CT Test on Ch. 8, 9, and 10

1 Sievert is equal to: A. 100 rems B. 100 rads C. 10 rems D. 10 rads

A. 100 rems

Which theory states that the sampling interval (pixel size) has to be sufficiently small to support the reconstruction and visualization of small objects? A. Nyquist B. Hounsfield C. McCormack D. Kernel

A. Nyquist

The definition of pitch in a multislice scanner, as defined by the International Electrotechnical Commission, states: A. P = distance the table travels per rotation (d)/total collimation (W) B. P = total collimation (W)/distance the table travels per rotation (d) C. P = distance the table travels per rotation (d) ´ total collimation (W) D. P = distance the table travels per rotation (d) + total collimation (W)

A. P = distance the table travels per rotation (d)/total collimation (W)

What term is used to refer to the size and shape of the beam emanating from the x-ray tube and passing through the patient? A. beam geometry B. fan beam C. cone beam D. cone geometry

A. beam geometry

Which of the following is a plot of the pixel values as a function of their frequency of occurrence? A. computed tomography histogram B. highlighting C. region of interest statistics D. multiple windowing

A. computed tomography histogram

What is the unit of the computed tomography dose index? A. gray B. Roentgen C. rem D. seivert

A. gray

A small focal spot size or lower tube current will result in: A. higher spatial resolution B. decreased detector cell size C. lower spatial resolution D. decreased sampling frequency

A. higher spatial resolution

The photodiodes convert _________ into ________. A. light; electrical signals B. light; x-ray photons C. electric signals; light D. x-ray photons; light

A. light; electrical signals

The averaging of all tissues in a voxel is: A. partial volume averaging B. streaking averaging C. beam-hardening averaging D. reconstruction averaging

A. partial volume averaging

What is the term used to describe a ratio of the difference the table travels per revolution to nominal beam collimation? A. pitch B. scan ratio C. dose-length product D. tilt ratio

A. pitch

Partial volume artifacts can be reduced with _____________ slice acquisitions and computer algorithms. A. thinner B. thicker C. shorter D. faster

A. thinner

Which of the following determines the maximum number of gray shades to be displayed on the television monitor? A. window width B. window level C. filtered back-projection algorithm D. contrast controls on the television monitor

A. window width

All of the following are major categories of artifacts except: A. streaks B. noise C. shading D. rings and bands

B. noise

Total data acquisition time is determined by: I. gantry speed II. helical pitch III. detector coverage A. I and II B. I and III C. I, II, and III D. II and III

C. I, II, and III

If the x-ray prepatient collimation width is 24 cm and the scanner has a four-row detector array, what is the detector row collimation? A. 4 mm B. 6 mm C. 5 mm D. 7 mm

B. 6 mm

One industry standard in data transfer and connectivity is: A. radiology information system B. Digital Imaging and Communications in Medicine C. picture archiving and communications system D. hospital information system

B. Digital Imaging and Communications in Medicine

On an image, partial volume artifacts will appear as: I. bands II. shading III. streaks A. II and III B. I and III C. I, II, and III D. I and II

B. I and III

Examples of deterministic effects include: I. skin erythema II. epilation III. cataracts A. II and III B. I, II, and III C. I and II D. I and III

B. I, II, and III

Examples of stochastic effects include: I. cancer II. leukemia III. hereditary effects A. I and III B. I, II, and III C. I and II D. II and III

B. I, II, and III

All of the following are limitations of positron emission tomography/computed tomography technology except: A. increased expense B. anatomical correlation C. increased radiation dose D. potential attenuation artifacts

B. anatomical correlation

As the window width increases, picture contrast: A. increases B. decreases C. is optimized to show the specific anatomical structures D. remains unchanged

B. decreases

What dose descriptor is used to describe a measurement of the total amount of exposure for a series of scans? A. computed tomography dose index volume B. dose-length product C. single-scan peak dose D. multiple-scan average dose

B. dose-length product

What is the most straightforward way to reduce or eliminate the motion of an object? A. decrease slice thickness B. increase scan speed C. increase slice thickness D. decrease scan speed

B. increase scan speed

A large window width indicates that there is a relatively ______________ gray scale. A. narrow B. long C. curved D. short

B. long

What is an indication of a computed tomography system's ability to freeze motions of the scanned object? A. high-contrast resolution B. temporal resolution C. spatial resolution D. low-contrast resolution

B. temporal resolution

What is/are the unit(s) of exposure? I. Roentgen (R) II. Sievert (Sv) III. coulomb per kilogram (C/kg) A. II and III B. I and II C. I and III D. I, II, and III

C. I and III

The most commonly used radiopharmaceutical for positron emission tomographic imaging is: A. 15O carbon monoxide B. 13N ammonia C. 18F-2-fluoro-2-deoxy-D-glucose (FDG) D. 11C methionine

C. 18F-2-fluoro-2-deoxy-D-glucose (FDG)

The overall goals of automatic tube current modulation are to: I. provide consistent image quality II. increase scan speed III. control dose to the patient A. II and III B. I, II, and III C. I and III D. I and II

C. I and III

Which of the following are factors of dose that can be controlled by the technologist? I. technique factors II. patient centering III. x-ray beam collimation A. I and II B. II and III C. I, II, and III D. I and III

C. I, II, and III

What types of artifacts can arise from insufficient projection sampling or from insufficient view sampling? A. ring artifacts B. shading artifacts C. aliasing artifacts D. burst artifacts

C. aliasing artifacts

What refers to an increase in the mean energy of the x-ray beam as it passes through the patient? A. partial volume B. attenuation C. beam hardening D. scatter radiation

C. beam hardening

Pixel size is determined by: A. field of view + matrix size B. matrix size/field of view C. field of view/matrix size D. field of view ´ matrix size

C. field of view/matrix size

What is the easiest and probably the most accurate method used to report dose? A. thermoluminescent dosimeter B. Geiger counter C. ionization chamber D. film dosimeter

C. ionization chamber

When the slice thickness is equal to the pixel size, the data acquired are said to be: A. anisotropic B. unitropic C. isotropic D. distropic

C. isotropic

Which technique factor determines the quantity of photons (dose) incident on the patient for the duration of the exposure? A. mA B. seconds C. mAs D. kV

C. mAs

What was the first dose descriptor to be identified? A. multiscan peak dose B. computed tomography dose index C. multiple-scan average dose D. dose profile

C. multiple-scan average dose

Deterministic effects follow a: A. linear dose B. nonlinear dose C. threshold dose D. nonthreshold dose

C. threshold dose

Which of the following controls the contrast of the computed tomography image? A. milliamperage B. peak kilovoltage C. window width D. window length

C. window width

When using FDG for a whole body scan, the uptake waiting period is usually: A. 30-50 minutes B. 15-45 minutes C. 60-120 minutes D. 45-90 minutes

D. 45-90 minutes

Which of the following are parameters of image quality? I. spatial resolution II. contrast resolution III. noise A. I and III B. II and III C. I and II D. I, II, and III

D. I, II, and III

The window width and window length settings for a given examination of the abdomen are 400 and 0, respectively. Which of the following is true? A. all structures between -200 and 200 will be black B. only those structures above 400 will have different shades of gray C. all structures between -200 and 200 will be white D. all structures between -200 and 200 will spread through the gray scale

D. all structures between -200 and 200 will spread through the gray scale

The window level in computed tomography is the: A. center of the computed tomography matrix B. range of computed tomography numbers C. pixel depth D. center of a range of computed tomography numbers

D. center of a range of computed tomography numbers

If the window width setting is 200 and the window length is 0, which of the following occurs? A. only those numbers between +100 and +200 appear gray B. computed tomography numbers between 0 and +200 appear black C. computed tomography numbers less than 100 appear gray D. computed tomography numbers greater than +100 appear white

D. computed tomography numbers greater than +100 appear white

If the pitch increases, the dose: A. increases B. pitch and dose are unrelated C. stays the same D. decreases

D. decreases

The overall goal of multislice computed tomography is to: A. improve spatial resolution B. decrease patient dose C. increase tube memory D. improve volume coverage speed performance

D. improve volume coverage speed performance

Both voluntary and involuntary motion appears as ____________ that are usually tangential to the high-contrast edges of the moving part. A. rings B. shading C. bands D. streaks

D. streaks

The radiation sensors convert ___________ to ___________. A. light; x-ray photons B. light; electrical signals C. electric signals; light D. x-ray photons; light

D. x-ray photons; light

The computed tomography number for water is +1000. True False

False