6.5.2 Ultrasound

• One key use of ultrasound in medical imaging is visualizing the developing fetus during pregnancy
• What is acoustic impedance defined as in ultrasound physics?

  Density × speed of sound
• Why is impedance matching necessary in ultrasound imaging?

  Reduces reflection at the skin
• Steps in ultrasound image generation

  1️⃣ Electrical current applied to piezoelectric crystals

  2️⃣ Crystals vibrate to produce ultrasound waves

  3️⃣ Waves reflect off tissue boundaries

  4️⃣ Reflected waves detected by transducer

  5️⃣ Electrical signals create image
• The ultrasound transducer both produces and detects ultrasound waves


  True
• What is the formula for calculating the distance to a tissue interface in echolocation?

  d = \frac{v \times t}{2}</latex>
• Ultrasound can be used to evaluate muscles, tendons, and ligaments

  True
• What causes the attenuation of ultrasound waves in tissues?

  Absorption, scattering, reflection
• The attenuation coefficient in the intensity equation is denoted by the Greek letter alpha
• The proportion of ultrasound reflected between two tissues is determined by the reflectivity
• Steps in the process of echolocation in ultrasound imaging

  1️⃣ The transducer emits high-frequency sound waves

  2️⃣ Waves reflect off tissue boundaries

  3️⃣ Echoes travel back to the transducer

  4️⃣ The transducer detects echoes and converts them into electrical signals

  5️⃣ Time-of-flight is used to determine depth

  6️⃣ A visual image of internal structures is created
• Ultrasound images are formed using the piezoelectric effect.
• Order the steps in generating a 2D ultrasound image:

  1️⃣ The transducer emits ultrasound waves

  2️⃣ Waves reflect off tissue boundaries

  3️⃣ Echoes return to the transducer

  4️⃣ The transducer converts echoes into electrical signals

  5️⃣ A flat, two-dimensional image is displayed
• What does ultrasound visualize in pregnancy scans?

  Developing fetus, placenta, uterus
• What is the formula for acoustic impedance?

  $Z =$$\rho v$
• What is the formula for attenuation in ultrasound waves?

  I(x) = I_0 e^{-\alpha x}</latex>
• Steps of echolocation in ultrasound imaging

  1️⃣ Transducer emits ultrasound waves

  2️⃣ Waves reflect off tissue boundaries

  3️⃣ Echoes return to transducer

  4️⃣ Transducer converts echoes to electrical signals

  5️⃣ Time-of-flight of echoes is measured

  6️⃣ Image of internal structures is formed
• Ultrasound transducers use piezoelectric crystals to generate sound waves.


  True
• Ultrasound waves reflect off tissue boundaries.


  True
• Match the ultrasound technique with its description:

  2D Ultrasound ↔️ Generates a flat, two-dimensional image

  3D Ultrasound ↔️ Constructs a three-dimensional image

  Doppler Ultrasound ↔️ Measures blood and fluid movement
• What does Doppler ultrasound measure in the body?

  Blood and fluid flow
• Why is ultrasound considered a safe imaging modality?

  No ionizing radiation
• Ultrasound is non-invasive, real-time, and radiation-free in medical applications.


  True
• What is the typical frequency range of ultrasound waves used in medical imaging?

  2-20 MHz
• Match the type of ultrasound imaging with its purpose:

  Pregnancy Scans ↔️ Visualizing the fetus

  Abdominal Scans ↔️ Examining the liver

  Cardiac Imaging ↔️ Assessing heart function
• Attenuation in ultrasound waves occurs due to absorption, scattering, and reflection of energy.


  True
• What effect is used to produce ultrasound waves?

  Piezoelectric effect
• What effect is used to produce ultrasound waves?

  Piezoelectric effect
• Match the medical use of ultrasound with its description:

  Pregnancy Scans ↔️ Visualizing the developing fetus

  Abdominal Scans ↔️ Examining organs like the liver

  Cardiac Imaging ↔️ Assessing the heart's structure
• The reflectivity of ultrasound waves is determined by the difference in acoustic impedances
• The intensity of ultrasound waves decreases as they travel through tissues due to attenuation
• Acoustic impedance is defined as the product of density and the speed of sound
• Ultrasound waves are produced by the piezoelectric effect in a transducer.
• The pulse-echo technique in ultrasound allows for the creation of detailed images of internal structures.


  True
• Doppler ultrasound is used to diagnose vascular conditions
• Ultrasound is a type of sound wave with a frequency above the human hearing range
• Match the ultrasound use with its description:

  Pregnancy Scans ↔️ Visualizing fetus, placenta, uterus

  Abdominal Scans ↔️ Examining liver, kidneys, gallbladder

  Cardiac Imaging ↔️ Assessing heart structure and function
• Attenuation of ultrasound waves is caused by absorption, scattering, and reflection of energy.


  True
• The ultrasound transducer both produces and detects ultrasound waves.


  True
• The pulse-echo technique allows ultrasound to create detailed images of structures