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Radiation protection > chapter 13 EXAM 6 FINAL > Flashcards

chapter 13 EXAM 6 FINAL Flashcards

1
Q

for monitored xray personnel the risk may be compared with the occupational risk for persons employed in other industries considered reasonably safe. These jobs have a risk of fatal accidents generally estimated to be about

A

1x10^-4 per year

1 in 10,000 a year

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2
Q

at a 90 degree angle to the primary xray beam at a distance of 1m the scattered xray intensity is generally about how much of the primary xray beam

A

about 1/1000 of the intensity of the primary xray beam

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3
Q

what poses the greates occupational hazard in diagnostic radiology

A

scattered radiation

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4
Q

what reduces the number of scattered radiation produced in a pt. and therefore reduces the radiographers dose

A

beam limitation devices

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5
Q

for regular diagnostic xrays, your protective lead apron should be how much lead

A

0,25

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6
Q

for fluoro your protective lead apron should be how much lead

A

0.5

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7
Q

all aprons should be inspected for cracks or other defects every

A

year

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8
Q

as the average energy of the beam increases, the percentage of radiation that is forward scattered does what and therefore…

A

increases

and therefore less side scattered radiation is available to strike imaging personnel

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9
Q

use of high speed image receptors does what to the personnel exposure

A

decreases personnel exposure

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10
Q

after the voluntary declaration of pregnancy, the RSO must

A

provide essential counseling

furnish an appropriate additional dosimeter

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11
Q

in pregnant personnel, the monthly EqD to the embryo fetus must not exceed

A

0.5mSv

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12
Q

in pregnant personnel, the EqD for the entier pregnancy must not exceed

A

5 mSv (0.5rem)

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13
Q

attenuation by the maternal tissues ovelying the fetus reduces the dose to the fetus to aprox.

A

30 % of the abdominal dose

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14
Q

t or f
when normal protective measures are taken it is nearly impossible for a radiographer to approach the fetal dose limit of 5mSv

A

true

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15
Q

specially designed maternity protective aprons consist of what lead equivalent over the entire length and width

A

0.5 mm lead equivalent

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16
Q

specially designed maternity protective aprons also have an extra what equivalent of lead protective panel that runs transversely across the width of the apron

A

1mm lead equivalent

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17
Q

3 basic principles of radiation protection

A

time
distance
shielding

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18
Q

the amt of radiation a worker receives is directly or indirectly proportional to the length of time the individual is in the path of ionizing radiation

A

directly proportional

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19
Q

exposure =

A

exposure rate * expsoure time

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20
Q

what is the most effective means of protection

A

distance

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21
Q

inverse square law

A

expresses the relationship between distance and intensity

I1/I2=D2^2/D1^2

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22
Q

the intensity of radiation is inversely or directly proportional to the square of the distance from the source

A

inversely

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23
Q

if you double the distance, the dose reduces by

A

4

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24
Q

if you triple the distance the dose reduces by

A

9

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25
Q

2 types of protective shielding

A
  1. structural protective barriers

2. accessory protective devices

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26
Q

structural protective barriers include

A

lead

concrete

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27
Q

accessory protective devices include

A

aprons
gloves
thyroid shields
protective glasses

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28
Q

protective structural shielding includes

A

walls and doors in xray room to shield form personnel and general public

29
Q

whose responsibility is it for determining the exact protection requirements for a particular imaging facility

A

the medical physicist

30
Q

primary protective barrier

A

barrier designed to shield an area from primary radiation

31
Q

what is the purpose of a primary protective barrier

A

to prevent direct or unscattered radiation form reaching personnel or general public located on the other side of the barrier

32
Q

if the peak energy is 130 kVp the primary protective barrier in a typical installation consists of

A

1.6 mm lead

33
Q

when the xray tube is 1.5-2.1m from the wall in question, the primary protective barrier must extend upward

A

2.1m

34
Q

secondary protective barrier

A

barrier designed to shield an area from secondary radiation

35
Q

what is the purpose of a secondary protective barrier

A

to protect against leakage and scatter radiation

36
Q

a secondary barrier should overlap the primary protective barrier by aprox

A

1.27cm

37
Q

in a typical installation the secondary barrier consists of how much lead

A

0.8mm lead

38
Q

control booth barrier must extend how high upward and be permanently secured to the floor

A

extend 2.1m up from the floor

39
Q

the lead glass window consist of how much lead

A

1.5mm lead equivalent

40
Q

appropriate lead equivalent in the control booth ensures the radiographer will not exceed a max allowance of what per week

A

1mSv per week

41
Q

in a well designed facility exposure to personnel should not exceed what per week

A

0.02mSv per week

42
Q

modular xray barriers are available in what lead equivalent

A

0.3-2mm

43
Q

clear lead acrylic overhead protective barrier

A

used as overhead xray barriers to provide open view during special procedures and heart catheterizations

44
Q

when lead equivalent thickness increases…

A

attenuation increases when kVp stays the same

45
Q

a what mm lead apron would be appropriate for mamo

A

a 0.25mm lead apron

46
Q

the neck and thyroid shield should be a minimum of what lead equivalent

A

0.5mm lead

47
Q

in protective eyewear, the lenses contain a minimal lead equivalent of

A

0.35mm lead

48
Q

the methods and devices that reduce exposure to personnel during fluro are

A 
adequate beam collimation 
adequate filtration 
gonadal shielding 
control of exposure factors 
use of high speed image receptors 
appropriate Source to skin distance
49
Q

the bucky slot shielding device must be at least what lead equivalent

A

0.25 lead eq

50
Q

without the bucky slot cover and the protective curtain in place the exposure rate for fluoroscopists would exceed what at a distance of what

A

1mGya/hr at a distance of 0.6m (2ft)

51
Q

where should the radiographer stand during mobile radiographic procedures

A

at a right angle to the xray beam

52
Q

in routine fluoro the max allowed entrance exposure rate dose to a pt. is

A

10 cGy/minute

53
Q

in HLC fluoro the max allowed entrance dexposure rate dose to a pt. can range upward to

A

20-40 cGy/minute

54
Q

NCRP currently recommends an annual EqD limit to the localized area of the skin and hands of

A

500 mSv

55
Q

most facilities room doors have attenuation for diagnostic energy xrays equivalent to that provided by

A

0.8mm of lead

56
Q

what are the 3 categories of radiation that can be generated in an xray room

A

primary radiation
scatter radiation
leakage radiation

57
Q

what part of the xray room requires the most protective shielding for safety purposes

A

the wall in the path of the direct radiation

58
Q

in a typical xray room the most important primary barrier is

A

behind the wall bucky unit

59
Q

if the xray tube housing is designed properly the leakage radiation will never exceed the regulatory limit of

A

1mGya/hr

60
Q

a busy general purposed xray room may have a workload of

A

500mA-min/week

61
Q

rooms in private offices may have workloads of less than

A

100mA-,in/week

62
Q

workload definition

A

product of the max mAs and the number of xray examinations performed each week

63
Q

use factor (U)

A

the percentage of time during which the xray beam is on and directed toward a primary protective barrier

64
Q

the use factor is also called

A

the beam factor

65
Q

occupancy factor (T)

A

a factor used to modify the shielding requirements for a particular barrier by taking into account the fraction of the work week during which the space beyond the barrier is occupied

66
Q

controlled area

A

a region adjacent to a wall of an xray room that is occupied by only occupationally exposed workers

67
Q

uncontrolled area

A

a region adjacent to a wall of an xray room such as a corridor or hall that is frequented by the general public

68
Q

for uncontrolled areas the weekly max permitted equivalent dose is equal to

A

20 microsieverts which is .02 mSv

69
Q

for controlled areas the weekly max permitted equivalent dose is equal to

A

1000 microsievert or 1 mSv

Radiation protection (12 decks)

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