Nested Balloon Catheter for Stable Radiotherapy Positioning
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Solution Overview
Problem
Invasive radiotherapy balloon catheters face challenges in maintaining a stable shape and position for uniform tumor bed irradiation, as existing solutions either risk balloon rupture or complicate imaging and irradiation due to the use of compressible media, leading to non-uniform irradiation and increased radiation exposure.
Innovation Solution
A balloon catheter design featuring a flexible, non-extendible outer balloon and a flexible, extendible inner balloon, with a connection channel for media inlet and storage, allowing for precise control of shape and position through imaging and maintaining dimensional stability without risking rupture, and enabling temporary use of contrast agents for visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a compressible medium (e.g., air) is used to fill the balloon for shaping, then the balloon achieves dimensional stability, but the risk of balloon rupture increases due to high compression requirements
Solution Approach 1:
The patent employs a nested balloon structure with an inner balloon (30) inside an outer balloon (20). The inner balloon is filled with compressible medium for dimensional stability, while the outer balloon contains it to prevent rupture. This nesting allows the system to achieve both compression stability and safety by containing the compressed medium within multiple layers.
Solution Approach 2:
The outer balloon (20) acts as a pre-established protective layer that cushions and contains the compressed medium within the inner balloon (30). This beforehand cushioning prevents direct contact between the high-compression medium and the patient's tissue, reducing rupture risk while maintaining dimensional stability during irradiation.
2Difficulty of detecting and measuring
If contrast agent is used to visualize the balloon catheter in CT imaging, then the balloon becomes visible, but the irradiation time or x-ray power must be increased to compensate for absorbed radiation
Solution Approach 1:
The patent extracts the contrast agent from the irradiation field by positioning it specifically in the intermediate space (21) between the inner and outer balloons, rather than filling the entire balloon volume. This allows CT visualization of the balloon's position and shape while minimizing the volume of contrast agent that would absorb therapeutic radiation, thereby reducing the need for increased x-ray power or irradiation time.
Solution Approach 2:
The intermediate space (21) between the inner and outer balloons serves as an intermediary zone where contrast agent can be positioned for imaging purposes without interfering with the therapeutic irradiation of the tumor bed. This mediator space allows separation of the diagnostic (imaging) and therapeutic (irradiation) functions, enabling visualization while minimizing radiation absorption during treatment.
3Stability of the object's composition
If a solid applicator is used to suppress surrounding tissue and mold the tissue around the applicator, then stable arrangement during irradiation is guaranteed, but the applicator cannot be removed in a minimally invasive manner after irradiation
Solution Approach 1:
The patent employs flexible balloon membranes (inner balloon (30) and outer balloon (20)) instead of rigid solid applicators. These flexible shells can be inflated to provide stable tissue molding and suppression during irradiation, then deflated for easy removal through the biopsy channel. The flexibility allows the balloon to conform to tissue contours while maintaining stability, and deflation enables minimally invasive removal without requiring surgical intervention.
4Ease of operation
If the balloon is made of extendible material to allow filling, then the balloon can be filled with medium for shaping, but the shape may deviate from the defined basic form due to local features
Solution Approach 1:
The nested balloon structure with an inner extendible balloon (30) and an outer non-extendible balloon (20) resolves the shape consistency issue. The inner balloon can expand to be filled with medium, while the outer balloon's non-extendible material constrains the overall shape to match the defined basic form. This nesting allows the system to combine the fillability of extendible material with the shape consistency of non-extendible material.
Solution Approach 2:
The patent applies different material properties to different parts of the balloon system: the inner balloon (30) uses extendible material for fillability, while the outer balloon (20) uses non-extendible material for shape control. This local differentiation of material qualities allows each layer to perform its specific function - the inner layer expands to accommodate filling, while the outer layer maintains the geometric accuracy required for uniform irradiation.
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
Ensures stable balloon shape and position during irradiation, minimizing the risk of rupture and radiation exposure, allowing for precise tumor bed irradiation and reducing the need for increased x-ray power or time, while facilitating easy removal and repositioning for fractionated treatments.
Implementation Method 1
the outer balloon is formed of a flexible, non-extendible material
Implementation Method 2
the inner balloon is formed of a flexible, extendible material
Data Source
AI summary
Balloon catheter, applicator, particularly for invasive radiotherapy, and method of controlling the balloon catheter with respect to its shape and position in a tissue to be treated prior to an irradiation. The balloon catheter provides a catheter shaft for introducing a probe, an outer balloon and an inner balloon, disposed inside the outer balloon, the inner space of the inner balloon connecting to a channel for connection to a media inlet and intermediate space between the outer balloon and the inner balloon connecting to a channel for connection to a media storage unit. In order that the balloon catheter can be securely controlled with respect to its shape and position in a patient in a simple but clear manner prior to irradiation, the outer balloon is formed of a flexible, non-extendible material and the inner balloon is formed of a flexible, extendible material.