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Flashcards in Radiation Protection Deck (62)
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1

radiation that has the ability to make an atom a charged particle

ionizing radiation

2

has to have mass
doesn't travel far

particulate radiation

3

what do we treat superficial with?

electrons

4

how do we treat deeper?

photons

5

energy and wavelength are ___ proportional

inversely

6

two major groups of radiation in rad therapy

external beam
brachytherapy

7

External beam:

linear accelerators/cobalt 60 machines
produce x-rays, gamma rays, and electrons

8

Brachytherapy sources:

137Cs, 192Ir, 125I
emit gamma rays, x-rays, alpha particles, and beta particles

9

example of alpha particles

helium nuclei
2 protons, 2 neutrons

10

alpha particles have a ___ LET

high

11

How do alpha particles do damage?

They have to get inside of you

12

how are alpha particles emitted?

from unstable nuclei
comes from nucleus
ex) radium or radon

13

where are beta particles edited from?

the nucleus

14

beta particles can be _____ or ______ charged

negative, positive

15

What is the rest mass of an electron?

.511 MeV
rest mass of an electron

16

how are beta particles best shielded?

plastic or glass

17

what equation is the photoelectric effect dependent on

z^3/e^3

18

what is the difference in x-rays and gamma rays?

gamma rays- nucleus
x-rays- orbitals

19

what percent of X-ray interaction is brems?

85%

20

what percent of x-ray interactions is characteristic?

15%

21

What are the sources of radiation?

-natural background
-man made

22

What are the natural background sources of radiation?

-cosmic: from space
-terrestrial: from ground
-internal exposure: radioactive material in body

23

What is an ex. of terrestrial radiation?

radon
2nd most common for lung cancer

24

Units for exposure

traditional: roentgen
SI: coulomb/ Kg of air

25

Units for absorbed dose

traditional: rad
SI: Gray

26

Unit for dose equivalent
** Quality Factor**

traditional: rem
SI: sievert

27

Unit for activity
brachytherapy
1 disintegration/sec

traditional: curie
SI: bequerel

28

1 roentgen= ? Coulomb/Kg of air

2.58x10^-4

29

quality factor of:
x-rays, gamma rays, and electrons

1

30

quality factor of:
thermal neutrons

5

31

quality factor of:
neutrons, heavy particles

20

32

Types of measurement devices:

-gas filled detectors
-TLD
-Film
-Pocket ionization chambers
-neutron detectors

33

types of gas filled detectors
-calibrated within 2%

-ionization chamber (pocket dosimeter)
-geiger muller detector (very sensitive, measures presence of radiation)

34

TLD

thermoluminescent dosimeter
lithium fluoride, dose can be stored for days
anneling process
1 hour: 400 degree C
24 hours: 80 degree C

35

pocket ionization chambers

immediate readout
initially expensive
for infrequently exposed
has to be charged to zero it out

36

neutron detectors

"rascal"
BF3 or Argon
bubble counters

37

OSL

optically stimulated
light in relation to dose
Al2 O3

38

rascal neutron detector
boriated polyethylene

above 10
our range 6-20

39

Regulatory Agencies:
National Council on Radiation Protection and Measurement

NCRP
set exposure levels

40

Regulatory Agencies:
International Commission on Radiation Protection

ICRP
set exposure levels

41

Regulatory Agencies:
Nuclear Regulatory Commission

NRC
isotope usage

42

Regulatory Agencies:
Food and Drug administration

FDA
linac license

43

Regulatory Agencies:
Department of Transportation

DOT
Transporting isotopes

44

Non stochastic effects
deterministic

threshold

45

stochastic

non threshold

46

dose response curves
(linear and quadratic)

probability increases with dose, not sensitivity

47

Somatic effects

in exposed individual
carcinogenesis

48

genetic effects

occurring in future children
mutagenesis

49

developmental effects

develop while in eutero
teratogenesis
embryologic

50

ALARA

as low as reasonably achievable

51

comparable risk

it shouldn't be more dangerous to work in our field than any other

52

genetically significant dose

GSD take into account all radiation types
measurement of genetic rise to an entire population

53

3 major rules of radiation

1. time
2. distance
3. shielding

54

In cobalt machines, exposure must be less than ____ at any point ___ m from the source

10 mR/ hour
1 m

55

if average radiation reads ___ then it is outside the range of reading

2 mR/ hr

56

What are the shielding factors?
B=pd^2/WUT

w- workload
u-use factor
t- occupancy factor
d- distance
b- transmission factor
p- point of interest dose

57

Safety equipment
examples of quality assurance testing

-warning signs
-warning lights
-door interlocks
-visual and aural communication (should be able to see and hear pt)
-beam on monitors
-emergency off controls (if not working, go straight to circuit breaker)
-QA

58

Brachytherapy

-must have license from NRC
-keep a log of sources in/out
-use shielded carriers
-post patient room
-personnel monitor
-warning signs and survey
-leak tests
-HDR (High Dose Rate)

59

Inventory:
removing
returning

removing- take inventory
sources removed, sources remaining
returning- sources remaining, complete inventory

60

administrative requirements and roles

ALARA
RSO- implement radiation protection program
RSC- oversee the use of the material
written procedure-
written directive- prescription

61

Medical event:

recordable event
misadministration
180-200 cGy per fraction

62

Disposal of radioactive waste

-facility dependent
-usually separated by half life
*must decay 10 half lives
-can be in different forms
*** All falls under NRC****