Final answer:
In ultrasound imaging, sonographers can adjust the Pulse Repetition Frequency (PRF), Duty Cycle, and Pulse Duration but not the frequency of the transducer itself, which is fixed for each transducer.
Step-by-step explanation:
When using ultrasound machines, sonographers can alter several settings to optimize the imaging based on the diagnostic needs. The parameters that can be adjusted include the Pulse Repetition Frequency (PRF), Duty Cycle, and Pulse Duration. However, they cannot directly change the frequency of the transducer as it is hardware dependent but can select different transducers with various fixed frequencies as needed. So, the correct answers would be B (PRF), D (Duty Cycle), and E (Pulse Duration).
Pulse Repetition Period is inverse to PRF and thus changes with it.
Pulse Repetition Frequency (PRF) is the number of pulses transmitted per second and is adjustable on the machine.
The Duty Cycle is the fraction of time the ultrasound is actually transmitting and can be manipulated since it depends on both the pulse duration and PRF.
Pulse Duration is the length of time the pulse lasts and is adjustable.