Microwave Ablation Probe Irrigation Cooling Structure
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Solution Overview
Problem
Microwave ablation probes face challenges in efficiently managing heat distribution during tissue ablation, leading to elongated lesions and increased mechanical strain due to limited heat exchange surface area and coolant flow rates.
Innovation Solution
The design incorporates a coaxial cable antenna with a radiating portion and a probe body featuring a heat exchange surface with increased surface area through corrugations, undulations, or ridges, allowing for enhanced cooling fluid flow and improved heat transfer via an irrigation path, which includes a liner and cannula with defined segments for fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a smooth surface is used in the irrigation path, then the device complexity is reduced, but the heat exchange surface area is insufficient leading to poor cooling efficiency
Solution Approach 1:
The irrigation path wall is designed with a porous structure that provides increased surface area for heat exchange between the cooling fluid and the probe components. The porous configuration allows efficient thermal transfer while maintaining a relatively simple overall device structure.
Solution Approach 2:
The surface area parameter of the irrigation path wall is modified by introducing porosity, transforming a smooth surface into a porous one. This parameter change significantly increases the heat exchange surface area, improving cooling efficiency without proportionally increasing device complexity.
2Temperature
If the heat exchange surface area is increased, then the cooling efficiency is improved, but the device complexity increases
Solution Approach 1:
A porous heat exchange surface is implemented in the irrigation path wall, providing extensive surface area for thermal exchange. This approach achieves effective temperature control while keeping the structural complexity manageable through the use of a standardized porous configuration.
Solution Approach 2:
The heat exchange surface is extended into the third dimension through porous structures that protrude from the irrigation path wall. This dimensional expansion increases the effective surface area without requiring a proportional increase in the overall device volume or complexity.
3Temperature
If the coolant flow rate is increased, then the cooling efficiency is improved, but the mechanical strain on the probe increases
Solution Approach 1:
The porous structure of the irrigation path wall provides multiple flow paths for the coolant, distributing the flow more evenly. This allows effective cooling at lower flow rates, reducing mechanical strain on the probe while maintaining adequate cooling efficiency.
Solution Approach 2:
The flow distribution parameter is improved through the porous structure, which creates multiple parallel flow paths. This parameter change allows the system to achieve effective cooling with reduced total flow rate, thereby reducing mechanical strain on the probe components.
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
This configuration reduces the temperature rise of the antenna and patient tissue, promoting more spherical lesions by increasing the heat transfer coefficient and reducing mechanical strain, while maintaining effective microwave energy delivery.
Implementation Method 1
at least one wall defining the irrigation path includes a heat exchange surface. The heat exchange surface has an average radius, where a surface area of the heat exchange surface is larger than a surface area of a smooth surface with a radius equal to the average radius
Implementation Method 2
an irrigation path configured to carry cooling fluid to and from the distal portion of the probe body
Implementation Method 3
Microwave ablation probes use an antenna, such as a monopole or dipole antenna, to radiate microwave energy into tissue for heating. Unlike radiofrequency ablation, which depends on ion movement and friction for heating, microwave ablation energy causes water molecules to rotate due to the polarity of the molecules and generates heat due to hysteresis
Data Source
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AI summary
A microwave ablation probe including a probe body including a shielded portion and a radiation window that is at least partially transparent to microwave energy. The shielded portion includes a cannula, a coaxial cable within the probe body, and an antenna comprising a radiating portion for emission of microwave energy at a distal portion of the probe body, wherein the radiating portion is aligned with the radiation window. The probe body defines an irrigation path configured to carry cooling fluid to and from the distal portion of the probe body. At least one wall defining the irrigation path comprises a heat exchange surface having an average radius, wherein a surface area of the heat exchange surface is larger than a surface area of a smooth surface with a radius equal to the average radius.