3D Motion Estimation from 2D MRI Slices for Adaptive Radiotherapy
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Solution Overview
Problem
Current MRI-guided radiotherapy systems face challenges in accurately localizing and tracking targets and organs at risk in 3D space, especially due to significant out-of-plane motion and the difficulty in simultaneously tracking both targets and organs at risk, which limits effective dose calculations and adaptive radiotherapy.
Innovation Solution
A computer-implemented method and system that estimate 3D motion from a series of 2D MRI slices by building a conversion model in a learning stage and applying it in a tracking stage to provide real-time 3D motion estimation, enabling accurate tracking of target position, deformation, and rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If 2D MRI slices are used for target localization, then imaging speed and soft tissue contrast are improved, but 3D motion localization accuracy deteriorates due to out-of-plane motion
Solution Approach 1:
The patent applies dimensionality change by transforming 2D MRI slices into 3D motion information through a conversion model. The system takes 2D motion field estimation from slices and converts it to 3D motion field representation, enabling accurate 3D target localization while maintaining the speed advantages of 2D imaging. This resolves the contradiction by adding the third dimension through computational transformation rather than requiring actual 3D imaging.
2Ease of operation
If sequential 2D slices are acquired alternating axial, coronal and sagittal, then target motion tracking is enabled, but simultaneous tracking of organs at risk becomes difficult
Solution Approach 1:
The patent applies universality by creating a conversion model that serves multiple functions simultaneously. The same 2D slice data and conversion model can track both targets and organs at risk in 3D space, eliminating the need for separate tracking approaches. The model universally handles different anatomical structures and motion types from the same 2D imaging data.
3Productivity
If only 2D slice information is gathered during treatment, then real-time tracking is possible, but offline retrospective dose calculation becomes difficult
Solution Approach 1:
The patent applies preliminary action by pre-building a conversion model during a learning stage that transforms 2D slice data into 3D motion field representations. This pre-computed model enables both real-time tracking and comprehensive offline dose calculations to be performed on the same 2D slice data, eliminating the need to choose between speed and information completeness.
Data Source
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AI summary
Described herein is a system and method of controlling real-time image-guided adaptive radiation treatment of at least a portion of a region of a patient. The computer-implemented method comprises obtaining a plurality of real-time image data corresponding to 2-dimensional (2D) magnetic resonance imaging (MRI) images including at least a portion of the region, performing 2D motion field estimation on the plurality of image data, approximating a 3-dimensional (3D) motion field estimation, including applying a conversion model to the 2D motion field estimation, determining at least one real-time change of at least a portion of the region based on the approximated 3D motion field estimation, and controlling the treatment of at least a portion of the region using the determined at least one change.