Attenuation Map Generation for MR-PET Systems
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Solution Overview
Problem
Current methods for determining attenuation maps in MR-PET systems are limited, as they either fail to accurately account for all materials or require time-consuming test measurements, and existing methods are not suitable for complete definition of attenuation maps, especially for bones and local coils.
Innovation Solution
A method involving the creation of multiple data sets to determine attenuation values, weighting these values based on their relevance, and combining them to generate an accurate attenuation map, which can include using different methods for different tissue types and incorporating confidence values to account for method-dependent uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple data sets are created and combined to determine attenuation values, then the accuracy and comprehensiveness of the attenuation map is improved, but the complexity of the method and processing increases
Solution Approach 1:
The attenuation map determination is segmented into multiple data sets, each focusing on specific materials or tissue types. Different evaluation methods are applied to different data sets based on their suitability for specific materials (e.g., one method for bones, another for soft tissue), and the results are combined through weighting. This segmentation allows each method to be optimized for its specific purpose while maintaining overall system manageability.
Solution Approach 2:
Different evaluation methods are applied locally to different data sets based on their specific characteristics and the materials they best represent. Each data set is evaluated with the method most appropriate for its content, and local weighting factors are applied to reflect the reliability and relevance of each evaluation result for specific regions or materials in the attenuation map.
2Reliability
If test measurements are performed to determine attenuation values, then the reliability of attenuation data is improved, but the examination time increases
Solution Approach 1:
Attenuation maps for system components (patient table, local coils, etc.) are determined in advance through test measurements and stored in a database. During the actual PET examination, these pre-determined attenuation maps are retrieved and combined with patient-specific data without requiring additional test measurement time. This preliminary action separates the time-consuming calibration work from the clinical examination process.
Solution Approach 2:
Instead of performing physical test measurements during each PET examination, the attenuation characteristics of system components are copied into digital attenuation maps that are stored and reused. These digital copies allow rapid retrieval and combination with patient data, eliminating the need for repeated physical measurements while maintaining reliability.
3Loss of information
If attenuation values for all materials are included in the attenuation map, then the completeness of the attenuation correction is improved, but the difficulty of determining and collecting attenuation values increases
Solution Approach 1:
The determination of attenuation values is segmented by material type and data set. Different evaluation methods are selected and applied based on the specific material being evaluated (e.g., bones, soft tissue, system components). This segmentation makes the complex task manageable by breaking it down into smaller, method-specific sub-tasks that can be handled independently and then combined.
Solution Approach 2:
The system uses a universal framework that can handle multiple material types and evaluation methods through a common data structure and combination process. The weighting mechanism provides a universal approach to integrating results from different evaluation methods, allowing the system to accommodate various materials and methods without requiring separate processing pipelines for each.
Data Source
AI summary
A method is disclosed for defining an attenuation map. In at least one embodiment, the method includes creating at least two data sets from which attenuation values are able to be determined; evaluating the data sets and determining attenuation values; weighting the attenuation values determined and creating the attenuation map by inserting the weighted attenuation values.