final Flashcards
1
Q
what controls x ray energy?
A
KVP
2
Q
what are INTENSIFYING screens used for?
A
to reduce patient exposure
3
Q
difference between voltage ripple and x-ray energy?
A
inverse - as voltage ripple increases x ray energy decreases
4
Q
lead screen on the back of the casette does what?
A
reduces compton scatter
5
Q
for a compensating filter in a lateral lumbar spine radiograph?
A
filter up
6
Q
xray production is slowed down due to an electromagnetic force field called
A
bremsstrahlung
7
Q
at what point are xrays produced in the tube?
A
when electrons strike the anode (focal spot, target)
8
Q
electron transition in tungsten that produces the highest energy xray?
A
P to K - characteristic 69.5 kEv
9
Q
in lateral spine thoracic radiograph where is the anode?
A
down
10
Q
what exposure factor controls the QUANTITY of xrays in the beam?
A
mAs
11
Q
what factor is selected to select filament size (large vs small)
A
mA
12
Q
which side of the radiograph exhibits the most blur?
A
cathode side
13
Q
which has the greatest specific ionization alpha or beta?
A
alpha
14
Q
define isotropic
A
360 degree emission
15
Q
which is most likely to occur in human tissue direct or indirect effect?
A
indirect effect
16
Q
what is the only similarity between particulate radiation and xray?
A
they can ionize
17
Q
define the term ionize
A
when an electron is totally removed from an atom
18
Q
xray tubes target is made of what?
A
tungsten
19
Q
if a tube overload occurs what must be done to fix it?
A
decrease mA and increase time
20
Q
how often must lead walls be replaced
A
NEVER
21
Q
what does a rectifier do?
A
converts AC to DC current
22
Q
what does an electromagnetic induction motor do
A
spins the rotor/anode target
23
Q
what type of radiation can be stopped by a piece of paper
A
alpha
24
Q
what is the charge on the focusing cup?
A
very negative
25
what is the difference between x ray and gamma ray
the origin gamma comes from nucleus - otherwise it is identical
26
where should anode for an AP thoracic spine film be
UP
27
primary parts of cathode
filaments large and small and focusing cup
28
ALARA
as low as reasonably achievable
29
which rectifier will provide the least radiation exposure to patient
high frequency (30% less)
30
compare the mass of an xray to an alpha particle
an xray has no mass - alpha particles have 4 AMU of mass
31
compare wavelengths of xrays to radio waves
xrays have shorter wavelengths
32
electrons travel from where to where
cathode to anode to make xrays
33
to double radiographic density you must
also double mAs
34
to double radiographic density using kVP
increase kVp by 15%
35
what is the controlling factor of radiographic density?
mAs
36
define linearity
the ability to manipulate mA and time and get the same mAs
37
define reproducibility
doing the exact same exposure over and over and getting the exact same results
38
relationship between frequency and wavelength
inverse
39
formula for heat units
kVP x mAs
40
what produces the majority of xrays in the xray beam
bremsstrahlung
41
optimum kvp for extremities under 10 cm
50-60
42
optimum kvp for spine imaging
70-90
43
two akas for SID
FFD and TFD
44
wave equation
speed of light = wavelength x freq
45
define LD 50/30
means lethal dose where 50% of exposed pop dies within 30 days
46
does a nonstochastic effect have a threshold?
YES (stochastic means random)
47
stochastic effect
does NOT have a threshold
48
males receiving radiation for ankylosing spondylitis experience increases in
leukemia
49
2 devices used to reduce compton scatter
collimation
bucky and compression band
lead lining in back of casette
50
hormesis
the notion that some radiation may actually be good for you
51
mutation that is unique to radiation exposure
none
52
relationship between SID and magnification
inversely related
53
two radiation induced malignancies
leukemia
| thryoid, skin, bone, lung cancers
54
interaction with matter that results in inner shell ionization
photoelectric absorption
55
differential absorption of xrays by tissues results in this photographic property
contrast on xray film
56
one disadvantage to use of radiographic grids
increases patient exposure dramatically
57
improper or wrong SID used on focus grid, pattern of grid cutoff looks like
both sides are cutoff so the film is underexposed on both lateral edges
58
personnel dosimeter should be worn
on the collar or outside apron
59
annual whole body MPD for occupational exposure is
5 REM
60
MPD for pregnant occupational worker
0.5 REM over the gestation period
61
how are kvp and compton scatter related
directly, as kvp goes up compton scatter goes up
62
the shortest latent period of all cancers is
leukemia
63
dust on an intensifying screen results in
little white specks on the processed film
64
color safe light required to be used with rare earth film screen combos
RED
65
a red safe light is considered universal - state the name of the safelight
GBX
66
degree and direction of central ray angle used with a crosshatch grid
none
67
5 mAs required at 40 SID what is necessary at 80 SID to maintain density
20 mAs (distance doubled so multiply by 4x)
68
radiation that comes from the tube housing in areas other than the port
leakage radiation
69
level of fetal exposure below which no abortion is recommended
10 RAD (bushong 10-25 rule)
70
what is film latitude?
range of error
71
a long latitude film will respond to a wide range of useful _____
density
72
relationship of film contrast to film latitude
inverse
73
the writing on the safelight filter is placed where
away from bulb so it wont melt - 4 ft
74
what is film base made of
mylar
75
what is the film emulsion made of
silver halide crystals in gelatin
76
what are intensifying screens made of
rare earth crystals
77
minimum speed for spine imaging
400
78
film speed for detailed extremities
100
79
safelight bulbs should be this watts
15 or less
80
black tree branch artifact caused by
static
81
humidity to store films
40-60%
82
latent image
invisible image on the film before processing
83
manifest image
the visible image on film after processing
84
an occupationally exposed person's own personal exposure if included in REM unit T/F
False
85
which is most likely to cause fog in an image
use of high kvp - creates longer range higher kvp goes further into range of compton scatter
86
grid that is designed so that strips coincide with the divergence of the xray beam
focused
87
image density can be DOUBLED by
inc kvp 15% and inc mAs by 100%
88
short scale of contrast wanted (high contrast)
decr kvp and incr mAs 2x
89
when OID is long it is more what kind of xrays produce image
divergent xrays produced
90
stochastic effect
requires no threshold of radiation exposure for effect to occur
91
linear non threshold
dose response relationship
92
non stoachastic threshold
requires a threshold to reach first
93
maximum permissible dose
max radiation dose would not be expected to produce significant radiation effect
94
what is the annual whole body MPD for occupationally exposed persons
5 REM
95
cumulative MPD old formula
5(n-18) n = age
96
new formula MPD
1X Age = 55 REM/year
97
on dosimeter report what does m mean
exposure received was so minimal it did not record
98
cardinal principles of radiation protection
time
distance
shielding
99
what allows a greater amount of weekly radiation exposure
controlled area - entire x ray room
100
max exposure rate of controlled area
less than 100 mR per week
101
max exposure rate of uncontrolled area
less than 10 mR per week
102
protective tube housing
must reduce leakage radiation to less than 100 mR/hour at one meter
103
SID indicator
must be accurate withing 2% of indicated SID
104
filtration
total 2.5 mm Al equivalent
105
PBL positive beam limitation
automatic collimation - must be accurate to within 2%
106
how often must film badges be sent in for processing
once every month
107
non-stochastic effects
erythema, cataracts, sterility
108
what factors influence the amount of effect produced by radiation
dose rate and area of body exposed
109
cells most sensitive to radiation
lymphocytes
110
law of bergonie and tribondeau
cells that are undifferentiated and rapidly dividing are more likely to be effected by xrays
111
major cell types at risk
embryonic
lymphocytes
erthyrocytes
sperm
112
women are more x ray resistant than men are T/F
true
113
acute radiation syndrome is relevant in diagnostic xray T/F
false
114
hematopoietic syndrome
200-1000 RAD whole body
115
GI syndrome
1000-5000 RAD whole body
116
CNS syndrome
over 5000 RAD
117
there is no UNIQUE radiation induced disease T/F
true
118
long term effects DO NOT occur in most irradiated individuals T/F
true
119
some ways to reduce exposure to patients
1. aim beam at a primary wall that is not facing a waiting room
2. collimate well each time
3. gonadal shields
4. set up patient correctly - high mA short time
5. use high freq rectifier for xray
6. use a high speed system
7. only use the bucky when appropriate (>10 cm or >60 kvp)
8. use compensating filters to assist
9. long SID
10. maintain equipment
11. proper record keeping
120
as speed increase detail/sharpness
decreases
121
slow speed has little ___ and is more
divergence and blurrier bigger
122
black crescent moon shapes artifact are from
bending film
123
what is not a cardinal principle of radiation protection
kvp
124
radiation does not add up T/F
true - damage does
