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Quality Control > Week #13 > Flashcards

Week #13 Flashcards

1
Q

What are the 3 main components of QC for fluoro equipment?

A

Visual inspection
Environmental inspection
Performance testing

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2
Q

According to SC35, how often should collimator operation, locks, table motion, angulation, compression devices, chronometer, protective devices be tested?

A

Quarterly

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3
Q

According to SC35 how often should collimator operation be evaluated to ensure the dimensions of the xray field do not exceed the area of the II

A

Annually

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4
Q

According to SC35, what percent should the xray field not exceed the area of the II by the SID?

A

3%

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5
Q

What lead equivalent should the protective curtain contain?

A

0.25mm

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6
Q

What percentage should the table angulation and motion be accurate within?

A

2 degrees

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7
Q

What indicator should be present when inspecting the high level irradiation control?

A

Ensure that an audible signal is present when in use

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8
Q

According to SC35, what is the limit for reproducibility variance between exposures?
What is the testing frequency?

A

CV less than or equal to 0.05
Each exposure within 15% of the mean
Annual

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9
Q

At 70 kv, what is the minimum half value layer of aluminum for fluoro?

A

2.5 mm

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10
Q

How is kvp accuracy tested in fluoro?

A

Expose a digital kvp meter under fluoro

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11
Q

According to HARP what is the testing frequency and acceptance limit for kvp accuracy?

A

Semi annual
8%

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12
Q

According to SC35 what is the testing frequency and acceptance limit for kvp accuracy?

A

Annual
10% for xray tube voltage
20% for xray tube current

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13
Q

Testing involves a series of fluoroscopic exposures, each at double the mA of the previous

A

mA linearity

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14
Q

What is the required testing frequency for ma linearity according to SC35?

A

Annual

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15
Q

At what percent of maximum heat should the alarm be activated when exposing a homogenous phantom under fluoro? What is this testing?

A

When 75% of maximum heat is achieved

Xray tube heat sensor

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16
Q

The ability to resolve objects in a resultant image when the difference in the attenuation between the objects and the background is large compared to noise

A

Spatial resolution

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17
Q

Ability to resolve small, black and white objects

A

High contrast resolution

18
Q

How is testing done for high contrast resolution?

A

Testing involves imaging a testing tool under fluoro
Depending on the size of the II, a minimum size mesh should be visualized
Follow manufacturer guidelines

19
Q

Ability to resolve relatively large objects with similar density

A

Low contrast resolution

20
Q

What is the minimum source to skin distance for fixed or stationary units?

A

Not less than 30cm or 15”

21
Q

What is the minimum source to skin distance for mobile units?

A

Not less than 30cm or 12”

22
Q

What is the minimum source to skin distance for specialized units?

A

Not less than 20cm or 8” for special applications that would be impossible to achieve at a minimum of 30cm or 38cm

23
Q

Scattered or reflected light in the output phosphor; causes an increase in brightness on the image

A

Veiling glare

24
Q

Occurs due to projecting image curved surface to flat surface, such as input phosphor to output phosphor (distortion is greater towards the lateral portion of the image)

A

Pincushion distortion

25
Q

Same as pincushion but magnification occurs at the centre

A

Barrel distortion

26
Q

A decrease in image brightness at the lateral portions of the image - caused by a combination of pincushion distortion and the coupling of the television camera to the output phosphor

A

Vignetting

27
Q

Warping of the image along an S shaped axis and is the result of strong magnetic fields changing the trajectory of the electrons moving across the image intensifier tube

A

S distortion

28
Q

What is used for testing of distortion?

A

Wire mesh tool under fluoro

29
Q

Can be due to quantum mottle or electronic noise present on fluoro monitor

A

Image noise

30
Q

What can be done if quantum mottle is identified on an image?

A

ma can be increased

31
Q

How do you test for image noise?

A

Expose a phantom at lowest mA and 80kvp. Increase mA to maximum value, if noise goes away it is quantum mottle, if it does not it is electronic noise

32
Q

Ability of imaging system to display events occurring close together in time as separate events

A

Temporal resolution

33
Q

Continuation of persistence of image; can blur objects as the II or object is moved

A

Image lag
- directly influences temporal resolution

34
Q

What is entrance exposure referred to as?

A

Air Kerma rate of radioscopic exposure

35
Q

Max. Air kerma
When equipment is not fitted with an automatic intensity control

A

50mgy/min

36
Q

Max. Air kerma
When equipment is fitted with an automatic intensity control

A

100mgy/min

37
Q

Max. Air kerma
When equipment is fitted with both an automatic intensity control and a high level irradiation control when the latter is activated

A

150mgy/min

38
Q

How do you test the automatic brightness control?

A

Place a dosimeter between a homogenous phantom and the xray source. Double the phantom thickness and repeat exposure.
**the exposure measurement should be approximately double the first measurement **

39
Q

According to HARP, what shall every fluoroscopic xray machine be equipped with?

A

-an audible signal that indicates completion of any preset time of use up to a maximum of 5 minutes
-a shield of at least 0.25mm lead equivalent at 100kvp

40
Q

What is the exposure rate limit for a machine that uses a zinc cadmium suplphide input phosphor?

A

-max. Entrance exposure of 12.5R/min
-entrance exposure rate of 5R/min for average patient

41
Q

What is the exposure rate limit for a machine that has a cesium iodide input phosphor?

A

-max. Exposure rate of 10R/min
-entrance exposure rate of 2.5R/min for an average patient

42
Q

According to HARP , what is the testing frequency for:
-max patient entrance exposure rate
-resolution
-limit timer
-automatic brightness control

A

Every 6 months and upon servicing the machine

Quality Control (9 decks)

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