Radiotherapy Planning Apparatus for Particle Beam Dose Dispersion

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Solution Overview

Problem

Radiotherapy using particle beams faces challenges in achieving precise dose distribution, particularly with heavy-ion beams, where the Spread-out Bragg peak often results in high doses on normal tissues due to leakage, and proton beams concentrate doses on the front side, leading to inefficiencies and potential tissue damage.

Innovation Solution

A radiotherapy planning apparatus that calculates initial irradiation directions and dose distributions using three-dimensional medical images, disperses these directions by predetermined angles in response to user instructions, and modifies the dose distribution to avoid concentration on normal tissues, thereby optimizing the treatment plan for particle beam therapy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a Spread-out Bragg peak is formed by using heavy-ion beams, then the dose can cover the entire tumor depth, but the dose leaks onto the rear side of the peak causing high doses on normal tissue

Engineering Contradiction:

Improvedose distribution precisionVSAvoiddose leakage on normal tissue

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the irradiation process into multiple repainting cycles, where the tumor is irradiated in the same direction multiple times with fractionated doses. This segmentation allows the dose to be accumulated precisely at the tumor location while minimizing leakage to surrounding normal tissues through repeated precise targeting.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculation of the optimal irradiation direction before actual treatment. By calculating the initial irradiation direction that achieves the desired dose distribution and then dispersing this direction by predetermined angles, the system prepares a pre-optimized treatment plan that prevents dose leakage before irradiation begins.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If a Spread-out Bragg peak is formed by using proton beams, then the dose is concentrated on the tumor, but the dose on the front side of the tumor reaches 80% of the peak causing potential tissue damage

Engineering Contradiction:

Improvedose concentration on tumorVSAvoidhigh dose on front side normal tissue

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetric angle dispersion to the irradiation directions. By dispersing the initial irradiation direction by predetermined angles in specific patterns, the system creates an asymmetric dose distribution that reduces the excessive dose on the front side of the tumor while maintaining effective dose concentration at the tumor target.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent changes the irradiation direction parameters by dispersing the initial direction by predetermined angles. This parameter modification transforms the dose distribution characteristics, reducing the front-side dose peak while maintaining tumor coverage effectiveness.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If particle beam irradiation is repeated multiple times for repainting, then dose distribution errors due to body motion are averaged, but the complexity of treatment planning increases

Engineering Contradiction:

Improvedose distribution accuracyVSAvoidtreatment planning complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements automated calculation systems that perform the complex repainting planning automatically. The calculation unit autonomously computes the initial irradiation directions and applies angle dispersion without requiring manual intervention for each repainting cycle, allowing the system to handle the complexity of multiple irradiation sessions while maintaining ease of operation.

Inventive Principle:

Principle #25Self-service

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 approach effectively reduces dose concentration on normal tissues, enhancing the safety and efficacy of radiotherapy by distributing doses more evenly and reducing the risk of tissue damage, especially when using heavy-ion beams.

Implementation Method 1

Particle beam therapy features concentrating a dose on only a tumor by the Bragg peak.

Methodology Applied

Scientific EffectBragg peak:

Implementation Method 2

The Bragg peak can be spread out by applying a particle beam in the same irradiation direction while changing depth of the Bragg peak.

Methodology Applied

Scientific EffectSpread-out Bragg peak:

Data Source

PatentUS11752362B2Radiotherapy planning apparatus, radiotherapy apparatus, and radiotherapy planning method

Publication Date: 2023.09.12 CANON MEDICAL SYST CORP

AI summary

According to one embodiment, a radiotherapy planning apparatus includes processing circuitry. The processing circuitry calculates initial irradiation directions of particle beams and an initial dose distribution corresponding to the initial irradiation directions by using a three-dimensional medical image concerning an object. The processing circuitry disperses some or all of the initial irradiation directions in response to a dispersion instruction via an input device. The processing circuitry modifies the initial dose distribution based on the dispersed irradiation directions.