Particle Therapy Scanning Path Calculation for Target Movement

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Solution Overview

Problem

Existing treatment planning systems for particle therapy lack the ability to arbitrarily set an ion beam scanning direction, particularly when considering three-dimensional target movement, making it difficult for operators to specify a scanning direction that aligns with the target's movement, leading to potential dose distribution errors.

Innovation Solution

A treatment planning system that includes an input device, arithmetic device, and display device, capable of calculating and displaying a scanning path by setting a pre-specified optional direction as the main direction for ion beam irradiation using scanning magnets, which takes into account the direction of target movement extracted from multiple tomography images, allowing for precise alignment of irradiation positions and adjustment of scanning paths to match target movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional treatment planning system determines scanning direction using fixed perpendicular scanning patterns, then the scanning path calculation is simple, but the dose distribution accuracy deteriorates when the target moves during irradiation

Engineering Contradiction:
Improvedose distribution accuracyVSAvoidscanning path calculation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system dynamically determines the main scanning direction based on the extracted target movement direction rather than using fixed perpendicular scanning patterns. The arithmetic device calculates the movement direction from multiple tomography images and uses this information to set the optimal scanning direction, allowing the scanning path to adapt to target movement while maintaining calculation feasibility

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the scanning direction parameter from fixed perpendicular directions to a dynamically determined direction that aligns with target movement. By extracting the movement direction vector from multiple tomography images and using it to define the main scanning direction, the system optimizes dose distribution accuracy without requiring complete recalculation of all scanning parameters

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the scanning direction is fixed perpendicular to the beam travel direction, then the scanning magnet control is simple, but the ability to align with target movement is lost

Engineering Contradiction:
Improvealignment with target movementVSAvoidscanning direction specification
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The system automatically extracts the target movement direction from multiple tomography images and uses this information to determine the main scanning direction without requiring manual operator input. The arithmetic device performs the extraction and calculation autonomously, making the system adaptive to target movement while keeping the operation interface simple

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses feedback from multiple tomography images to determine the target movement direction. By analyzing the positional changes of the target across multiple images, the system extracts the movement vector and uses it to optimize the scanning direction, creating a closed-loop system that adapts to actual target behavior

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If multiple tomography images are analyzed to extract target movement direction, then the scanning path aligns with target movement, but the data processing time increases

Engineering Contradiction:
Improvescanning path accuracyVSAvoidtreatment planning time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system extracts only the essential movement direction information from multiple tomography images rather than processing all image data. By focusing on extracting the movement vector from positional changes across images, the system achieves accurate scanning path alignment while minimizing data processing requirements and time

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution enables the creation of treatment planning data that achieves a highly uniform dose distribution by aligning the ion beam scanning direction with the target's movement, thereby reducing dose distribution errors and improving irradiation accuracy.

Implementation Method 1

The irradiation position on a lateral plane can be arbitrarily controlled by bending the direction of beam travel using two sets of scanning magnets

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Data Source

PatentEP2510979B1Treatment planning system, device for calculating a scanning path and particle therapy system
Publication Date: 2016.07.20 HITACHI LTD
  • EP2510979B1 patent drawingFigure 1
  • EP2510979B1 patent drawingFigure 2
  • EP2510979B1 patent drawingFigure 3

AI summary

In a particle therapy treatment planning system for creating treatment plan data, the movement of a target (patient's affected area) is extracted from plural tomography images of the target, and the direction of scanning is determined by projecting the extracted movement on a scanning plane scanned by scanning magnets 401, 402. Irradiation positions are arranged on straight lines parallel with the scanning direction making it possible to calculate a scanning path for causing scanning to be made mainly along the direction of movement of the target. The treatment planning system can thereby realize dose distribution with improved uniformity.