MLC Vertical Jaw Coordination for Zero Fluence Region Radiation

Solution Overview

Problem

Conventional radiation therapy methods for fluence maps with zero fluence regions require multiple segment fields, increasing total Monitor Units (MU) and treatment time, and can result in inaccurate dose delivery at the edges of adjacent fields due to penumbra and set-up time.

Innovation Solution

A radiation method and apparatus that determines a basic fluence map with non-zero and zero fluence regions, allowing for simultaneous radiation of non-zero fluence regions with coordinated movement of Multi-Leaf Collimator (MLC) leaf pairs and vertical jaws to shade or expose specific areas, reducing the need for multiple field divisions and minimizing set-up time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the radiation field is divided into multiple segment fields to handle zero fluence regions, then the fluence map can be radiated, but the total Monitor Units (MU) increases approximately one time to the original minimum total MU

Engineering Contradiction:

Improvefluence map radiation capabilityVSAvoidtotal Monitor Units

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The fluence map is divided into multiple sub-fields (first sub-field and second sub-field) separated by a zero fluence region. Each sub-field is radiated separately with independent MLC leaf pair groups, allowing the system to handle zero fluence regions while maintaining dose accuracy. This segmentation resolves the contradiction by enabling reliable radiation delivery to complex fluence maps without requiring excessive MU accumulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A vertical jaw is introduced as an intermediary component to shade the zero fluence region between the first and second sub-fields. This vertical jaw acts as a mediator that blocks radiation in the zero fluence area while allowing independent radiation delivery to adjacent sub-fields, eliminating the need for excessive MU buildup that would occur with conventional field division methods.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If multiple segment fields are used to radiate the fluence map, then zero fluence regions can be handled, but the treatment time increases due to set-up time for moving jaws and MLC between fields

Engineering Contradiction:

Improvezero fluence region handlingVSAvoidtreatment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The fluence map is divided into multiple sub-fields (first sub-field and second sub-field) separated by a zero fluence region. Each sub-field is radiated separately with independent MLC leaf pair groups, allowing the system to handle zero fluence regions while maintaining dose accuracy. This segmentation resolves the contradiction by enabling reliable radiation delivery to complex fluence maps without requiring excessive MU accumulation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A vertical jaw is introduced as an intermediary component to shade the zero fluence region between the first and second sub-fields. This vertical jaw acts as a mediator that blocks radiation in the zero fluence area while allowing independent radiation delivery to adjacent sub-fields, eliminating the need for excessive MU buildup that would occur with conventional field division methods.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple segment fields are used to radiate the fluence map, then zero fluence regions can be handled, but penumbra at the edge of segment fields causes inaccurate dose delivery

Engineering Contradiction:

Improvezero fluence region handlingVSAvoiddose delivery accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

A vertical jaw is introduced as an intermediary component to shade the zero fluence region between the first and second sub-fields. This vertical jaw acts as a mediator that blocks radiation in the zero fluence area while allowing independent radiation delivery to adjacent sub-fields, eliminating the need for excessive MU buildup that would occur with conventional field division methods.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Different groups of MLC leaf pairs are assigned to different sub-fields (first group for first sub-field, second group for second sub-field), allowing each group to be optimized for its specific region. This local optimization eliminates penumbra effects at field edges by ensuring continuous, uninterrupted radiation delivery within each sub-field without the need for jaw repositioning between adjacent fields.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11571590B2Radiation method and apparatus for radiating a fluence map having zero fluence region

Publication Date: 2023.02.07 SHANGHAI UNITED IMAGING HEALTHCARE

AI summary

The present disclosure provides a radiation method for radiating a fluence map having a zero-fluence region under a movement of MLC (Multi-Leaf Collimator) includes a determining step of determining at least one basic fluence map from the fluence map. The basic fluence map includes a first non-zero fluence region and a second non-fluence region having the zero-fluence region therebetween. The radiation method includes a first radiating step including radiating the first non-zero fluence region, along with moving a first group of leaf pairs and moving a vertical jaw to shade the first group of leaf pairs, and a second radiating step including radiating the second non-zero fluence region, along with moving a second group of leaf pairs and withdrawing the vertical jaw to expose the second group of leaf pairs.