Automatic Exposure Control with Weighted Dose for Dense Anatomy
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Solution Overview
Problem
Existing automatic exposure control (AEC) systems in x-ray imaging struggle to maintain high image quality when patients are not perfectly positioned, particularly in the presence of dense materials like bone, leading to premature termination of radiation due to uneven dose distribution across sub-chambers.
Innovation Solution
A method using a solid-state AEC with multiple sub-chambers that adjusts weights based on the time-course and gradient of accumulated dose to balance the influence of different materials, ensuring a weighted overall applied dose meets a predetermined cut-off, thereby optimizing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the accumulated dose of all sub-chambers is summed up without weighting, then the cut-off dose is reached faster and radiation exposure is reduced, but image quality deteriorates in regions with dense materials like bone
Solution Approach 1:
The patent applies different weighting factors to different sub-chambers based on their local characteristics (attenuation rate, dose accumulation speed). Sub-chambers behind dense materials receive higher weights while those behind less attenuating materials receive lower weights, ensuring each region contributes appropriately to the overall dose assessment without compromising image quality in high-attenuation areas
Solution Approach 2:
The patent dynamically changes the weighting parameters of sub-chambers based on their measured dose accumulation characteristics. By adjusting these weights according to the specific attenuation properties of materials in each sub-chamber's field of view, the system optimizes both radiation safety and image quality for different anatomical regions
2Measurement precision
If all sub-chambers are used to measure accumulated dose, then dose monitoring coverage is improved, but positioning precision requirements increase
Solution Approach 1:
The system automatically determines the attenuation characteristics and assigns appropriate weights to each sub-chamber without requiring manual positioning adjustments. The AEC system self-adjusts by measuring the dose accumulation rate in each sub-chamber and adapting the weighting scheme, eliminating the need for precise manual patient positioning
Solution Approach 2:
The weighting scheme is dynamic rather than static, automatically adapting to the actual patient positioning and anatomy. The system continuously monitors dose accumulation in each sub-chamber and adjusts weights in real-time, making the system robust to positioning variations while maintaining accurate dose monitoring coverage
3Ease of operation
If equal weights are assigned to all sub-chambers, then the system is simpler to operate, but dose distribution uniformity deteriorates in the presence of dense materials
Solution Approach 1:
The system uses feedback from the measured dose accumulation rates in each sub-chamber to automatically determine appropriate weighting factors. By monitoring how quickly each sub-chamber accumulates dose and adjusting weights accordingly, the system achieves uniform dose distribution without manual intervention or complex pre-programming
Solution Approach 2:
The AEC system automatically determines and assigns optimal weights to each sub-chamber based on their measured performance characteristics. This self-configuring capability eliminates the need for manual weight assignment while ensuring optimal dose distribution uniformity across all regions including those with dense materials
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
Ensures high image quality in regions with dense materials by adjusting weights to account for varying material attenuation, preventing premature radiation termination and reducing the need for re-imaging, thus saving time and resources while minimizing patient dose.
Implementation Method 1
The source is configured for emitting radiation, in particular x-rays. The detector is configured for detecting the radiation which passed the patient.
Implementation Method 2
dense materials like e.g., bone attenuate the radiation more than e.g., tissue
Data Source
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AI summary
The invention relates to a computer-implemented method for dose control with an automatic exposure control (1). The method comprises steps of receiving (REC-1) a first time-course (TC1), receiving (REC-2) a second time-course (TC2), and of receiving (REC-3) a cut-off dose (COD). The method comprises steps of determining (DET-1) a first weight (W1), determining (DET-2) a second weight (W2), multiplying (MULT-1) a latest value of the first time-course with the first weight (W1), wherein a first weighted accumulated dose is determined and of multiplying (MULT-2) a latest value of the second time-course with the second weight (W2), wherein a second weighted accumulated dose is determined. The method comprises steps of adding (ADD) the first and the second weighted accumulated dose, wherein a weighted overall applied dose (WOAD) is determined, comparing (COMP) the weighted overall applied dose (WOAD) with the cut-off dose (COD), and providing (PROV) the result of the comparison.