Waveguide RF Applicator Assembly for Stable Thermoacoustic Coupling
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Solution Overview
Problem
Sub-optimal coupling of RF applicators to tissue in thermoacoustic imaging systems leads to inefficient energy transfer, non-uniform energy deposition, tissue hotspots, and poor image quality due to air gaps between waveguide and solid inserts, which alter frequency characteristics unpredictably.
Innovation Solution
An RF applicator with an open-ended hollow waveguide and a solid insert having a recess, filled with a ceramic wax composite or conductive filler material to eliminate air gaps and ensure consistent frequency emission, along with a method of assembling the applicator by coating the insert, heating, and cooling to solidify the filler within the waveguide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hollow metal waveguides are fitted with solid inserts to provide filtering, then frequency selectivity is improved, but air gaps between waveguide and insert cause unpredictable frequency characteristics
Solution Approach 1:
The invention extracts and eliminates the harmful air gaps between the waveguide and solid insert by using a filler material that completely fills the space between facing surfaces. This removal of the problematic air gap eliminates the source of unpredictable frequency characteristics while preserving the beneficial frequency filtering provided by the solid insert.
Solution Approach 2:
The invention introduces a filler material as an intermediary substance between the waveguide and solid insert. This filler material serves as a mediator that eliminates air gaps and ensures consistent electrical contact, thereby stabilizing frequency characteristics while allowing the solid insert to maintain its frequency filtering function.
2Loss of information
If RF applicator is coupled to tissue for energy delivery, then imaging capability is improved, but sub-optimal coupling causes inefficient energy transfer and tissue hotspots
Solution Approach 1:
The invention extracts and removes the harmful air gaps between the waveguide and solid insert that cause inefficient energy transfer and non-uniform energy distribution. By eliminating these gaps with filler material, the system achieves optimal coupling and uniform energy delivery to tissue, preventing hotspots while maintaining effective imaging capability.
3Ease of manufacture
If solid insert is placed in waveguide without filler material, then manufacturing simplicity is improved, but air gaps form between facing surfaces
Solution Approach 1:
The invention applies filler material to the solid insert before insertion into the waveguide. This preliminary action ensures that when the insert is placed in the waveguide, the filler material is already positioned to fill any gaps between facing surfaces, achieving precise assembly without requiring complex post-assembly adjustments.
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
Enhances RF energy delivery to tissue with improved uniformity and consistency, reducing tissue overheating and enhancing image quality by eliminating air gaps and maintaining desired frequency characteristics.
Implementation Method 1
filler material between facing surfaces of the waveguide and the insert to fill gaps therebetween
Implementation Method 2
radio frequency (RF) source extending through the aperture and into the recess and being configured to generate RF energy pulses
Implementation Method 3
Thermoacoustic imaging uses short pulses of electromagnetic energy, such as RF pulses, directed into a subject to heat absorbing features within the subject rapidly, which in turn induces acoustic pressure waves
Implementation Method 4
acoustic pressure waves that are detected using acoustic receivers such as one or more thermoacoustic or ultrasound transducer arrays
Data Source
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AI summary
A radio frequency applicator comprises an open-ended, hollow waveguide having an aperture therein. A solid insert is positioned within the waveguide. The solid insert has a recess formed therein that is aligned with the aperture. Filler material is provided between facing surfaces of the waveguide and the insert to fill gaps therebetween. A radio frequency (RF) source extends through the aperture and into the recess and is configured to generate RF energy pulses.