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RAD 102: Radiographic Technique > Ch 31-34 > Flashcards

Ch 31-34 Flashcards

1
Q

Measure of the sensitivity and accuracy by which the image receptor converts the incoming data to the output viewing device
Measures ability to view small or low-contrast structures
Very important for digital mammography
SNR^2output/SNR^2input
Higher value increases the ability to view small/low-contrast structures that are greatly valued

A

Detective quantum efficiency (DQE)

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2
Q

All activities that provide adequate confidence that a radiology service will render consistently high-quality images and services
Evolutionary process that provides quality images and services
Medical, technical, or managerial in nature
Identifies, monitors, and resolves problems

A

Quality assurance

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3
Q

The aspect of quality assurance that monitors technical equipment to maintain superior standards
Rooted in the need to stabilize the various equipment components of the rad imaging chain

A

Quality control

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4
Q

Figure that is calculated as a percentrage of the total number of images produced during the period of the study

A

Total repeat rate

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5
Q

SNR

A

Signal-to-noise ratio (want it to be high)

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6
Q

4 things HIPAA set standards for

A

Electronic record security
Electronic formats for record keeping
Electronic identifiers and codes
Requirements for confidentiality and privacy rules

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7
Q

Largest hospital accreditation agency
Establishes quality standards, assesses them and provides certification that individual institutions have met the agency’s standards

A

Joint Commission on the Accreditation of Healthcare Organizations (JCAHO)

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8
Q

How often are x-ray machines checked?

A

Twice a year

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9
Q

Important for proper recorded detail

Biggest range that they can be & still be accurate: + or - 50%

A

Focal spot size estimation

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10
Q

3 types of focal spot test tools

A

Line pair resolution tools
Star test patterns (most common)
Pinhole cameras (least common)

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11
Q

Measured by using dosimetry equipment to determine amount of filtration (total filtration = inherent + added) that will reduce beam intensity to one-half of its original value
Physicists come in & test this
Computerized quality control dosimeters provide a digital readout of the HVL

A

Half-value layer

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12
Q

Why do you want the collimator to be accurate?

A

You could overexpose or clip anatomy

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13
Q

What percentage of accuracy must a collimator test tool be?

A

+ or – 2% SID

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14
Q

What percentage of accuracy must light field and x-ray beam congruence be?

A

SID allowance of +/-2%

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15
Q

What percentage of accuracy must the centering mark within the light field CR?

A

1%

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16
Q

What percentage of accuracy must the central ray be?

A

SID allowance of 1%

17
Q

What accuracy should the distance indicator be?

A

±10%

18
Q

What accuracy should the centering indicator be?

A

±2%

19
Q

Computerized dosimeter provide digital readouts/printouts of avg & single-pulse kVp
Make sure machine is using kVp that’s set

A

Kilovoltage accuracy

20
Q

What accuracy should the kilovoltage be?

A

±5 kVp

21
Q

3 types of timer accuracy tools

A 
Computerized dosimeters (more accurate and easier to use than tops)
Spinning top (single phase)
Motorized spinning top (can still be use today, three phase)
22
Q

What accuracy should the timer be?

A

±5%

23
Q

mA station accuracy confirmed by mR/mAs measurement

Computerized dosimeter

A

mR/mAs and Milliamperage Linearity

24
Q

What accuracy should mR/mAs and milliamperage linearity be?

A

+/-10% between mA stations

+/-10% between high and low mA stations

25
Q

Multiple exposures made with the same tech factors and seeing if it’s producing the same amount of radiation each time
Computerized dosimeter

A

Exposure reproducibility

26
Q

What accuracy should exposure reproducibility be?

A

±5%

27
Q

What are the source to skin distance limits in fluoroscopy?

A

Shouldn’t be capable of placing the tube target closer than 15” (38 cm) or for mobile/c-arm 12” (30 cm) to the patient’s skin surface

28
Q

What accuracy should ion sensitivity be in AECs?

A

±10%

29
Q

What accuracy should exposure reproducibility be in AECs?

A

±1%

30
Q

Commonly utilized computerized exposure control units that combine an AEC system with exposure factors to correspond to specific anatomical procedures

A

Automatically programmed radiography

31
Q

Device used to measure part thickness

A

Caliper

32
Q

Maximum kVp that result in images with appropriate contrast
Produces lower contrast and minimum patient dose
Has sufficient penetration

A

Optimal kVp

33
Q

4 advantages of fixed kVp exposure systems

A

Reduces x-ray tube wear because when lower mAs is used it doesn’t get as hot & wear down as easily
Allows for shorter exposure times
Thus reduces patient motion
Easier to memorize

34
Q

What is a disadvantage of fixed kVp exposure systems?

A

Higher amount of scatter results in reduced image contrast (more shades of gray)

35
Q

2 advantages of variable kVp exposure systems

A

Allows for small changes in exposure for small changes in part thickness
Higher contrast

36
Q

3 disadvantages of variable kVp exposure systems

A

More patient dose
Higher repeat rate
Tube wear, etc.

37
Q

kV used for a particular projection is varied depending on measured body part thickness
The thicker the body part the higher the value of kV assigned
A mAs value is specified for each body part to be examined; its value depends on IR exposure and other parameters
In use the radiographer sets the mAs specified for the part and measured part thickness; the value of kVp corresponding to that thickness is found on the chart

A

Variable kVp exposure system

38
Q

kVp is held constant for a given range of subject densities and contrasts while the mAs is varied to achieve an appropriate IR exposure

A

Fixed kVp exposure system

RAD 102: Radiographic Technique (7 decks)

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