Ultrasound Physics - Image Generation

Audience: Radiology Residents Learning Objectives: Describe the physics of ultrasound image generation Explain how transducer frequency impacts image quality Describe user controlled features that can impact image quality Summary: Mechanic energy transmitted as waves Alternating compression and rarefaction Waves are reflected, scattered, refracted, or absorbed Reflected waves produce the image you want Scatter, refraction, absorption decrease signal, increase noise and create artifacts Strength of Reflection is base on tissue interfaces The difference in acoustic impedance Surface Size Orientation High frequency probe – Low penetrance, high resolution Low frequency probe – high penetrance, low resolution Harmonics and compound imaging improve image quality and may reduce References: Hertzberg, Barbara S., and William D. Middleton. Ultrasound: the requisites. Elsevier Health Sciences, 2015. Hangiandreou, Nicholas J. "AAPM/RSNA physics tutorial for residents: topics in US: B-mode US: basic concepts and new technology." Radiographics 23.4 (2003): 1019-1033. Boote, Evan J. "AAPM/RSNA physics tutorial for residents: topics in US: Doppler US techniques: concepts of blood flow detection and flow dynamics." Radiographics 23.5 (2003): 1315-1327.