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Computed Tomography (CT) > CT Safety > Flashcards

CT Safety Flashcards

1
Q

“Radiation safety” refers to:

A

The methods and tools used to protect patients and personnel from ionizing radiation exposure

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2
Q

Organizations who set and enforce radiation standards include:

A 
ICRP
NRC
EPA
FDA
OSHA
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3
Q

How can x-rays cause damage to the body as it passes through?

A

Directly interacting with DNA bonds within cells

Producing ion pairs

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4
Q

Radiation can cause the most harm during what peak of pregnancy?

A

First trimester

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5
Q

Rad is equal to:

A

The absorption of 0.01 joules of energy per kilogram of matter

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6
Q

Radiation can be measured as:

A

Rad
Gray (1 Gy = 100 rads)
Rem
Sievert (1 Sv = 100 rem)

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7
Q

Radiation dose at the _____ is greater than the dose at the ______ of the body

A

Skin / Center

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8
Q

What is unique about the radiation profile of a single slice?

A

It is rounded and the radiation actually extends outside of the intended slice

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9
Q

“Radiation penumbra” refers to:

A

The radiation that “leaks” outside of the intended slice thickness

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10
Q

Why does a radiation penumbra occurs?

A

Imperfect collimation of the x-ray beam (not due to service problems, but due to natural CT physics)

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11
Q

What are some indicators of radiation dose?

A

CT Dose Index
MSAD
Dose-length Product
Effective Dose

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12
Q

CTDI did not account for what type of scans?

A

Helical scanning
Cone beam irradiation
Simultaneous acquisition of multiple slices in a single rotation

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13
Q

When would a CTDI value be inaccurate?

A

If adjacent slices overlapped or had gaps

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14
Q

Which indicator of radiation penumbra would correct the CTDI on conventional scans?

A

MSAD

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15
Q

Where do we see the radiation penumbra on MDCT slices?

A

Only the end slices of the volume

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16
Q

The DLP accounts for:

A

Performance of helical scans
Total number of slices
Slice thickness

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17
Q

What is unit used to express DLP?

A

mGy-cm

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18
Q

How can you calculate the effective dose?

A

Multiplying the absorbed dose by a weighting factor assigned to each organ / body region

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19
Q

Effective dose is an indication of the :

A

Overall risk to the patient from radiation

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20
Q

What unit is used to express the effective dose?

A

Sv

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21
Q

What scan parameters can inadvertently affect patient dose?

A 
mAs
Anatomical coverage
Slice thickness (single-row detectors)
Table increment
Pitch
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22
Q

On a single-row detector, how can you achieve fewer radiation penumbras?

A

Thicker slices

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23
Q

How can you decrease dose to a patient?

A

Decrease mAs / anatomical coverage

Increase slice thickness / table increment / pitch

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24
Q

What about the image quality would be most apparent when decreasing dose to a patient?

A

Increased noise

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25
Q

What scanning techniques can be used to minimize dose to the patients without repeating scans?

A

Noise reduction algorithms

Iterative reconstruction

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26
Q

What kind of material are some of the radiation shielding devices made of?

A

Lead
Tungsten
Bismuth

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27
Q

What is the federal government limit for occupational exposure?

A

5 rem in a given year

Pregnant workers: < 0.05 rem/month

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28
Q

The cumulative dose equivalent (in rem) must not exceed:

A

The age of the worker (in years)

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29
Q

Contrast agents are helpful in clarifying anatomical findings through what kind of mechanism?

A

Attenuation

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30
Q

What components used in CT are referred to as “negative contrast” in rectal administrations?

A

Air and water

31
Q

“Negative contrast” can improve visualization of:

A

Internal surface (stomach and bowel)

32
Q

What are the categories of CT contrast administration?

A 
Intravenous
Oral
Rectal
Intrathecal
Intra-articular
33
Q

What can we visualize with an intravenous CT contrast administration?

A

Blood vessels
Vascular lesions
Abdominal organs

34
Q

What can we visualize with an oral CT contrast administration?

A

Gastrointestinal tract

35
Q

What can we visualize with a rectal CT contrast administration?

A

Distal gastrointestinal tract

36
Q

What can we visualize with an intrathecal CT contrast administration?

A

Spine

37
Q

What can we visualize with an intra-articular CT contrast administration?

A

Joints (arthrography)

38
Q

What type of exams requires IV contrast agents?

A 
CTA
Brain
Neck
Chest
Abdomen
Pelvis
39
Q

What are the different types of IV contrast agents?

A

Non-ionic (does not break down / form ions)

Ionic (breaks down into two ions)

40
Q

What are typically used for injecting CT contrast media?

A

Single-use, disposable catheters or butterfly needles

41
Q

Which vein is the vessel of choice in the cubital fossa as far as injection site goes?

A

Basilic vein

42
Q

What are the different phases of contrast equilibrium?

A

Bolus
Non-equilibrium
Equilibrium

43
Q

When scanning is performed later than the portal venous phase, during the equilibrium phase, many hepatic tumors become:

A

Isodense with the liver

44
Q

What are the benefits of using a dual-head power injector?

A

Potential to decrease both contrast usage and radiation dose to patient

45
Q

What kind of complications can occur with an extravasation?

A

Tissue necrosis
Swelling
Pain

46
Q

How can you treat extravasations?

A

Elevation
Ice packs
Surgery

47
Q

What are some complications to an air embolism?

A 
(Larger) Shortness of breath
Chest pain
Hypotension
Paralysis
Seizures
48
Q

How can you treat air embolism?

A

Position in left lateral decubitus with head angled 30-40 degrees downward
100% oxygen administration

49
Q

Which type of IV contrast agents may you see more complications with?

A

Ionic

50
Q

What are the benefits to using oral contrast agents?

A

Reduce the risk of misdiagnosing fluid-filled bowel
Lesion location
Lesion infiltration

51
Q

What are the two basic varieties of oral contrast agents?

A

Iodine

Barium Sulfate

52
Q

What is the difference between oral agents used in CT compared to conventional radiography?

A

More diluted

53
Q

How can we speed up the barium sulfate contrast progress through the GI tract?

A

Mix it with iodinated oral agent

54
Q

What are some complications to using oral agents?

A

Diarrhea

Abdominal cramping

55
Q

What are some contraindications to barium sulfate agents?

A 
Colon perforation
Tracheosophageal fistula
Obstructing lesions of the small intestine
Pyloric stenosis
Known sensitivity to barium sulfate
56
Q

How should you scan a patient who has received intrathecal contrast?

A

Elevate the patient’s head
Confirm the proper density of the contrast agent
Roll patient to ensure contrast media does not separate from the CSF

57
Q

What might be done prior to injection an intra-articular contrast agent?

A

Some joint fluid may be removed

58
Q

If a patient is sedated, what kind of special monitoring device is recommended?

A

Pulse oximeter

59
Q

A stroke results from:

A

Lack of blood flow to the brain

60
Q

What is the normal range for oral temperature?

A

97-99

61
Q

What is the normal range for axillary temperature?

A

96.5-98.5

62
Q

What is the normal range for rectal temperature?

A

97.5-99.5

63
Q

What is the normal range for pulse rates in an adult?

A

70-100 BPM

64
Q

What is the normal range for pulse rates in an athletic adult?

A

45-60 BPM

65
Q

What is the normal range for pulse rates in a child?

A

95-110 BPM

66
Q

What is the normal range for pulse rates in an infant?

A

100-180 BPM

67
Q

Blood pressure is expressed as:

A

Systolic over Diastolic

68
Q

What does the systolic pressure indicate?

A

The force of ventricular contraction

69
Q

What does the diastolic pressure indicate?

A

The lowest pressure of the ventricle between heartbeats

70
Q

What are some pediatric concerns?

A 
Portray non-threatening environment
Obtain cooperation (possible sedation)
Minimize dose
71
Q

Pediatric protocols use lower values for:

A

mAs and kVps

72
Q

What’s the typical dose for IV contrast?

A

1-2 ml per kg

73
Q

Children will usually receive about ____ of the total volume of oral contrast as adults.

A

Half

Computed Tomography (CT) (8 decks)

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