How is an ultrasound image created from echoes and reflected sound waves?

**Q. Describe how an ultrasound image is created using the concept of echoes and reflected sound waves.** **A.** **1. Generation of Ultrasound Waves:** - A **transducer** (probe) emits high-frequency sound waves (ultrasound, >20 kHz) into the body. **2. Reflection & Echoes:** - When sound waves encounter tissue boundaries (e.g., muscle-fat interface), **partial reflection** occurs due to differences in acoustic impedance. - The **echoes** (reflected waves) return to the transducer. **3. Signal Processing:** - The transducer converts echoes into **electrical signals**. - A computer measures the **time delay** between emission and return of echoes to calculate the **depth** of tissues (*Distance = Speed × Time/2*). **4. Image Formation:** - Echo strength determines pixel brightness (strong echo = bright, weak echo = dark). - Multiple scan lines are combined to form a **2D cross-sectional image** (B-mode). **Key Terms:** - **Acoustic Impedance:** Resistance to sound wave propagation (depends on tissue density). - **B-mode:** Brightness mode for real-time imaging. --- *Need it adjusted for marks or board? Just ask!*