6b: Concepts for Diagnosis - Gray Scale

 

Gray Scale refers to imaging the strength of echo reflectivity, judged by brightness intensity during B-scan examination. 

 

Perpendicularity of the examining beam is critical. The object to be judged is brought to the center of the examining screen with the instrument gain set at 90 decibels to demonstrate all echoes maximally. Reduction of gain while observing the intensity of reflections helps establish tissue characteristics. The strongest echoes will remain visible on the screen at low settings while weaker reflections will disappear. Remember, it is essential to be perpendicular to any object you wish to evaluate in Gray scale.

 

Simultaneous A-scan can also be extremely helpful in determining echo strength. During A/B-scan examinations the moveable B-scan vector line establishes which A-Scan is displayed below the B-scan image. Perpendicularity can be established. Amplitudes of A-scan spikes can then be compared. Gain reduction is necessary to image both strong and weak reflections simultaneously.