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US PRACTICAL

US PRACTICAL. * NEAR ZONE is the nearest area to the transducer & it always has the same diameter of the transducer, BUT if the transducer: Linear the near zone length is long (Deeper).

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US PRACTICAL

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  1. US PRACTICAL

  2. * NEAR ZONEis the nearest area to the transducer & it always has the same diameter of the transducer, BUT if the transducer: • Linear the near zone length is long (Deeper). • Concave the near zone length is short. • * FAR ZONEis the farthest area from the transducer.

  3. Focal zone: is amethod of focusing the U/S beam by Concentrating the acoustic energy over a small area at Specific distance from the transducer . WE CAN MAKE THE FOUCSE BY TWO WAYS: • 1) Concave crystal. • 2) Acoustic lens .

  4. RESOLUTION: We have four different types of resolution: spatial, contrast, temporal, and energy resolution . *Spatial resolution : It is the ability to image small or high contrast objects. E.g., the best spatial resolution found in Mammogram. * Contrast resolution : It is the ability to distinguish one similar tissue from another. E.g., the best contrast resolution found in MRI.

  5. * Temporal resolution:It is the ability to measure & count motion.E.g., the best temporal resolution found in US "Doppler".* Energy resolution:It is the ability to measure & count energy.E.g., the best energy resolution found in NM.N.B.We consider all the resolution types in US EXCEPT Energy resolution.

  6. WE HAVE TWO TYPES OF :SPATIAL RESOLUTION(1) Axial (2) lateral

  7. AXIAL SPATIAL RESOLUTION : it could also call range, depth or longitudinal . • It is the ability to distinguish between two objects close to each other & located along the main axis .Factors affecting axial spatial resolution are: • 1) Spatial pulse length"if SPL increase, ASR will decrease" • 2) Frequency"if freq. increase, ASR & penetration decrease" • 3) pulse duration“ if PP increase, ASR will decrease • 4) Damping material has an affect also, "how quickly a pulse of US can be initiated & extinguished. • 5) Distance between 2 reflectors “ more D, more ASR

  8. *LATERAL SPATIAL RESOLUTION:It could also call transverse or asemouthal.It is the ability to distinguish between two objects close to each other & located perpendicular on the main axis.

  9. Factors affecting lateral spatial resolution are:1) Size (crystal diameter) "smaller diameter, more LSR"2) Beam width 3) Frequency" more freq, more LSR" 4) Distance between 2 reflectors" more D, more ASR"

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