Which imaging application has the lowest FDA-approved SPTA exposure values?

Which imaging application has the lowest FDA-approved SPTA exposure values?

• A. Ophthalmic
• B. Cardiac
• C. Peripheral vascular
• D. Fetal imaging

Answer: (A)

SPTA exposure reflects how much ultrasound energy per unit area is deposited over time at the location of highest energy in the beam. The eye is exquisitely sensitive to both heating and mechanical effects, and the retina has limited capacity to dissipate heat. Because even small energy deposits can cause retinal damage, safety standards impose very strict, low SPTA limits for ophthalmic imaging. Other imaging targets—like the heart, peripheral vessels, or a developing fetus—tolerate higher energy levels overall and require greater depth and resolution in many cases, so their FDA-approved SPTA exposure values are higher. In short, the eye’s high sensitivity drives ophthalmic imaging to the lowest permissible SPTA exposure.

SPTA exposure reflects how much ultrasound energy per unit area is deposited over time at the location of highest energy in the beam. The eye is exquisitely sensitive to both heating and mechanical effects, and the retina has limited capacity to dissipate heat. Because even small energy deposits can cause retinal damage, safety standards impose very strict, low SPTA limits for ophthalmic imaging.

Other imaging targets—like the heart, peripheral vessels, or a developing fetus—tolerate higher energy levels overall and require greater depth and resolution in many cases, so their FDA-approved SPTA exposure values are higher. In short, the eye’s high sensitivity drives ophthalmic imaging to the lowest permissible SPTA exposure.