How do you calibrate a standardized A-scan probe to obtain tissue sensitivity?

Calibrating a standardized A-scan probe to obtain tissue sensitivity is essential for accurate measurements in ophthalmic ultrasound. The correct method involves placing the probe on a tissue model and adjusting the decibel dial. This process allows you to simulate the human eye's tissue characteristics and provides a practical means to assess how the probe responds to tissue echoes.

Using a tissue model helps in establishing a reference for measurements, and adjusting the decibel dial ensures that the sensitivity levels are set appropriately to discern different tissue types based on their echogenicity. This adjustment is crucial, as it affects the amplitude of the received echoes, directly influencing the accuracy of the measurements you acquire.

Other methods, such as adjusting frequency output or modifying gain settings, focus more on altering the characteristics or amplification of the signal rather than directly assessing sensitivity in the context of biological tissues. Software calibration processes may be relevant in more computational setups but do not provide the direct interaction and adjustment afforded by using a physical tissue model, which is a practical and traditional method in sonography calibration.