MLC Leaf Position Detection Using Non-Contact Optical Feedback
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Solution Overview
Problem
Existing leaf position detection devices for multi-leaf collimators in radiotherapy systems suffer from issues such as device wear, poor reliability, and limited applicability in magnetic environments, with contact methods like thin film potentiometers and CCD cameras having short lifespans and magnetic grid detection requiring non-magnetic conditions.
Innovation Solution
A non-contact position detection device for multi-leaf collimators using a signal emitting component, signal feedback component, and processor to determine the moving stroke of leaves, which includes optical or laser signals and a PIN photoresistor for feedback, allowing accurate positioning in magnetic and radiation environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based position detection devices (thin film potentiometers, CCD cameras) are used, then position detection is achieved, but device wear occurs and reliability decreases
Solution Approach 1:
The patent replaces contact-based mechanical detection devices (potentiometers, CCD cameras) with a non-contact optical detection system. The optical detection device uses light sources and photodetectors to measure leaf position without physical contact, eliminating mechanical wear and improving reliability while maintaining measurement precision.
Solution Approach 2:
The patent introduces optical markers (reflective or emissive) as intermediaries between the leaf and the detection system. These markers enable indirect measurement of leaf position through optical signals, avoiding direct contact between the detection device and the moving leaf components.
2Measurement precision
If magnetic grid detection is used, then position detection is achieved, but non-magnetic conditions are required
Solution Approach 1:
The patent replaces magnetic field-based detection with an optical detection system that uses light sources and photodetectors. This optical system is not affected by magnetic fields, allowing position detection to function reliably in the magnetic environments typical of radiotherapy equipment while maintaining measurement precision.
3Reliability
If non-contact optical detection is used, then reliability and durability are improved, but device complexity increases
Solution Approach 1:
The patent divides the optical detection system into modular components: light sources, optical markers on each leaf, photodetectors, and signal processing units. This segmentation allows independent optimization of each component and simplifies installation and maintenance while maintaining high reliability through the non-contact measurement principle.
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 solution provides accurate, reliable, and durable leaf position detection in magnetic and radiation environments, enhancing the precision of radiotherapy treatments by ensuring precise radiation delivery.
Implementation Method 1
The signal emitting component may include an emitting element and a reflecting element
Implementation Method 2
which includes optical or laser signals and a PIN photoresistor for feedback
Implementation Method 3
a PIN photoresistor for feedback
Implementation Method 4
a reflecting element configured to reflect the signal emitted by the emitting element to the signal feedback component
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A position detection device of a multi-leaf collimator (MLC) is provided. The position detection device includes a signal emitting component, a signal feedback component, and a processor. The signal emitting component is configured to emit a signal. The signal feedback component is configured to receive the signal emitted by the signal emitting component and generate a feedback signal in response to the received signal. Installation positions of the signal emitting component and the signal feedback component are arranged so that the signal emitted by the signal emitting component can be projected onto the signal feedback component. The processor communicatively connected with the signal feedback component and configured to receive the feedback signal from the signal feedback component and determine a moving stroke of a leaf of the MLC based on the feedback signal.