Radiographic Detector Pipeline Cycle Segmentation
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Solution Overview
Problem
Pipeline-type signal processing circuits in radiographic image detectors introduce a time lag in dose detection, leading to delays in determining the start or end of x-ray radiation, which can result in overexposure and artifacts in x-ray images, especially when radiation time is short.
Innovation Solution
Implementing a radiographic image detector with a pipeline-type signal processing circuit that includes primary and secondary cycles, where at least one secondary cycle is conducted between two primary cycles, allowing for faster output of dose detection signals by using first and second signal holding devices to repeat signal input and output operations in cycles of shorter length than primary cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pipeline-type signal processing circuit is used for dose detection, then the signal processing capability is improved, but a time lag is introduced causing delay in detecting the start or end of radiation
Solution Approach 1:
The patent segments the signal processing cycles into primary cycles for image signal processing and secondary cycles for dose detection signal processing. This segmentation allows each cycle type to operate independently with optimized timing, enabling the dose detection signal to be output without waiting for the complete pipeline processing of image signals, thus reducing the time lag while maintaining signal processing capability.
Solution Approach 2:
The patent implements dynamic cycle control where the controller adjusts the timing and duration of primary and secondary cycles based on the specific processing requirements. The secondary cycle for dose detection can be executed with different timing characteristics than the primary image processing cycle, allowing flexible optimization of the detection speed without compromising overall system performance.
2Productivity
If the radiation time is short, then the imaging speed is improved, but the time lag in dose detection causes overexposure and artifacts
Solution Approach 1:
The patent performs preliminary dose detection signal processing in secondary cycles that can be executed concurrently with or before the main image signal processing. By preparing the dose detection signal in advance through the secondary cycle mechanism, the system can accurately determine the start and end of radiation even when the overall imaging time is short, preventing overexposure and artifacts while maintaining high imaging speed.
3Device complexity
If only one cycle is used for signal processing, then the device complexity is reduced, but the output time of dose detection signal is delayed
Solution Approach 1:
The patent divides the signal processing into multiple segments: primary cycles for image signal processing and secondary cycles for dose detection signal processing. This segmentation increases the functional capability without proportionally increasing overall complexity, as each cycle type follows a standardized pattern that can be implemented efficiently in the signal processing circuit.
Solution Approach 2:
The patent ensures continuous useful action by overlapping the execution of primary and secondary cycles. The secondary cycle for dose detection signal processing can begin before the primary cycle completes, and the controller manages both cycles continuously without idle waiting time. This continuous operation reduces the total output time of the dose detection signal while maintaining manageable device complexity through standardized cycle management.
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 reduces the delay in detecting the start of radiation, minimizing unnecessary exposure and improving image quality by enabling quicker detection of radiation onset, thus reducing the risk of overexposure and enhancing the efficiency of x-ray imaging.
Implementation Method 1
Each pixel includes a photoelectric conversion element for generating and accumulating the charges
Implementation Method 2
The integration amplifiers are individually provided on each signal line that is connected to respective pixels of one column, so that each integration amplifier integrates the signal charges from the signal line to convert the signal charges to an analog voltage signal
Implementation Method 3
The A/D converter converts the analog voltage signal as held in the sample-and-hold circuit to a digital voltage signal
Data Source
AI summary
A flat panel detector has pixels for obtaining image signals and detective pixels for detecting the amount of incident x-rays. A signal processing circuit is of a pipeline-type, wherein first and second buffer memories are connected to the output of an A/D converter. In a dose detecting operation, the signal processing circuit repeats primary cycles alternately with secondary cycles of a shorter length than the primary cycles. In the primary cycle, a dose detection signal based on electric charges from the detective pixels is input in the first buffer memory and, simultaneously, a dummy signal is output from the second buffer memory. In secondary cycle, the dose detection signal is output from the first buffer memory and, simultaneously, a second dummy signal is input in the second buffer memory. On the basis of the dose detection signals, a start-of-radiation detector detects the start of x-ray radiation.