Education is what survives when what has been learnt has been forgotten.
—BF Skinner
These two practice examinations, each consisting of 110 questions and answers, cover the material summarized in this book. The first ten questions pertain to Chapter 1, the second ten questions to Chapter 2, and so on. The examinations, which should be taken under examination conditions without access to a textbook, will help students to:
Practice for the real examination. Taking practice examinations helps you develop a strategy for dealing with difficult questions, such as guessing after eliminating all wrong answers or by temporarily skipping difficult questions and returning to complete them later.
Highlight weaknesses (and strengths). Taking these examinations should help identify your weaknesses as well as strengths. Weaknesses need to be corrected by consulting the appropriate chapter in this review book or, if greater depth is required, by consulting a textbook.
Build confidence. Successful completion of the examinations demonstrates that the subject material has been understood, which will ease pre-examination nervousness.
The following guidelines should assist readers to perform successfully in any examination.
- Read and follow all examination instructions.
- Read each question carefully.
- Do not assume information.
- Focus on key words.
- Eliminate obviously incorrect answers.
- Reread the questions and verify your answers.
- Answer all questions, even if you have to guess.
- Don’t spend more than 2 minutes on any one question.
A1 Which of the following is not an SI unit?
a. Meter
b. Kilogram
c. Second
d. Roentgen
e. Becquerel
A2 The key difference between 600-keV x-rays and gamma rays is:
a. velocity
b. frequency
c. wavelength
d. momentum
e. origin
A3 What is the air kerma (mGy) 10 m from a radiation source when the air kerma at 1 m is 100 mGy?
a. 1
b. 10
c. 100
d. 1,000
e. 10,000
A4 For a fixed kVp, which generator likely results in the shortest exposure time?
a. Constant potential
b. High frequency
c. Three phase (12 pulse)
d. Three phase (6 pulse)
e. Single phase
A5 The maximum photon energy in an x-ray beam is determined by the x-ray tube:
a. current (mA)
b. voltage (kV)
c. exposure time (s)
d. ripple (%)
e. filtration (mm Al)
A6 Characteristic x-rays are characteristic of the material in the:
a. target
b. anode
c. filter
d. window
e. filament
A7 The power deposition in an x-ray tube anode when operated at 80 kV and 100 mA is:
a. 8 kJ
b. 8 kW
c. 8 kW/s
d. 8 keV
e. depends on exposure time
A8 The nominal size (mm) of a small focus on a standard x-ray tube is most likely:
a. 0.1
b. 0.3
c. 0.6
d. 1
e. 2
A9 The ratio of heat to x-rays produced in x-ray tubes is most likely:
a. 1:99
b. 10:90
c. 50:50
d. 90:10
e. 99:1
A10 How long (second) would it take a very hot anode to lose ~90% of its heat?
a. 0.3
b. 3
c. 30
d. 300
e. 3,000
A11 Which particle has the lowest rest mass?
a. Electron
b. Neutron
c. Proton
d. Alpha particle
e. Photon
A12 An atom that loses an outer shell electron is best described as being an:
a. isomer
b. isobar
c. isotone
d. isotope
e. ion
A13 The atomic number (Z) dependence of the photoelectric effect varies approximately as
a. Z3
b. Z2
c. Z
d. 1/Z2
e. 1/Z3
A14 In water, at what energy (keV) are photoelectric and Compton effects equally likely to occur?
a. 0.5
b. 4.0
c. 25
d. 70
e. 88
A15 If μ is 0.1 cm−1, and the density is 2 g/cm3, the mass attenuation (cm2/g) coefficient is:
a. 0.05
b. 0.2
c. 1.9
d. 2.1
e. 20
A16 The total attenuation by 10 half-value layers is most likely:
a. 64
b. 128
c. 256
d. 512
e. 1,024
A17 The x-ray beam HVL is least likely to be affected by the x-ray tube:
a. output (mGy)
b. voltage (kV)
c. voltage ripple (%)
d. filtration (mm Al)
e. target material (Z)
A18 What grid characteristic is most likely to determine the scatter removal performance?
a. Grid ratio
b. Focus distance
c. Gap distance
d. Strip height
e. Line density
A19 The most likely reason that grids are seldom used for portable chest radiography is that:
a. portable x-ray output is low
b. lower kV won’t penetrate grid
c. grid alignment is difficult
d. scatter is very low
e. air gap minimizes scatter
A20 When 0.1 J of energy is absorbed by an organ with a mass of 10 kg, the organ dose (mGy) is most likely:
a. 0.01
b. 0.1
c. 1
d. 10
e. 100
A21 The size of a typical film grain (μm) is most likely:
a. 0.1
b. 1
c. 10
d. 100
e. 1,000
A22 The percentage (%) of light transmitted through two films, each with a density of 1.0, is most likely:
a. 0.001
b. 0.01
c. 0.1
d. 1
e. 10
A23 Which is most likely to increase when a screen–film system replaces film alone?
a. Patient dose
b. Exposure time
c. Tube mAs
d. Receptor blur
e. Motion blur
A24 Compared to a regular screen, a detail screen of the same phosphor likely has a lower:
a. resolution
b. speed
c. noise
d. effective Z
e. density
A25 If all 8 bits in a byte are set to 1, then the decimal number is:
a. 8
b. 255
c. 511
d. 1,023
e. 11111111
A26 How much memory (MB) is needed to store a 1k × 1k radiograph with 256 shades of gray?
a. 0.1
b. 0.25
c. 0.5
d. 1
e. 2
A27 Which of the following materials is most likely a photostimulable phosphor?
a. BaFBr
b. CsI
c. NaI
d. PbI
e. Se
A28 Photoconductors convert x-ray energy directly into:
a. light
b. charge
c. heat
d. voltage
e. radio waves
A29 Replacing analog chest imaging with digital technology is least likely to improve image:
a. resolution
b. processing
c. retrieval
d. storage
e. transmission
A30 The minimum number of images required to perform energy subtraction is:
a. 1
b. 2
c. 3
d. 4
e. >4
A31 The target material in a mammography x-ray tube is most likely:
a. Be (Z = 4)
b. Al (Z = 13)
c. Mo (Z = 42)
d. Ag (Z = 47)
e. Ba (Z = 56)
A32 In a linear grid for mammography, a fiber interspaced grid is preferred over aluminum because it likely reduces:
a. dose
b. scatter
c. mottle
d. receptor blur
e. focal blur
A33 High image contrast is least likely achieved in mammography by the use of:
a. low photon energies
b. high film gradients
c. short exposures (<0.1 s)
d. breast compression
e. scatter removal grids
A34 The optimal grid ratio in magnification mammography is most likely:
a. no grids used
b. 2:1
c. 4:1
d. 8:1
e. 16:1
A35 The Mammography Quality Standards Act does not require:
a. reject analysis
b. processor sensitometry
c. physics testing
d. ACR accreditation
e. FDA certification
A36 The purpose of photocathodes in image intensifiers is to convert light into:
a. x-rays
b. heat
c. voltages
d. electrons
e. ultraviolet
A37 A typical II conversion factor (cd/m2 per μGy/s), is most likely:
a. 2
b. 20
c. 200
d. 2,000
e. 20,000
A38 Plumbicon TV cameras, used in cardiac imaging, most likely reduce:
a. vignetting
b. mottle
c. flicker
d. lag
e. scatter
A39 Reducing II input area by activating electronic magnification likely increases:
a. skin dose
b. image distortion
c. amount of vignetting
d. image brightness
e. field of view
A40 Digital cardiac imaging would likely use an acquisition rate (images per second) of:
a. 4
b. 7.5
c. 15
d. 30
e. 60
A41 The typical anode cooling rate (kW) of a standard CT x-ray tube is most likely:
a. 1
b. 3
c. 10
d. 30
e. 100
A42 A beam-shaping filter is most likely used in CT scanners to reduce:
a. detector dynamic range
b. beam hardening
c. detector cross-talk
d. off-focus radiation
e. scatter radiation
A43 The detected x-ray pattern transmitted through the patient at a single x-ray tube angle is best described as a:
a. ray
b. projection
c. back projection
d. convolution
e. tomographic slice
A44 Use of a soft tissue filter, as opposed to a bone filter, to reconstruct CT images would most likely reduce:
a. mottle
b. scatter
c. dose
d. artifacts
e. scan times
A45 A window width of 100 and window level of 50 likely results in a pixel value of 10 appearing as:
a. black
b. almost black
c. gray
d. almost white
e. white
A46 The advantage of helical over axial CT is most likely a reduction in:
a. radiation doses
b. scan times
c. scatter radiation
d. reconstruction times
e. slice sensitivity profiles
A47 Total exam time (s) for a single-phase adult abdomen on a 64-slice MDCT is likely:
a. 0.3
b. 1
c. 3
d. 10
e. 30
A48 When the weighted CTDIw is 10 mGy, and the pitch is 0.25, the volume CTDIvol (mGy) is most likely:
a. 2.5
b. 5
c. 10
d. 20
e. 40
A49 Compared to an adult (mAs = 100%), the most likely mAs (%) for a body CT scan of a 1-year-old would be:
a. 10
b. 30
c. 50
d. 70
e. >70
A50 Partial-volume artifacts in CT are best minimized by reducing:
a. section thickness
b. scan time
c. matrix size
d. focal blur
e. scan length
A51 The highest subject contrast of an iodinated blood vessel likely occurs at a photon energy (keV) of:
a. 30
b. 40
c. 50
d. 70
e. 100
A52 Lowering the kV in screen–film mammography most likely reduces:
a. contrast
b. dose
c. mAs
d. scatter
e. exposure time
A53 What x-ray tube voltage (kV) would likely maximize the visibility of iodinated contrast in the carotid arteries?
a. 30
b. 50
c. 70
d. 90
e. 110
A54 Which of the following factors is least likely to affect image sharpness?
a. Detector composition
b. Focal spot size
c. Exposure time
d. Detector thickness
e. Image magnification
A55 When the MTF from focal and receptor blur are both equal to 0.1 (at 2 lp/ mm), the imaging system MTF at this spatial frequency is most likely:
a. 0.2
b. 0.1
c. 0.05
d. 0.02
e. 0.01
A56 Spatial resolution of a standard fluoroscopy unit is most likely limited by the:
a. focal spot
b. input phosphor
c. output phosphor
d. optical system
e. TV system
A57 CT scanner spatial resolution performance would most likely improve when increasing the:
a. focal spot
b. detector width
c. tube current
d. scan time
e. image matrix
A58 Visibility of low-contrast lesions in a digital radiograph would most likely be improved when increasing:
a. focus size
b. image magnification
c. air kerma
d. beam filtration
e. display luminance
A59 The detector air kerma (μGy) that produces one frame in DSA imaging is most likely:
a. 5
b. 15
c. 50
d. 150
e. 500
A60 A receiver operator characteristic curve likely measures:
a. diagnostic performance
b. error rate
c. test specificity
d. test sensitivity
e. cost-effectiveness
A61 The most radiosensitive part of the cell is most likely the:
a. cell membrane
b. chloroplast
c. nucleus
d. mitochondrion
e. ribosome
A62 Which particle is likely to have the highest linear energy transfer (LET)?
a. Electron
b. Positron
c. Proton
d. Neutron
e. Alpha particle
A63 The uniform whole-body dose (Gy) that would kill half the exposed population is most likely:
a. 1
b. 2
c. 4
d. 8
e. 16
A64 The chronic threshold dose (Gy) for cataract induction is most likely:
a. 1
b. 2
c. 5
d. 10
e. >10
A65 The threshold equivalent dose (mSv) for the induction of stochastic effects is likely:
a. 0 (no threshold)
b. 0.1
c. 1
d. 10
e. 100
A66 Which of the following does not concern itself with radiation risk estimates?
a. ICRP
b. UNSCEAR
c. BEIR
d. ICRU
e. NCRP
A67 The organ weighting factor for gonad exposure recommended by the ICRP (Publication 103) in 2007 is:
a. 0.01
b. 0.04
c. 0.08
d. 0.20
e. 0.30
A68 The most sensitive period for the induction of severe mental retardation in pregnant patients is most likely:
a. up to 10 days
b. 2 to 7 weeks
c. 7 to 15 weeks
d. 15 to 25 weeks
e. >25 weeks
A69 Which is likely the best indicator of the risk of a radiation-induced skin reaction?
a. backscatter fraction
b. entrance air kerma
c. energy imparted
d. air kerma–area product
e. skin dose
A70 The total energy (J) deposited in a patient undergoing a head CT scan is most likely:
a. 0.1
b. 1
c. 10
d. 100
e. 1,000
A71 For the same air kerma, blackening of film by 30 keV photons, compared to the blackening by 300 keV photons, is most likely:
a. much less
b. slightly less
c. similar
d. slightly more
e. much more
A72 A Geiger-Muller detector would likely be used to measure:
a. low-level contamination
b. x-ray tube outputs
c. patient exposures
d. operator exposures
e. x-ray leakage
A73 The effective dose (mSv per year) to an interventional radiology fellow is most likely:
a. 1
b. 5
c. 10
d. 20
e. 50
A74 The current (2008) regulatory dose limit (mSv per year) to the eye lens of a radiologist is:
a. 50
b. 100
c. 150
d. 300
e. 500
A75 The amount of lead shielding (mm) in the wall of a CT facility is most likely:
a. 0.5
b. 1
c. 1.5
d. 3
e. 5
A76 The effective dose (mSv) from a chest x-ray examination is most likely:
a. 0.05
b. 0.2
c. 1
d. 3
e. 10
A77 The effective dose (mSv) for an upper barium examination is most likely:
a. 0.2
b. 1
c. 5
d. 25
e. >25
A78 The risk of a breast cancer from a screening mammogram in a 50-yearold woman is most likely three per:
a. 100
b. 1,000
c. 10,000
d. 100,000
e. 1,000,000
A79 The average dose (mSv per year) from radon (+ daughters) in the United States is most likely:
a. 1
b. 2
c. 3
d. 4
e. 5
A80 Which imaging modality contributed least to the U.S. population medical dose (2006)?
a. Interventional radiology
b. Radiography/fluoroscopy
c. CT
d. Nuclear medicine
e. Mammography
A81 An activity of 1 mCi equals (Bq):
a. 37,000
b. 370,000
c. 3,700,000
d. 37,000,000
e. 370,000,000
A82 Which of the following emits positrons?
a. 3H
b. 32P
c. 18F
d. 99mTc
e. 226Ra
A83 A radionuclide produced in a cyclotron is most likely to decay by:
a. Beta minus decay
b. Beta plus decay
c. Alpha decay
d. Isomeric transition
e. Neutron emission
A84 Which of the following is not a radiopharmaceutical localization mechanism?
a. Diffusion
b. Phagocytosis
c. Capillary blockage
d. Elution
e. Cell sequestration
A85 Which nuclide would be most likely to make use multiple PHA windows?
a. 67Ga
b. 123I
c. 131I
d. 99mTc
e. 133Xe
A86 Which radionuclide is least likely to be used for PET imaging?
a. 18F
b. 67Ga
c. 68Ga
d. 15O
e. 82Rb
A87 Which of the following tests is least likely to be performed on a radiopharmaceutical?
a. Flood uniformity
b. Pyrogenicity
c. Radiochemical purity
d. Radionuclide purity
e. Sterility
A88 The intrinsic (RI) and collimator (RC) resolution are related to the system resolution (R) as:
a. RI + RC
b. (RI − RC)1/2
c. 1/(RI + RC)1/2
d. (RI2 + RC2)
e. (RI2 + RC2)1/2
A89 Which is least related to artifacts in scintillation camera imaging?
a. Chemical shift
b. Cracked crystal
c. Edge packing
d. Nonuniformity
e. Off-peak imaging
A90 Which organ likely receives the highest dose for an uptake of 1 μCi activity (no biologic clearance)?
a. Adult thyroid
b. Fetal thyroid
c. Spleen
d. Liver
e. Kidneys
A91 A 2-MHz transducer has an wavelength (mm) in tissue of approximately:
a. 0.01
b. 0.03
c. 0.1
d. 0.3
e. 1
A92
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