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Phys 254 > Quiz 3 Review Modules 3+4 > Flashcards

Quiz 3 Review Modules 3+4 Flashcards

1
Q

Which of the following is an example of internal focusing?

  1. Shaped crystal
  2. Moving Mirror
  3. Delay lines
  4. Lens
A

Shaped crystal

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2
Q

Which of the following is the most effective way to increase the length of the fruanhofer zone?

  1. Increase the frequency
  2. Increase the aperture
  3. Increase the power
  4. All of the above
A

Increase the power

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3
Q

Which of the following focal lengths would be considered a short focused probe?

  1. 1-3 cm
  2. 1-4 cm
  3. 2-6 cm
  4. 4-10 cm
A

1-4 cm

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4
Q

If the aperture of a 5 MHz array switches from a 4 crystal segment to a 5 crystal segment while scanning to a depth of 5 cm what is true of the near zone length in soft tissue?

  1. It will half
  2. It will double
  3. It will increase
  4. It will decrease
A

It will increase

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5
Q

Side lobes are lower energy beams that radiate away from the primary beam. T/F?

A

True

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6
Q

The depth of the near field increases with increasing transducer diameter. T/F?

A

True

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7
Q

What is the diameter of the beam, relative to the transducer face, at a distance of one near field length in an unfocused transducer?

A

1/2

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8
Q

Which of the following is improved by the addition of mechanical focusing?

  1. Axial resolution
  2. Lateral resolution
  3. Contrast resolution
  4. Temporal resolution
A

Lateral resolution

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9
Q

What is the equation for calculating the far field angle of divergence?

A
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10
Q

Which of the following factors does not effect beam width?

A

Lateral resolution

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11
Q

What is the ongoing process of electronically changing the delay of returning echoes in an array transducer so that they are brough into phase?

A

Dynamic focusing

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12
Q

How is electronic focusing achieved in conventional arrays?

A

Voltage delays

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13
Q

The diameter of an unfocused, 5 MHz, single disc probe is 8mm. If the diameter of this probe changes to 10mm; what would happen to the beam width at the transition point?

A

It increases

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14
Q

What is an advantage of focusing other than decreased beam width in the near field length?

  1. Decreased divergence of the far field
  2. Decreased near zone length
  3. Increased near zone length
  4. None of the above
A

None of the above

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15
Q

When scanning the liver, the technologist decides to add an extra focus. Which of the following actions will maintain a suitable frame rate?

A

Decreased the field of view

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16
Q

What is the limiting factor for pulse repetition frequency?

A

Depth

17
Q

Which of the following transducer would provide the largest near zone length for study of a thyroid gland?

  1. 7.5 MHz, 4 mm diameter
  2. 7.5 MHz, 6 mm diameter
  3. 10 MHz, 4 mm diameter
  4. 10 MHz, 6 mm diameter
A

10 MHz, 6 mm diameter

18
Q

Which of the following would have the biggest impact on improving lateral resolution?

  1. Curving the crystal
  2. Increasing the aperture
  3. Increasing the damping
  4. Increasing the frequency
A

Curving the crystal

19
Q

What will happen to the angle of divergence in the far field if the diameter of the crystal is increased?

A

Decreases

20
Q

Which of the following is an alternative name for axial resolution?

A

Range

21
Q

Based on the information provided in this image, what type of resolution is responsible for poorly resolved cystic structure indicated by the arrow?

A

Elevational resolution

22
Q

How is transmit focus achieved in an array probe?

A

Delaying the voltages pulses to the crystal

23
Q

What is required to improve a machines capability for contrast resolution?

A

Increase the bit depth

24
Q

How would a sonographer define contrast resolution?

A

The ability to distinguish between subtle gray scale differences in soft tissue

25
Q

What is the arrow marked as “A” demonstrating?

A

Slice thickness

26
Q

What is the arrow marked as “B” demonstrating?

A

Beam width

27
Q

When frequency is increased, what happens to the transmitted pulse in the patient?

A

Penetration is decreased

28
Q

What are the three different types of spatial resolution?

A
  1. Range
  2. Angular
  3. Section thickness
29
Q

What is the best range resolution when scanning with a 4 MHz unfocused probe that has a crystal radius of 5 mm in a 2 cycle system

A

0.39 mm

30
Q

If the angle of divergence in the far field increases then what can one conclude about the near field length?

A

It is decreased

Phys 254 (19 decks)

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