RIU 320 Lecture Notes - Lecture 70: Refraction, Sound

• School: GVSU
• Department: Radiation and Imaging - Ultrasound
• Course: RIU 320
• Professor: Angela Malone

Document Summary

Created when a sound pulse changes direction during transmission. Refraction occurs when a sound wave strikes a boundary obliquely and the media on either side of the boundary have different propagation speed. Assumption #1, sound travels in a straight line, is invalid. The copy is side by side, or at the same depth as the true. With two-dimensional imaging, sonographers may believe that the imaging plane is thin and uniform, similar to a thin slice of cheese. In reality, the imaging plane is three dimensional and is neither thin nor of uniform thickness. The beam flares out like the bell of a trumpet. Therefore, reflections from structures above or below the assumed imaging plane may appear in the image. Slice thickness is also called section thickness artifact or partial volume artifact. Slice thickness artifact is related to the dimension of the beam that is perpendicular to the imaging plane. Elevational resolution is determined by the thickness of the imaging plane.