What causes edge shadowing in ultrasound?

Abstract. Acoustical shadowing occurring at the edges of curved objects is one of the most frequently observed artifacts in ultrasound imaging. This artifact has been generally ascribed to refraction and reflection effects at the boundary between the curved object and the surrounding tissues.

What is ultrasound refraction?

Refraction. Refraction occurs when the ultrasound signal is deflected from a straight path and the angle of deflection is away from the transducer (Animation 1.2. 5). Ultrasound waves are only refracted at a different medium interface of different acoustic impedance.

What does TGC stand for ultrasound?

This application report explains a vital functionality in Medical Ultrasound Systems called Time Gain Control or Time Gain Compensation (TGC).

What is dirty shadowing in ultrasound?

Clean and dirty shadowing are common phenomena in ultrasound (US) imaging. Clean shadowing is thought to be produced by sound-absorbing materials (ie, stones), and dirty shadowing is thought to be produced by sound-reflecting materials (ie, abdominal gas), but these properties are not consistent.

How do you fix the reverberation artifact ultrasound?

The artifact can be improved by changing the angle of insonation. If the angle is changed, the pulse is reflected off at an angle and either a) does not encounter the second parallel strong reflector, or b) is reflected away from the transducer.

Which is an example of acoustic shadowing on an ultrasound?

Posterior acoustic shadowing refers to a darkening of the ultrasound image beneath a structure with a large amount of reflectivity. Examples of this include decreased signal underneath tumors, calcifications, or foreign bodies (Figure 13.4).

How do I get rid of reverberation artifact ultrasound?

What is the difference between overall gain and TGC?

The TGC creates uniformity in the brightness of the echoes when used in conjunction with the overall gain. The best approach is to center all the TGC settings before adjusting the overall gain. After adjusting the overall gain, the TGC can then be adjusted to compensate for attenuation at specific depth.

How do I adjust TGC?

How do I adjust TGC on an image?

1. Touch anywhere on the screen and slide your finger left or right to activate the Gain control.
2. Use the Near, Mid, and Far sliders to adjust the image as needed by tapping a slider and moving your finger right or left to increase or decrease the percentage.

What are 3 artifacts produced during ultrasound?

Reverberation, Comet Tail, and Ring-Down Reverberation artifacts arise from multiple echoes generated between highly reflective and parallel structures that interact at a perpendicular angle to the ultrasound beam.

Where are reverberation artifacts most likely to occur?

Reverberation artifact occurs at tissue interfaces with large differences in acoustic impedance. A classic example of reverberation artifact occurs in the normal lung at the pleural surface, called A-lines ( Figures 6.1 and 6.2 ).