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Questions and Answers
What is the range of frequencies used in diagnostic medical ultrasound?
What is the range of frequencies used in diagnostic medical ultrasound?
What is the velocity of a sound wave through soft tissue?
What is the velocity of a sound wave through soft tissue?
What is the frequency of a 7.5 MHz transducer?
What is the frequency of a 7.5 MHz transducer?
What is the wavelength of a sound wave with a frequency of 3MHz?
What is the wavelength of a sound wave with a frequency of 3MHz?
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What is the relationship between wavelength, frequency, and velocity of a sound wave?
What is the relationship between wavelength, frequency, and velocity of a sound wave?
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What is the unit of measurement for the strength of a sound wave?
What is the unit of measurement for the strength of a sound wave?
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What is the principle employed by the transducer to generate sound waves and detect echo signals?
What is the principle employed by the transducer to generate sound waves and detect echo signals?
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What is the result of the Returning echoes on the ultrasound screen?
What is the result of the Returning echoes on the ultrasound screen?
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What is the term used to describe an area that contains no echoes on the ultrasound image?
What is the term used to describe an area that contains no echoes on the ultrasound image?
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What is the formula used to calculate the wavelength of ultrasound waves?
What is the formula used to calculate the wavelength of ultrasound waves?
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What is the term used to describe an area that contains only a few echoes on the ultrasound image?
What is the term used to describe an area that contains only a few echoes on the ultrasound image?
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What is the role of the transducer in ultrasound imaging?
What is the role of the transducer in ultrasound imaging?
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What is the frequency range used in Obstetrics and Gynaecology ultrasound applications?
What is the frequency range used in Obstetrics and Gynaecology ultrasound applications?
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What is the purpose of the analogue to digital converter in the ultrasound system?
What is the purpose of the analogue to digital converter in the ultrasound system?
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In which mode of ultrasound display is the echo plotted on the screen as a function of depth?
In which mode of ultrasound display is the echo plotted on the screen as a function of depth?
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What is the frequency range used in paediatric brain ultrasound applications?
What is the frequency range used in paediatric brain ultrasound applications?
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What is the purpose of the image memory in the ultrasound system?
What is the purpose of the image memory in the ultrasound system?
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What is the frequency range used in thyroid and scrotum ultrasound applications?
What is the frequency range used in thyroid and scrotum ultrasound applications?
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What does the display of echoes on a TV monitor show?
What does the display of echoes on a TV monitor show?
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What is emphasized in M-mode display?
What is emphasized in M-mode display?
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What is measured using M-mode display?
What is measured using M-mode display?
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What is combined with M-mode in Colour M-mode imaging?
What is combined with M-mode in Colour M-mode imaging?
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What is displayed in conjunction with the corresponding segment of the cardiac cycle in Colour M-mode imaging?
What is displayed in conjunction with the corresponding segment of the cardiac cycle in Colour M-mode imaging?
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What modality does Doppler ultrasound combine with to study blood vessels and blood flow?
What modality does Doppler ultrasound combine with to study blood vessels and blood flow?
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What is a necessary understanding for a sonographer to have in order to perform and interpret a Doppler examination?
What is a necessary understanding for a sonographer to have in order to perform and interpret a Doppler examination?
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What type of Doppler modulation is associated with slow flow velocity?
What type of Doppler modulation is associated with slow flow velocity?
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What is a limitation of ultrasound imaging?
What is a limitation of ultrasound imaging?
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What is a potential biological effect of high-intensity pulsed wave ultrasound?
What is a potential biological effect of high-intensity pulsed wave ultrasound?
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What is an advantage of ultrasound imaging?
What is an advantage of ultrasound imaging?
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What is the primary media used for image recording in ultrasound?
What is the primary media used for image recording in ultrasound?
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Study Notes
Ultrasound Basics
- Definition: A form of energy with frequencies above human hearing (20 Hz - 20 kHz); medical ultrasound operates between 2 - 15 MHz.
- Wavelength (λ): Distance a wave travels in one cycle; calculated using the formula ( c = f \cdot \lambda ).
- Velocity of Sound: Average speed through soft tissue is approximately 1540 m/s.
Transducer Functionality
- Transducer Role: Acts as both transmitter and receiver of ultrasound waves, converting acoustic energy to electrical signals and vice versa.
- Pulse-Echo Principle: Utilizes the piezoelectric effect, which involves quartz crystals (PZT) that change shape in an electric field to generate and detect sound waves.
Basic Terminology in Ultrasound
- Anatomical Orientation: Includes planes such as anterior/posterior, sagittal, inferior/superior, transverse, medial/lateral, coronal, and oblique.
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Ultrasound Image Terminology:
- Echogenic: Areas containing echoes.
- Anechoic/Echolucent: Echo-free areas.
- Hypoechoic: Areas with few echoes.
- Hyperechoic: Highly echogenic areas producing strong echoes.
Image Formation
- Dots on Screen: Electrical signals produce dots whose brightness reflects the strength of returning echoes.
- Digital Imaging: Involves digital scan converters, image memory storing images as digits and pixels.
Ultrasound Display Modes
- A-Mode: One-dimensional display; shows echoes as spikes on a baseline representing time/distance; used for ocular localization.
- B-Mode: Two-dimensional display; visualizes returning echoes as shades of grey on a monitor, dependent on echo intensity.
- M-Mode: Displays moving structures; measures amplitude and rate of motion in real-time, often used in cardiac assessments.
- Doppler Ultrasound: Analyzes blood flow and vessel anatomy using various modes (color, spectral, audio).
Scanning Applications
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Frequency Ranges for Different Applications:
- Abdomen: 2.5 - 5 MHz
- Obstetrics and Gynecology: 2.5 - 5 MHz
- Vascular: 5 - 12 MHz
- Pediatrics: 6 - 7 MHz
- Small Parts: 10 - 14 MHz
- Musculoskeletal: 7 - 14 MHz
Advantages and Limitations
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Advantages:
- Non-invasive and cost-effective.
- Provides real-time imaging of moving structures.
- Exceptional differentiation of soft tissues.
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Limitations:
- Ineffective on calcified bone, air, and gas.
- Operator-dependent; accuracy can be affected by experience.
- Challenges with obese patients and evaluating through scarred tissues.
Biological Effects
- Heat Production: Minimal for diagnostic ultrasound due to vibrating molecules.
- Cavitation: Possible with high-intensity pulsed wave ultrasound; can damage cell walls.
- Safety: No known adverse biological effects of B-mode ultrasound on humans.
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Description
Learn the basics of ultrasound imaging, including its definition, biological effects, imaging principles, and clinical applications. Understand the different modes of ultrasound and how they are used in medical imaging.
