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Grr > Physics > Flashcards

Physics Flashcards

1
Q

EM radiation velocity?

A

3 * 10^8 m/s

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2
Q

What is the K shell binding energy of tungsten?

A

-69.5 keV

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3
Q

Relationship between Z and K shell binding energy

A

K shell binding energy is proportional to Z^2

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4
Q

Relationship between xray production and mA

A

linear increase

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5
Q

Relationship between xray production and kVp

A

Increasing kVp by 15% will double intensity of spectrum

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6
Q

What do you give to detect extrahepatic biliary atresia and how much

A

phenobarbitol
5 mg/kg/day
2 divided doses
3-5 days

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7
Q

Half life of gallium

A

78hours

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8
Q

Iso-osmolality iodinated contrast media

A

300 mOsm/kg

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9
Q

low-osmolality iodinated contrast media

A

600 mOsm/kg

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10
Q

high-osmolality iodinated contrast media

A

1200 mOsm/kg

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11
Q

human plasma

A

295 mOsm/kg

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12
Q

CTDIw

A

1/3 CTDI central + 2/3 CTDI peripheral

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13
Q

CTDIvol

A

CTDIw/Pitch

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14
Q

Window levels for Brain

A

W 80, L +40

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15
Q

Window levels for Lung

A

W 1500, L -400

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16
Q

Window levels for Abdomen

A

W 440, L +50

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17
Q

Window levels for Bone

A

W 1600, L +500

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18
Q

Adult Head Avg Dose CTDI

A

58 mGy, effective dose (1-2 mSv)

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19
Q

Adult Abd CTDI

A

18 mGy, effective dose (8-11 mSv)

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20
Q

Peds Abd CTDI

A

15 mGy

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21
Q

ACR “reference” dose, for which if they are above should be investigated:
CTDIvol for Head

A

75 mGy

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22
Q

ACR “reference” dose, for which if they are above should be investigated
CTDIvol for Adult Abd

A

25 mGy

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23
Q

ACR “reference” dose, for which if they are above should be investigated
CTDIvol for Peds

A

20 mGy

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24
Q

Embryo Dose in CT A/P

A

30 mGy

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25
Q

Individual dose monitoring mandated if occupational dose is greater than ___ of annual dose limit ____.

A

10%, 500 mrem

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26
Q

CT Head CTDIvol

A

CTDIvol of 60 mGy.

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27
Q

CT Head CTDIvol

A

CTDIvol of 60 mGy.

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28
Q

diagnostic workstation avg monitor brightnes

A

500 cd/m2

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29
Q

diagnostic workstation avg monitor brightnes

A

500 cd/m2

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30
Q

The instantaneous RF power (W) of a body coil in MR operated at 1.5 T is typically ____. However, remember that this RF is only switched on for the duration of a typical pulse (ms or so), so the energy consumption is not going to be large.

A

10000 W

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31
Q

The instantaneous RF power (W) of a body coil in MR operated at 1.5 T is typically ____. However, remember that this RF is only switched on for the duration of a typical pulse (ms or so), so the energy consumption is not going to be large.

A

10000 W

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32
Q

ultrasound mode A

A

echo intensity as a function of time or depth is A (Amplitude) display mode

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33
Q

ultrasound mode A

A

echo intensity as a function of time or depth is A (Amplitude) display mode

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34
Q

Which does not affect spatial resolution? Detector “size”, focal spot, and patient motion, radiation intensity?

A

radiation intensity ALWAYS affect spatial resolution performance, and nothing else dose (directly). Radiation intensity (number of photons), as such, is essentially irrelevant for resolution performance which means image blurriness, but will affect lesion visibility by impacting on mottle.

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35
Q

Which does not affect spatial resolution? Detector “size”, focal spot, and patient motion, radiation intensity?

A

radiation intensity ALWAYS affect spatial resolution performance, and nothing else dose (directly). Radiation intensity (number of photons), as such, is essentially irrelevant for resolution performance which means image blurriness, but will affect lesion visibility by impacting on mottle.

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36
Q

The maximum patient eye lens dose (mGy) after 5 minutes of fluoroscopy in interventional neuroradiology is likely___ Gy?

A

150 mGy

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37
Q

Which does not affect spatial resolution? Detector “size”, focal spot, and patient motion, radiation intensity?

A

ALWAYS affect spatial resolution performance, and nothing else dose (directly). Radiation intensity (number of photons), as such, is essentially irrelevant for resolution performance which means image blurriness, but will affect lesion visibility by impacting on mottle.

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38
Q

max patient eye dose after 5 min of fluro

A

150 mgy

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39
Q

max patient eye dose after 5 min of fluro

A

150 mgy

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40
Q

In cardiac ultrasound imaging, the pulse repetition period is most likely (ms):

A

0.25 ms, which corresponds to a Pulse Repetition Frequency of 4 kHz

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41
Q

listening period of cardiac ultrasound corresponds to penetration depth of

A

20 cm

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42
Q

listening period of cardiac ultrasound corresponds to penetration depth of

A

20 cm

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43
Q

frequency encoding gradient of single 128 x 196 Spin Echo MR image

A

128

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44
Q

frequency encoding gradient of single 128 x 196 Spin Echo MR image

A

128

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45
Q

sampling echo of single 128 x 196 Spin Echo MR image

A

196

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46
Q

sampling echo of single 128 x 196 Spin Echo MR image

A

196

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47
Q

The ideal fluoroscopic x-ray tube voltage in cardiac imaging is about ___ kV since this results in an average energy of ~35 keV that matches the k-edge energy of iodine contrast

A

he ideal fluoroscopic x-ray tube voltage in cardiac imaging is about 75 kV since this results in an average energy of ~35 keV that matches the k-edge energy of iodine contrast (Z = 53; k-edge 33 keV) that is ALWAYS administered to the patient to visualize the cardiac vasculature.

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48
Q

effective dose of chest CT

A

5 mSv

49
Q

effective dose of CXR (1 ct = 100 CXR)

A

.05 mSv

50
Q

effective dose of CXR (1 ct = 100 CXR)

A

.05 mSv

51
Q

In chest CT, increasing the x-ray beam filtration would likely result in a lesion contrast that is

A

decreased

52
Q

In chest CT, increasing the x-ray beam filtration would likely result in a lesion contrast that is

A

decreased

53
Q

At the same techniques, increasing the patient size in chest CT from 70 kg to 100 kg will likely change the patient dose by (%):

A

decrease by 30%

54
Q

At the same techniques, increasing the patient size in chest CT from 70 kg to 100 kg will likely change the patient dose by (%):

A

decrease by 30%

55
Q

Which type of electronic (digital) correction is least likely to be applied to a gamma camera image?

a. Energy Incorrect
b. Sensitivity
c. Linearity
d. Septal penetration

A

septal penetration

56
Q

Which type of electronic (digital) correction is least likely to be applied to a gamma camera image?

a. Energy Incorrect
b. Sensitivity
c. Linearity
d. Septal penetration

A

septal penetration

57
Q

In chest MRI, doubling the duration of an RF pulse would likely cause the longitudinal Magnetization “flip angle” to be:

A

doubled

58
Q

In chest MRI, doubling the duration of an RF pulse would likely cause the longitudinal Magnetization “flip angle” to be:

A

doubled

59
Q

MP for clinical review station, MR/CT, general workstation, viewing mammogram

A

1 MP workstations are used in a clinician review station, 2 MP are used for MR/CT, 3 MP is a general purpose radiologists workstation (chest x-rays), and 5 MP is required for viewing mammogram

60
Q

MP for clinical review station, MR/CT, general workstation, viewing mammogram

A

1 MP workstations are used in a clinician review station, 2 MP are used for MR/CT, 3 MP is a general purpose radiologists workstation (chest x-rays), and 5 MP is required for viewing mammogram

61
Q

M mode imaging

A

echo intensities as a function of time

has intensities about four times higher than in B mode imaging

62
Q

M mode imaging

A

echo intensities as a function of time

has intensities about four times higher than in B mode imaging

63
Q

The average compressed breast thickness (mm) in the US is about ___ mm, which is much more that the ___ thick phantom that physicists currently use to measure mammography doses.

A

60 mm for avg breast

42 mm for breast phantom

64
Q

The average compressed breast thickness (mm) in the US is about ___ mm, which is much more that the ___ thick phantom that physicists currently use to measure mammography doses.

A

60 mm for avg breast

42 mm for breast phantom

65
Q

Energy deposited (joules) in the anode in an abdominal radiograph (100 kW; 0.1 s exposure) is most likely:

A

10,000 joules

66
Q

Energy deposited (joules) in the anode in an abdominal radiograph (100 kW; 0.1 s exposure) is most likely:

A

10,000 joules

67
Q

Increased bandwidth causes S:N to go up or down

A

makes S:N worse

68
Q

Increased bandwidth causes S:N to go up or down

A

makes S:N worse

69
Q

for every primary photon emerging from patient, there are _scatter photons

A

5

70
Q

for every primary photon emerging from patient, there are _scatter photons

A

5

71
Q

Coils:
Gradient
Shielding
Shim

A

Gradient - spatial information
Shielding - reduce magnitude of fringe magnetic field from main magnet
Shim - improve homogeneity

72
Q

halving FOV of collimation does what to spatial resolution

A

nothing

73
Q

halving FOV of collimation does what to spatial resolution

A

Collimation generally does not change spatial resolution, or the Entrance Air Kerma

74
Q

halving FOV of collimation does what to spatial resolution

A

Collimation generally does not change spatial resolution, or the Entrance Air Kerma

75
Q

The minimum Focus to Skin Distance (cm) on a mobile fluoroscopy unit is ___ to make sure that the patient’s skin can’t get too close to the x-ray source.

A

30 cm

For fixed fluoroscopy units, this distance is 38 cm (FDA rules).

76
Q

The minimum Focus to Skin Distance (cm) on a mobile fluoroscopy unit is ___ to make sure that the patient’s skin can’t get too close to the x-ray source.

A

30 cm

For fixed fluoroscopy units, this distance is 38 cm (FDA rules).

77
Q

In extremity ultrasound, increasing the Pulse Repetition Frequency is unlikely to permit an increased:

A

imaging depth

78
Q

In extremity ultrasound, increasing the Pulse Repetition Frequency is unlikely to permit an increased:

A

imaging depth

79
Q

projection is all the ___ at a given rotational angle of the xray tube

A

rays

80
Q

projection is all the ___ at a given rotational angle of the xray tube

A

rays

81
Q 
Which one does not reduce motion blur?
increased:
exposure time
tube voltage
tube current
matrix size
A 
exposure time
everything else (voltage, current, matrix size) decreases blur
82
Q 
Which one does not reduce motion blur?
increased:
exposure time
tube voltage
tube current
matrix size
A 
exposure time
everything else (voltage, current, matrix size) decreases blur
83
Q

reducing image slice thickness has the biggest impact on what

A

thin slices will be NOISIER

84
Q

reducing image slice thickness has the biggest impact on what

A

thin slices will be NOISIER

thin slices will not affect in plane resolution, only long axis resolution

85
Q

reducing image slice thickness has the biggest impact on what

A

thin slices will be NOISIER

thin slices will not affect image contrast, in plane resolution, only long axis resolution

86
Q

reducing image slice thickness has the biggest impact on what

A

thin slices will be NOISIER

thin slices will not affect image contrast, in plane resolution, only long axis resolution

87
Q

replacing plastic apron (Z = 8) with lead equivalent apron (z=80) will increase abrosption of xrays by

A

1000 (bc mainly photoelectric interaction, Z^3)

88
Q

replacing plastic apron (Z = 8) with lead equivalent apron (z=80) will increase abrosption of xrays by

A

1000 (bc mainly photoelectric interaction, Z^3)

89
Q

CTDIvol is___ to scan length

A

indepdent
CTDIvol is INDEPENDENT of scan length. CTDIvol tells you about the quality of an individual CT slice; the total amount of radiation that you use to perform the CT examination is the Dose Length Product (CTDIvol x Scan Length).

The correct answer is: Independent of

90
Q

CTDIvol is___ to scan length

A

indepdent
CTDIvol is INDEPENDENT of scan length. CTDIvol tells you about the quality of an individual CT slice; the total amount of radiation that you use to perform the CT examination is the Dose Length Product (CTDIvol x Scan Length).

The correct answer is: Independent of

91
Q

fission products are most likely to emit

A

beta - emitters

92
Q

fission products are most likely to emit

A

beta - emitters

93
Q

antiscatter grid most likely seen at

A

bedside

94
Q

antiscatter grid most likely seen at

A

bedside

95
Q

S distortion in Image Intensifier fluoroscopic imaging is a result of extraneous:

A

mag field

96
Q

S distortion in Image Intensifier fluoroscopic imaging is a result of extraneous:

A

mag field

97
Q

The current US regulatory eye lens dose limit in interventional radiology (mSv/year) is

A

150 mSv

98
Q

The current US regulatory eye lens dose limit in interventional radiology (mSv/year) is

A

150 mSv

99
Q

Diagnostic workstation brightness is measured in

A

cd/m2, which is sometimes referred to as nits. A typical diagnostic workstation has a working brightness value of a few hundred cd/m2.

100
Q

Diagnostic workstation brightness is measured in

A

cd/m2, which is sometimes referred to as nits. A typical diagnostic workstation has a working brightness value of a few hundred cd/m2.

101
Q

In gamma cameras, the detected pulse height is ____ to the energy deposited in a gamma camera crystal (NaI).

A

In gamma cameras, the detected pulse height is directly proportional to the energy deposited in a gamma camera crystal (NaI). This is the basis of all Pulse Height Analysis.

102
Q

In gamma cameras, the detected pulse height is ____ to the energy deposited in a gamma camera crystal (NaI).

A

In gamma cameras, the detected pulse height is directly proportional to the energy deposited in a gamma camera crystal (NaI). This is the basis of all Pulse Height Analysis.

103
Q

SPECT and PET image reconstruction makes use of _____algorithm

A

SPECT and PET image reconstruction makes use of Iterative Reconstruction algorithm

104
Q

SPECT and PET image reconstruction makes use of _____algorithm

A

SPECT and PET image reconstruction makes use of Iterative Reconstruction algorithm

105
Q

Total Cardiac SPECT imaging time (minutes) is most likely:

A

15 min

106
Q

Total Cardiac SPECT imaging time (minutes) is most likely:

A

15 min

107
Q

Gamma cameras usually have ___PMTs

A

37

108
Q

Gamma cameras usually have ___PMTs

A

37

109
Q

nuclear isotopes have same number of__

A

protons

110
Q

nuclear isotopes have same number of__

A

protons

111
Q

If the parent is long lived, it is called +++; if the parent is short lived, it is called _____. The parent in the 99Mo/99mTc generator has a half-life of only 67 hours, so is called ____.

A

If the parent is long lived, it is called secular; if the parent is short lived, it is called transient. The parent in the 99Mo/99mTc generator has a half-life of only 67 hours, so is called transient. Note that equilibrium is established after 24 hours, which is four daughter half-lives.

112
Q

If the parent is long lived, it is called +++; if the parent is short lived, it is called _____. The parent in the 99Mo/99mTc generator has a half-life of only 67 hours, so is called ____.

A

If the parent is long lived, it is called secular; if the parent is short lived, it is called transient. The parent in the 99Mo/99mTc generator has a half-life of only 67 hours, so is called transient. Note that equilibrium is established after 24 hours, which is four daughter half-lives.

113
Q

Use of non-circular orbits in body SPECT imaging is most likely to result in images with improved:

A

resolution

114
Q

Use of non-circular orbits in body SPECT imaging is most likely to result in images with improved:

A

resolution

115
Q

Low energy collimators are made of __, whereas medium energy collimators are “_____” because these are much thicker. We do/do not collimators to image annihilation photons anywhere, but get positional information by detecting these photons in coincidence in PET cameras.

A

Low energy collimators are made of foil, whereas medium energy collimators are “cast” because these are much thicker. We don’t use collimators to image annihilation photons anywhere, but get positional information by detecting these photons in coincidence in PET cameras.

116
Q

K shell binding energy of oxygen

A

0.5 keV

117
Q

K shell binding energy of Lead

A

88 kev

118
Q

K shell binding energy of Lead

A

88 kev

119
Q

k shell beinding energy of iodine and barium

A

33 and 36 keV

Grr (10 decks)

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