Thermoacoustic Probe Nested Waveguide Design
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Solution Overview
Problem
The side-by-side configuration of RF applicator and acoustic receiver in thermoacoustic probes results in inefficient energy transfer, reduced signal strength, non-uniform energy deposition, tissue hotspots, and poor image quality due to sub-optimal coupling, along with RF interference and spurious acoustic signals.
Innovation Solution
A thermoacoustic measurement probe design featuring an open-ended hollow RF waveguide that surrounds and is mechanically joined to a thermoacoustic transducer, with the transducer positioned inside the waveguide's cavity to enhance signal overlap and reduce interference, allowing for improved energy transfer and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the RF applicator and acoustic receiver are configured side-by-side in a handheld probe, then the device can be operated as a single integrated probe, but the signal strength is reduced due to limited overlap between the RF beam and acoustic receiver directivity pattern
Solution Approach 1:
The patent places the acoustic receiver inside the hollow cavity of the RF waveguide, creating a nested configuration where one component is positioned within the structural envelope of the other. This nesting arrangement maximizes the overlap between the RF beam and acoustic receiver directivity pattern while maintaining integrated probe operation.
Solution Approach 2:
The patent transitions from a side-by-side spatial arrangement to a concentric/circular arrangement by positioning the acoustic receiver within the hollow cavity of the RF waveguide. This dimensional reconfiguration allows the acoustic receiver to be surrounded by the RF waveguide, creating maximum overlap in all radial directions rather than limited overlap in a single direction.
2Device complexity
If the RF applicator and acoustic receiver are configured side-by-side, then the structure is simpler, but RF interference from the RF applicator adversely affects signal quality
Solution Approach 1:
The patent extracts the acoustic receiver from the external side-by-side position and places it inside the hollow cavity of the RF waveguide. This repositioning removes the acoustic receiver from the direct path of RF interference while maintaining structural simplicity through the nested configuration.
Solution Approach 2:
The hollow cavity of the RF waveguide serves as an intermediary structure that houses the acoustic receiver while providing electromagnetic shielding. The waveguide structure itself acts as a barrier that protects the acoustic receiver from external RF interference while allowing the RF beam to pass through to the tissue.
3Ease of manufacture
If the RF applicator and acoustic receiver are configured side-by-side, then manufacturing is simpler, but spurious acoustic signals such as plane waves are stronger and detrimental to acoustic signal fidelity
Solution Approach 1:
The patent nests the acoustic receiver within the hollow cavity of the RF waveguide, creating a compact integrated structure that is straightforward to manufacture as a single assembly. This nesting configuration simultaneously reduces spurious acoustic signals by positioning the acoustic receiver at the center where plane wave artifacts are minimized.
Solution Approach 2:
The patent changes the spatial arrangement from side-by-side to concentric positioning, placing the acoustic receiver inside the RF waveguide cavity. This dimensional change creates a configuration where the acoustic receiver is surrounded by the waveguide structure, which helps eliminate spurious plane wave artifacts while maintaining manufacturing simplicity.
4Measurement precision
If the acoustic receiver is tilted in relation to the RF applicator in a side-by-side configuration, then overlap is improved for better signal strength, but RF interference and plane wave artifacts are not reduced
Solution Approach 1:
The patent abandons the tilted side-by-side configuration and instead places the acoustic receiver inside the hollow cavity of the RF waveguide. This creates a concentric arrangement where the acoustic receiver is surrounded by the RF waveguide, achieving maximum overlap in all directions while simultaneously eliminating RF interference and plane wave artifacts through the shielding effect of the waveguide structure.
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 achieves maximal overlap between the RF beam and acoustic receiver directivity, significantly reducing RF interference and allowing for smaller probe dimensions while improving signal strength and image fidelity.
Implementation Method 1
Thermoacoustic imaging uses short pulses of electromagnetic energy, such as RF pulses, directed into a medium to heat absorbing features within the medium rapidly, which in turn induces acoustic pressure waves
Implementation Method 2
it is common to employ waveguides to guide electromagnetic waves or sound with minimal loss of energy by restricting expansion of the electromagnetic waves propagating within the waveguides to one or two dimensions
Implementation Method 3
to provide the desired filtering these hollow metal waveguides are fitted with a solid insert formed of high dielectric constant material
Data Source
AI summary
A thermoacoustic measurement probe may include an open-ended hollow radio-frequency (RF) waveguide; and a thermoacoustic transducer, wherein the open-ended hollow RF waveguide, in the form of a sleeve, surrounds and is mechanically joined to the thermoacoustic transducer.