Microwave Ablation Probe Fluid Cooling and Navigation
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Solution Overview
Problem
Current microwave surgical devices face challenges in precisely controlling temperature during tissue ablation procedures, particularly in lung tissue, due to the small temperature difference between malignant and healthy cells, leading to potential damage to surrounding healthy tissue and rapid device failures from increased reflected power.
Innovation Solution
A system incorporating a percutaneous microwave ablation device with a fluid-cooling system, temperature sensors, and a navigation system using CT images and fiducial markers to accurately guide the device to the target tissue, ensuring precise energy application and minimizing damage to healthy tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic energy is applied to heat tissue for ablation, then malignant cells are destroyed, but healthy surrounding tissue may be damaged due to the small temperature difference between malignant and healthy cells
Solution Approach 1:
The patent applies local quality by creating a non-uniform temperature distribution through controlled microwave heating. The system targets specific regions (tumor cells) for heating while maintaining different temperature zones - the tumor region reaches ablation temperatures (41-45°C or higher) while surrounding healthy tissue is kept below damaging thresholds. This is achieved through controlled energy delivery and fluid cooling systems that create localized thermal zones.
Solution Approach 2:
The patent employs periodic action through intermittent or pulsed microwave energy delivery combined with fluid cooling cycles. The system alternates between heating phases (applying electromagnetic energy to raise tumor temperature) and cooling phases (circulating fluid to remove heat from surrounding healthy tissue). This periodic cycling allows the tumor to accumulate thermal damage while protecting adjacent healthy structures.
2Power
If microwave energy is increased to improve ablation effectiveness, then tumor destruction is enhanced, but reflected power increases causing rapid device failures
Solution Approach 1:
The patent implements feedback control by monitoring reflected power levels and tissue temperature during microwave delivery. The system uses sensors to detect changes in impedance (indicative of reflected power) and temperature, then automatically adjusts the microwave generator output to maintain optimal power levels. This closed-loop control prevents excessive reflected power that would cause device failure while ensuring effective tumor ablation.
Solution Approach 2:
The patent applies dynamics by making the microwave power delivery adaptive and variable rather than fixed. The system dynamically adjusts power levels based on real-time conditions including tissue properties, probe position, and cooling fluid flow rate. This dynamic control allows the system to operate at high power when conditions are favorable while reducing power when reflected power increases, preventing device failure.
3Object-affected harmful factors
If precise temperature control is implemented to protect healthy tissue, then damage to healthy cells is minimized, but device complexity increases
Solution Approach 1:
The patent uses an intermediary substance (cooling fluid) to mediate heat transfer between the tissue and the ablation probe. The fluid circulates through channels in or around the probe, absorbing excess heat from healthy tissue while allowing the tumor region to reach ablation temperatures. This fluid intermediary simplifies temperature control compared to direct electronic control, as it passively manages heat distribution through convection and phase change.
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
The system enables precise temperature control and effective ablation of malignant tissue while minimizing damage to healthy tissue, with the fluid-cooling system preventing device failures from heat buildup.
Implementation Method 1
fluid-cooled or dielectrically-buffered microwave devices may be used in ablation procedures. During operation of the microwave ablation device, if the flow of coolant or buffering fluid is interrupted, the microwave ablation device may exhibit rapid failures due to the heat generated from the increased reflected power.
Implementation Method 2
Treatment may involve inserting ablation probes into tissues where cancerous tumors have been identified. Once the probes are positioned, electromagnetic energy is passed through the probes into surrounding tissue.
Data Source
AI summary
An ablation system including an image database storing a plurality of computed tomography (CT) images of a luminal network and a navigation system enabling, in combination with an endoscope and the CT images, navigation of a locatable guide and an extended working channel to a point of interest. The system further includes one or more fiducial markers, placed in proximity to the point of interest and a percutaneous microwave ablation device for applying energy to the point of interest.