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RAD4 > Final > Flashcards

Final Flashcards

1
Q

At what frequency do US waves travel through soft tissue?

A

1540 m/s

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2
Q

What are the three important properties of US?

A

Wavelength, wave frequency, acoustic velocity

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3
Q

What are the 4 interactions of US with tissues?

A

Absorption, reflection, scatter, refraction

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4
Q

What is absorption?

A

The strongest interaction between US and ST

Strongly contribute to beam attenuation during propagation

Increases as US frequency increases

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5
Q

What is reflection?

A

It occurs at the surface of a medium

Allows of image reconstruction

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6
Q

What is scatter?

A

Occurs in all directions from particles whose dimensions are smaller then the US wavelength

Causes a loss of wave intensity out of the main direction of the US beam

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7
Q

What is refraction?

A

When the US beam bend when it enters a medium of different wave velocity at non-normal incidence

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8
Q

When the US beam travels from an area of low sound velocity to an area of high sound velocity, the beam will —-

A

bend away from normal

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9
Q

When the US beam travels from an area of high sound velocity to an area of low sound velocity, the beam will —

A

bend toward normal

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10
Q

What is continous US

A

An older style of US
When the transducer will continously send out US waves

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11
Q

What is continous US

A

An older style of US
When the transducer will continuously send out US waves and would need a receiver to receive the reflected waves

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12
Q

What is pulsed US?

A

A new style of US

Usually 3-5 cycles in a length

Allows the transducer to receive the waves back and form an image

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13
Q

What is the piezoelectric effect?

A

The process of the US waves being reflected and scattered back to the transducer, which then is converted in electrical signals to create an image

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14
Q

What is the transducer?

A

The most important component of the US system
Produces US pulses and receives US echoes

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15
Q

How strong is a curvilinear transducer and what is it used for?

A

4MHz
Used for abdomen, pelvis, obstetric applications

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16
Q

How strong is a linear transducer and what is it used for?

A

7MHz
Used for vascular applications and superficial structures

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17
Q

How strong is a transvaginal and transrectal transducer?

A

8MHz

18
Q

What is lateral resolution?

A

How close two objects can be perpendicular to the axis of the beam and still be detected as two distinct entities

19
Q

What controls lateral resolution?

A

Beam width and shifting the focus on the US machine

20
Q

What is axial resolution?

A

The ability to separate structures parallel to the US beam
Based on wavelength

21
Q

What are the requirements of an US machine?

A

Uninterrupted power supply, processes to transform the acquired data into an image, a means to display the image, a hard drive to record the examination

22
Q

What are the limitations of US in general?

A

Highly operator dependent
Bone and air cause the US wave to reflected
As US waves interact they lose energy as heat, degrading image quality that can render a non-diagnostic image

23
Q

What is A mode

A

Amplitude mode

24
Q

What is A mode used for?

A

Ophthalmology and was used to determine mid-line in the brain

25
Q

What is B mode?

A

Brightness mode
A mode pulse are converted into “brightness dots”

26
Q

What is B mode used for?

A

Baby scan, brain scans, testes

27
Q

What is M mode?

A

Motion mode
Shows how the structures intersected by a line (placed along the area of interest) move toward or away from the probe over time

28
Q

What is M mode used for?

A

Heart rate

29
Q

What is Fresnel zone?

A

Near field

30
Q

What is Fraunhofer zone

A

Far field

31
Q

What is the direct piezoelectric effect?

A

An applied pressure wave generating a voltage pulse that is used in the reception of echo pulses

32
Q

What is the converse piezoelectric effect?

A

An applied voltage producing a pressure waves and is responsible for US transmission

33
Q

What makes up a routine abdominal US examination?

A

Aorta, pancreas, liver, biliary system, kidneys and spleen

34
Q

What are the complication involved with an urgent abdominal US?

A

No fasting - gallbladder wall appears thickened and mimic a pathology

35
Q

How do you prepare the patient for an urgent abdominal US

A

Have the patient on an IV drip, analgesics and antibiotics if WCC is high

36
Q

How do you prepare a diabetic patient for an abdominal US?

A

Plan the appointment around the patient’s schedule to facilitate fasting and the meal associated with insulin

37
Q

What should a patient do to prepare for an abdo US if they take medication?

A

Depending on the medication, have the patient wait until after the examination to take it, or have them drink a small glass of water to wash it down

38
Q

What do you do if the patient forgets to fast?

A

This is common with non-English speaking, elderly and patients with poor memory
Rebook the appointment

39
Q

What are two causes of gastric stasis?

A

Ileus - where the peristaltic motion of the bowels cease due to neurogenic obstruction
Positional stasis - when the patient eats a meal directly prior to going to bed and rises shortly before the examination time

40
Q

What are the clinical indications of an abdo US specific to the pancreas?

A

Painless jaundice, palpable central abdominal mass, raised serum amylase, pain consistent with pancreatitis

41
Q

What are the clinical indications of an abdo US specific to the liver?

A

Abnormal liver function test, clinical enlarged liver, pain in RUQ, mets, apparent jaundice, f/u from other imaging modalities

42
Q

What are the clinical indications of an abdo US specific to the biliary tree?

A

Investigation of jaundice, abdominal pain, ?gallstones, symptoms of acute cholecystitis

RAD4 (3 decks)

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