Using a 5 MHz, 40 mm linear array transducer to image a structure, what is the width of the image?

• A. 20 mm
• B. 40 mm
• C. 60 mm
• D. 80 mm

Answer: (B)

The width of the image is set by the transducer’s aperture in the lateral direction. A 40 mm linear array has a physical width of about 40 mm, so the field of view across the image is essentially 40 mm. The 5 MHz frequency affects how detail is resolved and how deep the ultrasound can image, not how wide the image appears. So the image width corresponds to the transducer width, about 40 mm. The other options would require a larger aperture or stitching multiple scans, which isn’t how a single-frame image from this transducer is produced.