Deformable MRI Phantom for 4D Motion Tracking
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Solution Overview
Problem
Current MRI quality assurance phantoms fail to accurately simulate deformable anatomical structures for 4D motion tracking in radiation therapy, leading to inaccuracies in tumor targeting and increased risk to healthy tissues due to poor soft tissue visualization and motion compensation.
Innovation Solution
A deformable phantom with a housing made of MRI-invisible material, containing a sealed reservoir filled with MRI signal-producing material, featuring a reciprocating piston and sleeve for simulating physiological motion and deformation, along with point dosimeters for precise radiation dose measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rigid structure motion phantoms are used for motion simulation, then the structure is stable and easy to manufacture, but the phantom cannot accurately simulate deformable anatomical structures for 4D motion tracking
Solution Approach 1:
The patent applies the dynamics principle by replacing rigid structures with deformable materials that can dynamically change shape to simulate physiological motion. The phantom incorporates soft tissue-equivalent materials that can deform in response to applied forces, enabling accurate simulation of 4D motion patterns including breathing, cardiac motion, and organ deformation. This dynamic capability allows the phantom to maintain measurement precision for tumor targeting while accommodating the necessary complexity through controlled material properties rather than complex mechanical structures.
Solution Approach 2:
The patent utilizes parameter changes by varying the physical and mechanical properties of the phantom materials to match different tissue types and motion characteristics. The deformable structure employs materials with specific viscoelastic properties, density variations, and deformation characteristics that can be adjusted to simulate different anatomical structures and motion patterns. This allows accurate simulation of deformable motion while maintaining a relatively simple overall structure compared to rigid phantoms with multiple rigid components.
2Measurement precision
If CT and CBCT imaging are used for motion tracking, then the imaging speed is fast, but the soft tissue visualization is poor leading to positioning errors
Solution Approach 1:
The patent applies the copying principle by creating a physical phantom that replicates the deformable motion characteristics of real anatomical structures. The phantom serves as a tangible copy that can be directly manipulated and imaged with MRI, providing accurate soft tissue visualization without requiring complex real-time imaging sequences. The deformable structure in the phantom replicates the motion patterns of organs like the liver and lungs, enabling accurate tumor position tracking while maintaining shorter treatment times through simplified imaging requirements.
3Measurement precision
If breath hold and gating techniques are employed to estimate tumor position, then the tumor position can be localized, but the treatment time increases and position uncertainty remains
Solution Approach 1:
The patent applies preliminary action by pre-configuring the phantom with deformable structures that are already positioned and shaped to represent the target organ and tumor. The phantom can be rapidly imaged in its pre-deformed state without requiring real-time breath hold or gating during treatment. The deformable structure is prepared in advance with known motion characteristics, allowing treatment planning and execution to proceed more efficiently while maintaining accurate tumor position localization through the pre-established geometric relationships in the phantom.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables realistic simulation of 4D deformable motion, improving the accuracy of radiation therapy by allowing real-time physiological motion tracking and precise targeting of moving tumors, thereby reducing treatment margins and minimizing healthy tissue exposure.
Implementation Method 1
one or more point dosimeters are located on or within the deformable structure. The one or more point dosimeters are one or more scintillators located on or within the deformable target
Implementation Method 2
a sealed reservoir filled with a MRI signal producing material
Data Source
AI summary
A deformable phantom, according to the present invention, has a housing made of a MRI invisible material enclosing a sealed reservoir filled with a MRI signal producing material, a piston slidably mounted within a sleeve and extending into the sealed reservoir, wherein the sleeve is slidably mounted to the housing and extends into the sealed reservoir, a deformable structure within the sealed reservoir, and one or more point dosimeters located on or within the deformable structure. The piston and sleeve move opposite to one another to conserve a constant fluid volume within the sealed reservoir as the piston moves in and out of the sealed reservoir to cause motion and/or deformation of the deformable structure.