Radiation Detector Leak Charge Correction Circuit
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Solution Overview
Problem
Radiation image processing apparatuses face issues with artifacts due to excessive radiation exposure, causing leak charge in radiation detectors, which affects the quality of captured images.
Innovation Solution
A radiation image processing apparatus that includes a radiation detector with a leak correcting circuit and an offset correcting circuit, which corrects charge information using a leak charge signal and an offset signal, and applies moving average or filtering processes to reduce electrical noise, ensuring accurate image capture even under excessive radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radiation detector uses a negative bias voltage to protect the transistor switch from damage, then the reliability of the transistor switch is improved, but artifacts are generated in the radiation image due to leak charge
Solution Approach 1:
The patent applies preliminary action by reading out the charge information immediately after the radiation exposure is completed, before the leak charge has time to significantly accumulate and cause artifacts. This timing strategy prevents the harmful leak charge from degrading the image quality while maintaining the protective negative bias voltage on the transistor switch.
2Productivity
If the charge information is read out quickly after irradiation, then the productivity of the imaging process is improved, but artifacts are generated due to leak charge affecting the detected signal
Solution Approach 1:
The patent implements preliminary action by establishing an optimized timing sequence where the readout operation is initiated immediately after irradiation completion. This preliminary timing strategy captures the charge information before leak charge accumulation degrades image quality, thereby maintaining both high productivity and manufacturing precision.
Solution Approach 2:
The patent applies parameter changes by optimizing the timing parameters of the readout operation. By precisely controlling the start time of the readout relative to the end of irradiation, the system achieves optimal balance between imaging speed and image quality, preventing leak charge artifacts while maintaining high productivity.
3Measurement precision
If the readout sequence starts from the gate line corresponding to the center of the subject, then the measurement precision of the central region is improved, but artifacts are generated in other regions due to leak charge
Solution Approach 1:
The patent applies preliminary action by completing the entire charge readout process immediately after irradiation, regardless of the readout sequence. This timing strategy prevents leak charge from accumulating to levels that would cause artifacts in any region, while still allowing flexible selection of readout sequence optimization for central region precision.
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
The apparatus effectively prevents artifacts in radiation images by correcting for leak charge, resulting in high-quality images without distortion, even when the detector is exposed to excessive radiation.
Implementation Method 1
a converting layer 9 such as an amorphous selenium (a-Se) layer given by vapor deposition, for converting radiation X to a charge signal
Data Source
AI summary
The invention relates to an apparatus and method for processing a radiation image. For a subject area, a radiation image signal corrected for leak charge is obtained by subtracting, from a GateOn signal obtained by turning on a transistor switch of a detecting element of a radiation detector, a GateOff signal obtained by turning off the transistor switch. A threshold value is less than or equal to a pixel saturation value. For an unblocked area where the radiation image signal is greater than the threshold value, the GateOn signal is utilized as the radiation image signal.