Flat-Panel X-Ray Detector Lag Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
X-ray apparatuses with amorphous silicon detectors suffer from lag or persistence issues due to trapped charges, which cause image smearing and errors in diagnosis, especially in vascular applications where image acquisition rates are high and integration times are variable, making existing error correction methods inadequate.
Innovation Solution
A method that synchronizes the flat-panel detector's read and integration phases with a clock signal to measure and correct latent charges in real-time, using an algorithm to eliminate lag images directly from exposure images without a predefined correction model, and applies noise-reducing algorithms to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a predefined error correction model is used to correct latent charges, then correction results are optimal when acquisition mode and integration time are constant, but the correction becomes inadequate when acquisition modes change or integration times vary
Solution Approach 1:
The patent transitions from a static predefined correction model to a dynamic real-time correction system. The correction algorithm continuously adapts to current acquisition conditions by measuring actual lag charges during each integration phase and applying context-specific correction factors, enabling accurate correction across varying acquisition modes and integration times.
Solution Approach 2:
The patent changes the correction approach from using fixed parameters in a predefined model to dynamically adjusting correction parameters based on real-time measurements. The system modifies correction factors according to actual lag charge levels, acquisition mode, and integration time duration, making the correction adaptive to changing conditions.
2Productivity
If multiple radiology images are acquired per second in vascular applications, then productivity increases, but lag charges from previous images smear subsequent images causing diagnostic errors
Solution Approach 1:
The patent applies preliminary correction action by measuring lag charges at the beginning of each integration phase and applying the appropriate correction factor before the actual exposure image is fully acquired. This preliminary measurement and correction approach prevents lag smearing from affecting the final image quality even at high acquisition rates.
Solution Approach 2:
The patent implements a feedback mechanism where lag charges are continuously measured during integration phases and used to adjust correction factors for subsequent images. This closed-loop feedback system ensures that correction accuracy is maintained across multiple images acquired per second by constantly adapting to the current lag state of the detector.
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 significantly reduces lag effects, enabling accurate real-time correction of latent charges across varying acquisition modes and integration times, maintaining image quality without errors caused by lag images.
Implementation Method 1
The photodiodes of the detector plate create a charge whenever its different points are stimulated by the residual rays
Implementation Method 2
The importance of the lag image in the X-ray detectors decreases with time as the traps get emptied by thermal effect
Data Source
AI summary
A method for the correction of lag charges in a flat-panel X-ray detector makes it possible, for each integration phase of the detector, to determine an initial read phase situated just before said integration phase. The method of the invention enables the measurement, for each integration phase, of the charges present in the detector at the corresponding initial read phase, the production of a lag image from the latent charges measured in the initial read phase and the subtraction of the lag image from the raw image. The use of the measurement of charges enables the direct correction of the lag image in the acquisition without the use of a correction module as in the prior art.