Asymmetric Tomosynthesis Angle Interval for MLO View Artifact Reduction
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Solution Overview
Problem
Conventional breast tomosynthesis methods using symmetric recording angle intervals result in artifacts due to asymmetrical breast positioning, particularly in MLO views, leading to reduced image quality and incomplete tissue detection.
Innovation Solution
Employing an asymmetrical recording angle interval relative to the central position, with a larger angular range on the side from which the breast projects into the interspace between the compression plate and X-ray detector, and adjusting the X-ray dose based on tissue distribution and size, to optimize tissue detection and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetrical recording angle interval is used around the central position, then the recording process is simple and standardized, but tissue regions are cut off in MLO views and artifacts are generated reducing image quality
Solution Approach 1:
The patent applies asymmetry by shifting the recording angle interval asymmetrically relative to the central position. Instead of recording symmetrically from -25° to +25°, the interval is shifted to cover the range from approximately -15° to +35° for MLO views. This asymmetric positioning ensures that the breast tissue, which projects into the interspace from one side, is fully captured without being cut off, while minimizing exposure of the radiation field to tissue-free regions, thereby eliminating artifacts and improving image quality.
2Area of stationary object
If the X-ray source is moved to the side opposite the breast projection, then the radiation field covers more tissue-free region, but increasing proportion of projecting tissue is not detected
Solution Approach 1:
The patent changes the parameter of recording angle interval positioning from symmetric to asymmetric. By shifting the angle interval toward the side from which the breast projects into the interspace, the system optimizes the balance between covering tissue-free regions and detecting projecting tissue. This parameter change ensures that the radiation field predominantly covers tissue-containing regions while minimizing exposure to tissue-free areas, thereby maximizing tissue detection completeness.
3Measurement precision
If the recording angle interval is shifted asymmetrically, then tissue detection is optimized and artifacts are reduced, but the recording process becomes more complex
Solution Approach 1:
The patent employs feedback by using a prior recording (pre-shot) to determine the asymmetry variable and breast size. The control device automatically evaluates the pre-shot image and uses this information to calculate the appropriate asymmetric recording angle interval and X-ray dose settings. This feedback mechanism automates the complex asymmetric recording process, eliminating the need for manual configuration and reducing operational complexity while maintaining optimized image quality.
4Ease of manufacture
If uniform X-ray dose is applied across all projection angles, then the exposure process is simple, but tissue distribution asymmetry is not accounted for leading to suboptimal image quality
Solution Approach 1:
The patent applies local quality by varying the X-ray dose according to the local tissue distribution. The control device calculates different X-ray doses for different projection angles based on the asymmetry variable and breast size determined from the pre-shot. Regions with higher tissue density or greater tissue path length receive higher doses, while tissue-free regions receive lower doses. This localized dose adjustment optimizes tissue detection quality while minimizing unnecessary radiation exposure.
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 enhances image quality by minimizing undetected tissue regions and artifacts, allowing for higher-quality tomosynthesis data sets with improved detection of breast and axillary tissue, while also optimizing the X-ray dose for patient safety.
Implementation Method 1
an X-ray device which, as known in principle, contains an X-ray source and an X-ray detector
Data Source
AI summary
A method records a tomosynthesis data set of a breast of a patient with an X-ray device. The device contains an X-ray detector for the support of the breast, a compression plate for the breast and being parallel to the X-ray detector, and an X-ray source, which is movable in a basic angle interval around a central position, in which the midperpendicular of the detector area corresponds to the central ray of the X-ray source. The tomosynthesis data set is reconstructed from projection images recorded at different projection angles over a recording interval. A recording angle interval that is asymmetrical relative to the central position is used in the case of an asymmetrically positioned breast, in particular for an MLO view.