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Flashcards in chapter 5 EXAM 3 Deck (66):
1

radiation survey instruments

area monitoring devices that direct and measure radiation

2

personnel dosimetry

the monitoring of radiation exposure to any person occupationally exposed on a regular basis to ionizing radiation

3

exposure monitoring is required when radiation workers are likely to receive

10% or more of the annual ocupational EfD limit in any single year due to their work activity

4

most healthcare facilities issue dosimeters when personnel could receive

1% of the annual occupational EfD limit in any month

5

what is the purpose of personnel dosimeter

for your safety.
determines the amt. of exposure by measuring the amt. of ionizing radiation the dosimeter has been exposed to
detects and measures the amt. of radiation it has been exposed to

6

placement of personnel dosimeter
during routine radiographic procedures

attached to the clothing on the front of body at collar level to approximate the dose to thyroid, head and neck

7

placement of personnel dosimeter
when a protective apron is worn

outside apron at collar level in the front

8

placement of personnel dosimeter
as a second monitor when a protective apron is worn

1st dosimeter worn at collar level
2nd dosimeter worn beneath apron at waist level (measures dose to lower body trunk)

9

commercial lead aprons have how much lead equivalent

0.5 mm lead equivalent over all

10

commercial lead aprons have how much lead equivalent in a less heavy version

0.35mm lead in the front and 0.25mm lead in the back

11

monitor for the embryo-fetus

wears primary dosimeter at collar level
second monitor records dose to the abdomen worn at waist level

12

extremity dosimeter

used when performing fluoroscopic procedures when hand is near primary beam
measures dose to hands of the wearer

13

extremity dosimeter contains the following info

account number, name, wear date, R or L hand, size and reference number

14

TLD stands for

thermoluminescent dosimeter

15

characteristics of personnel dosimeters

lightweight/easy to carry
durable
able to detect large and small exposures
outside influences should not affect its performance
inexpensive

16

4 types of personnel dosimeters

1. optically stimulated luminescense (OSL)
2. film badges
3. thermoluminescent dosimeter (TLD)
4. pocket ionization chambers

17

when were optically stimulated luminescense dosimeters developed

the late 1990's

18

optically stimulated luminescense (OSL)

most common type
are replacing film badges
a combo of film and TLD while eliminating their disadvantages

19

OSL dosimeter contains

an aluminum oxide detector
and is read by a laser light

20

the OSL dosimeter can be worn for

1 year but commonly is switched out every 1-3 months

21

what is the inhouse reader called that landauer does sell

microStar
this allows occupational exposure to be read the day of occurrence

22

what are the 3 different filters in an OSL badge

1. copper
2. aluminum
3. tin

23

T or F
aluminum absorbs the least in an OSL badge

true

24

T or F
copper attenuates the most in an OSL badge

true

25

when high energy radiation strikes the OSL dosimeter,

the laser reading would show a similar reading through all the filters

26

when low energy radiation strikes the OSL dosimeter,

the laser reading would be more pronounced in the region covered by the aluminum filter

27

T or F
OSL dosimeters are extemely sensitive

true
the increased sensitivity makes it ideal for monitoring employees working in low radiation environments

28

control monitor

the monitoring company provides this with each batch of dosimeters to make sure when they are transferred the reading is not compromised by anything that comes from the outside environment.

29

advantages of OSL monitors

lightweight, durable
color coded
tamperproof
extended wear frequencies
increased sensitivity
inexpensive

30

an OSL dosimeter has an accurate reading as low as

1 mrem (10microseiverts) for xray and gamma ray photons with energies ranging from 5KeV to greater than 40 MeV

31

disadvantages of OSL monitors

exposure is recorded only in body area where it was worn
exposure cannot be determined on day of exposure
must wear it for it to be efficient

32

Film Badge consists of

film holder
metal filters
film packet

33

when did film badges come into use

1940's

34

film holder

made of plastic
has low atomic number

35

metal filters

located inside film holder
made of aluminum and copper
allow measurement of approximate energy of radiation
determine direction it reached film
determines if exposure was from scatter or primary radiation

36

film packet

sensitive to doses ranging from 0.1 mSv to 5000mSv
doses below this are not usually detected and reported as minimal
lead foil on back of film to absorb scatter coming from behind dosimeter

37

radiation interacting with film badge causes the film to

blacken

38

function of control badge

serves as a basis for comparison

39

increased optical density on a film badge is read with

a densitometer

40

personnel monitoring reports

accurately records and maintains records to meet state and federal regulations
supplies written personnel report to health care facility

41

change in employment by radiation worker

must convey the data pertinent to accumulated equivalent dose to the new employer to be placed on file

42

advantages of film badges

permanent legal record of personnel exposure
economical
mechanical integrity

43

disadvantages of film badges

temp and humidity can cause fogging
exposure cannot be determined on day of exposure
less sensitive to ionizing radiation

44

thermoluminescent dosimeter (TLD) detector is made of

sensing material is lithium flouride

45

how TLD dosimeter works

radiation causes electrons in the lithium flouride molecules to absorb energy and become excited to higher energy levels and become trapped.
after being passed through special heating process trapped electrons return to normal state and emit light

46

TLD analyzer measures

the amount of ionizing radiation by heating crystals to free trapped electrons and records amount of light emitted

47

advantages of TLD

interacts with ionizing radiation as human tissue does
exposures as low as 1.3x10^-6c/kg can be measured precisely
environmental factors do not affect it
may be worn up to 3 months
crystals can be reused

48

disadvantages of TLD

high initial cost
readout process destroys stored info

49

pocket ionization chamber

most sensitive type of personnel dosimeter
use in diagnostic imaging is uncommon
looks like a pen

50

2 types of pocket ionization chambers

1. self reading type (built in electrometer)
2. non self reading type

51

components of pocket ionization chamber

contains 2 electrodes one positive one negative
when charged electrodes are exposed to xrays or gamma rays the positive electrode becomes ionized and discharges mechanism in proportion to amount of radiation to which it has been exposed

52

t or f
you need a special charging unit for a pocket ionization chamber

true

53

pocket ionization chambers are sensitive to exposures ranging from

0 to 5.2x10^-5 c/kg

54

advantages of pocket ionization chamber

immediate readout
compact
convenient
accurate and sensitive
ideal for short duration

55

disadvantages of pocket ionization chamber

expensive
must be read each day
subject to mechanical shock
could get false reading if dropped

56

3 types of radiation survey instruments for area monitoring

1. ionization chamber-type survey meter (cutie pie)
2. geiger muller detector (GM) (seen in nuc med)
3. proportional counter

57

requirements for radiation survey instruments for area monitoring

portable
durable
reliable
interact with ionizing radiation similar to human tissue
detect all common types of radiation
cost effective
calibrated annually

58

ionization chamber-type survey meter
CUTIE PIE

small in size
measures exposure rate (c/kg)
used for area surveys
measures x and gamma radiation

59

sensitivity range of the CUTIE PIE

measures intensities from 1 mR to several R

60

advantage of the cutie pie

able to measure a wide range of radiation exposure within a few seconds

61

disadvantages of the cutie pie

delicate
without adequate warm up reading may be inaccurate
cannot measure diagnostic procedures because exposure times are too short

62

what is the cutie pie most commonly used to measure

exposure rates at various distances from patient who has received radioactive material for diagnostic or therapeutic use

63

proportional counter

serves no purpose in diagnostic imaging
used in alb setting to detect alpha and beta radiation

64

geiger muller detector

primary portable radiation survey instrument for area monitoring in nuclear medicine facilities
detects area contaminated by radioactive material
locates lost radioactive source or low level radioactive contamination

65

geiger muller detector components

has an audible sound system that alerts operator to the presence of ionizing radiation

66

disadvantages of the geiger muller detector

not independent of energy of incident photon
saturates or jams when placed in very high intensity radiation area giving a false reading