X-ray AEC Stop Timing Prediction for Communication Lag
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Solution Overview
Problem
The existing X-ray radiographing systems face issues with excessive dose exposure due to delays in automatic exposure control (AEC) processes, particularly caused by communication lag between the radiographic device and the radiation generation device, leading to deteriorated image quality and unnecessary subject exposure.
Innovation Solution
A radiographic device with an image detection unit, dose detection unit, stop timing prediction unit, and communication unit that predicts and sends a stop timing notification to the radiation generation device before the actual stop time, accounting for communication lag to ensure timely irradiation cessation and prevent excessive dose exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time cumulative dose measurement and stop signal transmission is performed during X-ray irradiation, then the subject is prevented from excessive exposure, but communication lag causes delayed stop timing and excessive dose accumulation
Solution Approach 1:
The system performs preliminary action by predicting the stop timing in advance based on the current cumulative dose and dose rate, then transmits the stop signal before the actual stop time is reached. This anticipatory approach compensates for communication lag, ensuring the X-ray source stops at the correct time despite transmission delays.
Solution Approach 2:
The system implements feedback by continuously measuring the cumulative dose during irradiation, comparing it against the target dose, and dynamically adjusting the stop timing prediction. This closed-loop control ensures accurate exposure termination even when communication conditions vary.
2Device complexity
If the stop signal is transmitted after the cumulative dose reaches the target value, then the control logic is simplified, but excessive dose exposure occurs due to communication lag
Solution Approach 1:
Instead of waiting for the cumulative dose to reach the target value before transmitting the stop signal, the system calculates and transmits the stop signal in advance based on predicted stop timing. This preliminary action prevents excessive dose accumulation while maintaining relatively simple control logic.
Solution Approach 2:
The system applies preliminary anti-action by transmitting the stop signal before the harmful effect (excessive dose accumulation due to communication lag) can occur. The predicted stop timing is calculated to account for communication delay, ensuring the X-ray irradiation stops at the correct time.
3Measurement precision
If pre-irradiation is performed to measure dose per unit time before main irradiation, then appropriate dose can be determined for main irradiation, but unnecessary exposure of the subject occurs
Solution Approach 1:
The system uses feedback by continuously measuring the cumulative dose during the main irradiation process itself, rather than requiring a separate pre-irradiation measurement step. The real-time dose measurement feeds back to the control system, which dynamically determines when to stop irradiation based on the target dose, eliminating unnecessary pre-irradiation exposure.
Solution Approach 2:
The system maintains continuity of useful action by performing dose measurement continuously during the main irradiation process rather than separating measurement and irradiation into distinct phases. This allows the measurement and treatment to occur simultaneously, eliminating the need for separate pre-irradiation measurement that would expose the subject to unnecessary radiation.
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 solution reduces excessive dose exposure and improves image quality by ensuring accurate and timely cessation of radiation, even in the presence of communication delays, thereby enhancing the reliability of X-ray radiography.
Implementation Method 1
an X-ray image detection device which uses a flat panel detector (FPD) instead of an X-ray film or an imaging plate (IP) in the related art is put into practical use. The FPD is one in which pixels accumulating signal charges corresponding to a dose of X rays which are incident are arranged in a matrix, and converts the signal charge accumulated in each pixel into a voltage signal using a signal processing circuit so as to detect an X-ray image
Implementation Method 2
a dose detection unit that detects an arrival dose of the radiation arriving at the imaging region
Data Source
AI summary
An AEC unit of an electronic cassette sets a dose target value and a short-circuited pixel used for AEC based on a radiographing condition. When a control unit of the electronic cassette detects start of irradiation of X rays, the AEC unit starts integration of a cumulative dose of X rays which are incident to a target region based on a dose detection signal output by the short-circuited pixel. The AEC unit predicts a stop timing at the time point t1, waits until the time point t2 which is a predetermined time earlier than a scheduled stop time, and sends a stop timing notification to an X-ray generation device at the time point t2. When the stop timing notification is received, a X-ray source control device immediately inputs an irradiation stop command so as to stop an operation of an X-ray source.