Radiation Protection (ch.3) Flashcards
(164 cards)
1
Q
radiation weighting factor (Wr) is
A
a number assigned to different TYPES of radiations in order to better determine their effect on tissue, such as xrays vs alpha particles.
2
Q
monthly gestational dose-equivalent limit for embryo/fetus of a pregnant radiographer is
mSv?
A
5 mSv
500 mrem
not to exceed .5 mSv in 1 month
3
Q
annual occupational whole body dose equivalent limit
mSv?
rem?
A
50 mSv
5 rem
4
Q
annual occupational whole body dose equivalent limit for students under 18
mSv?
rem?
A
1 mSv
.1 rem
100 mrem
5
Q
annual occupational dose equivalent limit for the lens of the eye
mSv?
rem?
A
150 mSv
15 rem
6
Q
annual occupational dose equivalent limit for the thyroid, skin, and extremities is
mSv?
rem?
A
500 mSv
50 rem
7
Q
a time of 1.5 mins is required for a particular fluoroscopic examination, whose exposure rate is 275 mR/hr. what is the approximate radiation exposure for the radiologic staff present in the fluoroscopy room during the examination?
A
6.87 mR
1.5min X 1hr X 275mR
—- —– = 6.87 mR
60min 1 hr
8
Q
If the exposure rate to an individual standing 4.0 m from a source of radiation is 10 mR/hr, what will be the dose received after 20minutes at a distance of 6m from the source?
A
1.48 mR in 20 mins i1/i2 = D2^2/ D1^2
so..
10/x = 36/16
= 4.44 in one hour (60 minutes)
so… divide 4.44 by 3 (since 20min goes into 60min 3x)
final answer = 1.48 mR in 20 minutes
9
Q
fluoroscopic and radiographic exposure switch type
A
dead man type
so it shuts off when the switch is released
10
Q
what cell type has the greatest radiosensitivity in the adult human?
A
lymphocytes
11
Q
Spermatids radiosensitivity to radiation
A
highly sensitive
12
Q
muscle cells radiosensitivity
A
low radiosenstivity
13
Q
nerve cells radiosensitivity
A
least radiosensitive
EXCEPT in fetal life, then they are highly radiosensitive
14
Q
the interaction between ionizing radiation and the target molecule that is MOST likely to occur is the:
A. Direct effect
B. Indirect effect
C. Target effect
A
indirect effect
occurs most frequently with xrays and matter
15
Q
what is the approximate entrance skin exposure (ESE) for the average AP supine abdomen xray? how about AP c-spine?
A
Abdomen: 300 mrad = .35 rad
C-spine: 80 mrad
16
Q
how will x-ray photon intensity be affected if the SID is doubled?
A
the intensity will decrease 4x
17
Q
occupational radiation monitoring is required when it is possible taht the individual might receive more than?
A
1/10th the annual dose limit
18
Q
MONITORING DEVICES COMPONENTS
A
MONITORING DEVICES COMPONENTS
19
Q
Film badges give a read out by
A
the silver halide is ionized by x-ray photons to give a readout
20
Q
Pocket dosimeter, does it contain an ionization chamber?
A
yes
21
Q
TLD’s give readouts by
A
exposing lithium fluoride crystals to ionizing radiation and then heating, these crystals give off a light that is proportional to the amount of radiation received.
22
Q
OSL dosimeters give a read out by
A
exposing aluminum oxide crystals to ionizing radiation and then to a laser, which gives off a light proportional to the amount of radiation received.
23
Q
sources of natural background radiation contributing to whole-body radiation dose include
A
terrestrial radionuclides (external: cosmic from space and internal: within earths crust)
and
internal radionuclides (within our own bodies.. food we ingest)
24
Q
irradiation of water molecules within the body and their resulting breakdown is termed
A
radiolysis
25
free radicals result from
radiolysis
26
what contributes MOST to occupational exposure
compton scatter
27
thompson scatter is another name for
classic scatter
28
the x-ray interaction with matter that is responsible for the majority of scattered radiation reaching the IR is
compton scatter
29
in photoelectric effect what happens
a low energy photon ejects an inner shell electron leaving a space, which is filled from an electron from the above shell
30
with mA increased to maintain intensity, how is the ESE affected as the SSD is increased
the ESE increases
| since the mA was increased
31
late radiation-induced somatic effects are effects that occur: (when)
effects that occur years after initial exposure
32
examples of late radiation-induced somatic effects
cataracts
cancer
genetic mutations
33
each time an x-ray beam scatters, its intensity at 1m from the scattering objects is what fraction of its original intensity?
1/1,000
34
the x-ray beam should scatter ___ times before reaching the operator
twice
35
annual occupational whole-body dose equivalent limit is?
mSv?
rem?
50 mSv
| 5 rem
36
a Thermoluminescent dosimetry (TLD's) system would use what type of crystal?
lithium fluoride
37
sources of secondary radiation include:
leakage radiation
and
scattered radiation
38
leakage radiation is when radiation exits the...
tube housing
39
background radiation is ____ occurring radiation that is emitted from...
natural occurring radiation
| that is emitted from the earth and also exists within our bodies
40
what is used to account for the differences in tissue sensitivity to ionizing radiation when determining effective dose E?
tissue weighting factor (Wt)
41
the photoelectric effect is more likely to occur with
absorbers having a high atomic number (Z number) (heavier weight)
and
positive contrast media (high density, like barium)
42
photoelectric effect and patient dose
the photoelectric effect is largely responsible for patient dose
43
In radiation protection, the product of absorbed dose and the correct modifying factory (rad X QF)is used to determine
rem (sV)
44
what is the unit of measure that expresses the dose-effect relationship?
rem
| its the dose equivalent
45
what measures dose equivalent
| what is its units
rem
| Sv
46
```
the annual dose limit for medical imaging personnel includes radiation from:
A. occupational exposure
B. background radiation
C. medical X-rays
D. all the above
```
A. occupational exposure only
47
what anomaly is possible if an exposure dose of 40 rad (400 mGy) were delivered to a pregnant uterus in the third week of pregnancy?
organ anomaly (bc their organs are starting to form)
48
what trimester is the fetus most radiosensitive
first
49
when would neurologic anomalies be formed in a fetus
in the later trimesters
50
when can fetal irradiation result in embryonic reabsorption or spontaneous abortion?
during the first two weeks of gestation
51
BREAK
BREAK
52
Fractionation
if the radiation is delivered in portions over a period of time
53
medical and dental radiation accounts for what percentage of the general publics exposure to to HUMAN-MADE radiation?
90%
54
epithelial tissue radiosensitivity
very radiosensitive
55
non dividing cells radiosensitivity:
ex. of non dividing cells
least radiosensitive
neurons and neuroglia
56
how does filtration affect the primary beam
it filters out low energy photons which hardens the beam and
| increases the average energy of the primary beam
57
what is the minimum lead requirement for lead aprons according to the NCRP
.5 mm Pb
58
an optically stimulated luminescence dosimeter contains what component
aluminum oxide crystals
59
aluminum oxide crystals (used in OSL dosimeters) give a readout that is ___ to the amount of radiation received
proportional
60
immature cells examples
undifferentiated cells
and
stem cells
61
Radiosensitivity of:
immature cells:
mature cells:
immature: highly sensitive
mature: low sensitivity
62
what is the term used to describe x-ray photon interaction with matter AND the transference of part of the photons energy to matter?
scatter
| key word is PART of the photons energy
63
the term that describes the reduction in the intensity (quantity) of an x-ray beam as it passes through matter
attenuation
64
scattering occurs when there is
a PARTIAL transfer of the protons energy to matter
65
what is the ESE (entrance skin exposure) of a:
chest x-ray:
AP lumbar:
chest x-ray: 12 mrad (.012 rad)
AP lumbar: 350 mrad (.35 rad)
66
primary radiation barriers must be at least how high?
7ft
67
the annual dose limit for occupationally exposed individuals is valid for___ types or radiation
x and gamma radiations only
68
patient dose increases as fluoroscopic FOV..
decreases
69
FSS stands for
focal spot size
70
what unit measures the quantity of ionization in the air
Roentgen
71
Rem stands for
radiation equivalent man
72
a method of expressing radiation quality can be defined by
LET
73
X-rays and gamma rays have what type of LET radiation
low
74
the skin response to radiation exposure that appears as hair loss is known as
epilation
75
Anoxic:
Hypoxic:
Anoxic: without oxygen
Hypoxic: low oxygen
76
tissues are most radiosensitive when they have what type of oxygen levels
when they are highly oxygenated
77
which type of dose-response relationship represents radiation-induced leukemia and genetic effects
linear, non threshold
78
late effects are also called
stochastic effects
79
childhood malignant diseases, such as cancers or leukemia can result from irradiation during what trimester
first
80
what is the 10-day rule
says that the first 10 days following the onset of a womans period is the safest time to schedule a procedure of the pelvis/abdomen
81
tissues having a ____density absorb more xray beam
higher
82
is fat easy or hard to penetrate?
easy, along with lungs
83
leakage radiation must not exceed
100 mR/hr at 1m
84
screen speeds does what to patient dose
High speed intensifying screens:
Low speed intensifying screens:
high speed intensifying screens allows for a lower mAs and therefore a lower patient dose
low speed intensifying intensifying screen needs more mAs and have a higher patient dose
85
what effects both the quality and quantity of the primary beam
half value layer
and
kV
86
quality of a beam is from:
quantity of a beam is from:
quality: kV, HVL, LET
quantity: mA
87
xrays have high/low
Energy:
LET:
mass:
low energy
low LET
no mass
88
primary radiation barriers thickness
secondary radiation barriers thickness
primary: 1/16"
secondary: 1/32"
89
which group of exposure factors will deliver the least patient dose?
A. 300 mA, 250 ms, 70 kVp
B. 300 mA, 125 ms, 80 kVp
C. 400 mA, 90 ms, 80 kVp
D. 600 mA, 30ms, 90 kVp
D. because it has the lowest mAs and high kVp to decrease the patient dose
90
for radiographic examination of the skull, it is generally preferred that the skull be examined in the _____ projection/position, because____
PA since the entrance skin dose is significantly greater than the exit dose.
this way it puts the radiosensitive organs to the IR and away from the primary beam
91
at 1m from the patient, the intensity of the beam is
reduced by a factor of 1,000 or
| .1% of its original intensity
92
an increase of 1.0 mm added aluminum filtration of the x-ray beam would have what effect
increase in average energy of the beam, makes it harder
and
decrease pt dose bc its filtering out low energy photons
93
filtrations job is to
remove low energy X-RAY photons to reduce pt dose
94
x-ray photons from the focal spot are what type of beam
heterogenous
95
the amount of time that x-rays are being directed toward a particular wall is referred to as
use factor
96
the number of x-ray exposures made each week is referred to as
workload
97
occupancy factor consists of
who occupies particular areas (radiation workers and non radiation workers)
98
radiation effects that appear days or weeks following exposure due to high radiation doses are called
acute radiation syndrome
99
acute radiation syndrome is likely to occur if the whole body gets...
600 rad at one time
100
hematologic system consists of
blood
liver
bone marrow
spleen
101
-penia
decrease, lack of
102
first stage of acute radiation syndrome is called:
symptoms are:
prodromal
nausea, vomiting, diarrhea, fatigue
103
BREAK
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104
the unit of measurement used to express occupational exposure
rem (sV)
105
what is responsible for the dose to biologic material
rem (sV) because it includes RBE to tissues
106
bucky slot cover has ___mm Pb
.25 mm Pb
107
fluoro mA must not exceed
| a timer will time if fluoro is on more than
5 mA
| 5 minutes
108
fluoro protective curtain must contain ____mm Pb
.25 mm Pb
109
which type of personnel radiation monitoring device can provide an immediate reading
how:
downfall to this type:
ionization chamber: pocket dosimeter or pocket ionization chamber
its like a pen and you hold it up and look through it to see the reading but it doesn't keep an ongoing count
110
if the ESE for an exposure is 25mrad, what will be the intensity of the scattered beam perpendicular to and 1m from the patient?
.025 mrad
25 X 1/1000
111
what factors contribute to scatter PRODUCTION
kVp (the higher the kVp the more scatter that is PRODUCED)
field size (larger field, larger amount of scatter produced)
thickness and condition of the tissue (thicker/more dense, more scatter produced)
112
the automatic exposure device that is located immediately under the xray table is the
ionization chamber
113
scintillation camera is used in
nuclear medicine
114
the law of Bergonie and Tribondeau states that cells are more radiosensitive if they are
highly proliferative (highly mitotic)
immature
115
undifferentiated cell
immature
116
stem cells
immature cells
117
LET and RBE relationships
direct
118
which of the following radiation-induced conditions is most likely to have the longest latent period?
leukemia
temporary infertility
acute radiation lethality
leukemia
119
late effects aka
stochastic
or
genetic effects
120
diagnostic xrays have an RBE of
1.0
121
the most radiosensitive portion of the GI tract is
small bowel bc its cells are highly mitotic
122
the photoelectric effect is an interaction between an x-ray photon and...
an inner shell electron
123
filters used in xray tubes are generally composed of
aluminum
124
what kind of radiation is produced at the tungsten target of the xray tube, from the filament
brems and characteristic
125
which interaction results in an incident electron which is deflected and results in energy loss?
Brems
126
an increase in beam filtration will increase_(what factor)___ and decrease __(what factor)___
increase HVL
increase energy
decrease mR output
127
what is used to determine the biologic damage in living tissues
RBE
128
the purpose of filters in a film badge is to
measure radiation quality (energy) to see what dose the tech is getting
129
which body parts are included in the whole body dose?
| which ones are not?
Gonads
and
blood forming organs
NOT EXTREMITIES bc they high a higher annual dose limit
130
energy is also referred to as
quality of the beam
131
which personnel monitoring devices is said to be the most sensitive and most accurate
OSL dosimeter bc it can measure as low as 1mrem
132
a large dose to the whole body all at once is said to be (harmful?)
most harmful since the body doesnt have time to repair itself as it would to a large dose to a specific area at one time
133
how much protection is provided from a 100 kVp xray beam when using a .5 mm Pb apron
how about a 50 kVp xray beam at .5 mm Pb apron
100 kVp: 75%
| 50 kVp: 99%
134
local tissue damage is from what effect of ionizing radiation (early, late)
late, long term effect unless it happens shortly after exposure
135
red blood cells radiosensitivity
| red blood cells are also called
very radiosensitive
| erythrocytes
136
```
the classification of acute radiation syndrome include all of the following except
A. CNS
B. GI tract
C. neonatal
D. hematologic
```
C. neonatal bc acute radiation syndrome is an early somatic effect
137
compton scatter ejects an ___ shell electron
outer
138
effective dose refers to
whole body dose
139
whole body dose is also referred to as ____ dose
effective
140
blood changes short or long term effects
short
141
types of secondary radiation barriers include
A. the control booth
B. lead aprons
C. the xray tube housing
all of them
| because secondary radiation is from scatter and leakage radiation
142
pair production occurs at
1.022 MeV
| this does not occur in diagnostic xray
143
radiation effects that are during the life of the exposed individual is said to be _____ effects
somatic effects
144
radiation effects to the gonads of an exposed individual and are passed on are said to be ____ effects
genetic effects
145
the dose that it takes to bring about a noticeable erythema is referred to as _ _ _
SED
| erythema: reddening of the skin
146
controlled area vs uncontrolled area
controlled: means the area may always be occupied, by radiation workers and requires maximum shielding, must not exceed 100mR/week
uncontrolled: occupied by the general public, must not exceed 10mR/week
147
```
periods of time:
gestation:
congenital:
neonatal:
in vitro:
in vivo:
```
gestation: pregnancy
congenital: condition that exists at birth
neonatal: from birth thru the first month of life
in vitro: living outside a living body (in a test tube)
in vivo: within a living system
148
somatic effects are (early or late) effects
both, depending on the time they manifest effects
149
BREAK
BREAK
150
stochastic effects (early or late)
late
151
"all or nothing" effects
stochastic
| either the organ develops cancer or it doesn't
152
when would a radiographer be required to wear 2 dosimeters?
when they are pregnant
or
when performing a vascular procedure
153
how much radiation to the reproductive organs can cause temporary infertility? what about permanent sterility?
temporary infertility: 200 rad
| sterility: 500 rad
154
table top exposure rate during fluoro shall not exceed
10 R/min
155
radiation induced skin erythema has what kind of curve?
non linear, threshold
156
alpha particle consists of
2 protons and 2 neutrons
157
beta particle is composed of
an electron
158
radiation output is measured in
roentgen: ionization in air.. the output hits air
159
becqueral measures
radioactivity
160
the interaction between xray photons and tissue that is responsible for radiographic contrast is
photoelectric effect
| also contributes significantly to pt dose
161
lead aprons should be checked for cracks...(how often)
yearly
162
what theory relates to DNA
target theory
163
radon is found
in the earth
and
in houses
and cigarettes
164
quality factor is also called
RBE
