Varying the excitation voltage to each element in the group used to form the ultrasound pulse is called?

• A. Dynamic aperture
• B. Interelement isolation
• C. Subdicing
• D. Apodization

Answer: (D)

Varying the excitation voltages across the elements to shape the transmitted beam is apodization. By tapering the amplitudes of the elements in the array (for example with a Hanning or other window), you suppress the outer lobe energy in the beam pattern, which reduces sidelobes and improves image contrast. This technique directly modifies how much each element contributes to the pulse, which is exactly what the question describes.

Dynamic aperture, on the other hand, deals with changing how many elements are active to optimize focusing at different depths, not with weighting the excitation. Interelement isolation refers to preventing electrical interaction between elements to reduce cross talk, and subdicing involves splitting elements into smaller parts to alter the beam and reduce grating lobes—neither of these describe changing the excitation levels among elements.