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Questions and Answers
What defines the width of a crystal in the ultrasound probe anatomy circa 1988?
What defines the width of a crystal in the ultrasound probe anatomy circa 1988?
- 1/4 wavelength ($ rac{1}{4} imes ext{λ}$)
- Full wavelength ($2 imes ext{λ}$)
- 1 wavelength ($1 imes ext{λ}$)
- 1/2 wavelength ($ rac{1}{2} imes ext{λ}$) (correct)
What factor primarily causes the issue of unfocused ultrasound transducers?
What factor primarily causes the issue of unfocused ultrasound transducers?
- Lack of backing layer
- Fraunhofer diffraction (correct)
- Narrow aperture size
- High frequency output
Which statement correctly describes the Near Field Depth (NFD)?
Which statement correctly describes the Near Field Depth (NFD)?
- It has a dependency on the crystal diameter and wavelength. (correct)
- It is constant and does not vary with aperture size.
- It can only be calculated with digital systems.
- It is directly proportional to the frequency.
In the context of the pure analogue AAA systems, what is a key component that plays back the recorded sound?
In the context of the pure analogue AAA systems, what is a key component that plays back the recorded sound?
Which reason is commonly given for not relying on analogue systems in ultrasound technology?
Which reason is commonly given for not relying on analogue systems in ultrasound technology?
What role does the user play in the functioning of an ultrasound probe?
What role does the user play in the functioning of an ultrasound probe?
Which component of the ultrasound probe is essential for converting electrical energy to mechanical energy?
Which component of the ultrasound probe is essential for converting electrical energy to mechanical energy?
What is a disadvantage of using P.Z.T. in ultrasound probes?
What is a disadvantage of using P.Z.T. in ultrasound probes?
What is meant by 'ringing' in the context of ultrasound probes?
What is meant by 'ringing' in the context of ultrasound probes?
How does the matching layer in an ultrasound probe function?
How does the matching layer in an ultrasound probe function?
Which aspect of the ultrasound probe does the backing layer influence?
Which aspect of the ultrasound probe does the backing layer influence?
What is one advantage of using digital probes in ultrasound technology?
What is one advantage of using digital probes in ultrasound technology?
What happens to the ultrasound waves if the P.Z.T. has high acoustic impedance?
What happens to the ultrasound waves if the P.Z.T. has high acoustic impedance?
What is the purpose of the matching layer in an ultrasound probe?
What is the purpose of the matching layer in an ultrasound probe?
How does a phased array probe achieve beamforming?
How does a phased array probe achieve beamforming?
What is the role of the backing layer in an ultrasound probe?
What is the role of the backing layer in an ultrasound probe?
Which control adjusts the image depth in ultrasound scanning?
Which control adjusts the image depth in ultrasound scanning?
What happens when sound reflects off both the front and back of the matching layer?
What happens when sound reflects off both the front and back of the matching layer?
What is indicated by the order of firing in crystals of an ultrasound probe?
What is indicated by the order of firing in crystals of an ultrasound probe?
Which aspect is NOT a pre-send control in ultrasound technology?
Which aspect is NOT a pre-send control in ultrasound technology?
What type of crystals are used in an ultrasound probe's array?
What type of crystals are used in an ultrasound probe's array?
What is the first function of a receiving beam former?
What is the first function of a receiving beam former?
Which of these components affects the scan image width?
Which of these components affects the scan image width?
What role does the transmit beamformer play in an ultrasound machine?
What role does the transmit beamformer play in an ultrasound machine?
Which component is responsible for pre-processing the ultrasound signals?
Which component is responsible for pre-processing the ultrasound signals?
What are some of the disadvantages of ultrasound machines mentioned?
What are some of the disadvantages of ultrasound machines mentioned?
How does the receive beamformer differ from the transmit beamformer?
How does the receive beamformer differ from the transmit beamformer?
What is one of the functions of the pre-send controls in ultrasound machines?
What is one of the functions of the pre-send controls in ultrasound machines?
What is the purpose of the digital analogue converter (DAC) in ultrasound technology?
What is the purpose of the digital analogue converter (DAC) in ultrasound technology?
What does the amplitude processing of received signals involve?
What does the amplitude processing of received signals involve?
Why are some components of ultrasound machines considered fragile?
Why are some components of ultrasound machines considered fragile?
What pattern can be identified in the binary sequences presented?
What pattern can be identified in the binary sequences presented?
What is the role of increasing ‘different greys’ as mentioned in the content?
What is the role of increasing ‘different greys’ as mentioned in the content?
How do the sequences relate to digital output?
How do the sequences relate to digital output?
Which characteristic is shared by all the binary sequences in the content?
Which characteristic is shared by all the binary sequences in the content?
What can be inferred about the structure of the binary sequences?
What can be inferred about the structure of the binary sequences?
What is the significance of the repeated elements in the sequences?
What is the significance of the repeated elements in the sequences?
Which of the following best describes a possible application of the binary sequences?
Which of the following best describes a possible application of the binary sequences?
What type of information can the binary sequences potentially encode?
What type of information can the binary sequences potentially encode?
How might the differentiation in greys be significant in terms of graphic representation?
How might the differentiation in greys be significant in terms of graphic representation?
What does the variety in binary sequences suggest about encoding efficiency?
What does the variety in binary sequences suggest about encoding efficiency?
What is the primary function of the analogue digital controller (ADC)?
What is the primary function of the analogue digital controller (ADC)?
What does the T.EQ setting accomplish in the signal processing chain?
What does the T.EQ setting accomplish in the signal processing chain?
In coherent signal processing, what is the primary objective once the signal is digitized?
In coherent signal processing, what is the primary objective once the signal is digitized?
What is the purpose of scan conversion in the signal processing workflow?
What is the purpose of scan conversion in the signal processing workflow?
During which stage is incoherent signal processing executed?
During which stage is incoherent signal processing executed?
Which of the following describes demodulation in the context of signal processing?
Which of the following describes demodulation in the context of signal processing?
What does cine memory store in ultrasound systems?
What does cine memory store in ultrasound systems?
Which control options are available post-digital receive?
Which control options are available post-digital receive?
What is the output of the ADC typically represented as?
What is the output of the ADC typically represented as?
What role do user controls provide in the ultrasound system processes?
What role do user controls provide in the ultrasound system processes?
What does the term 'coherent signal processing' refer to?
What does the term 'coherent signal processing' refer to?
In the context of signal processing, what is TGC primarily used for?
In the context of signal processing, what is TGC primarily used for?
What type of signal does demodulation typically produce?
What type of signal does demodulation typically produce?
Flashcards
Near Field Depth (NFD)
Near Field Depth (NFD)
The distance from the center of the ultrasound transducer to the point where the beam begins to diverge significantly.
Diffraction
Diffraction
The phenomenon where an ultrasound beam spreads out as it travels through tissue, causing a loss of resolution.
Annular Array Transducer
Annular Array Transducer
A type of ultrasound transducer that uses multiple crystals arranged in a circle to create a focused beam.
Rayleigh Distance
Rayleigh Distance
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Analogue Probe
Analogue Probe
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Transmit beamformer function
Transmit beamformer function
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Crystal array
Crystal array
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Fan (Scan image width)
Fan (Scan image width)
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Frequency
Frequency
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Focus
Focus
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Digital-to-analog converter (DAC)
Digital-to-analog converter (DAC)
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Receive processing
Receive processing
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Receive beamformer
Receive beamformer
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Binary sequence
Binary sequence
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Bit
Bit
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Decoding
Decoding
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Binary Code
Binary Code
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Encoding
Encoding
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Binary System
Binary System
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Calculating possible combinations
Calculating possible combinations
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Signal Amplitude
Signal Amplitude
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Signal Frequency
Signal Frequency
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Voltage Level Representation
Voltage Level Representation
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Beam forming
Beam forming
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PZT (Piezoelectric Transducer)
PZT (Piezoelectric Transducer)
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Backing Layer
Backing Layer
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Matching Layer
Matching Layer
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Acoustic Window
Acoustic Window
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PZT's Efficiency for Energy Conversion
PZT's Efficiency for Energy Conversion
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PZT's Impedance Disparity
PZT's Impedance Disparity
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Crystal (in ultrasound probe)
Crystal (in ultrasound probe)
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Array (Ultrasound probe)
Array (Ultrasound probe)
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3D Ultrasound Scanning
3D Ultrasound Scanning
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Focus (Pre-send control)
Focus (Pre-send control)
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Frequency (Pre-send control)
Frequency (Pre-send control)
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Auto Gain
Auto Gain
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User Gain Control
User Gain Control
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Time Gain Compensation (TGC)
Time Gain Compensation (TGC)
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T.EQ. (Time & Equalization)
T.EQ. (Time & Equalization)
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Analog-to-Digital Conversion (ADC)
Analog-to-Digital Conversion (ADC)
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Coherent Signal Processing
Coherent Signal Processing
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Demodulation
Demodulation
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Image Formation
Image Formation
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Scan Conversion
Scan Conversion
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Cine Memory
Cine Memory
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Post-Processing
Post-Processing
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Digitization
Digitization
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Pre-Digital Receive Controls
Pre-Digital Receive Controls
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Post-Digital Receive Controls
Post-Digital Receive Controls
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Image Building
Image Building
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Study Notes
Ultrasound Probe Anatomy
- Ultrasound probes, circa 1988, used annular arrays.
- Crystal width was ½λ (lambda).
Problems of Unfocused Ultrasound Transducers
- Fresnel Diffraction (plane wave) occurs in the near field.
- Fraunhofer Diffraction (spherical spreading) occurs in the far field.
- Near field depth (NFD) is calculated by NFD = D2/4λ or π2/λ.
- D is diameter or radius of crystal aperture
- λ is wavelength
Pure Analogue (AAA) Systems
- Ultrasound signals received by electromagnetic microphones were recorded onto vibrational devices.
- Signals were played back through another vibrational device (a speaker).
- Issues included high interference, inability to manipulate signals, and expensive/fragile components.
Ultrasound Machine Anatomy (Basic)
- A basic ultrasound machine has transmit and receive beam formers.
- There's transmit power control, digitisation, amplitude processing, and image formation.
- Post-processing, cine memory, and output to the screen complete the process.
Ultrasound Transducer Array Block Diagram
- Components include pre-send controls, beam former, transmit beam former, receive beam former, amplitude and phase processing, coherent image former, demodulation/compression, non-coherent image former, display, post-processing, cine memory, and scan conversion.
Transmit Beam Former
- The transmit beam former takes the preset electrical output from the machine.
- It combines this with user controls to form the correct electrical signals to excite the crystals in the probe array.
- The electrical output from the machine and the user selection are combined.
Digital-Analogue Converter (Coordinator)
- The digital-analogue coordinator coordinates the analogue response.
- The response from crystals within the probe produces the correct beam of ultrasound.
- This combines the beam formed by the transducer and user selection settings.
Ultrasound Probe Anatomy - Digital Probes
- Digital probes have ultrasound insulation, a backing layer, a PZT crystal array, a matching layer, and an acoustic window.
Ultrasound Probe Anatomy – PZT Advantages
- Efficient conversion between electrical and mechanical energy, relatively easy machining.
- Relatively easy to manufacture in various shapes and sizes.
Ultrasound Probe Anatomy – PZT Disadvantages
- Impedance drastically different from soft tissue, leading to extensive ringing.
Ultrasound Probe Anatomy – Backing Layer
- Ideally, the backing layer has a lower impedance than the PZT material to reduce ringing.
- This material should ideally have high acoustic impedance to absorb reflected ultrasound waves, reducing unwanted ringing.
Ultrasound Probe Anatomy – Matching Layer
- A matching layer is also needed to help transmit sound.
- The layer's impedance is chosen to be a square root of that of the PZT and the human tissue.
Ultrasound Probe Anatomy – Acoustic Window
- A protective layer, the acoustic window, comes between the matching layer and the human body.
- Its impedance helps transfer sound efficiently to the body while being a transparent barrier.
Ultrasound Probe Anatomy - Different Probe Types
- There are various probe types, including those with linear and array crystal distributions.
Ultrasound Probe Anatomy– Beamforming Phased Array
- It clarifies how phased array probes work and how 3D scanning is executed.
- Electrical current sequentially activates crystals for precise beam formation and focusing.
Ultrasound Probe Anatomy– Receiving Beam Former
- It takes raw analogue electrical signals and amplifies them into usable output.
- It enables user control of gain settings and TGC adjustments for improved signal balance.
Ultrasound Probe Anatomy – Analogue Digital Converter
- It converts the raw analogue signals into suitable digital outputs for the display.
Ultrasound Probe Anatomy – Coherent Signal Processing
- The scanner digitizes and processes signals from multiple crystals to create a coherent signal.
Ultrasound Probe Anatomy – Demodulation and Incoherent Signal Processing
- Demodulation converts the processed coherent signal into an incoherent signal for display output.
Ultrasound Probe Anatomy – Cine Memory
- Stores the raw digital data from the ultrasound imaging process.
Ultrasound Probe Anatomy – Scan Conversion
- Takes each scan line and displays results as part of the image.
- Analogue-to-digital converters (ADCs) convert output from image formers into digital outputs suitable for display.
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Description
Explore the anatomy and technology of ultrasound probes, including the challenges faced by unfocused transducers and the basic components of ultrasound machines. Delve into concepts such as Fresnel and Fraunhofer diffraction, as well as pure analogue systems. This quiz is designed for those interested in medical imaging technology and ultrasound physics.
