What is the term for the ability to distinguish two structures along a path parallel to the sound beam, which is directly related to operating frequency and depends on the transducer and the medium?

What is the term for the ability to distinguish two structures along a path parallel to the sound beam, which is directly related to operating frequency and depends on the transducer and the medium?

• A. Axial Resolution
• B. Lateral Resolution
• C. Temporal Resolution
• D. Contrast Resolution

Answer: (A)

Axial resolution is the ability to distinguish two structures that lie along the direction of the sound beam. This resolution hinges on the spatial pulse length, which is the number of cycles in the pulse multiplied by the wavelength. Higher operating frequency shortens the wavelength, thus shortening the spatial pulse length and improving axial resolution. Since the wavelength depends on the speed of sound in the medium and the frequency, both the transducer and the medium directly influence this parameter. In practice, two reflectors along the beam can be resolved when they are about half a spatial pulse length apart. By contrast, lateral resolution depends on beam width and focusing, temporal resolution relates to frame rate, and contrast resolution concerns gray-scale differences.

Axial resolution is the ability to distinguish two structures that lie along the direction of the sound beam. This resolution hinges on the spatial pulse length, which is the number of cycles in the pulse multiplied by the wavelength. Higher operating frequency shortens the wavelength, thus shortening the spatial pulse length and improving axial resolution. Since the wavelength depends on the speed of sound in the medium and the frequency, both the transducer and the medium directly influence this parameter. In practice, two reflectors along the beam can be resolved when they are about half a spatial pulse length apart. By contrast, lateral resolution depends on beam width and focusing, temporal resolution relates to frame rate, and contrast resolution concerns gray-scale differences.