Multi-Leaf Collimator Leaf Position Verification

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Solution Overview

Problem

Multi-leaf collimators (MLCs) in radiation treatment systems are complex and prone to failures, requiring precise calibration of individual leaf positions to ensure accurate beam shaping, but existing methods lack robust verification mechanisms for aperture accuracy, leading to potential inaccuracies in radiation delivery.

Innovation Solution

An image-based aperture verification system is integrated into the MLC, using an image sensor to generate images of the leaves, which are then processed to transform oblique-view images into top-view images, allowing for precise verification of leaf positions against a treatment plan, and comparison with other verification systems to ensure accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple verification systems are used to verify leaf positions, then measurement precision and reliability are improved, but device complexity increases

Engineering Contradiction:

Improveleaf position verification accuracyVSAvoidverification system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The verification system is segmented into multiple independent verification methods: image-based verification using oblique-view images, top-view images, and comparison with treatment plan apertures. Each segmentation provides a different perspective or method of verification, collectively achieving high measurement precision without requiring a single overly complex verification mechanism

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces intermediary verification elements such as oblique-view images captured by sensors, top-view image transformations, and aperture comparison intermediaries. These intermediaries serve as mediators between the physical leaf positions and the verification process, enabling accurate measurement without direct complex measurement of each leaf position

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If visual inspection and real-time verification are enabled, then user confidence and reliability are improved, but loss of time in verification processes increases

Engineering Contradiction:

Improveaperture accuracy verificationVSAvoidverification time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by pre-generating treatment plan apertures and pre-establishing verification protocols before actual leaf positioning. Oblique-view images are captured and transformed into top-view images in advance, allowing rapid comparison and verification without time-consuming processing during the actual verification moment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces manual mechanical verification methods with automated image-based verification systems. Computers automatically capture images, transform views, compare apertures, and generate verification results, eliminating time-consuming manual inspection while maintaining high reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10758748B2Verification of leaf positions for multi-leaf collimator using multiple verification systems

Publication Date: 2020.09.01 ACCURAY LLC

AI summary

A method includes determining a first estimate of leaf positions for a plurality of leaves of a multi-leaf collimator (MLC) in a reference coordinate space based on an image generated by an image-based aperture verification system, wherein the leaf positions for the plurality of leaves define an aperture for the MLC. The method further includes determining a second estimate of the leaf positions for the plurality of leaves in the reference coordinate space based on data from an additional source. The method further includes verifying the leaf positions for the plurality of leaves based on comparing the first estimate to the second estimate, wherein the leaf positions are verified if the first estimate deviates from the second estimate by less than a threshold value.