Full Field Digital Mammography Dynamic Range Extension
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Solution Overview
Problem
Digital mammography using CMOS image sensors faces challenges in capturing high dynamic range images due to linear response and saturation issues, leading to limited contrast-to-noise ratio and underexposed clinically significant areas, particularly in dense breast tissue.
Innovation Solution
A method involving multiple exposures with varying parameters are combined using image recombination techniques to create a single Full Field Digital Mammogram with greater dynamic range, utilizing digital flat panel detectors with electron well density below 500 electrons per square micron to minimize readout noise and enhance image quality across the breast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CMOS image sensors with small well size are used, then electronic noise is reduced and contrast in dense breast tissue is enhanced, but the sensors saturate at low signal levels and cannot capture the full dynamic range of breast tissue
Solution Approach 1:
The breast imaging task is segmented into multiple exposures with different parameters (kVp, mAs, compression force) rather than attempting to capture the full dynamic range in a single exposure. Each exposure targets specific tissue density ranges, and the results are combined to form a complete high dynamic range image.
Solution Approach 2:
The imaging parameters (kVp, mAs, compression force) are systematically varied across multiple exposures to adapt the sensor's restricted dynamic range to different tissue densities. By changing these parameters, the same sensor can optimally image both dense and fatty tissue in separate exposures.
2Productivity
If a single exposure is used to capture the full dynamic range, then the imaging process is simple and quick, but clinically significant areas of dense tissue remain underexposed with poor contrast-to-noise ratio
Solution Approach 1:
Multiple exposures with optimized parameters are performed in rapid succession before the patient can move, capturing different tissue density ranges. This preliminary capture of multiple data sets is then combined computationally to achieve the desired contrast-to-noise ratio in dense tissue while maintaining overall imaging efficiency.
3Adaptability or versatility
If high-latitude film with non-linear response is used, then wide dynamic range images can be obtained with tolerance to overexposure, but digital flat panel detectors with linear response cannot achieve the same dynamic range
Solution Approach 1:
The non-linear chemical response of high-latitude film is replaced by a computational image processing system that combines multiple linear digital images. The film's dynamic range advantage is replicated through digital algorithms that weight and combine images from multiple exposures, eliminating the need for specialized film 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
This approach effectively increases the dynamic range of mammography images, improving visibility and contrast in both dense and less dense breast tissue areas, providing clinically useful images with reduced noise and enhanced contrast-to-noise ratio.
Implementation Method 1
A full-breast mammography image is thus obtained from x-ray signals of wide dynamic range, ranging from the maximum intensity of a nearly unobstructed x-ray beam transmitted through the skin boundary
Implementation Method 2
One type of flat panel detector employs CMOS image sensors, which have an inherently linear response with poor latitude
Data Source
AI summary
Methods of imaging a breast comprising acquiring a sequence of image data sets having differing exposure parameters; and combining the image data sets into a mammography image having greater dynamic range than the dynamic range of any single component image data set. Disclosed methods may further comprise determining an exposure parameter of one or more component image data sets prior to acquiring the sequence of image data sets. The step of determining an exposure parameter of one or more component image data sets may comprise determining exposure duration or an exposure irradiation level. Also disclosed are mammography apparatus and systems to obtain images according to the disclosed methods.