ultrasound iii

ultrasound iii - BE101 Foundations of Biomedical Imaging...

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UCSD BE101 Fa06 Lecture 12 Slide 1 BE101 Foundations of Biomedical Imaging Fall 2009 David Hall, Ph.D. Department of Bioengineering University of California–San Diego Ultrasound III
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UCSD BE101 Fa06 Lecture 12 Slide 2 Equipment Clinical Use Biological Effects and Safety Future Expectations Suetens’s: Chapter 7 (pages 172-183) Today’s Outline
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UCSD BE101 Fa06 Lecture 12 Slide 3 Ultrasound scanner is small and mobile (unlike other modalities). Transducer connected to Signal Processing box which displays Images in real-time. Variety of ducers for different applications. Highly portable Pocket-size scanners are being developed. Equipment
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UCSD BE101 Fa06 Lecture 12 Slide 4 One-Dimensional Array Transducers Mechanical movement of ducer yields several practical difficulties. Constant displacement between steps and maintaining tissue contact. To reduce mechanical motion, use electronic scanning with an “array transducer” – a collection of many small identical crystals that can be excited independently. Most common are “linear array” and “phased array” transducers, consisting of a 1-D array of crystals: Equipment
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UCSD BE101 Fa06 Lecture 12 Slide 5 One-Dimensional Array Transducers Linear Array: Moves beam linearly by firing its elements sequentially. Equivalent to mechanical translation ( large acoustic window). Phased Array: Changes beam direction by tuning phases of elements. Equivalent to mechanical tilting (small acoustic window – cardiology). Also enables focusing along each line and sector image obtained Equipment 64 to 94 elements close together
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UCSD BE101 Fa06 Lecture 12 Slide 6 One-Dimensional Array Transducers Linear Array: (typically 512 elements over 12 cm) Can also perform focusing by firing neighboring elements (8 to 16) in time-staggered fashion and repeat pattern along total array: Achieve 1 mm Lat. Res. at focal depth. Equipment
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One-Dimensional Array Transducers Phased Array: (typically 64 to 128 elements) Sweep beam through pie-shaped wedge or “sector”. All elements fired for one line (opposed to 8 to 16 for linear array).
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This note was uploaded on 04/30/2010 for the course BENG 101 taught by Professor Silva,g during the Fall '08 term at UCSD.

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ultrasound iii - BE101 Foundations of Biomedical Imaging...

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