1
Q
- Q: State the inverse square law formula for intensity
A
A: I1/I2 = (d2^2)/(d1^2)
2
Q
- Q: Give the heat unit formula including generator factor
A
A: HU = kVp × mA × s × generator factor (1 single phase 1.35 three phase
3
Q
- Q: Approximate energy of tungsten K alpha x rays
A
A: Kα ≈ 59 keV
4
Q
- Q: Formula linking effective focal spot and anode angle
A
A: Effective focal spot = actual focal spot × sin(anode angle)
5
Q
- Q: Define modulation transfer function
A
A: MTF measures contrast reproduction versus spatial frequency
6
Q
- Q: Define detective quantum efficiency
A
A: DQE measures detector efficiency accounting for signal and noise
7
Q
- Q: Define signal to noise ratio
A
A: SNR = mean signal divided by standard deviation of noise
8
Q
- Q: Define noise power spectrum
A
A: NPS describes noise distribution across spatial frequencies
9
Q
- Q: Primary cause of a ring artifact in CT
A
A: Faulty or miscalibrated detector element
10
Q
- Q: Main cause of severe streak artifacts in CT
A
A: Photon starvation from dense objects leading to beam hardening
11
Q
- Q: Define truncation artifact in CT
A
A: Distortion from anatomy outside scanned field of view
12
Q
- Q: Primary purpose of the bowtie filter in CT
A
A: Shape beam to match patient profile and reduce peripheral dose
13
Q
- Q: Define CTDI100
A
A: Dose measured by a 100 mm pencil chamber
14
Q
- Q: Convert DLP to effective dose method
A
A: Effective dose ≈ DLP × region specific conversion factor
15
Q
- Q: Hounsfield unit value for air
A
A: Air = -1000 HU
16
Q
- Q: Hounsfield unit value for water
A
A: Water = 0 HU
17
Q
- Q: Typical Hounsfield range for cortical bone
A
A: High positive HU values commonly > +1000
18
Q
- Q: Approximate HU for fat
A
A: Around -100 HU
19
Q
- Q: Describe window level and width roles
A
A: Level sets center HU width sets displayed range
20
Q
- Q: Magnification factor formula in radiography
A
A: MF = SID divided by SOD
21
Q
- Q: Penumbra formula
A
A: Penumbra = focal spot size × (OID / SOD)
22
Q
- Q: Define focal spot blooming
A
A: Enlargement of effective focal spot at high tube current
23
Q
- Q: Purpose of tube rating chart
A
A: Prevent tube damage by limiting exposures and guiding cooling
24
Q
- Q: DQE impact statement
A
A: Higher DQE yields better image quality at lower dose
25
25. Q: MTF at zero spatial frequency
A: MTF(0) = 1
26
26. Q: Define aliasing in digital imaging
A: Artifact from undersampling that yields false patterns
27
27. Q: Common cause of motion artifacts in CT
A: Patient motion during acquisition
28
28. Q: Method to reduce motion in MRI
A: Use faster sequences and breath hold techniques
29
30
29. Q: Time of flight principle in PET
A: Use photon arrival time difference to localize annihilation
31
32
30. Q: Define linear attenuation coefficient
A: Probability per unit length of photon interaction
33
34
31. Q: Explain photopeak in scintillation detectors
A: Peak for full energy deposition of incident gamma photon
35
32. Q: Define energy resolution of a detector
A: Ability to distinguish photon energies expressed as percent
36
33. Q: Define dead time in nuclear detectors
A: Time after event when detector cannot register new events
37
34. Q: Common units for radioactivity
A: Becquerel and curie
38
35. Q: Define biological half life
A: Time for half of substance to clear from body biologically
39
36. Q: Define physical half life
A: Time for half of radioactive atoms to decay
40
37. Q: Define effective half life
A: Combined effect of physical and biological half lives
41
38. Q: Role of scout or topogram in CT planning
A: Plan scan range and check patient positioning
42
39. Q: What determines CT longitudinal resolution
A: Detector collimation and reconstruction interval
43
40. Q: Iterative reconstruction effect on spatial resolution
A: Maintains or improves resolution while reducing noise
44
41. Q: Dose area product unit
A: Gy multiplied by cm squared
45
42. Q: Function of a KAP meter
A: Integrate air kerma across beam to give DAP reading
46
43. Q: Estimate peak skin dose method
A: Use conversion factors or skin dosimeter with geometry data
47
44. Q: Automatic exposure control sensor types
A: Phototimer or ionization chamber types
48
45. Q: How grid improves image contrast
A: Removes scattered photons before detector
49
46. Q: Moving grid advantage
A: Blurs grid lines to prevent visible grid artifacts
50
47. Q: Describe Potter Bucky mechanism
A: Oscillating grid in bucky reduces grid line visibility
51
48. Q: Main determinants of DR spatial resolution
A: Detector element size and focal spot size
51
49. Q: Define fill factor in flat panel detectors
A: Fraction of pixel area sensitive to x rays
52
50. Q: MTF 10 percent spatial frequency use
A: Measure system limiting resolution
53
54
51. Q: Contrast detail curve definition
A: Graph of detectability for objects of different size and contrast
55
56
52. Q: Quantum efficiency versus DQE
A: Quantum efficiency is photon detection fraction DQE includes noise
57
58
53. Q: C arm angulation purpose
A: Adjust tube and detector orientation to avoid overlap and improve view
59
60
54. Q: Define last image hold in fluoroscopy
A: Retain last frame to avoid extra exposure
61
62
55. Q: Advantage of pulsed fluoroscopy
A: Reduce dose by intermittent exposures
63
64
56. Q: Define cine mode in fluoroscopy
A: High frame rate capture for motion analysis
65
66
57. Q: Define entrance surface air kerma
A: Air kerma at patient skin before backscatter
67
68
58. Q: Define backscatter factor
A: Ratio of dose including backscatter to incident air kerma
69
70
59. Q: Reduce dental artifact in CT method
A: Use MAR algorithms adjust gantry
71
72
60. Q: Gantry tilt use in CT head
A: Align scan plane to anatomic landmarks to reduce dental inclusion
73
74
61. Q: Streak versus beam hardening differences
A: Streaks from motion or photon starvation beam hardening causes cupping
75
76
62. Q: Define cupping artifact
A: Reduced central attenuation due to beam hardening
77
78
63. Q: Role of pre whitening filter
A: Improve signal processing before image reconstruction
79
80
64. Q: Effect of increasing matrix size
A: Smaller pixels higher spatial resolution
81
82
65. Q: Typical reconstruction matrix used in CT
A: 512 by 512 is common
83
84
66. Q: Define multiphase CT protocol
A: Acquisitions at arterial portal venous
85
86
67. Q: Define bolus tracking in CTA
A: Trigger acquisition when contrast at ROI reaches threshold
87
88
68. Q: Contrast washout significance for adrenal lesions
A: Rapid washout suggests benign adenoma
89
90
69. Q: Sensitivity formula
A: True positives divided by true positives plus false negatives
91
92
70. Q: Specificity formula
A: True negatives divided by true negatives plus false positives
93
94
71. Q: Positive predictive value formula
A: True positives divided by true positives plus false positives
95
96
72. Q: Negative predictive value formula
A: True negatives divided by true negatives plus false negatives
97
98
73. Q: Positive likelihood ratio formula
A: Sensitivity divided by one minus specificity
99
100
74. Q: ROC curve purpose
A: Assess diagnostic performance across thresholds
101
102
75. Q: Define area under ROC
A: Measure of test accuracy from 0.5 to 1.0
103
104
76. Q: Define interobserver variability
A: Differences in interpretation between readers
105
106
77. Q: Define intraobserver variability
A: Differences when same reader interprets repeatedly
107
108
78. Q: Double reading in radiology meaning
A: Two readers review images to improve detection
109
110
79. Q: Time gain compensation in ultrasound
A: Adjust amplification as function of depth
111
112
80. Q: Color Doppler aliasing explanation
A: Velocity exceeds Nyquist limit producing wrap around
113
114
81. Q: Harmonic imaging advantage in ultrasound
A: Use tissue harmonics for improved clarity
115
116
82. Q: Speckle definition in ultrasound
A: Grainy appearance from interference patterns
117
118
83. Q: Acoustic shadowing definition
A: Hypoechoic area distal to highly attenuating structure
119
120
84. Q: Acoustic enhancement definition
A: Increased echogenicity distal to fluid filled structure
121
122
85. Q: Flip angle effect in MRI
A: Alters signal intensity and contrast in gradient echo
123
124
86. Q: Define TR in MRI
A: Repetition time between successive RF pulses
125
126
87. Q: Define TE in MRI
A: Echo time between RF pulse and received echo
127
128
88. Q: Sequence for T2 weighted images
A: Long TR and long TE spin echo
129
130
89. Q: Sequence for T1 weighted images
A: Short TR and short TE spin echo
131
132
90. Q: Fat suppression techniques in MRI
A: Frequency selective saturation or inversion recovery
133
134
91. Q: STIR imaging use
A: Fat suppression and edema detection
135
136
92. Q: FLAIR sequence purpose
A: Null CSF signal to highlight periventricular lesions
137
138
93. Q: Chemical shift artifact description
A: Misregistration between fat and water
139
140
94. Q: Susceptibility artifact description
A: Signal loss or distortion near field inhomogeneities
141
142
95. Q: Parallel imaging basic principle
A: Use multiple coil elements to accelerate acquisition
143
144
96. Q: Examples of parallel imaging algorithms
A: SENSE and GRAPPA
145
146
97. Q: Echo planar imaging main use
A: Fast imaging for diffusion and functional MRI
147
148
98. Q: Magnetization transfer imaging purpose
A: Suppress macromolecular signal to enhance contrast
149
150
99. Q: Cause of eddy current artifacts
A: Rapid gradient switching inducing currents in conductors
151
152
100. Q: Daily MRI QA checks
A: Visual bore inspection coil connection check
Radiography
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Decks in class (17)
# Cards
