The inner crystal of an annular phased array transducer creates a ______ focus beam and collects information only from the ______ depths. All other information from the inner crystals sound pulse is ______.

• A. Deep; Deepest; Used
• B. Shallow; Shallowest; Ignored
• C. Mid; Mid-depth; Averaged
• D. None; All; Preserved

Answer: (B)

In an annular phased array, concentric rings are used to shape the focus. The smallest ring—the inner crystal—produces a beam that converges closest to the transducer, giving a shallow focal depth. When relying on this inner ring, it detects information from the shallowest depths, while signals from deeper regions fall outside its narrow focal area and are not used. Those extra signals are ignored to keep the data consistent with a shallow-focus mode. So the inner crystal creates a shallow focus beam, collects information only from the shallowest depths, and ignores other information.