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Physics > Pulsed Echo Instrumentation > Flashcards

Pulsed Echo Instrumentation Flashcards

1
Q

What is a Transducer?

A

Transforms electrical energy into acoustic energy during transmission and converts returning acoustic energy into electrical energy during reception.

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2
Q

What are the two major functions of an ultrasound system?

A
  • Transmission of electrical signals to the transducer
  • Reception of electrical signals from the transducer
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3
Q

What is the role of the Pulser in an ultrasound system?

A

Creates and controls the electrical signals sent to the transducer that generate sound pulses.

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4
Q

What does the Beam Former do in an ultrasound system?

A

Determines the firing delay patterns for phased arrays.

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5
Q

What is the Master Synchronizer’s function?

A

Maintains and organizes the proper timing and interaction of the system’s components.

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6
Q

What are the 6 major components of ultrasound systems?

A
  • Pulser and Beam Former
  • Receiver
  • Display
  • Storage
  • Master Synchronizer
  • Transducer
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7
Q

What is the definition of Pulser Voltage?

A

Determined by Pulser voltage; the time between one voltage spike and the next.

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8
Q

What is the significance of Pulse Repetition Period (PRP)?

A

Determines imaging depth.

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9
Q

What is the relationship between Signal-to-Noise ratio (S/N) and image quality?

A

S/N ratio is directly related to image clarity, comparing meaningful information to contamination (noise).

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10
Q

What effect does increasing Output Power have on vascular imaging?

A

Most commonly improves image quality.

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11
Q

What is Noise in the context of ultrasound imaging?

A

A random and persistent disturbance that obscures or reduces a signal’s clarity.

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12
Q

Fill in the blank: The Pulser determines the amplitude (power output), ______, & PRF.

A

Pulse Repetition Period

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13
Q

What does the Receiver do in an ultrasound system?

A

Transforms the electrical signals from the transducer into a form suitable for display.

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14
Q

What does the Display present?

A

Processed data in various formats such as a flat screen monitor or spectral plot.

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15
Q

What does Storage in an ultrasound system do?

A

Archives the ultrasound studies.

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16
Q

True or False: The brightness of the entire image is affected by the Pulser Voltage.

A

True

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17
Q

What are the Adjustable user concerns regarding ultrasound imaging?

A
  • Thermal Index
  • Mechanical Index
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18
Q

What is another name for Pulser Output?

A
  • Output Gain
  • Output Power
  • Acoustic Power
  • Transducer Output
  • Acoustic Output
  • Pulser Power
  • Energy Output
  • Transmitter Output
  • Power
  • Gain
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19
Q

What is a Beam Former?

A

A sophisticated electronic device that receives the pulser’s single electrical spike and distributes it to the numerous active elements of an array transducer.

It establishes the correct time delays for dynamic receive focusing and adjusts electrical spike voltages via apodization.

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20
Q

What is the function of the ‘transmit-receive’ Switch?

A

Protects the delicate receiver components from powerful signals created for pulse transmission.

It directs the electrical signals from the transducer to the appropriate electronic and processing components within the ultrasound system.

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21
Q

What is a Channel in ultrasound systems?

A

Made up of a single PZT element in the transducer, the electronics in the beam former/pulser, and the wire that connects them.

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22
Q

What is the purpose of Amplification in ultrasound technology?

A

Each electronic signal returning from the transducer is made larger (dB).

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23
Q

Define Oreamplification.

A

The process of improving the quality of a signal before it is amplified, occurring as close to the active elements as is practical.

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24
Q

What is Compensation in ultrasound imaging?

A

Corrects for attenuation with regards to path length/depth to create an image of uniform brightness (dB).

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25
Q

What are the two functions of Compression in ultrasound?

A
  • Keeps electrical signal levels within the accuracy range of the system’s electronics
  • Keeps an image’s gray scale content within the range of detection by the human eye (20 shades)
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26
Q

True or False: Compression only affects strong signals.

A

False. It only affects weak signals.

27
Q

What does user-controlled compression modify?

A

The gray scale mapping of ultrasound images (dB).

28
Q

What are the two parts of the Demodulation process?

A
  • Rectification: converts all negative voltages into positive voltages
  • Smoothing/Enveloping: places a smooth line around the ‘bumps’ and evens them out.
29
Q

Fill in the blank: The Demodulation process changes the electrical signals within the receiver into a form more suitable for _______.

A

display on a monitor.

30
Q

What does the Demodulation process allow the sonographer to control?

A

Whether low-level gray scale information within the data will appear on the displayed image.

31
Q

What is Dynamic Frequency Tuning?

A

A technique that optimizes frequency for imaging based on depth

This method enhances image quality by using higher frequencies for shallow imaging and lower frequencies for deeper imaging.

32
Q

What does JRA stand for?

A

Justification of Radiation Exposure

JRA emphasizes the importance of minimizing radiation exposure during imaging procedures.

33
Q

What is Shallow Imaging in ultrasound?

A

Imaging that focuses on structures close to the transducer

This typically involves shorter listening times and higher frequency signals.

34
Q

What is the effect of Delay in ultrasound imaging?

A

It refers to the time taken for echoes to return to the transducer

Delay impacts the timing and quality of the received signals.

35
Q

What is Slope in relation to ultrasound imaging?

A

The rate of change in gain across the depth of the image

Slope is important for optimizing image quality at varying depths.

36
Q

What is the significance of a shorter listening time?

A

It allows for quicker imaging and reduces the chance of motion artifacts

Shorter listening times are often associated with shallow imaging techniques.

37
Q

What does Knee refer to in a Time Gain Compensation (TGC) curve?

A

The point where variable compensation begins

It indicates a transition in how compensation is applied as depth increases.

38
Q

What is the effect of a shorter PRP?

A

It increases the Pulse Repetition Frequency (PRF)

A shorter PRP allows for more frequent pulse emissions, improving real-time imaging.

39
Q

What are the components of a TGC curve?

A
  1. Near Gain
  2. Far Gain
  3. Variable Compensation
  4. Maximally Compensated Reflections
  5. Maximum Compensation Limit

These components help to adjust the gain of the ultrasound signal based on depth.

40
Q

What is Near Gain in the context of TGC?

A

The first part of a TGC curve where reflections undergo small, constant compensation

This applies to superficial depths where echo signals are generally stronger.

41
Q

What does Far Gain indicate in a TGC curve?

A

The depth at which variable compensation begins

Far Gain is critical for adjusting the gain for deeper structures.

42
Q

What is the role of the Receiver’s Gain?

A

To amplify the received signals after they return to the transducer

This component is essential for enhancing the clarity of the image.

43
Q

What are the advantages of Digital Beam Formers?

A
  1. Software programming
  2. Extremely stable
  3. Versatile

Digital beam forming technology improves image processing and allows for advanced imaging techniques.

44
Q

What is Deep Imaging in ultrasound?

A

Imaging that focuses on structures located further from the transducer

This method typically involves longer listening times and lower frequency signals.

45
Q

What is meant by As Low As Reasonably Achievable (ALARA)?

A

A principle to minimize patient’s ultrasound exposure while maintaining image quality

ALARA encourages the use of the least amount of radiation necessary for effective imaging.

46
Q

What are the three brightness controls in ultrasound?

A
  1. Power Output/ Acoustic Output
  2. Time Gain Compensation
  3. Receiver’s Gain

These controls allow operators to adjust the overall brightness and clarity of the ultrasound image.

47
Q

What does the fourth part of a TGC curve represent?

A

Reflections that are maximally compensated by the system

This ensures that the signals returned from deeper structures are adequately amplified.

48
Q

What does the fifth part of a TGC curve indicate?

A

The maximum amount of compensation that the receiver can provide

This limit is crucial for understanding the capabilities of the ultrasound system.

49
Q

What are the main receiver functions?

A

Amplification, Compensation, Compression, Demodulation, Reject

These functions process signals in ultrasound imaging.

50
Q

What does amplification do in receiver functions?

A

Alters signal-to-noise ratio

It increases the strength of the received signals.

51
Q

What is the effect of compensation in receiver functions?

A

Alters patient exposure

It adjusts the signals based on depth to maintain image quality.

52
Q

What is the role of compression in receiver functions?

A

Changes brightness of entire image

It reduces the dynamic range of signal amplitudes.

53
Q

What does demodulation accomplish?

A

Prepares electrical signals to be suitable for display

This includes processes like rectification and enveloping/smoothing.

54
Q

What does the reject function do?

A

Weak echoes appear or are eliminated from image

This function filters out low-amplitude signals.

55
Q

How does receiver gain affect an ultrasound image?

A

Changes gray scale

It modifies the brightness of the image.

56
Q

What is time gain compensation (TGC)?

A

Depth Gain Compensation (DGC)

TGC adjusts the gain at various depths of the tissue.

57
Q

What does swept gain do?

A

Compression, dynamic range

It adjusts the gain over a range of frequencies.

58
Q

True or False: Receiver gain affects the signal-to-noise ratio.

A

False

Receiver gain does not affect the signal-to-noise ratio.

59
Q

What should be decreased first if the image is too bright?

A

Amplification

Reducing amplification can help in achieving a balanced image brightness.

60
Q

What happens when compensation is applied based on reflector depth?

A

Signals treated differently

This is crucial for maintaining image quality across varying depths.

61
Q

Fill in the blank: The receiver function that eliminates weak echoes is called _______.

A

Reject

This function helps to enhance the quality of the displayed image.

62
Q

What is the effect of changing the receiver gain?

A

Changes brightness of entire image

The entire image can appear brighter or darker depending on the gain adjustment.

63
Q

What is the purpose of threshold in receiver functions?

A

Suppression, priority control

It helps to prioritize certain signals over others.

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