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IN THE NAME OF GOD

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

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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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