Ultrasound physics Doppler Shift Quiz

5 MHz transducer strikes a red blood cell. RBC moving towards transducer. Let's say the reflected frequency is 5,003,000 Hz. What is the Doppler shift, and is it a positive or negative Doppler Shift?

• 3000 Hz, Positive

• 3000 Hz, Negative

• 5003000 Hz, Positive

• 5003000 Hz, Negative

Same probe and frequency, now the RBC moving Away from the transducer. Let's say the reflected frequency is 4,997,000 Hz. What is the Doppler shift? Is it a positive or negative Doppler Shift?

• Positive Doppler Shift

• Negative Doppler Shift

• No Doppler Shift

• Cannot be determined

Example of a board question: The Doppler shift with a 4 MHz transducer is 3,000 Hz. If the sonographer switches to an 8 MHz transducer, what happens to the Doppler shift?

• What is changing in this question?

• Is it increasing or decreasing?

• How does that affect Doppler shift?

Calculate the Doppler shift based on this information: Transducer: 8 MHz, Velocity of blood: 100 cm/s, Doppler angle: 60°.

• 2.08 kHz

• 3.21 kHz

• 5.55 kHz

• 4.62 kHz

Calculate the Doppler shift based on this information: Transducer: 4 MHz, Velocity of blood: 300 cm/s, Doppler angle: 60°.

• 2.0 kHz

• 3.0 kHz

• 4.0 kHz

• 5.0 kHz

Calculate the Doppler shift based on this information: Transducer: 4 MHz, Velocity of blood: 100 cm/s, Doppler angle: 0°.

• 0 Hz

• 157 Hz

• 5.2 kHz

• 20 kHz

Do you understand how to rearrange the equation to solve for an unknown variable? This will help you answer questions and understand the relationships.

• Yes, I understand how to rearrange equations.

• No, I need more practice on rearranging equations.

• Somewhat, but I could use more examples.

Review CW transducers: Which of the following is a characteristic of CW transducers mentioned in the text?

• High sensitivity

• Low power consumption

• Ability to measure high velocities

• All of the above

In the image below is the blood flowing toward the transducer or away from the transducer?

• Can not determine

• Toward

• Away

For a 2 MHz transducer, if the blood is moving away from the transducer and the reflected frequency is 1,995,000 Hz, what is the Doppler shift, and is it positive or negative?

• 5000 Hz, Positive

• 5000 Hz, Negative

• 1995000 Hz, Positive

• 1995000 Hz, Negative