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Skin Radiation therapy > radiation safety and parts of accelerator > Flashcards

radiation safety and parts of accelerator Flashcards

1
Q

suoerficial xrays kv

A

40-100

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2
Q

superficial xrays can treat to what depth

A

.5cm

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3
Q

dose orthovoltage

A

100-300kv

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4
Q

superficial xrays use HVL of?

orthovoltage uses HVL of ?

A

superficiAL- AL

orthovoltage- Cu`

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5
Q

ssd of orthovoltage

A

50cm

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6
Q

what depth can orthovoltage be treated to

A

2-3cm

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7
Q

whats the accelerating waveguide

A

a hollow tube that allows ekectrons to be accelerated after the cathode until they leave the waveguide

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8
Q

what components are in the drive stand

A

klysteon, cooling system, waveguie and circulator

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9
Q

i provide microwave power to accelerate electrons

A

klystron

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10
Q

what does klystron do

A

provides microwave power to accelerate elctrons

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11
Q

i stop microwaves from returning to the klystron

A

circulator

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12
Q

circulator is between ____ and _____

A

klystron and waveguide

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13
Q

what does circulator do

A

it acts like a valve and directs microwave from klystron to the waveguide and prevents microwaves from returning to the klystron

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14
Q

components of the gantry

A

electron gun, accelerator structure and treatment heasd

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15
Q

______ produces electrons and injecs them into th accelerator structure

A

electron gun

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16
Q

shape and material of linac cathode

A

tungdten that is sphere shape

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17
Q

2 types of accelerator waveguides

A

can be vertical or horizontal

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18
Q

when is vertical vs horizontal waveguides

A

vertical, are shorter distance and poduces lower energy in treament machine
horizontal is longer and produces higher energies and longer distance

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19
Q

whta is in the treatment head for photons

A

bending magnet, x ray target, primary collimator, beam flattening filter, ion chamber and secondary collimator

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20
Q

what part of the LINAC limits th3e FS

A

primary collimator

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21
Q

benading magnet

A

may bend electrons through eledctrons 90-270 degrees onto x ray target

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22
Q

after electrons leave bending magnet where do electrons go

A

go to primary collimator

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23
Q

what is in the tx machine for photons thats not used for eledctrons

A

the target and beam flattening filter are in field when treating photons

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24
Q

what is in the treatment head for electrons but not photons

A

eledctrons use 1-2 scattering foils and remove target

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25
Q

what is located on the carousel

A

beam flattening filter (for photons)

and scattering foils for electrons

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26
Q

what does beam flattning filter do in terms of treating a photon field

A

imorives dose uniformity

more photons absorbed from central axis than from the periphery of the beam

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27
Q

1st vs second scattering foil

A

used for eldctrons
the first fol is used to mak pencil beam into usable beam
the second foil is used to beam more uniform

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28
Q

how much bremstralung contamination is in elctron beam

A

<5% of thed beam

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29
Q

how many leaves are in MLCs in LINAC

A

52-160

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30
Q

percentaged of leakage

A

2.5-4%

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31
Q

what is used in arm of an EPID

A

amophorus silicon

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32
Q

where does the electron go after the bending magnet

A

goes to the target (in photons) and to the scattering foil in electrons

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33
Q

creation of photons

A

1- klystron creates electrons
2-wave guide brings electrons from klystron to electron gun
3-electron gun injects electrons to accelerator guide
4-accelerator guide makes electrons in straight line
5-electrons acclerated to speed of light
6-hits bending magnet to 270 degrees
7-e beams hits target in photons or scattering foil in electron
8- collimator shapre xray beam
9-tx pt

34
Q

what is typically used for shielding

A

Pb

35
Q

what materials are used ot shield when compton is primary interaction

A

concrete or steel

36
Q

what is traditional personel monitoring system

A

film monitor

37
Q

how do film monotors measure dose

A

they havea film pack which once developed are cmopared to non exposed areas by someone with light densimoter

38
Q

what is cons of film monitors

A

not super accurate, is an estimated dose

artifacts occur when exposed to heat and humidity

39
Q

pros of film monitors

A

cheap

40
Q

what is used in TLD

A

Crystaline sustance

LiF

41
Q

How are TLD measured

A

composed of crystalin substance when crystak is heated electrons return to initial state and dose received is proportional to damage of the crystal substqance

42
Q

what is the cons of TLD

A

Can only have reading done once

43
Q

what dosimeter is best for personel monitoring now

A

osl

44
Q

what dosimeters use crystals

A

TLD and OSL

45
Q

What devices measure PERSONEL monitoring

A

TLD, OSL and film monitor

46
Q

what dosimiter is best at finding contamination XRT or low level XRT

A

geiger muller counter

47
Q

what is the clicking detector

A

geiger muller

48
Q

whatXRT detector can directly and immediately give quantitative dose info

A

ion chamber

49
Q

what is con of GM counter

A

does not give specific quantitative dose

50
Q

GM counter uses what to detect XRT

A

gas filled tube

51
Q

what XRT detector is used for brachytherapy

A

GM is used in HDR tx room to find lost sources asnd confirm no contamination

52
Q

what detector is used in nuc med imaging

A

scintilation detectors

53
Q

what detectors are event or pulse detectors

A

GM detectors and scintilation detectors

54
Q

what crystals ae used in scintilation detectors

A

NaI

55
Q

when the scintilation detector stops working what does this indicate

A

a v large xrt field

56
Q

what detector uses crystals for radiation measurement

A

scintilation detectors for XRT expsoure, and TLD and OSL for personel monitoring

57
Q

occupational exposure of the lens oF the eye anually

A

150mSv

58
Q

occupational exposure of b.m, breast, lung, gonad, skin, extremity

A

500mSv

59
Q

ft of shielding primary and secondary barrier for 6mv

A

primary 6 f secondary 3-4ft

60
Q

ft of shielding primary and secondary barrier for 15Mv

A

pimary 7-9 ft

secondary 4-5ft

61
Q

activity is defined as

A

radiactiv disintegrations/ time

62
Q

xposure is defined as

A 
only for photons 
# ionization / photons unit mass of air
63
Q

asorbed dose is defined as

A

energy absorbed / mass of any material

64
Q

largest contribution of internal radiation

A

potassium

65
Q

what is alpha beta ratio for arly responding tissus

A

10

66
Q

what is alpha beta ratio for late responding tissues

A

3.5

67
Q

what test is required t=packages with >1mci and half life of 30 days

A

wipe test

68
Q

what dose and half life requires wipe tests

A

> 1mCi

30 days 1/2 life

69
Q

how to dispose of rdioactive waste

A

sewer system included flushing draining or put it into emptying tank
incineration rquires licensing
transfer to recipient
burial requires special license

70
Q

what methods of radioactive waste disposal requires license

A

incineration and burial

71
Q

how long should records be maintained about disposal of radioactive waste

A

3 years

72
Q

shielding around stored radioisotopes should reduce XRT to ?

A

<2mrem/hr at 1m

73
Q

caution radiation area dose

A

> 5mrem/hr

74
Q

caution high radiation area dose

A

> 100mrem/hr

75
Q

caution grave danger very high XRT area dose

A

> 500cGy/hr

76
Q

whats considered to be the cathode of the linac

A

electron gun

77
Q

how to find the avg energy of an MV photon beam

A

its 1/ 3 of the energy of the electron beam

78
Q

_____ sets the maximum FS

A

primary collimator

79
Q

what part of th LINAC signals for the machine to shut off after the dose has been delivered

A

ionization chamber

80
Q

the LINAC is presurized with ___ to -risk for electrical breakdown

A

sf6

Skin Radiation therapy (40 decks)

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