Radiotherapy Motion Tracking via 2D Slice Segmentation

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Solution Overview

Problem

The long acquisition time of 3D MRI images makes them unsuitable for tracking movement-related tumor changes during radiation therapy sessions, necessitating a more efficient method to manage patient motion and adjust radiation delivery in real-time.

Innovation Solution

A radiotherapy system that includes an image acquisition device, a processor device, and a radiotherapy device, which determines a primary plane of motion, acquires 2D slices to define a 3D volume, and constructs a 4D image to track motion by comparing snapshots over time, allowing for real-time adjustments in radiation delivery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 3D MRI images are used to track tumor changes, then measurement precision is improved, but acquisition time increases making real-time tracking impossible

Engineering Contradiction:
Improvetumor change detection accuracyVSAvoidimage acquisition time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent divides the 3D volume into multiple 2D slices that can be acquired and processed independently. Instead of acquiring a complete 3D MRI volume which takes several minutes, the system acquires individual 2D slices sequentially, reducing the time for each measurement while maintaining the ability to reconstruct 3D information when needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from 3D volumetric imaging to 2D planar imaging to reduce acquisition time. By acquiring 2D slices and using motion estimation algorithms, the system achieves real-time or near-real-time tracking capability while preserving sufficient measurement precision through computational methods.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If 3D MRI images are acquired frequently to track motion, then motion tracking accuracy is improved, but treatment time is excessive

Engineering Contradiction:
Improvemotion tracking accuracyVSAvoidtreatment session efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the imaging process into multiple rapid 2D slice acquisitions rather than performing slow 3D scans. This allows frequent motion assessment during treatment without significantly extending total treatment time, as each 2D slice can be acquired much faster than a full 3D volume.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system acquires 2D slices at selected time points during treatment rather than continuously acquiring full 3D volumes. This partial sampling approach provides sufficient motion tracking accuracy while maintaining treatment efficiency, avoiding the excessive time cost of frequent complete 3D scans.

Inventive Principle:
Principle #16Partial or excessive action

3Measurement precision

If multiple 2D slices are acquired to define 3D volume, then motion detection precision is improved, but device complexity increases

Engineering Contradiction:
Improvemotion detection precisionVSAvoidimage acquisition and processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent simplifies the imaging system by using multiple independent 2D slice acquisitions instead of complex 3D volumetric scanning. Each 2D slice can be acquired with simpler imaging parameters, and the combination of multiple 2D slices provides sufficient information for motion detection without requiring complex 3D imaging hardware or processing.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3413971B1Motion management in image-guided radiotherapy
Publication Date: 2020.07.08 ELEKTA AB
  • EP3413971B1 patent drawingFigure 1
  • EP3413971B1 patent drawingFigure 2
  • EP3413971B1 patent drawingFigure 3

AI summary

Systems and methods for managing motions of an anatomical region of interest of a patient during image-guided radiotherapy are disclosed. An exemplary system may include an image acquisition device, a radiotherapy device, and a processor device. The processor device may be configured to determine a primary plane of motion of the anatomical region of interest and determine a plurality of 2D slices parallel to the primary plane. The plurality of 2D slices may define a 3D volume substantially enclosing the anatomical region of interest. The processor device may also be configured to control the image acquisition device to acquire a plurality of 2D images based on the plurality of 2D slices and determine a motion of the anatomical region of interest based on at least a subset of the acquired plurality of 2D images. The processor device may be further configured to control radiation delivery based on the determined motion.