URR part 3 Flashcards
The location of the ultrasound beam where the diameter is the most narrow is called the:
focus
The Focal Zone is the region around the focus where the beam is:
relatively narrow
_____ has half of its portion located in the Fresnel zone and half of its portion located in the Fraunhofer zone.
focal zone
According to the Doppler equation, for any given velocity, the frequency shift will increase by increasing the:
transmit frequency
Which of the following predicts the onset of turbulent flow?
a. concentration of energy
b. continuity rule
c. aliasing
d. Reynolds numer
d
While evaluating arteries in the body with color Doppler, you are unable to obtain signals from the deeper vessels. What should you do to enhance your ability to demonstrate deep flow?
decrease the ultrasound frequency
Which of the following helps improve the axial resolution in a B-mode image?
a. increase the aperture size
b. increase the bandwidth
c. use focusing with an acoustic lens
d. increase dynamic range
b
Noise arising from small amplitude sound waves intering with each other is called what?
acoustic speckle
What appears as very small amplitude echoes from electrical interference that affects low level echolucent areas?
noise
How many bits are required to display 15 different shades of gray?
4
Line density in a rectangular image is:
the number of scan lines per centimeter
Which of the following will have the greatest improvement of temporal resolution?
a. double the line density and decrease depth by half
b. double the persistence and scan structures more shallow
c. decrease depth from 10 cm to 5 cm and reduce scan lines by half
d. change frequency from 3 MHz to 6 MHz and decrease the line density by half
c
Which of the following is the most appropriate response when a patient refuses an exam?
a. immediately stop the exam and leave
b. convince the patient that the doctor really wants the exam and proceed
c. ignore the patient’s request and continue as planned
d. place restraints and/or sedation and proceed with examination
a
The two most common color mays used in color flow imaging are:
variance and velocity
The velocity scale on the color map is 17 cm/s. If the flow direction is at zero degrees to the sound beam axis, the colors on either end of the bar would represent:
an average velocity of 17 cm/s
You are performing 3D sonography and notice the volume rate is 8 Hz. What does this represent?
number of volumes displayed per second
How many frames must be presented for the human eye to perceive the display without flickering?
30
Which of these is a binary number?
a, 12211221
b. 10000000
c. 98765432
d. 01010102
b
When practicing universal precautions, you should do all of the following except:
a. wash gloves between exams for reuse from one patient to another
b. wash hands immediately after gloves are removed
c. change gloves when moving from one patient to another
d. wear face masks or eye protection whenever there is a possibility of blood splashing into your face
a
When an ultrasound system creates an image in 1/20 of a second, what will be the frame rate?
20 Hz
Which of the following will improve temporal resolution?
a. more pulses per scan line
b. longer time frame
c. longer go-return time
d. low line density
d
Which of the following describes a narrow dynamic range?
a. low contrast
b. low compression
c. bistable
d. low grayscale
c
____ is the number of oscillations per unit of time
the frequency of the sound wave
Sonographic images are usually compressed before sending to PACS in order to:
reduce the time to transmit the image