For a linear phased array transducer the footprint or the face of the transducer that comes into contact with the skin is described as a small square about 1 cm on each side.

For a linear phased array transducer the footprint or the face of the transducer that comes into contact with the skin is described as a small square about 1 cm on each side.

• A. Round pad about 0.5 cm
• B. Small square about 1 cm on each side
• C. Large rectangle about 2 cm
• D. Narrow strip about 0.2 cm

Answer: (B)

The key idea is identifying the skin-contact surface of the probe. For a linear phased array, this face—the footprint—is a small, square area about 1 cm on each side. This compact, square contact area matches the design of the linear array, which uses many small elements arranged in a line and needs a convenient, uniform surface for good acoustic coupling and easy maneuverability across the skin. A larger or differently shaped surface would not fit the typical probe design or provide the same practical handling and coupling quality. The other shapes described don’t fit the usual linear array footprint. A round pad about 0.5 cm is smaller and round, which isn’t the standard contact face for this type of probe. A large rectangle about 2 cm would be more cumbersome and less representative of the common linear-array face. A narrow strip about 0.2 cm would not adequately cover the array nor provide stable coupling.

The key idea is identifying the skin-contact surface of the probe. For a linear phased array, this face—the footprint—is a small, square area about 1 cm on each side. This compact, square contact area matches the design of the linear array, which uses many small elements arranged in a line and needs a convenient, uniform surface for good acoustic coupling and easy maneuverability across the skin. A larger or differently shaped surface would not fit the typical probe design or provide the same practical handling and coupling quality.

The other shapes described don’t fit the usual linear array footprint. A round pad about 0.5 cm is smaller and round, which isn’t the standard contact face for this type of probe. A large rectangle about 2 cm would be more cumbersome and less representative of the common linear-array face. A narrow strip about 0.2 cm would not adequately cover the array nor provide stable coupling.