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Flashcards in Designing for radiation protection Deck (72)
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1
Q

Diagnostic-Typed protective Tube Housing

A

This is required for both the radiographer and patient from off focus or leakage radiation by restricting the emission of x-rays to the area of the useful or primary beam.

2
Q

Diagnostic-Typed protective Tube Housing leakage has to be:

A

Reduce the leakage to less than 100 mR/hr at 1 m from the protective housing.

3
Q

Bucky slot cover: how thick and what is it made of?

A

0.25mmPb

4
Q

Protect curtain: how thick and what is it made of?

A

0.25mmPb

5
Q

what factors Affecting Barrier Thickness?

A

distance, occupancy, controlled area vs uncontrolled area, workload, use factor, kvp

6
Q

What are primary barriers?

A

lead and concrete

7
Q

What are secondary barriers

A

leakage radiation, scatter radiation: steel, glass, gypsum, wood

8
Q

The x-ray beam and light beam must coincide to within ____ of the SID.

A

2%

9
Q

Positive Beam Limitation (PBL) – automatic light localizer must be within __ of the SID

A

2%

10
Q

Source-to-image distance indicator – SID indicator must be provided, and must be accurate within ___.

A

2%

11
Q

filtration

A

Reduces exposure to the patient’s skin and superficial tissue by absorbing most of the lower energy photons.

12
Q

change in beam quality due to filtration is referred to as:

A

“hardening” of the beam.

13
Q

Two types of Filtration available:

A

Inherent filtration and Added filtration

14
Q

Added filtration:

A

Usually consists of sheets of aluminum (or its equivalent) of appropriate thickness.

15
Q

Where is added filtration located:

A

outside the glass window of the tube housing above the collimator shutters
Readily accessible to service personnel

16
Q

Total filtration should be at least:

A

2.5mm Al.

17
Q

Mobile diagnostic units and fluoroscopic equipment also require________________ total permanent filtration when the tube is operating over 70 kvp

A

2.5-mm aluminum equivalent

18
Q

What is the most widely selected as filter material because it effectively removes low energy?

A

aluminum

19
Q

positive stuff about aluminum

A

lightweight, relatively inexpensive and readily available

20
Q

Compliance with the Radiation Control for Health and Safety Act of 1968 states

A

diagnostic x-ray beam must always be adequately filtered.

21
Q

Total filtration equals:

A

Inherent filtration plus added filtration

22
Q

ability of x-ray units to duplicate certain radiation exposure for any given combination of kilovolts at peak value (KVP).

A

Reproducibility

23
Q

ability of the output radiation intensity at a select Ma value should remain constant (mAs)

A

Linearity

24
Q

The variation in x-ray intensity should not exceed ___. (reproductivity)

A

5%

25
Q

linearity should not exceed ____ change in intensity from one mA station to the adjacent.

A

10%

26
Q

Provide radiation shielding for both imaging department personnel and the general public.

A

protective barrier

27
Q

three Categories of radiation sources can be generated in an x-ray room

A

Primary radiation, secondary radiation, and leakage radiation

28
Q

Two categories of secondary radiation:

A

scatter and leakage radiation

29
Q

_____ sheets of appropriate thickness placed in the walls are generally used.

A

Lead

30
Q

Two types of barriers:

A

Primary and secondary

31
Q

to prevent primary radiation from reaching personnel or members of the general public.

A

primary barrier

32
Q

how thick should the primary barrier be:

A

2mm Pb equivalent

33
Q

Primary barrier consist of ______________ and extend _____ upward from the floor.

A

1/16 inch lead; 1/16 7 feet

34
Q

Any wall to which the useful beam can be directed is designated:

A

a primary protective barrier.

35
Q

What is most often used as a primary protective barrier?

A

any wall to which the useful beam can be directed

36
Q

what may be used instead of lead?

A

Concrete, concrete block, or brick

37
Q

Factors that affect barrier thickness

A

distance, occupancy factor , control or uncontrolled area

38
Q

Distance (Factors that affect barrier thickness)

A

The distance between the source of radiation and the barrier.

39
Q

Occupancy factor (T) (Factors that affect barrier thickness)

A

Radiation barriers are installed to protect personnel and general public from radiation.
To calculate this, one must account for the workweek activities in that room

40
Q

If a region adjacent to a wall of an x-ray room is used only by occupationally exposed personnel, that location is designated as a _______.

A

controlled area

41
Q

an area such as a nearby hall or corridor that is frequented by the general public is termed ________

A

uncontrolled areas

42
Q

consists of radiation that has been deflected from the primary beam.

A

secondary barrier

43
Q

Secondary barrier

A
  • scatter radiation and leakage radiation
  • lead is not required
  • Gypsum board, glass or lead acrylic is adequate.
  • control booth barrier for the protection of the radiographer
  • Intercepts leakage and scattered radiation only.
44
Q

In a typical installation the secondary barrier consists of _______. This barrier must extend______ upward from the floor.

A

1/32 inch lead; 7 feet (2.1 m)

45
Q

Three types of gas-filled radiation survey instruments

A
  1. The ionization chamber-type survey meter (fig. 10-11)
  2. The proportional counter and
  3. The Geiger-Muller (GM) detector
46
Q

Ionization Chamber-Type Survey Meter also known as

A

cutie pie

47
Q

Ionization Chamber-Type Survey Meter

A
  • Used for area surveys
  • Measures x-radiation and gamma radiation.
  • Used to monitor diagnostic x-ray installations exposure times
  • Exposure rates of patients containing therapeutic doses of radioactive materials.
  • Exposure rates in radioisotope storage facilities.
48
Q

Proportional Counter:

A
  • serves no useful purpose in diagnostic imaging.
  • It is generally used in a laboratory setting to detect alpha and beta radiation and small amounts of other types of low-level radioactive contamination.
49
Q

area monitoring devices that detect and measure radiation

A

Radiation survey instruments

50
Q

indicates the presence or absence of radiation

A

detection system

51
Q

measures only cumulative radiation intensity

A

dosimeter system

52
Q

3 personal monitors used

A

Film
Optically stimulated dosimetry
Thermoluminescent dosimetry

53
Q

2 area monitors used

A

Ion chamber

Geiger counter

54
Q

Radionuclide assay measurement device

A

Proportional counter

55
Q

Nuclear medicine/ ct imaging measurement device

A

scintillation detectors

56
Q

What is the active ingredient in film? (monitoring radiation)

A

photographic emulsion

57
Q

What is the active ingredient in optically stimulated dosimetry? (OSL)

A

aluminum oxide (Al2O3)

58
Q

What is the active ingredient in thermoluminescent dosimetry? (TLD)

A

Lithium Fluoride (LiF)

59
Q

The SSD (source to skin distance) must be not less than ___ on the stationary fluoro and not less than ____ on mobile fluoro

A

38cm; 30cm

60
Q

primary radiation is the _______ beam

A

useful

61
Q

The intensity of scatter radiation ____ from the patient is approximately ____ of the intensity of the useful beam at the patient,

A

1m; 0.1%

62
Q

Rad tech receive most of their occupational radiation exposure during _________

A

fluoroscopy

63
Q

Design limits for a controlled area are based on the annual recommended occupational dose limit of _____.

A

50 mSv/yr

64
Q

geiger- muller counter

A

limited to 1 mGy/hr portable- survey for low radiation levels and radioactive contamination

65
Q

The use factor for a secondary barrier is always ___

A

1

66
Q

The ionization of gas is the basis for _______________.

A

gas filled radiation detector

67
Q

high sensitivity means:

A

that an instrument can detect very low radiation intensities

68
Q

photocathode

A

a device that emits electron when illuminated

69
Q

dynode gain

A

the ratio of secondary electron to incident electron

70
Q

the size of the electron pulse is ____ to the energy absorbed by the crystal from incident photon.

A

proportional

71
Q

TLD is:

A

emission of light by a thermally stimulated crystal following irradiation.

72
Q

Lithium fluoride is:

A

nearly tissue-equivalent radiation dosimeter

Decks in 000 Radiation Safety Class (71):