Multi-Leaf Collimator Position Error Correction
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Solution Overview
Problem
Position errors in the leaves of a multi-leaf collimator (MLC) during radiotherapy procedures due to mechanical inaccuracies and movement inconsistencies, affecting the precision of radiation beam collimation and treatment efficacy.
Innovation Solution
A method and system that determine a first position for each leaf, including its movement direction and angle, to calculate an offset value, which is then used to adjust the target position, utilizing a processor and storage system to analyze encoder values and movement phases, ensuring accurate leaf positioning within the radiation field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If motors are used to drive leaves to move forward or backward, then the radiation field can be scaled, but position errors occur in the movement of the leaves
Solution Approach 1:
The system uses encoders to continuously monitor the actual position of each leaf and feeds this information back to the control system. The control system compares the actual position with the target position and dynamically adjusts the motor control signals to eliminate positioning errors, ensuring accurate leaf positioning throughout the radiation field scaling process.
Solution Approach 2:
The system dynamically adjusts motor control parameters such as voltage, current, and pulse width modulation (PWM) duty cycle based on real-time feedback from encoders. By changing these electrical parameters in response to position deviations, the system compensates for mechanical inaccuracies and achieves precise leaf positioning.
2Manufacturing precision
If offset values are determined and applied to correct position errors, then positioning accuracy is improved, but the system complexity increases
Solution Approach 1:
The system pre-calculates and stores offset values for different leaf positions and movement directions in lookup tables during system initialization or calibration. When the leaves need to move to a specific position, the control system retrieves the appropriate offset value from the pre-computed table and applies it immediately, avoiding complex real-time calculations and reducing computational complexity during operation.
Data Source
AI summary
Methods and systems for correcting position errors for a multi-leaf collimator (MLC) are provided. A method may include determining a first position for each of the plurality of leaves. The information associated with the first position may include a first movement direction and a first angle. A movement of the each of the plurality of leaves along the first movement direction may be configured to move toward or away from a center of the radiation field. The method may also include determining an offset value associated with the first position based on the first angle and the first movement direction; and determining a target position of the each of the plurality of leaves based on the offset value.