US Physics 241-270
Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will:
Decrease the wavelength
You notice a loss of detail in the lateral dimension of the ultrasound image. What can you do to improve this?
Decrease the scan line density
You are performing a sonogram on a patient with highly attenuating tissue. Which of the following solutions would be most likely to improve penetration through the tissue?
Choose a lower-frequency transducer
This image was obtained with a linear array transducer. The trapezoidal field of view increases the field of view. How is the trapezoidal shape created?
Electronic beam steering
In the image above, how many transmit focal zones are being used?
What type of probe was used to take this image?
What best describes the method used to create the triangular-shaped image format in the above?
Electronic steering with most elements fired for each pulse-echo sequence. Small time differences steer the beam
You can reduce beam width to improve spatial resolution in the image by which of the following?
Which transducer frequency would have the thinnest crystal?
One with a 15 MHz center frequency
What component of pulsed-wave transducer helps to reduce the spatial pulse length and improve axial resolution?
Which transducer would have a lower density in the far field compared to the near field?
Curved, Tightly curved array and Phased array
What transducer component reduces reflection at the transducer/skin interface?
Axial resolution is improved with:
Increased bandwidth, Shorter pulse length or Shorter wavelength (All of the above)
What is a side lobe?
Sound beam emitted from the transducer that travels in a different direction from the main beam
What is the purpose of curving the transducer elements or applying a lens over the elements?
To provide focusing in the out-of-plane (elevational) direction
What advantage is obtained by steering a linear array transducer to create a trapezoidal shape to the display as demonstrated in this image?
Improved field of view
What type of transducer was used to create this image of the uterus?
Tightly curved array
What disadvantage is related to the Tightly curved array transducer?
Lateral resolution degrades with depth
What advantage is related to the Tightly curved array transducer?
Field of view is improved
What best describes the difference between the ultrasound frequencies used for Doppler and for B-mode imaging with a given transducer?
The frequency for Doppler is usually lower than for imaging
In order to focus a sound beam relatively far away from the transducer, it is advantageous to:
Increase the diameter of the element
Which factor LEAST influences axial resolution?
Spatial pulse length is equal to:
The wavelength times the number of cycles in the pulse
What is the disadvantage of using multiple transmit focal zones?
Decreased temporal resolution
What is the advantage of using multiple transmit focal zones?
Increased lateral resolution
What factor LEAST influences lateral resolution?
Which transducer will exhibit the LEAST amount of volume averaging?
1.5D or multi-row array
The ability to differentiate between two regions having similar echogenicity, such as in this liver image with focal fat, is termed:
Imaging frame rate decreases when you?
Increase sector width
The optimal technology for cardiac scanning is:
US Physics 241-270