Interactions Of Ionizing Radiation Flashcards
(106 cards)
1
Q
characteristic radiation occurs from what effect?
A
from photoelectric effect
2
Q
in elastic interaction, what happens to E of e-?
A
given to e- in target
3
Q
in inelastic interaction, what happens to E of e-?
A
only partially given up to target
4
Q
Brems aka
A
radiative collision interaction
5
Q
what happens to photon in transmission
A
- photon passes w/no interaction
- no E exchanged
6
Q
coherent scatter aka
A
aka classical, unmodified, thompson
7
Q
photoelectric effect has what kind of absorption?
A
true E absorption
8
Q
does photoelectric effect depend on E?
A
yes- as E increases, photoelectric effect decreases (inversely prop)
9
Q
auger e-
A
-mono E e- produced by absorption of characteristic xrays by atom & reemission of E in form of orbital e- ejected from atom
10
Q
photonuclear interaction (photodisintegration) occurs at what E?
A
15MeV
11
Q
compton scatter aka
A
modified scatter
12
Q
compton depends on
A
- E of photon- inv prop (Z does NOT affect it)= decr w/incr E
- e- density- depends on # of e- per gram
13
Q
pair production occurs at what E?
A
higher E; 10 MeV
14
Q
pair production depends on
A
Z (dir prop to z^2)
15
Q
linear attenuation coefficient definition
A
- probability per unit thickness that any one photon will be attenuated
- fx of photons removed from a beam per cm of absorber
- fx of photons removed per unit thickness
16
Q
linear attenuation coefficient affected by e- density?
A
yes, e- density of absorber
17
Q
Co-60/1.25 MeV dmax
A
0.5 cm
18
Q
4 MV dmax
A
1 cm
19
Q
6 MV dmax
A
1.5 cm
20
Q
10 MV dmax
A
2.5 cm
21
Q
15 MV dmax
A
3 cm
22
Q
18 MV dmax
A
3.5 cm
23
Q
20 MV dmax
A
3.5 cm
24
Q
25 MV dmax
A
5 cm
25
QF (quality factor) formula
dose equiv= absorbed dose * QF
26
xray QF
1
27
gamma QF
1
28
e- QF
1
29
thermal n QF
5
30
alpha particle QF
20
31
n QF
20
32
p+ QF
10
33
R (Roentgen) unit for
exposure in air
34
absorbed dose measured in
rad or Gy
35
250keV dmax
surface
36
6MeV dmax
1.2 cm
37
9MeV dmax
2.0 cm
38
12MeV dmax
2.5 cm
39
when streams of fast moving e- interact w/target of anode, 2 types of x-rays generated:
- brems
| - characteristic
40
max electronic buildup
secondary e- are set into motion when high photons strike medium
41
characteristic radiation is what kind of interaction?
collision
42
characteristic radiation has what kind of spectrum?
discrete
43
in characteristic radiation e- interacts with ?
e- of target
44
characteristic radiation collisions are?
excitation or ionization
45
characteristic radiation happens when e- does what?
fills vacancy
46
characteristic radiation has no importance in what?
MV
47
characteristic radiation can produce ? e-?
auger
48
in elastic interaction, what is conserved?
momentum & KE?
49
in elastic interaction, what is not lost?
E
50
in inelastic interaction, what is conserved?
momentum; KE not
51
Brems most created for
therapy
52
in Brems, e- attracted to
nucleus
53
what happens to e- in Brems?
passes near, slows down, and loses KE
54
Brems has what kind of spectrum?
continuous
55
in Brems, intensity is proportional to ?
beam current
56
in Brems, x-rays emitted what direction?
any angle
57
in Brems, photon E is equal to ?
E lost by e-
58
in coherent scatter what happens to e-?
not enough E to free e- (vibrates) but E absorbed
59
what does coherent scatter produce?
very low E photon, scatters
60
photoelectric effect in what E range
10-30 kvp
61
in photoelectric effect, photon interacts with?
atom & ejects orbital e-
62
in photoelectric effect, what is the KE of photon?
initial photon E minus binding E
63
photoelectric effect involves what e-?
inner shell
64
in photoelectric effect, what is created?
vacancy= characteristic xrays
65
in photoelectric effect if angle is 90 deg, what kind of E?
low
66
in photoelectric effect if angle is 10 deg, what kind of E?
high
67
is photoelectric effect dependent on Z?
- yes, directly proportional to Z^3 (mass coef dependent)
| - Z^4- atomic coef dependent
68
probability of Brems varies with ?
Z^2 of target material
69
is photoelectric effect dependent on E?
yes
70
photonuclear interaction aka
photodisintegration
71
photonuclear interaction (photodisintegration) is an interaction between what?
photon & nucleus
72
in photonuclear interaction (photodisintegration), makes nucleus unstable and emits ?
neutron (why we shield) & gamma
73
in photonuclear interaction (photodisintegration) what happens to incoming photon?
complete absorption
74
Compton scatter E range
60kVp-10MeV
75
Compton used in
radiation therapy
76
in Compton scatter, photon has how much E?
more thank outer shell e-
77
in Compton scatter, incoming photon interacts with?
outer shell e- (loosely bound)
78
what is a scattered e- called
recoil e-
79
in Compton scatter, E is?
both absorbed & scattered
80
pair production can only occur when what happens
photon has 1.02 MeV threshold dose
81
in pair production what happens to photon
complete absorption
82
in pair production what happens to photon E
converted to positron & e- (matter created)
83
in pair production, what happens to positron
loses KE & recombines with free e- (annihilation rxn)
84
what is is called when positron combines with free e-
annihilation rxn
85
linear attenuation coefficient formula
0.693/HVL
86
linear attenuation coefficient unit
1/cm or cm^-1
87
linear attenuation coefficient affected by E?
yes, increase E, decrease u (inv prop)
88
linear attenuation coefficient affected by Z?
yes, increase Z, increase u (dir prop)
89
linear attenuation coefficient is affected by ? of absorber
state
90
QF definition
-compares biological effectiveness of particulate radiation to std xray rad
91
R (Roentgen) only applies at what E
3 MeV
92
R (Roentgen) only applies to what radiation
x-ray & gamma
93
R (Roentgen) only happens when?
e- equilibrium exists
94
R (Roentgen) SI unit
C/kg
95
R (Roentgen) only measures what?
products of ionization- not photons
96
R (Roentgen) is NOT
E or intensity or absorbed
97
R (Roentgen) is? C/kg
2.58 x 10^-4 C/kg
98
1 R air kerma deposits ? of absorbed dose in air
0.877 rad
99
F factor is
the tissue dependent conversion from kerma to absorbed dose
100
absorbed dose defines
quantity
101
absorbed dose applies to
all types of radiation & E ranges
102
absorbed dose applies in areas where ?
e- equilibrium does NOT exist
103
max electronic buildup depends on
photon E & medium composition
104
Dmax is defined as
max dose obtained at depth where electron equilibrium reached
105
Binding energy per nucleon is
8 MeV per nucleon
106
Most important physical quantities that are conserved in a nuclear reaction are
- charge
- mass number
- linear momentum
- mass-energy
