Post on 01-Jan-2016
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DESCRIPTIONUltrasound Imaging. Basic Principle: sound wave pulse emitted at >20 kHZ , some reflected, and some transmitted. Reflection from single signal – A-scan. Reproduced from http://folk.ntnu.no/stoylen/. B-Mode Imaging. E nergy displayed as:- amplitude, as in A-mode, - PowerPoint PPT Presentation
Ultrasound ImagingBasic Principle: sound wave pulse emitted at >20 kHZ, some reflected, and some transmitted. Reflection from single signal A-scan
Reproduced from http://folk.ntnu.no/stoylen/The second part of the class will deal with the specifics of CT reconstruction, but in the meantime, lets talk a little bit about ultrasound. 1B-Mode ImagingEnergy displayed as:- amplitude, as in A-mode, - brightness, as in B-mode, - motion curve, as in M-mode. 2D image formed with linear or angular sweep.
Reproduced from http://folk.ntnu.no/stoylen/
The A-mode imaging that I described before typically refers to the response to a single wave, while the objective of B-mode is to construct a planar image. This can be achieved through a linear sweep or an angular sweep. 2B-Mode 2D Imaging Image built line by line: i) emitting the pulse, ii) waiting for reflected echoes iii) tilt beam & emit next pulse. Cardiac application: 2D visualization of beating heart. Reproduced from http://folk.ntnu.no/stoylen/
One detail that is important to the implementation of B-mode imaging is that the image is built line-by-line in a manner that entails a wait for the pulse to be reflected and received. 3Doppler Imaging Idea: moving source of sound undergoes Doppler shift. Moving trainBlood flow: exploit frequency shift to estimate motion.
Reproduced from http://folk.ntnu.no/stoylen/ & Wikimedia Commons.