Test 3 Study Flashcards
1
Q
how do you calculate exposure?
A
exposure rate x exposure time
2
Q
if the distance from the source exceeds 5 x’s the source diameter, it can be treated as a what?
A
point source
3
Q
the distance from the source must exceed ________ the source diameter, to be treated as a point source
A
5 x’s
4
Q
where should tech stand during fluoro?
A
behind radiologist
5
Q
thickness of the absorber that will reduce the rad intensity to 1/2 it’s original value
A
half value layer (HVL)
6
Q
thickness of absorber that ill reduce the rad intensity to 1/10th of it’s original value
A
tenth value layer (TVL)
7
Q
1 TVL = ? HVL
A
3.3
8
Q
____________ is the equivalent whole body dose
A
effective dose
9
Q
equivalent whole body dose is the ___________________ to various organs/tissues
A
weighted avg of the rad dose
10
Q
D x Wt = ?
A
effective dose
11
Q
absorbed dose x Wr x Wt = ?
A
effective dose
12
Q
rad weighting factor for XR?
A
1
13
Q
rad weighting factor for gamma ray?
A
1
14
Q
rad weighting factor for neutrons?
A
5 - 20
15
Q
rad weighting factor for protons?
A
2
16
Q
rad weighting factor for alpha particles?
A
20
17
Q
tissue weighting factor for gonads?
A
0.20
18
Q
tissue weighting factor for bone marrow?
A
0.12
19
Q
tissue weighting factor for colon, lung, or stomach?
A
0.12
20
Q
tissue weighting factor for liver, breast, thyroid?
A
0.05
21
Q
tissue weighting factor for skin?
A
0.01
22
Q
we assume that the occupational effective dose to be _____ of the monitor dose.
A
10%
23
Q
leakage rad. must be ________________________ from the protective housing
A
less than 100 mR/hr @ a distance of 1 meter
24
Q
100 mR/hr = ? mGy/hr
A
1 mGy/hr
25
SID indicator must be accurate to w/in?
2% of indicated SID
26
XR beam & light beam must coincide to?
w/in 2% of SID
27
when PBL is activated, the collimators are automatically adjusted so that the ________________________
rad field matches the film size
28
regulatory standards requires the PBL to have an accuracy by
2% of the SID
29
filtration reduces exposure to pt's skin/tissue by absorbing most of the ______________ from the heterogeneous beam
lower energy photons
30
filtration _______ the avg energy (qual.) of beam
increases
31
the increase in avg energy of beam by filtration is referred to as?
hardening of beam
32
includes the glass envelope encasing the XR tube, the insulating oil, & the glass window
inherent filtration
33
inherent filtration amounts to approx.?
0.5 mm of Al equivalent
34
collimator provides an additional ______ of Al equivalent
1 mm
35
consists of sheet of Al or its equivalent of appropriate thickness, located outside the glass window of the tube housing above the coll. shutters
added filtration
36
added filtration is usually ____ of Al equivalent
1 mm
37
the inherent & added filtration should combine to equal the required ____________ (fixed tube, above 70 kVp)
2.5 mm of Al
38
(reproducibility) the variation in the XR intensity should not exceed?
5%
39
the max acceptable variation in linearity is _____ from one mA station to an adjacent mA station
10%
40
should it be possible to expose an IR while the tech stands unprotected outside a fixed protective barrier (control booth)
no
41
the exposure control should be ______ to the operating console and not to a ____________
fixed; long cord
42
the exposure switch on a mobile XR system must allow the operator to remain at least ______ from the XR tube
2 meters
43
the SSD must not be less than ____ on stationary fluoro equipment
38 cm
44
the SSD must not be less than ____ on mobile fluoro equipment
30 cm
45
the I.I. serves as a primary protective barrier and it must be ___________ equivalent
2 mm of pb equivalent
46
filtration must be at least __________ equivalent
2.5 mm of Al equivalent
47
bucky slot must be covered w at least __________ equivalent
0.25 mm of pb
48
the protective curtain must be of at least _________ equivalent
0.25 mm of pb equivalent
49
a cumulative timer must produce an audible signal when the fluoro T has exceeded?
5 mins
50
the image receptor assembly serves as a what?
primary protective barrier
51
a quantity that reflects not only the dose but also the volume of tissue irradiated
dose area product (DAP)
52
DAP is a better indicator of?
risk
53
DAP _________ w increasing field size
increases
54
the intensity of the XR beam at the table top should not exceed ___________ for ea. mA station of operation @ 80 kVp
2.1 R/min
55
DAP for regular fluoro?
10 R/min
56
DAP for high level fluoro?
20 R/min
57
primary protective barrier wall should be _____ inch of pb
1/16th"
58
primary protective barrier wall should be ______ high
7 ft
59
secondary protective barrier wall should be made of _____ inch of pb
1/32"
60
height of secondary protective barrier?
from beginning of primary barrier w a 1/2" overlap, up to the ceiling
61
from where do techs receive most of their occupational rad exposure?
fluoro
62
an area that is occupied primarily by radiology personnel & pt
controlled area
63
what is the rad limit for a controlled area?
1 mSv/wk (100 mrem/wk)
64
rad limit for uncontrolled area?
2 mrem/wk
65
the level of radiation activity in the room
workload
66
a busy general purpose XR room may have a workload of __________
500 mA-min/wk
67
the % if T during which the XR beam is on & directed toward a particular protective barrier; "beam-on T"
use factor
68
the use factor for a 2ndary barrier is always considered as?
1
69
NCRP recommends use factor of ? for walls
1/4
70
NCRP recommends use factor of ? for floors
1
71
protective barriers are designed w the assumption of ____ kVp for general radiography
100
72
protective barriers are designed w the assumption of ____ kVp for mammo
30
73
most exams are conducted at an avg of ___ kVp
75
74
instruments designed for rad detection operate in what mode?
pulse or rate
75
in what mode is presence of rad indicated by ticking, chirping or beeping sound?
pulse mode
76
in what mode is the instrument response expressed in mGy/hr (mR/hr)
rate mode
77
instruments designed to measure the radiation intensity operate in what mode?
integrate
78
the determination by sci. methods of the amount, rate & distribution of rad emitted from a source of ionizing rad
dosimetry
79
2 general types of detection instruments used
fields survey instruments (for lg scale; nuclear waste, etc) & personnel monitors
80
is ionization chamber type survey meter used for measuring or detecting?
measuring
81
is geiger-mueller counters used for detection or measuring?
detecting
82
aka Cutie Pie
ionization chamber
83
what is the basis for gas filled rad detectors in the ionization chamber?
ionization of gas
84
what is useful for rad surveys when exposure levels are in excess of 1 mR/hr ( 10 microgray/hr)
ionization chamber
85
disadvantage of ionization chamber?
not well suited to detect alpha rad & low levels of rad
86
what is accurate, sensitive to wide range of rad energies, portable, can measure 1 mR/hr to several thousand R/hr?
ionization chamber
87
Geiger-Mueller counter works on what principle?
ionization of gas
88
3 gases used in Geiger-Mueller counter?
Helium, Argon, Neon
89
what is useful in detecting low level radioactive contaminations?
Geiger-Mueller counter
90
what detection device is used in nuclear med?
Geiger-Mueller counter
91
is the Geiger-Mueller counter a good measurement device of rad?
no
92
what crystals produce small flashes of light when exposed to radiation in a scintillation counter?
sodium iodide or cesium iodide crystals (Thallium activated)
93
the light produced by sodium iodide or cesium iodide crystals in a scintillation counter is detected by a ___________ & is converted into ___________ which can be measured.
photomultiplier tube; electric signals
94
the scintillation counter is the most sensitive detector of?
gamma & XR rad
95
what is useful in the detection of lost rad sources?
scintillation counter
96
the ratio of secondary e-'s to incident e-'s
dynode gain
97
the photocathode does what?
amplifies e-'s
98
most scintillation counters are what?
hygroscopic
99
term for something that absorbs moisture & will swell & crack
hygroscopic
100
what prevents the crystals of scintillation counter from swelling & cracking?
hermetic seal of Al containment
101
device that emits e-'s when illuminated by light
photocathode
102
the process of emitting e-'s by a photocathode when stimulated by light
photoemission
103
what 3 ways can you express the estimation of pt dose?
entrance skin dose (ESD), gonadal dose, bone marrow dose
104
what is the medium of ESD?
air
105
ESD is most often referred to as?
pt dose
106
what can be calculated using a nomogram?
ESD
107
what is measured using TLDs (most often)
ESD
108
avg ESD of fluoro is?
40 mGy/min
109
a family of curves for estimating output XR intensity from a single-phase radiographic unit
nomogram
110
avg rad dose to the entire bone marrow is?
mean marrow dose
111
US mean marrow dose = ?
1 mGy/yr (100 mrad/yr)
112
the gonadal dose that, if received by every member of the pop, would produce the total genetic effect on the pop as the sum of the indiv. doses actually received
genetically significant dose (GSD)
113
what is estimated thru lg scale epidemiologic studies?
GSD
114
glandular dose should not exceed _______ w contact mammo & _________ w a grid
1 mGy/view; 3 mGy/view
115
according to US public health data, _____ of the total pt effective dose is from CT
70%
116
overlapping slices in CT _______ pt dose
increases
117
increased CT pitch _________ pt dose
reduces
118
the higher the multi-slice value in CT, the ______ the pt dose
less
119
pt dose is lower w higher multislice CT bc the ______________ for a given imaged anatomy
beam penumbra is less
120
repeat exams should be kept below?
5%
121
____ kVp & ____ mAs reduce pt dose
high; low
122
digi rad can be conducted at what to lower pt dose?
higher kVp
123
what film screen speed combo reduces pt dose?
fast speed film screen
124
pos pt ______ to primary beam for upper extrem's to min exposure
lat
125
when is a shadow shield necessary?
when sterile conditions are needed
126
organogenesis period is?
2 wk - 10th wk of pregnancy
127
1st 2 weeks of pregnancy?
all or nothing effect
128
current estimated levels of human radiation exposure to medical imaging rad?
3.2 mSv
129
current estimated levels of human rad exposure to natural rad?
3 mSv
130
current estimated levels of human rad exposure to Radon?
2 mSv
131
total current estimated levels of human rad exposure?
6.3 mSv
132
annual legal dose limit in US
50 mSv/yr (5000 mrem/yr; 5 rem/yr)
133
legal dose limit for entire pregnancy in US?
5 mSv (500 mrem; 0.5 rem)
134
legal monthly dose limit for pregnancy in US?
0.5 mSv (50 mrem; 0.05 rem)
135
the requirement for personnel monitoring is _________ of the annual occupational effective dose limit. which is?
10% or more; (0.5 rem)
136
film badges measure __________ irradiation
whole body
137
most common type of personnel monitor?
film badge
138
film badge should be changed how often?
every month
139
film badges are sensitive down to ________
10 mrem
140
film badge readings are made based on what?
control badge
141
control badges are kept in a?
radiation free area
142
concerned w providing occupational rad protection & minimizing rad dose to the public
health physics
143
lines that represent positions of equal rad exposure in the fluoro room
isoexposure lines
144
variation in XR intensity should not exceed?
5%
145
the max acceptable variation in linearity is ____ form one mA station to an adjacent mA station
10%
146
SSD must not be less than ________ on a stationary fluoro
38 cm (15")
147
SSD must not be less than ________ on a mobile fluoro
30 cm (12")
148
primary rad is the what?
useful beam
149
the intensity of scatter rad 1 m from the pt is approx ___ of the intensity of the useful beam to the pt
0.1%
150
annual recommended occupational dose limit?
50 mSv/yr
151
the use factor for secondary barriers is
1 (always)
152
basis for gas-filled radiation detectors?
ionization of gas
153
device that emits e-'s when illuminated
photocathode
154
ratio of secondary e-'s to incident e-'s
dynode gain
155
exposure to techs is measured in?
rems (Sv)
156
exposure (R) refers to ras intensity in?
air
157
dose in _____ is used to identify irradiation of pt's.
- rems
- rads
- R
- Sv
rads
158
pt dose can be expressed as entrance skin exposure, _______ dose, & _______ dose
mean marrow & gonadal
159
for nursing personnel present during mobile XR, a personnel monitoring device is?
not required
160
highest occupational exposure of diagnostic XR personnel occurs during:
a. fluoro
b. mobile XR
c. CT
d. both a & b
d
161
exposure to tech during mobile C-arm fluoro is lowest is XR tube is placed?
under the pt
162
best way for tech to reduce occupational exposure is to follow principles of:
a. ALARA
b. T & D
c. shielding
d. all of the above
d
163
techs working in ______ receive higher occupational exposure.
a. mammo
b. CT
c. interventional rad
d. surgery
c. interventional rad
164
a tech can reduce their exposure during fluoro by stepping:
a. back from the pt
b. behind radiologist
c. close to pt's head
d. a & b
d. a & b
165
the data on the personnel rad. monitoring report must always include the:
a. current exposure
b. cumulative annual exposure
c. skin dose
d. a & b
d. a & b
166
minimum allowable thickness for protective apron is?
0.25 mm Pb/Eq
167
A 1.0 mm Pb/Eq is _______________ for tech's during fluoro
too heavy
168
best way to hold pt's who cannot support themselves is?
to use restraining devices
169
tech's can reduce pt dose by reducing:
a. # of repeat exams
b. kVp used
c. D from tube
d. unnecessary doctor orders
a. # of repeat exams
170
gonadal shielding should be used...
a. on sinus/skull XRs
b. when gonads lie on/near useful beam
c. on all pt's 40+ yrs
d. all of the above
b. when gonads lie on/near useful beam
171
humans are most sensitive during?
fetal stages
172
a local dose of ____ rad(s) or more can cause gonadal dysfunction
10 rads
173
gonadal responses to rad have been observed at doses as low as ____ rads
10
174
exposure is measured by multiplying _______ by ________
exposure rate, exposure T
175
if a tech is exposed to 4 mR/hr for 45 mins, what is the total exposure?
3 mR
176
when using the inverse square law during fluoro, the pt should be considered a(n) _______ source of rad
point
177
if a tech is receiving 200 mR/hr standing 1 ft from pt, what is their exposure rate when they step back to a distance of 2 ft from pt?
50 mR/hr
178
NCRP publishes annual DLs for ________ exposure.
a. public
b. occupational
c. prenatal
d. all of the above
d. all of the above
179
DL's are based on a __________ dose-response relationship to rad.
linear, non-threshold
180
the DL for the general public is _______ the DL for occupational exposure
1/10th
181
what is the annual effective dose limit recommended for occupational exposure?
5 rem
182
recommended cumulative lifetime exposure for a tech is calculated by?
1 rem x age in yrs
183
what is the total DL of the embryo & fetus?
0.5 rem
184
how long is the 1st trimester?
3rd - 10th wk
185
recommended DL for the pregnant tech is _______ mrem/mo
50 mrem/mo
186
best approach to reducing occupational exposure?
a. maintain annual DL
b. follow ALARA
c. reduce your exposure to 1/2 the NCRP's DL's
d. wear protective apparel at all T's
b. follow ALARA
187
report about rad dose & affect to ppl
ICRP Report # 116
188
report about rad protection of equipment/devices
NCRP Report # 102
189
advises/recommended regulations on rad
NCRP/IRCP
190
enforces regulations on rad
FDA
191
on C-arm, where is there more rad? XR tube? or IR?
tube side
192
min thickness for protective eyewear?
0.35 mm Pb/Eq
193
what angle is there the least amount of backscatter?
90º (right angle)
194
exposure switch (in control booth) should be at least ____ inches from any open edge of booth & must be a _______ switch
30"; fixed
195
intermittent fluoro cuts rad by?
1/2
196
the beams that pass through the compensating filter are _____ by comparison to the original beam
weaker
197
I.I. acts as a what?
primary protective barrier of 2 mm Pb/Eq
198
standards state that exposure in air from fluoro equipment shall not exceed?
10 R
199
who is responsible for governing the use of rad. sources?
RSO (rad safety officer)
200
what is the dose equivalent limit for hands of a tech?
50 rem
201
primary factor in protecting tech from backscatter?
use pb shielding
202
pb/Eq for pb aprons?
0.5 mm pb/eq
203
how much is the rad exposure reduced if D btw pt & tech is doubled?
4 x's
204
a dose that is not expected to produce significant effects
DE limits
205
DE limit a rad student may receive in 1 yr if they're less than 18 yrs old?
1 mSv
