By adjusting imaging depth, the operator changes PRP, PRF, and duty factor. Which item is not changed by depth?

By adjusting imaging depth, the operator changes PRP, PRF, and duty factor. Which item is not changed by depth?

• A. Pulse duration
• B. PRP
• C. PRF
• D. Duty factor

Answer: (A)

Varying imaging depth changes how long the system must wait for echoes, so the pulse repetition period lengthens and the pulse repetition frequency shortens. It also affects the duty factor, since that factor is tied to how often pulses are sent within a given time. The length of each emitted pulse, the pulse duration, is set by the transducer’s excitation and damping and does not depend on how deep you image. So depth changes PRP, PRF, and duty factor, but not pulse duration.

Varying imaging depth changes how long the system must wait for echoes, so the pulse repetition period lengthens and the pulse repetition frequency shortens. It also affects the duty factor, since that factor is tied to how often pulses are sent within a given time. The length of each emitted pulse, the pulse duration, is set by the transducer’s excitation and damping and does not depend on how deep you image. So depth changes PRP, PRF, and duty factor, but not pulse duration.