SPECIAL - Radiation Safety Flashcards
1
Q
X-ray tube leakage limit
A
<1 mGy per 1 hour at 1 meter
2
Q
Average effective dose for PA + lateral chest x-ray
A
0.1 mSv
3
Q
Average effective dose for mammography
A
0.4 mSv
4
Q
Average effective dose for CT head
A
2 mSv
5
Q
Average effective dose for CT chest
A
7 mSv
6
Q
Average effective dose for CT abdomen wo
A
10 mSv
7
Q
Average effective dose for nuclear stress test
A
10 mSv
8
Q
Average effective dose for CTA chest
A
15 mSv
9
Q
Average effective dose for CT abdomen w/wo
A
20 mSv
10
Q
Threshold for temporary and permanent sterility (males)
A
2.5 and 5 Gy, respectively
11
Q
Threshold for temporary and permanent sterility (females)
A
1.5 and 6 Gy, respectively
12
Q
Spatial resolution for screen film mammo
A
13 lp/mm in parallel direction and 11 lp/mm in the perpendicular direction; relative to anode-cathode axis
13
Q
Spatial resolution for digital mammo
A
7 lp/mm
14
Q
Spatial resolution for screen film radiography
A
6 lp/mm
15
Q
Spatial resolution for digital radiography
A
3 lp/mm
16
Q
Spatial resolution for fluoroscopy
A
2-3 lp/mm
17
Q
Spatial resolution for ultrasound
A
2 lp/mm
18
Q
Spatial resolution for CT
A
0.7 lp/mm
19
Q
Spatial resolution for MRI
A
0.3 lp/mm
20
Q
Spatial resolution for gamma camera
A
0.1 lp/mm
21
Q
Modality soft tissue contrast (x-ray vs. mammo vs. CT vs. MRI)
A
MRI > CT > mammography > general radiography
22
Q
Radiographic units operated above 70 kVp should have total filtration of at least… (aluminum equivalent)
A
2.5 mm
23
Q
Fetal absorbed dose of 10 mGy increases risk of childhood cancer by…
A
3.5x (per QEVLAR)
24
Q
Average glandular dose for single image of breast phantom (with grid)
A
<3 mGy (applies to phantom, not actual patients)
25
Average glandular dose for single image of breast phantom (no grid)
<1 mGy (applies to phantom, not actual patients)
26
Effect of lead apron
0.5 mm Pb stops 95% of radiation (or 99% per Ram)
27
Lead should be worn if within...
6 feet
28
Federal regulation for entrance skin dose rate (fluoro)
cannot exceed 88 mGy/min (measured at 30 cm from detector surface)
29
Federal regulation for high level control entrance skin dose rate (fluoro)
cannot exceed 176 mGy/min (measured at 30 cm from detector surface); must have an audible alarm
30
Personnel dose standing 1 meter from patient
1/1000 of patient dose
31
Joint commission sentinel event (fluoro)
cumulative dose of 15 Gy or more to a single field; requires root-cause analysis and visit by JC inspector
32
Entrance air kerma limit for DSA
no limit for DSA
33
Air kerma relates to which risk type?
deterministic risk (CAK does too)
34
Kerma air product relates to which risk type?
stochastic risk
35
KERMA (meaning)
Kinetic Energy Release per unit MAss
36
Typical entrance dose rate (fluoro)
30 mGy/min
37
CTDI is over or under-estimated for obese patients?
over-estimated
38
CTDI is over or under-estimated for pediatric patients?
under-estimated
39
What is a CTDIvol reference dose?
set by ACR (75th percentile), if above should be investigated
40
Risk of radiation-induced cancer (adults)
5% per Sv (1/10 for patients >50 y/o)
41
Risk of radiation-induced cancer (peds)
15% per Sv
42
"Image Gently"
pediatric dose reduction campaign for CT
43
"Step Lightly"
pediatric dose reduction campaign for IR
44
"Pause and Pulse"
pediatric dose reduction campaign for fluoro
45
"Image Wisely"
adult counterpart to pediatric campaign
46
Fetal dose in CT abdomen/pelvis
30 mGy
47
Dose for stochastic effects in pregnancy
>25 mGy (increase in risk of childhood cancer by 1%)
48
Dose for deterministic effects in pregnancy
>50 mGy
49
Dose for fetal death in pregnancy
>100 mGy; only applicable <14 days post-conception
50
CTDIvol reference dose for adult head CT (per ACR)
75 mGy; doses above this need to be investigated
51
CTDIvol reference dose for adult abd/pelvis CT (per ACR)
25 mGy; doses above this need to be investigated
52
CTDIvol reference dose for peds abd/pelvis CT (per ACR)
20 mGy; doses above this need to be investigated
53
Fetal radiation dose for consideration of pregnancy termination
>50 mGy between weeks 2-15
54
ALARA prefers increasing power or gain? (US)
gain (no extra energy imparted to patient)
55
TI for OB imaging
<0.7
56
TI where US should not exceed 30 min
1.0-1.5
57
TI where US should not exceed 1 min
2.5-3.0
58
TI where US should not be used
>3.0
59
FDA limits for MI
1.9 for an adult, 1.0 for OB
60
All US equipment required to display TI and MI by who?
FDA
61
Risk-benefit discussion required at what TI and MI?
TI >1.0 and MI >0.5
62
SAR limits (MRI)
3 W/kg per 15 min for head and 4 W/kg per 15 min for body (per FDA)
63
Average annual dose per person in the US
6 mSv (3 mSv from medical sources, 3 mSv from background)
64
Threshold for radiation symptoms in majority of population
1 Gy (usually mild nausea or anorexia)
65
Cataracts dose
0.5 Gy
66
Transient erythema dose
2 Gy (Ram says 2-5 Gy)
67
Temporary epilation dose
3 Gy (Ram say 5-10 Gy)
68
Chronic erythema dose
6 Gy
69
Permanent epilation dose
7 Gy (Ram says 10-15 Gy)
70
Telangiectasia dose
10 Gy
71
Dry desquamation dose
13 Gy (Ram says 10-15 Gy)
72
Moist desquamation dose
18 Gy (Ram says >15 Gy)
73
Secondary ulceration dose
24 Gy
74
Two largest sources of radiation exposure in medical imaging
CT > nuclear medicine
75
Fetal dose threshold with essentially no risk of birth defects, mental retardation, or fetal death (deterministic effects)
<50 mGy
76
Fetal iodine uptake onset
8-10 weeks
77
Effective dose from background radiation in the US per year
3 mSv/year
78
Radiation personnel whole body dose limit
50 mSv/year
79
Radiation personnel eye dose limit
150 mSv/year
80
Radiation personnel target organ dose limit
500 mSv/year
81
Pregnant radiation worker dose limit
5 mSv or 0.5 mSv/month after declaring pregnancy
82
Radiation dose limit for members of the public
1 mSv/year (effective dose)
83
Minor (<18 y/o) radiation worker dose limit
10% of adult limits
84
Individual dose monitoring required when occupational dose is likely to exceed...
10% of the annual dose limit
85
Radiation dose rate for unrestricted areas
<0.02 mSv/hour; should be surveyed weekly with ionization chamber
86
Radiation dose rate for restricted areas
>0.02 mSv/hour; should be surveyed daily with ionization chamber
87
Whole body dose threshold for cerebral edema + time of onset
100 Gy, time of onset is 1 day
88
Whole body dose threshold for GI failure + time of onset
10 Gy, time of onset is 1 week
89
Whole body dose threshold for hematopoietic failure + time of onset
5 Gy, time of onset is 1 fortnight (2 weeks)
90
Increased risk of fatal cancer with 20 mSv of effective dose
1/1000 risk of fatal cancer (Ram)
91
Most radiosensitive organs
gonads (testes/ovaries) > breasts > red marrow, lungs, GI tract; per NRC
92
Most radioresistant organs
muscle, brain, spinal cord
93
Linear no-threshold model
cancer risk increases proportionally with radiation dose (even with the smallest doses)
94
Threshold model
smallest doses below a threshold present no cancer risk
95
Hormesis model
low doses of radiation decrease cancer risk, despite higher doses increasing risk
96
Linear no-threshold model is used for all solid tumors except...
leukemia (uses linear quadratic model)
97
LD 50/60 meaning + dose
lethal dose for 50% of the population within 60 days; 4 Gy
98
Radiation worker exposure limits are covered in CFR ___
CFR-20
99
Purpose of ACR relative radiation levels
used to estimate radiation risk of an exam
100
ACR relative radiation level: O
0 mSv
101
ACR relative radiation level: ☢
<0.1 mSv (peds <0.03 mSv)
102
ACR relative radiation level: ☢☢
0.1-1 mSv (peds 0.03-0.3 mSv)
103
ACR relative radiation level: ☢☢☢
1-10 mSv (peds 0.3-3 mSv)
104
ACR relative radiation level: ☢☢☢☢
10-30 mSv (peds 3-10 mSv)
105
ACR relative radiation level: ☢☢☢☢☢
30-100 mSv (peds 10-30 mSv)
106
Deterministic vs. stochastic effects
deterministic effects require a threshold to be met; stochastic effects are dose-dependent
