What is the commonly assumed speed of sound in soft tissues for ultrasound range calculations?

What is the commonly assumed speed of sound in soft tissues for ultrasound range calculations?

• A. 1100 m/s
• B. 1540 m/s
• C. 2000 m/s
• D. 3000 m/s

Answer: (B)

In ultrasound depth calculations, the speed of sound in soft tissue is commonly taken as about 1540 meters per second. This value is used because the transducer measures the time it takes for an acoustic pulse to travel to a reflector and back, so depth is estimated from the round-trip time with the relation depth ≈ (speed × time)/2. Soft tissues such as muscle and liver generally have speeds in the roughly 1450–1600 m/s range, and 1540 m/s serves as a practical average that gives consistent, accurate depth estimates across typical exams. Using too low a speed would understate depths, while using too high a speed would overstate them. The other numbers—1100 m/s, 2000 m/s, or 3000 m/s—do not reflect the common soft-tissue speeds; 3000 m/s is closer to speeds in bone or dense materials, and 2000 m/s is faster than most soft tissue, leading to inaccurate depth calculations.

In ultrasound depth calculations, the speed of sound in soft tissue is commonly taken as about 1540 meters per second. This value is used because the transducer measures the time it takes for an acoustic pulse to travel to a reflector and back, so depth is estimated from the round-trip time with the relation depth ≈ (speed × time)/2. Soft tissues such as muscle and liver generally have speeds in the roughly 1450–1600 m/s range, and 1540 m/s serves as a practical average that gives consistent, accurate depth estimates across typical exams. Using too low a speed would understate depths, while using too high a speed would overstate them. The other numbers—1100 m/s, 2000 m/s, or 3000 m/s—do not reflect the common soft-tissue speeds; 3000 m/s is closer to speeds in bone or dense materials, and 2000 m/s is faster than most soft tissue, leading to inaccurate depth calculations.