US Physics 211-240
Card Set Information
US Physics 211-240
The spectrum of frequencies emitted by a pulsed-wave transducer is known as:
What is the optimal thickness for the matching layer?
One-fourth of the wavelength
A method used to improve frame rates with multizone electronic focusing is termed:
Which of the following best describes the f number?
Focal length divided by the aperture
If you wish to use an array transducer that allows you to control transmit focal depth, what type would you select?
Linear array, Convex array, Phased array or Annular array (Any of the above)
If you wish to perform a sonogram with the largest possible field of view in both the near field and at depth, what type of array transducer would be most preferable?
A commonly used material in modern transducer elements is:
Lead zirconate titanate
You are using a linear array transducer to evaluate the thyroid grand. For standard B-mode imaging, this transducer most likely produces pulses of how many cycles?
One to three
What is the purpose of applying multiple matching layers to the transducer face?
Multiple matching layers result in increased transducer bandwidth
For a nonfocused transducer, the region between the transducer element and the point at which the sound beam is narrowest is called the:
Near zone length
Axial resolution is chiefly determined by:
What is the main advantage of using an intracavitary prove compared to a standard transducer?
Since the intracavitary prove is closer to the area of interest, a higher-frequency transducer can be used, resulting in superior spartial resolution
What defines the best axial resolution that can be obtained with a given transducer?
Spartial pulse length ÷ 2
The illustration depicts acoustic pressure vs. distance in a medium in which a sound wave is present. What sound parameter is measured by the length of the bar labeled A in the illustration?
What term describes the ability of an imaging device to separate closely spaced objects?
What happens when pressure is applied to a piezoelectric crystal?
It emits an electrical signal
What type of transducer was used to obtain this image?
The interpreting physician has asked you to use a stand-off pad to evaluate a superficial mass. What is the main advantage the stand-off pad provides to improve the image?
The stand-off pad increases the distance between the transducer and the mass, making it more likely that the mass will be located closed to the elevational focus of the sound beam
What array transducer fires all of the elements for each acoustic scan line, using small time delays to steer the beam?
The shape corresponding to the image created by a phased array transducer most closely corresponds to which of the following?
A linear array will produce which of the following images shapes?
A, C or E
If you are using a transducer with poor elevation resolution, which of the following problems are you most likely to encounter?
Inability to clearly demonstrate small cystic structures
What can you do to achieve a higher frame rate?
Decrease: number of focal zones, line density and sector width (All of the above)
What can you do to improve contrast resolution in the ultrasound image?
Use a 1.5D or multi-row array transducer
Increasing which of the following will result in improved axial resolution?
Which represents the best measure of resolution for modern day ultrasound scanners?
Which of the following transducers produces side lobes?
Mechanical sector, Linear sequential array, Phased array or Convex array (All of the Above)
Which transducer type is best suited to vascular imaging?
Which transducer type is best suited to cardiac imaging?
Which of the following can NOT be evaluated with a tissue-equivalent phantom?