Which transducer maintains the same line density in near and far fields?

• A. Linear array
• B. Curved array
• C. Phased array
• D. Tightly curved array

Answer: (A)

Line density is the number of scan lines displayed per centimeter across the image. A transducer that keeps this spacing constant from near to far field uses parallel scanlines, so the lines do not spread out as depth increases. A linear array fires elements to produce parallel beams, resulting in scanlines that stay evenly spaced regardless of how deep you image. That means the line density remains the same in near and far fields.

In contrast, curved or phased arrays produce fan- or sector-shaped beams that diverge with depth, causing lines to spread apart as depth increases. This changes the spacing between lines and reduces line density in the far field. So the linear array is the type that maintains constant line density from near to far field.