Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

FRCR Part 1 Physics > Patient Dosimetry (Erin) > Flashcards

Patient Dosimetry (Erin) Flashcards

1
Q

In Xray:
Does a higher tube current (mA) increase or decrease patient dose?

A

Increases patient dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

In Xray:
Does a longer exposure time (s) increase or decrease patient dose?

A

Increases patient dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

In Xray:
Does a wider collimation increase or decrease patient dose?

A

Increase patient dose (reduces scatter and irradiated area)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

In Xray:
Dose a smaller FOV increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

In Xray:
does a higher kVP increase or decrease patient dose?

A

Increases patient doseA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List the 4 beam properties that increase patient dose in xray?

A

Higher mA
higher kVp
Larger FOV
Wider collimation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

In Xray:
Dose a larger FOV increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In Xray:
Does a lower tube current (mA) increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

In Xray:
Does a shorter exposure time (s) increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In Xray:
Does filtration increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In Xray:
Does the use of a grid increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In Xray:
Does reduced receptor sensitivity increase or decrease patient dose?

A

IncreasesN

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

List the 3 scanner properties that increase patient dose in Xray

A

No filtration
Use of a grid
Reduced receptor sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In Xray:
Does NO filtration increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In Xray:
Does a lack of grid increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In Xray:
Does increased receptor sensitivity increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

List the 2 patient properties which increase patient dose in xray imaging

A

Closer to focal spot (xray source)
Larger patient habitus (larger skin surface to absorb maximum dose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Does moving the patient further from the focal spot increase or decrease patient dose in xray?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

In Xray:
Does moving the patient closer to focal spot increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In fluoroscopy:
Does a lower kVp increase or decrease patient dose?

A

Increases (a less penetrating beam means more radiation absorbed particularly on the skin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In fluoroscopy:
Does continuous or pulsed technique give a higher patient does?

A

Continuous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In fluoroscopy:
Does a larger area of collimation increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

In fluoroscopy:
Does a smaller area of collimation increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In fluoroscopy:
Does the use of a grid increase or decrease patient dose?

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In fluoroscopy:
Does NO grid increase or decrease patient dose?

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In fluoroscopy:
Does increase electrical magnification (zoom modes) increase or decrease patient dose?

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

In fluoroscopy:
Does increased geometric magnification (moving patient closer to the source) increase or decrease patient dose?

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

In fluoroscopy:
Does an obese patient receive increased or decreased dose?

A

Increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

List the 3 scanner properties that increase dose in fluoroscopy

A
  1. Use of a grid
  2. Increased electrical magnification (zoom mode)
  3. Increased geometric magnification (i.e moving patient closer to the source, or detector closer to source)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

In CT:
Does higher mA increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

In CT:
Does lower mA increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

In CT:
Does higher kV increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

In CT:
Does lower kV increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

In CT:
Does longer exposure time increase or decrease patient dose?

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

In CT:
Does shorter exposure time increase or decrease patient dose?

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

In CT:
Does NOT using mA modulation increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

In CT:
Does using mA modulation increase or decrease patient dose?

A

Decrease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

In CT:
Does wider collimation increase or decrease patient dose?

A

Increases
However if collimation is too small the system will compensate by increasing mA/kVp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

In CT:
Does decreasing pitch increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

In CT:
Does increasing pitch increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

In CT:
Does a smaller patient receive increases or decreased dose?

A

Increased
More xrays will penetrate to the centre and deposit a higher dose
NB a larger patient will receive more total xrays but dose is measured per unit mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

In Nuclear Imaging:
Does an increased amount of injected activity increase or decrease patient dose?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

In Nuclear Imaging:
Does an decreased amount of injected activity increase or decrease patient dose?

A

Decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

In Nuclear Imaging:
What is the result of reduced patient drinking/urination on patient dose?

A

Increased patient dose (slower loss of activity from bladder)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

In Nuclear Imaging:
What is the result of increased patient drinking/urination on patient dose?

A

Decreased patient dose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the effective dose of a cardiac CT?

A

12mSv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the effective dose of a CT abdomen pelvis

A

10mSv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What is the effective dose of a CT head?

A

2mSv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

LAC equation?

A

μLAC = 0.693* / HVL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

MAC equation?

A

μMAC = μLAC/ρ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

To calculate the intensity of a beam (I) of x-ray photons after they have passed through a filter…(equation)

A

I = Io e-μd

e = energy
u = LAC
d = thickness of filter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Describe how radiation can directly affect biological molecules

A

Atoms within the DNA molecule are directly ionised by radiation leading to molecular damage
Breaking atomic bonds or causing base alteration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Describe how radiation can indirectly affect biological molecules

A

Water molecules interact with radiation to create free radicals which then migrate to the DNA molecule and cause molecular damage (breaking atomic bonds or causing base alteration)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

How is absorbed dose (D) measured (formula)

A

D = E/m
E = energy deposited in a medium
M = mass of medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What unit is absorbed dose measured in

A

Gray (Gy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is 1Gy equal to in J/kg

A

1Gy = 1J/kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is 1Gy in mGy

A

1Gy = 1000mGy (milligray)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What is 1mGy in uGy

A

1mGy = 1000 uGy (microgray)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the radiation weighting factor of X-rays and gamma photons

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is the radiation weighting factors of electrons and/positrons

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the weighting factor of alpha particles

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

How is equivalent dose calculated

A

D (absorbed dose) x Radiation weighting factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Do alpha particles have a high or low LET

A

High LET

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Do beta particles have a high or low LET

A

Low LET

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What units is equivalent dose measured in

A

Sv
(1Sv = 1000mSv)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

How is effective dose calculated

A

Sum of (Equivalent dose x tissue weighting factor)

67
Q

What is the tissue weighting factor for bone marrow, breast, colon, lungs and stomach

68
Q

What is the tissue weighting factor for the gonads

69
Q

What is the tissue weighting factor for the bladder, liver, oesophagus and thyroid

70
Q

What is the tissue weighting factor for brain, bone surfaces skin and salivary glands

71
Q

Rank in order from most tissue sensitive to least tissue sensitivity
Gonads
Salivary glands
Liver
Bone marrow

A

Most Sensitive

  • Bone marrow
  • Gonads
  • Liver
  • Salivary Glands

Least sensitive

72
Q

What are the 3 damage effects can radiation have on DNA

A

No biological effect (tissue repaired)
Cell death
Cell mutation

73
Q

What are some examples of deterministic effects

A

Cataract formation
Skin erythema/necrosis/ulceration
Bone marrow suppression
Sterility (can be temporary or permanent depending on dose)
Death

74
Q

When do deterministic effects typically occur

A

Soon after exposure

75
Q

What are deterministic effects due to

A

Cell death

76
Q

How does the severity of deterministic effects change with increasing dose

A

Severity of deterministic effects increase with increasing dose (above a certain threshold)

77
Q

How does the probability of stochastic effects change with increasing dose

A

Probability of stochastic effects increases with increasing dose

78
Q

What does ALARP stand for

A

As low as reasonably practicable

79
Q

When do stochastic effects typically occur

A

Many years after exposure

80
Q

What is the main stochastic effect we are concerned about

81
Q

What is the cancer risk for exposure to 1mSv

A

1 in 20,000 for 1mSv exposure

82
Q

What is the Gy threshold for skin necrosis

83
Q

What is the Gy threshold for cataract formation

84
Q

What is the Gy threshold for bone marrow suppression

85
Q

What is the Gy threshold for skin erythema

86
Q

What is the Gy threshold for Testes - temporary sterility

87
Q

What is the threshold for stochastic effects

A

NO THRESHOLD

88
Q

What is the excess childhood cancer risk per 1mSv of exposure

A

1 in 13,000 per mSv

89
Q

What is the natural risk of paediatric cancer

90
Q

What foetal dose (in mSv) will double the natural risk of paediatric cancer

91
Q

What is the typical effective dose of an extremity xray

92
Q

What is the typical effective dose of chest xray

93
Q

What is the typical effective dose of a lumbar spine xray

94
Q

What is the typical effective dose of barium enema

95
Q

What is the typical effective dose of CT head

96
Q

What is the typical effective dose of a CTAP

97
Q

What is the typical effective dose of a CT Chest

98
Q

What is the typical effective dose of a bone scan (NM)

99
Q

What is the typical effective dose of PDG PET Scan

100
Q

What is the typical effective dose of a lung perfusion scan (NM)

101
Q

For a point source what law does the dose rate follow

A

Inverse square law

102
Q

What is the inverse square law equation

A

1/d(squared)

103
Q

Doubling your distance from an xray source decreases your dose by a factor of ………

104
Q

How much protection do lead aprons provide from the primary xray beam

A

NONE
They protect against scattered radiation but not the primary beam

105
Q

What materials are commonly used for radiation shielding

A

Lead and tungsten

106
Q

What crystals are TLD made from

A

Lithium fluoride
Or
Calcium fluoride

107
Q

Why is lithium fluoride used for TLD

A

Because has a similar atomic number to soft tissue

108
Q

How do TLD work?

A

Small crystals which absorb ionising radiation and emit light when exposed to heat

109
Q

Can TLD be reused

A

Yes
Usually worn for 1-2 months then sent away for processing
Then reused

110
Q

How many TLDs does a body dosimeter comprise of?

111
Q

What are the functions of the 2 TLDs in a body dosimeter

A

One TLD measures skin dose
The other TLD measures dose at a depth of 1cm

112
Q

What does KERMA stand for

A

Kinetic energy released to matter

113
Q

What is KERMA very similar to

A

Absorbed dose (especially at lower energies)

114
Q

What piece of equipment allows air kerma to be measures

A

Ionisation chamber

115
Q

Is the dose area product linked to stochastic or deterministic risk

A

Stochastic

116
Q

What is the typical exposure from a long haul flight

117
Q

What is the largest source of background radiation

A

Exposure to radon

118
Q

With a lead thickness of 0.25mm what % of photons are transmitted

119
Q

With a lead thickness of 0.35mm what % of photons are transmitted

120
Q

With a lead thickness of 0.5mm What % of photons are transmitted

121
Q

What particles does radon gas produce

A

Alpha particles

122
Q

What unit is Kerma measured in

123
Q

if someone is a classified worker how long must their dose records be kept for

A

Minimum 30 years

124
Q

For how long do classified workers need dose records kept?
How often do they need a medical exam?
How old do they have to be?

A

Must be >18yrs
Have their dose records kept for minimum of 30 years
Undergo a medical examination before they are classified then annually thereafter

125
Q

All procedures must have a DAP or dose administered recorded T or F

126
Q

How is the DRL decided

A

Every procedure must have a DAP or dose administered recorded
From all these recordings a local DRL is set as the third quartile of the median dose
National DRL set as the third quartile of all the relevant local DRL

127
Q

Can TLD differentiate between the type of radiation you are exposed to?

128
Q

Can TLD measure dose rate?

129
Q

Can TLD be used to measure eye doses?

A

Yes as they can be made into various shapes, they can be used for assessment of example eye or finger doses

130
Q

Can TLD be reused?

131
Q

Can TLD be used to measure superficial and deep doses?

132
Q

Are film dosimetry badges able to differentiate between the different types of radiation exposure?

133
Q

Can film badges differentiated between the different energies of photons?

134
Q

What are film badges made from

A

Silver halide

135
Q

Advantages of film badges

A
  • Cheap
  • Can distinguish between different energies of photons
  • Can measure doses from different types of radiation
  • Provide a permanent record
    C- Accurate for exposures > 100 millirem
136
Q

Can film badges be reused?

137
Q

Which are more expensive TLD or film badges?

138
Q

Can TLD store dose records?

A

No once information is read out it is lost

139
Q

Are TLD or film badges more sensitivty

A

Relatively similar

140
Q

Can TLD provide a direct reading of dose

141
Q

Can TLD provide a permanent record of dose?

142
Q

Can TLD measure radioactive contamination?

143
Q

How many times can the dose of a TLD be read?

144
Q

Are TLD affected by environmental factors?

145
Q

What is the sensitivity of film badges in mSv

A

0.1-0.2mSv

146
Q

Can film badges be used to measure finger dose

147
Q

Do film badges provide permanent record of exposure

148
Q

How often are film badges usually replaced?

A

1 month
Due to fogging

149
Q

Do film badges measure the effective dose T/F?

A

False
Measure absorbed dose

150
Q

What are the most commonly used detectors in electronic dosimeters?

A

Silicone diode detector

151
Q

What is the most sensitive type of dosimeter

A

Electronic dosimeters
Sensitive to the nearest 1uSv

152
Q

What is a drawback to electronic dosimeters

153
Q

How many more times sensitive are electronic dosimeters compared to TLD

154
Q

Benefits of electronic dosimeters

A
  • Can provide direct electronic readout
    -Can provide live/real time readouts
  • Don’t need processing like TLD
155
Q

Can electronic dosimeters measure dose and dose rates

156
Q

Do electronic dosimeters provide a direct reading

157
Q

Are electronic dosimeters good for measuring pregnancy dose

158
Q

What is the effective dose for an AXR

159
Q

What is the effective dose for a dental xray

A

0.004/0.005mSv

160
Q

What is the effective dose of a barium swallow

162
Q

Air kerma rate (mGy/s) can be measured using…?

A

An ionisation chamber, at a known distance from the X-ray tube

163
Q

In CT: what is beam modulation?

A

A method of reducing the dose by altering the mA dynamically, depending on what part of the body you’re at (done automatically by a computer)

FRCR Part 1 Physics (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions