Socarative Quiz 3

Question 1

Which of the following differenitietes the far field from the near field?

1. It is more uniform
2. It is less divergent
3. It is less attenuating
4. It is optimal for resolution

Answer 1

It is more uniform

Question 2

Which of the following factors are considered when determining the usable beam shape?

1. Spatial resolution, contrast resolution and temporal resolution
2. Spatial resolution and temporal resolution only
3. Spatial resolution and contrast resolution only
4. Crystal thickness and frequency
5. Spatial resolution and aperture

Answer 2

Spatial resolution and aperture

Question 3

During a scan, a sonographer adjusts the focal depth from 5 cm to 6 cm. What two automatic adjustments must be made by the system to maintain the same lateral. Resolution at the new focal depth?

Answer 3

Increase the transmit delay curve and increase the aperture

Question 4

A gallbladder stone with a width of 2 mm is reported on a CT scan. What width of the stone will be reported with ultrasound, using a mechanical probe with an element radius of 3 mm, scanning the stone at the point of maximum resolution?

Answer 4

3 mm
(Point spreading, because the structure is in the area of focus it gets bigger until 3mm. This goes for structures at 1mm. If they were above the 3mm then it would it would be whatever the size of the structure is)

Question 5

As sound propagates from reflectors the aperture increase as the delay correction is reduced. What is this known as?

Answer 5

Receive focus

Question 6

What is the depth resolution of a 3 cycle system, using a 10 mm disc transducer, operating at 5 MHz at a distance of one NZL?

Answer 6

Let’s pull out some numbers
Ring down = 3
Diameter = 10 mm
Operating frequency = 5 MHz
NZL = 1

Depth resolution = what?
Because we are looking for depth then we know that are looking for LARD or Axial resolution.

There for A/R = 1/2 SPL
SPL = lambda X RD
Lambda = C/F or 1.54/5 or 0.3

SPL = 0.3 x 3
SPL = 0.9mm

A/R or Depth resolution = 0.45mm

Question 7

A single disc probe that has NZL of 80 mm can be focused at a depth of 100mm T/F?

Answer 7

False

Question 8

What is the minimum number of rows of crystals a transducer requires to electronically focus the elevational plane?

Answer 8

3 minimum. 2 would be the minimum for steering.

Question 9

Which of the following is the most important factor in determining a systems contrast resolution?

1. Bit depth
2. Matrix size
3. Dynamic range
4. Number of gray scale maps

Answer 9

Bit depth

Question 10

When scanning a frame rate of 20 Hz is indicated on the display. Assuming a single focus is used, which of the following will result in a frame rate of 40 Hz?

1. Increase the PRF
2. Half the depth of interest
3. Half the number of scan lines per frame
4. Half both the depth and scan lines per frame

Answer 10

1. Half the depth of interest
2. Half the number of scan lines per frame