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IN THE NAME OF GOD

Explore the principles of real-time imaging in ultrasound, including advantages like rapid updates and improved resolution with increased lines of sight. Learn about limitations such as limited field of view and the role of frame rate in minimizing motion artifacts.

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IN THE NAME OF GOD

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  1. IN THE NAME OF GOD Chapter 7 IMAGE FORMATION IN REAL-TIME IMAGE

  2. Principle of real-time imaging • The displayed image is continuously & rapidly updated with new scan at least 30 time per second. • A different position of transducer produce information a long a new line of sight. • Motion artifact is not important as the frame rate is fast. • The resolution of the image is improved as the number of line of sight is increased. • Major disadvantage is the limited FOV

  3. Lines of sight • The interested area is swept and multiple images are formed one after another each composed of multiple lines of sight. • Every scan line requires one pulse of ultrasound waves to probe interfaces along it’s path.

  4. Lines of sight • As motion becomes more rapid a faster frame rate is necessary to display the structure without jerkiness. • Frame rate: 5-40 image per second. • Number of scan line: 50 & 200 depending a scan condition.

  5. Time constraints • A finite amount of time is necessary for travel of ultrasound wave. • Extending the scanning depth requires increased measurement time.

  6. The maximum frame rate • FR (number of image acquired per second); R scan range, n number of lines of sight, and PRF pulse repetition Frequency • Both frame rate and number of line can be adjusted downward. • The number of lines may be reduced without a loss resolution by narrowing the field of view.

  7. Beam width • Multiple small objects equidistant from the transducer are not resolved when encompassed by the beam. • Multiple samplings with successive narrow beams enable the objects to be observed as separate structures.

  8. Increasing resolution with more line of sight; Lateral resolution) • Lateral resolution of the image is improved as the number of line of sight is increased.

  9. Temporal resolution • As motion becomes more rapid, a faster frame rate is necessary. Point to be considered are: • Restrictive instances of the frame rate: • The need for good spatial resolution, provided by a large number of lines of sight. • The finite transit time for ultrasound pulse.

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