Adaptive Averaging for Medical X-Ray Image Noise Reduction
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Solution Overview
Problem
Existing medical X-ray examination methods face a trade-off between image quality and X-ray dose, with statistical image noise limiting the maximum achievable image quality, especially in subtraction imaging where averaging reduces contrast and worsens noise.
Innovation Solution
A method for operating a medical X-ray device that records a mask image and subsequent X-ray images, determines the degree of deviation between them, and adjusts the averaging amount based on this deviation to generate a second subsequent image, which is then combined with the mask image to form an overall image, thereby reducing noise independently and maintaining contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plurality of X-ray images is recorded and averaged to form the mask image, then the noise in the mask image is reduced, but the noise in the second X-ray images remains significant and limits the overall image quality
Solution Approach 1:
The patent applies dynamics by adaptively adjusting the averaging amount based on the degree of deviation detected between the mask image and second X-ray images. The system dynamically modifies the averaging process - using higher averaging when deviation is low (indicating no movement) and reducing or eliminating averaging when deviation is high (indicating movement occurred). This dynamic adaptation allows the system to optimize noise reduction while preserving contrast in moving regions, resolving the contradiction between reducing noise and maintaining image quality.
Solution Approach 2:
The patent changes the parameter of averaging amount from a fixed value to a variable that depends on the degree of deviation. By calculating the deviation between corresponding pixels in the mask image and second X-ray images, the system adjusts the averaging amount parameter accordingly. This parameter change enables the system to apply different levels of noise reduction to different regions, improving overall image quality while avoiding contrast loss in regions with movement.
2Object-affected harmful factors
If averaging is applied to second X-ray images to reduce noise, then the noise is reduced, but the contrast of moving structures is reduced
Solution Approach 1:
The patent applies local quality by treating different regions of the image differently based on their deviation characteristics. Regions with low deviation (no movement) receive higher averaging to maximize noise reduction, while regions with high deviation (movement) receive lower or zero averaging to preserve contrast. This localized differentiation allows the system to reduce noise in static regions without sacrificing contrast in moving regions, effectively resolving the contradiction between noise reduction and contrast preservation.
Solution Approach 2:
The system dynamically determines the averaging amount for each pixel or region based on the calculated degree of deviation. This dynamic approach allows the averaging parameter to adapt to local image characteristics, applying noise reduction only where appropriate and preserving contrast where movement is detected. The dynamic adjustment of averaging amount based on real-time deviation analysis resolves the contradiction by making the noise reduction process selective rather than uniform.
3Object-affected harmful factors
If the X-ray dose is reduced to minimize patient exposure, then the radiation risk is reduced, but the signal-to-noise ratio deteriorates and image quality decreases
Solution Approach 1:
The patent applies preliminary action by recording multiple first X-ray images and averaging them to create a low-noise mask image before the actual examination phase. This pre-acquired mask image serves as a reference that can be subtracted from subsequent second X-ray images. By performing this noise reduction in advance, the system enables the use of lower doses during the actual examination while maintaining image quality through the subtraction process, effectively resolving the contradiction between radiation exposure and signal-to-noise ratio.
Solution Approach 2:
The system creates a copy of the anatomical structure in the form of a mask image that can be subtracted from subsequent images. This mask image, acquired with sufficient dose to ensure low noise, serves as a template that removes the need to repeatedly expose the patient at high doses. The subtraction process uses this copied reference to eliminate static anatomical structures, allowing low-dose acquisition of moving structures while maintaining image quality, thus resolving the radiation exposure versus signal-to-noise ratio contradiction.
Data Source
AI summary
Methods are provided for operating a medical X-ray device to improve the image quality of an X-ray examination. In one example, the method includes recording at least one first X-ray image of a body region as a mask image; providing a first subsequent image and recording a second X-ray image of the body region, wherein the second X-ray image represents the body region at a later recording time than the first subsequent image; determining a degree of deviation relating to a deviation between the first subsequent image and the second X-ray image; determining an averaging amount in dependence on the degree of deviation; generating a second subsequent image from the second X-ray image or from the first subsequent image together with the second X-ray image, wherein the averaging amount specifies the proportions in which the first subsequent image and the second X-ray image are mixed; and forming an overall image from the mask image and the second subsequent image.