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Flashcards in chapter 13 EXAM 6 FINAL Deck (69):
1

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

1x10^-4 per year
1 in 10,000 a year

2

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

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

3

what poses the greates occupational hazard in diagnostic radiology

scattered radiation

4

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

beam limitation devices

5

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

0,25

6

for fluoro your protective lead apron should be how much lead

0.5

7

all aprons should be inspected for cracks or other defects every

year

8

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

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

9

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

decreases personnel exposure

10

after the voluntary declaration of pregnancy, the RSO must

provide essential counseling
furnish an appropriate additional dosimeter

11

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

0.5mSv

12

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

5 mSv (0.5rem)

13

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

30 % of the abdominal dose

14

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

true

15

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

0.5 mm lead equivalent

16

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

1mm lead equivalent

17

3 basic principles of radiation protection

time
distance
shielding

18

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

directly proportional

19

exposure =

exposure rate * expsoure time

20

what is the most effective means of protection

distance

21

inverse square law

expresses the relationship between distance and intensity
I1/I2=D2^2/D1^2

22

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

inversely

23

if you double the distance, the dose reduces by

4

24

if you triple the distance the dose reduces by

9

25

2 types of protective shielding

1. structural protective barriers
2. accessory protective devices

26

structural protective barriers include

lead
concrete

27

accessory protective devices include

aprons
gloves
thyroid shields
protective glasses

28

protective structural shielding includes

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

29

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

the medical physicist

30

primary protective barrier

barrier designed to shield an area from primary radiation

31

what is the purpose of a primary protective barrier

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

32

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

1.6 mm lead

33

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

2.1m

34

secondary protective barrier

barrier designed to shield an area from secondary radiation

35

what is the purpose of a secondary protective barrier

to protect against leakage and scatter radiation

36

a secondary barrier should overlap the primary protective barrier by aprox

1.27cm

37

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

0.8mm lead

38

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

extend 2.1m up from the floor

39

the lead glass window consist of how much lead

1.5mm lead equivalent

40

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

1mSv per week

41

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

0.02mSv per week

42

modular xray barriers are available in what lead equivalent

0.3-2mm

43

clear lead acrylic overhead protective barrier

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

44

when lead equivalent thickness increases...

attenuation increases when kVp stays the same

45

a what mm lead apron would be appropriate for mamo

a 0.25mm lead apron

46

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

0.5mm lead

47

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

0.35mm lead

48

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

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

49

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

0.25 lead eq

50

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

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

51

where should the radiographer stand during mobile radiographic procedures

at a right angle to the xray beam

52

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

10 cGy/minute

53

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

20-40 cGy/minute

54

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

500 mSv

55

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

0.8mm of lead

56

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

primary radiation
scatter radiation
leakage radiation

57

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

the wall in the path of the direct radiation

58

in a typical xray room the most important primary barrier is

behind the wall bucky unit

59

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

1mGya/hr

60

a busy general purposed xray room may have a workload of

500mA-min/week

61

rooms in private offices may have workloads of less than

100mA-,in/week

62

workload definition

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

63

use factor (U)

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

64

the use factor is also called

the beam factor

65

occupancy factor (T)

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

controlled area

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

67

uncontrolled area

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

68

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

20 microsieverts which is .02 mSv

69

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

1000 microsievert or 1 mSv