Digital Radiography Detector Readout Noise Compensation
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Solution Overview
Problem
Existing digital radiography (DR) detectors face challenges in maintaining image quality due to extraneous signals from low-frequency magnetic fields and parasitic capacitance, which degrade image integrity during the readout process, especially when concurrent with x-ray exposure.
Innovation Solution
The method involves obtaining and processing various frames such as dark, leakage, and image data frames to correct for noise and artifacts, using a combination of dark correction, noise correction, and null row readouts to isolate and subtract extraneous signals, thereby enhancing image quality without the need for invasive external hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If image readout is performed concurrently with x-ray exposure to improve productivity, then image acquisition speed is improved, but extraneous signals from low-frequency magnetic fields and parasitic capacitance degrade image quality
Solution Approach 1:
The patent segments the image readout process into multiple phases: a first readout phase during x-ray exposure that captures both image signals and extraneous signals, and a second readout phase after exposure that captures primarily extraneous signals. By separating the measurement of desired signals from unwanted signals into distinct temporal segments, the system can later subtract the extraneous component from the combined measurement, thereby maintaining high acquisition speed while ensuring image quality.
Solution Approach 2:
The patent performs preliminary measurement of extraneous signals during the x-ray exposure period itself, rather than waiting until after exposure. By capturing the extraneous signal component concurrently with the image signal and then subtracting it in post-processing, the system eliminates the need to wait for exposure completion before beginning readout, thus maintaining high productivity while ensuring reliability.
2Measurement precision
If invasive external hardware is used to detect x-ray exposure events to improve measurement precision, then exposure detection accuracy is improved, but system complexity and delays increase
Solution Approach 1:
The patent enables the DR detector system to self-detect x-ray exposure events by monitoring its own output signals for characteristic patterns that indicate exposure. The system uses software-based analysis of the readout data to identify exposure events, eliminating the need for separate external detection hardware. This self-service approach maintains measurement precision while reducing system complexity and avoiding the delays associated with external hardware communication.
Solution Approach 2:
The patent replaces potential mechanical or external hardware-based exposure detection systems with a software-based detection method that analyzes electrical signals already present in the detector system. By substituting physical detection hardware with computational analysis of existing signals, the system achieves accurate exposure detection without adding device complexity or introducing communication delays.
3Reliability
If multiple correction frames are obtained and processed to remove extraneous signals to improve image quality, then image quality is improved, but processing time and complexity increase
Solution Approach 1:
The patent implements a periodic readout scheme where the detector alternates between reading image signals during exposure and reading extraneous signals between exposures or during specific time windows. This periodic structure allows the system to efficiently capture both types of data in an organized manner that minimizes processing overhead, enabling comprehensive signal correction while maintaining reasonable processing time.
Solution Approach 2:
The patent performs preliminary organization and initial processing of correction frames during the data acquisition phase itself. By pre-organizing the multiple frames into categories (image frames, dark frames, flat-field frames, extraneous signal frames) and performing initial corrections during or immediately after acquisition, the system reduces the computational burden for final image reconstruction, thereby improving image quality without excessive processing time delays.
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 removes image artifacts and improves radiographic image quality by asynchronously detecting and compensating for extraneous signals, ensuring high-quality image acquisition during x-ray exposure without external hardware intervention.
Implementation Method 1
Each pixel generally includes a photosensor and a switching element... hydrogenated amorphous silicon (a-Si:H) is commonly used to form the photodiode
Implementation Method 2
a backplane includes an array of thin-film transistor (TFT) switches... hydrogenated amorphous silicon (a-Si:H) is commonly used to form the photodiode and the thin-film transistor switch
Data Source
AI summary
A radiographic imaging system and digital detector detect extraneous signals during DR detector image readout and compensate or remove extraneous signal artifacts from radiographic images. Novel capture and post processing procedures prevent undesirable noise artifacts from appearing in final radiographic images.