Alternative Electron Density Map for MR Artifact Reduction

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Solution Overview

Problem

Magnetic resonance (MR) imaging-derived electron density maps for radiotherapy planning are often inaccurate due to image artifacts, leading to uncertainties in dose distribution calculations.

Innovation Solution

A processing system computes a first electron density map and a simplified second map, which is less susceptible to artifacts, and then uses these to generate an alternative map by replacing artifact areas with data from the second map, ensuring errors are within clinical tolerance limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a first electron density map is computed from MR imaging data, then detailed tissue information is obtained, but image artifacts reduce reliability

Engineering Contradiction:

Improveelectron density map accuracyVSAvoidartifact susceptibility

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The image data is segmented into multiple tissue classes with different electron density characteristics. By dividing the complex imaging problem into distinct tissue categories (e.g., soft tissue, bone, air), the system can apply class-specific electron density values, reducing the impact of artifacts on overall map accuracy while preserving detailed tissue information.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A lookup table serves as an intermediary between the MR image intensities and electron density values. This lookup table maps image intensity ranges to corresponding electron density values, allowing the system to translate artifact-prone continuous intensity data into discrete, clinically relevant electron density categories, thereby reducing artifact propagation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If bulk density assignment is used for tissue classes, then processing is simplified, but electron density map accuracy decreases

Engineering Contradiction:

Improveprocessing simplicityVSAvoidelectron density accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The system varies electron density parameters within defined ranges for different tissue classes rather than using fixed bulk values. This allows the electron density map to adapt to local tissue characteristics while maintaining the simplified lookup table approach, thus improving accuracy without significantly increasing processing complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electron density assignment becomes dynamic by allowing range-based values instead of fixed bulk densities. The system can select specific electron density values within acceptable ranges based on local image characteristics and clinical requirements, making the simplified processing method more accurate while retaining ease of implementation.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10870017B2Fall-back solution for uncertain regions in MRCAT images

Publication Date: 2020.12.22 KONINKLIJKE PHILIPS NV

AI summary

The present invention teaches a method and system for computing an alternative electron density map of an examination volume. The processing system is configured to compute a first electron density map using a plurality of imaging data, compute a second electron density map, wherein the second electron density map is a simplified version of the first electron density map, and compute the alternative electron density map, using the first electron density map and the second electron density map.