Non-metallic Lung Phantom for MRI-CT Compatibility
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Solution Overview
Problem
Existing CT-based phantoms for radiotherapy are incompatible with MRI-based systems due to the presence of metal components, which are affected by strong magnetic fields, necessitating a phantom for quality maintenance and precision evaluation in MRI-based radiotherapy.
Innovation Solution
A lung phantom unit designed with a non-metallic lung simulation block, a phantom driving cylinder, and a driving device that uses air compression and expansion to mimic lung and tumor motions, allowing operation without being affected by magnetic or electric fields, and includes a flexible connection tube and adjustable shelves for positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing CT-based phantom with metal components is used, then radiotherapy quality maintenance is enabled, but the phantom cannot be used with MRI-based systems due to magnetic field interference
Solution Approach 1:
The invention extracts and removes all metal components from the phantom structure. The phantom is constructed entirely from non-metallic materials including the acrylic tank, lung mimic sponges, tumor mimic materials, and connection tubes, eliminating magnetic field interference while maintaining functionality for both MRI and CT-based radiotherapy systems
Solution Approach 2:
The invention replaces electromagnetic-driven mechanical components (motors) with a pneumatic system. Air is injected through connection tubes into the phantom to directly inflate the lung mimic, eliminating metal motors and electromagnetic mechanisms that would be affected by magnetic fields, thereby enabling compatibility with MRI-based radiotherapy systems
2Strength
If metal components are used in the phantom, then structural strength and positioning precision are improved, but the phantom operation is affected by magnetic and electric fields
Solution Approach 1:
The invention uses composite non-metallic materials to achieve both strength and magnetic field compatibility. The tank is made of acrylic, the lung mimic uses sponges with specific density, and connection tubes use flexible non-metallic materials, creating a composite structure that provides structural integrity without magnetic field interference
Solution Approach 2:
All metal components that would compromise reliability in magnetic fields are completely removed from the phantom system, including motors, fasteners, and structural elements, replacing them with non-metallic alternatives that maintain structural strength while ensuring operation stability in both MRI and CT environments
3Object-affected harmful factors
If a long connection tube is used to connect the driving device, then the driving device can be positioned away from the magnetic field, but the tube length increases complexity
Solution Approach 1:
The connection tube acts as an intermediary element that transmits pneumatic pressure from the driving device to the phantom while allowing spatial separation. The tube enables the driving device to be positioned outside the magnetic field zone while still controlling the phantom's inflation and deflation cycles, managing the complexity through standardized pneumatic connection protocols
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 precise measurement of lung and tumor motion changes due to air pressure variations, facilitating customized radiotherapy suitable for various breathing patterns and compatibility with both MRI and CT-based imaging systems.
Implementation Method 1
a driving device for compressing and expanding air accommodated in the phantom driving cylinder
Implementation Method 2
a connection tube having one side communicatively connected to the phantom driving cylinder and the other side communicatively connected to the lung simulation block
Data Source
AI summary
A lung phantom unit for radiotherapy according to an embodiment of the present disclosure may arrange, at a location not affected by a magnetic field, a phantom driving cylinder and a driving device which may move a lung mimic and a tumor mimic in a lung simulation block. The lung phantom unit may be used for general purpose even as a phantom for MRI-based and CT image-based radiotherapy. Since lung and tumor motions are implemented by air injection, it may be possible to precisely measure the motion and volume change of a lung according to subtle changes in air pressure so that customized radiotherapy suitable for a patient having various breathing patterns is possible.