations in particular due to scattered radiation or due to other physical effects such as beam hardening, afterglow effects, or the like, it is proposed, for example, that the radiographs are corrected by means of synthetic radiographs, calculated from a geometry that is determined in advance or know or from a model of the geometry, wherein the geometry or the model of the geometry at least roughly corresponds to the measurement object.