MRI Distortion Correction for Radiotherapy Plan Quality
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Solution Overview
Problem
Magnetic Resonance Imaging (MRI) suffers from reduced geometric accuracy compared to CT scans, affecting the quality of radiotherapy treatment plans, as the exact location and volume of structures can be distorted due to the main magnetic field, leading to inefficient and inaccurate quality assurance in treatment planning.
Innovation Solution
A treatment plan evaluation tool calculates a quality indicator based on magnetic field homogeneity, considering distortion, dose, tissue sensitivity, radiation beam orientation, and distance between organs at risk and tumors, providing warnings and geometric corrections to improve treatment plan quality and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MRI is used for treatment planning, then soft tissue contrast and tumor delineation are improved, but geometric accuracy deteriorates
Solution Approach 1:
The patent introduces a distortion correction map as an intermediary element that mediates between the MRI image data and the treatment planning process. This map, generated from phantom measurements, serves as a correction layer that compensates for MRI's inherent geometric inaccuracies without sacrificing its superior soft tissue contrast capabilities
Solution Approach 2:
The patent applies parameter changes by transforming the MRI image space using distortion correction factors. The correction map contains spatial transformation parameters that adjust the coordinates and geometry of structures in the MRI image to match the actual anatomical positions, thereby improving geometric accuracy while preserving the original image's soft tissue differentiation
2Reliability
If geometric distortion correction is applied, then treatment plan accuracy is improved, but quality assurance complexity increases
Solution Approach 1:
The patent implements preliminary action by performing distortion correction measurements using a phantom before actual patient treatment planning. The correction map is generated in advance and can be stored for reuse, eliminating the need to perform complex correction measurements for each individual treatment plan while maintaining high accuracy
Solution Approach 2:
The patent uses a phantom as a copy or surrogate of the actual imaging scenario to characterize distortion. The phantom replicates the imaging conditions and geometry, allowing distortion parameters to be measured and corrected in a controlled environment before applying the correction to patient images
3Device complexity
If manual inspection methods are used to assess geometric accuracy, then system complexity is reduced, but measurement accuracy and efficiency deteriorate
Solution Approach 1:
The patent replaces manual visual inspection with an automated computational system. The distortion correction map enables automatic calculation of geometric accuracy metrics by comparing expected versus actual positions of structures, substituting subjective manual assessment with objective, repeatable computational measurements
Data Source
AI summary
It is an object of the invention to improve quality assurance when using MRI images for radiotherapy treatment planning. This object is achieved by a treatment plan evaluation tool A configured for calculating a quality indicator for a radiotherapy treatment plan. The radiotherapy treatment plan originates from a planning image, wherein the planning image is an MRI image acquired under a presence of a main magnetic field having a magnetic field inhomogeneity. The treatment plan evaluation tool is further configured to receive information about the magnetic field inhomogeneity and the treatment plan evaluation tool is further configured to calculate the quality indicator based on the information about the magnetic field homogeneity.