______ are the same as the side lobes, but occur with array transducers.

______ are the same as the side lobes, but occur with array transducers.

• A. Echoes
• B. Artifacts
• C. Harmonics
• D. Grating lobes

Answer: (D)

When an ultrasound array forms a beam, energy is focused in the main direction, but some energy naturally appears in other directions around that beam—these are side lobes. In array transducers, if the element spacing is large relative to the wavelength, those secondary directions can become pronounced and show up as additional strong directions of energy known as grating lobes. They look like side lobes but are tied to the regular, periodic structure of the array. Grating lobes can produce false echoes from structures outside the main beam, degrading image quality. Other terms like echoes are just the actual returned signals, harmonics are multiples of the transmitted frequency from nonlinear propagation, and artifacts is a broad category that doesn’t specifically name this phenomenon. Grating lobes are the correct descriptor because they are the array-specific counterparts to side lobes.

When an ultrasound array forms a beam, energy is focused in the main direction, but some energy naturally appears in other directions around that beam—these are side lobes. In array transducers, if the element spacing is large relative to the wavelength, those secondary directions can become pronounced and show up as additional strong directions of energy known as grating lobes. They look like side lobes but are tied to the regular, periodic structure of the array. Grating lobes can produce false echoes from structures outside the main beam, degrading image quality. Other terms like echoes are just the actual returned signals, harmonics are multiples of the transmitted frequency from nonlinear propagation, and artifacts is a broad category that doesn’t specifically name this phenomenon. Grating lobes are the correct descriptor because they are the array-specific counterparts to side lobes.