Physics unit 5

beam-hardening

A ____ artifact is caused by attenuation of the beam as it passes through the patient. Select one: a. beam-hardening b. ring c. star d. streak

Data acquisition system

DAS stands for which of the following? Select one: a. Data acquisition system b. Digital activation signal c. Digital acquired space d. Digital analog server e. Digital analog system

Metal clips

Streak artifacts on a CT image are usually due to: Select one: a. Beam Hardening b. Bone/soft tissue interface c. Bowel gas d. Detector imbalance e. Metal clips

False

The HU of water is always 1. Select one: True False

False

Detector alignment is not critical in CT. Select one: True False

Is the long axis of the body

During spiral CT examination of a supine patient, the z-axis: Select one: a. Is the anterior-posterior axis. b. Is the lateral axis, left to right. c. Is the lateral axis, right to left. d. Is the long axis of the body. e. Varies with the examination.

Are faster than third-generation CT imaging systems.

Fourth-generation CT imaging systems: Select one: a. Are faster than third-generation CT imaging systems. b. Have rotate-rotate geometry. c. Incorporate area-beam geometry. d. May use selenium or film as the image receptor. e. Require prepatient collimation.

5 cm

How much z-axis tissue will be imaged during a 20 s procedure if the slice width is 5 mm at a pitch of 1 and the gantry rotation time of 2 s? Select one: a. 5 cm b. 10 cm c. 100 cm d. 5 mm e. 10 mm

30 cm

If a 20-second spiral CT examination is acquired at a pitch of 1.5 with collimation of 10 mm, what volume of tissue was imaged? Select one: a. 3 cm b. 30 cm c. 300 cm d. 3 mm e. 30 mm

sodium iodide crystals

In the CT detector, the x-ray photon is absorbed by: Select one: a. sodium iodide crystals b. photostimulable fluorohalides c. polyester d. none of the above

True

Patient dose during CT is measured according to the CTDI. Select one: True False

False

The primary advantage to the helical scanner is that a full 360-degree set of data is acquired for each section. Select one: True False

all of the above

The smaller the scan field size in CT, the: Select one: a. better the resolution b. faster the scan time c. less risk of motion d. all of the above

1

What range of beam pitch is recommended for multislice spiral CT? Select one: a. 0.5 to 1 b. 0.5 to 2.0 c. 0.5 to 4 d. 1 e. 1 to 2

MPR

Which advanced workstation function can reconstruct images into another plane? Select one: a. MPR b. MIP c. VRT d. SSD

1.25 mm3

A CT image is made with a 5 mm slice thickness and a 0.5 mm pixel size. What is the size of the voxel? Select one: a. 0.75 mm3 b. 1.00 mm3 c. 1.25 mm3 d. 1.5 mm3 e. 2.5 mm3

Picture elements

A CT image matrix contains which of the following? Select one: a. Algorithms b. Equations of information c. Picture elements d. Silver halide information units e. Slice sensitivity 1.00

0.7 mm

A CT imaging system has a limiting resolution of 7 lp/cm. An object of what size can be resolved? Select one: a. 0.35 mm b. 0.5 mm c. 0.7 mm d. 1.4 mm e. 3.5 mm

Axial

A CT imaging system produces which type of image? Select one: a. Axial b. Biaxial c. Fulcrum plane d. Longitudinal e. Transverse

Is the numerical value of a pixel

A Hounsfield unit: Select one: a. Has a value from -100 to +100. b. Has a value from -500 to +500. c. Is the numerical value of a pixel. d. Is the numerical value of anode heat generated. e. Is the volume of a voxel expressed in mm3.

streak

A _____ artifact is caused by motion when performing CT examinations. Select one: a. beam-hardening b. ring c. star d. streak

star

A _____ artifact is caused by the presence of metal in the patient when performing CT. Select one: a. beam-hardening b. ring c. star d. streak

The scintillation detectors have higher geometric efficiency.

A comparison of scintillation and gas-filled detectors shows that: Select one: a. Both have approximately the same total detection efficiency. b. Both rely heavily on Compton interaction. c. Only scintillation detectors require prepatient collimation. d. The gas-filled detectors have higher intrinsic efficiency. e. The scintillation detectors have higher geometric efficiency.

It can image a 0.5 mm object.

A device has the MTF characteristics represented by B. Which of the following statements is true for that device? Select one: a. A 2 lp/cm, only one half of an object can be imaged. b. At 10 lp/cm, the response is excellent. c. It can image a 0.5 mm object. d. Its imaging ability increases with increasing spatial frequency. e. Longer imaging time than in A will be required.

clean up scatter

A grid pattern is not added to the CT image to: Select one: a. clean up scatter b. confirm centering c. aid in patient positioning d. describe precise location

Better spatial resolution

A principal advantage of multislice spiral CT compared with step-and-shoot CT is all of the following except: Select one: a. Better spatial resolution b. Faster imaging c. Larger tissue volume d. Lower patient dose e. Three-dimensional image reconstruction

Reduction of partial volume.

A principal advantage of reconstruction in any z-axis position is: Select one: a. Image acquisition during a single breath-hold. b. Improved contrast resolution. c. Improved spatial resolution. d. Larger volume of tissue imaged. e. Reduction of partial volume.

Hounsfield

A series of tissue density values that evolved for CT measurements is called _____ units. Select one: a. Hounsfield b. SI c. Attenuation d. All of the above

matrix

An array of numbers arranged in a grid of rows and columns is called a: Select one: a. pixel b. voxel c. matrix d. scan profile

50 kW

Approximately what is the minimum power requirement for the high-voltage generator and x-ray tube for spiral CT? Select one: a. 10 kW b. 20 kW c. 30 kW d. 40 kW e. 50 kW

False

Because of their simplistic nature, first-generation CT scanners were much smaller than those used today. Select one: True False

Maximum intensity projection

CT angiography relies on a reconstruction process that is called: Select one: a. Longitudinal reformation b. Maximum intensity projection c. Shaded surface display d. Surface-rendered e. Volume-rendered

Single-focus x-ray tubes

CT imaging systems incorporate: Select one: a. Charged electrostatic plates b. High-frequency radiographic grids c. Light-localizing, variable-aperture collimators d. Multiple reconstruction algorithms e. Single-focus x-ray tubes

improved contrast resolution

CT is able to differentiate between tissues with similar densities compared with conventional radiography due to: Select one: a. digital magnification b. the use of a computer for data processing c. improved contrast resolution d. axial slices

Reduce patient dose.

CT is preformed at high kVp principally to: Select one: a. Improve image contrast. b. Minimize beam hardening. c. Reduce patient dose. d. Reduce scatter radiation. e. Reduce x-ray tube loading

True

CT radiation beams are double collimated. Select one: True False

True

CT tubes commonly fail after several months. Select one: True False

True

CT x-ray tubes produce a massive amount of heat as compared to conventional radiographic tubes. Select one: True False

all of the above

Computed tomography sections are available as: Select one: a. coronal b. transverse c. sagittal d. all of the above

determines the midpoint of the gray range

Contrast is adjusted by windowing, changing window width and window level. Window level determines the: Select one: a. number of gray levels displays b. determines the midpoint of the gray range c. size of the field of view d. slice thickness

number of gray levels displays

Contrast is adjusted by windowing, changing window width and window level. Window width determines the: Select one: a. number of gray levels displays b. determines the midpoint of the gray range c. size of the field of view d. slice thickness

Are due to the polyenergetic beam.

During CT imaging, beam hardening artifacts: Select one: a. Are due to the polyenergetic beam. b. Can be corrected by preprocessing. c. Produce CT numbers higher in the periphery. d. Result in brighter pixels in the center of the patient. e. Result in higher attenuation in the center of the patient.

1.5

During a 360-degree x-ray rotation, the patient couch moves 15 mm during each revolution. Slice thickness is 10 mm. What is the slice pitch? Select one: a. 0.66 b. 1.25 c. 1.5 d. 1.66 e. 2.0

Days

Early reconstruction of raw compute tomography data took a few ______ to form a recognizable image. Select one: a. Minutes b. Hours c. Days d. Weeks

1 and 2

Factors that affect image quality in CT consist of: 1. spatial resolution 2. noise 3. contrast media Select one: a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3

head

First-generation CT scanners scanned the _____ only. Select one: a. head b. thorax c. abdomen d. pelvis

only rotating tube

Fourth-generation CT scanners use the following configuration: Select one: a. translate tube and rotating detectors b. rotating tube and detectors c. only rotating detectors d. only rotating tube

8

If a pitch of 1.0 is being used with a section thickness of 8 mm, what is the proper table speed? Answer: (in mm/sec)

1.25

If the CT table is moving at 10 mm/sec., and a section thickness of 8 mm is being acquired, what is the pitch? Answer to the second digit beyond the decimal point.

5

If the pitch of 0.5 is being used with a section thickness of 10 mm, what is the proper CT table speed? Answer: AnswerIncorrect mm/sec Whole number is fine. Just type the number.

1.20

If the table is moving at 12 mm/sec., and a section thickness of 10 mm is being acquired, what is the pitch? Answer to the second digit beyond the decimal point.

6.25

If the table is moving at 5 mm/sec., and a pitch of 0.8 is being used, what is the section thickness for this CT scan in mm? Answer: ____ mm Answer to the second digit beyond the decimal point. Just type the number.

3.33

If the table is moving at 5 mm/sec., and a pitch of 1.5 is being used, what is the section thickness? Answer: Answer In correct mm Answer to the second digit beyond the decimal point. Just the number.

digital

Images created with Computed Tomography and Magnetic Resonance Imaging can be manipulated to control the contrast, density, or even projected in a different plane. This is possible because the images that are created are: Select one: a. not made with x-rays b. digital c. made with magnetic fields d. not placed on film

Determines patient dose

In a CT imaging system, prepatient collimation: Select one: a. Controls pixel size b. Controls scatter radiation that reaches the detector c. Determines image noise d. Determines patient dose e. Determines slice thickness

In a full circle around the patient.

In computed tomography, how does the x-ray tube move? Select one: a. In a full circle around the patient. b. Back and forth in a half-circle under and around the patient. c. Side to side in a horizontal plane over the patient. d. None of these.

A detector

In its simplest configuration, the CT imaging system consists of an x-ray source and which of the following? Select one: a. A detector b. A selenium plate c. A video display terminal d. An image intensifier e. An x-ray beam collimator

water, linear attenuation coefficient

In reference material for CT is ________ and is related to the _______ of the tissue. Select one: a. water, field of view b. water, linear attenuation coefficient c. muscle, gray level d. bone, mass attenuation

all of the above

Modern pulsed CT scanners operate at: Select one: a. 120 kVp b. 1 to 5 msec pulses c. up to 1,000 mA d. all of the above

True

Motion on a CT image is a function of exposure time. Select one: True False

Increasing mAs

Noise on a CT image can be reduced by: Select one: a. Increasing kVp b. Increasing mAs c. Increasing matrix size d. Reducing image time e. Reducing pixel size

Matrix size

Noise on a CT image increases with an increase in: Select one: a. kVp b. mA c. Matrix size d. Pixel size e. Slice thickness

less concentrated than for general examinations

Oral contrast for CT should be mixed so it is: Select one: a. the same as for general diagnostic examinations b. more concentrated than for general examinations c. less concentrated than for general examinations d. contrast media is not necessary

Thicker slices

Partial volume artifacts are more likely with: Select one: a. Higher kVp b. Higher mA c. Larger pixel size d. Thicker slices e. Thinner slices

Have a multiple detector array.

Second-generation CT imaging systems: Select one: a. Have a multiple detector array. b. Have rotate-rotate geometry. c. Require imaging speeds from 1 to 5 minutes. d. Require special patient preparation. e. Use increments of 1 degree per view.

Predetector collimator

Sensitivity profile in CT is determined principally by the: Select one: a. Bow-tie filter b. Predetector collimator c. Prepatient collimator d. Reconstruction algorithm e. Ramp function

Sensitivity profile

Slice thickness can also be expressed as which of the following? Select one: a. Dose profile b. Low-contrast resolution c. Resolution profile d. Sensitivity profile e. Spatial profile

1 mm

Spatial resolution for CT imaging systems is approximately: Select one: a. 1 cm b. 10 cm c. 100 cm d. 1 mm e. 10 mm

Pixel size

Spatial resolution in CT imaging depends principally on: Select one: a. Focal spot size. b. kVp. c. Pixel size. d. Postpatient collimation. e. Slice thickness.

The ability to identify small high-contrast objects.

Spatial resolution refers to which of the following? Select one: a. The ability to classify large low-contrast objects. b. The ability to identify small high-contrast objects. c. The ability to identify tissues of varying composition. d. The binary number system. e. The constancy of the imaging system over time.

all of the above

The CT console provides the radiographer access to: Select one: a. the software program b. data acquisition c. data display d. all of the above

all of the above

The CT radiation beam is collimated: Select one: a. at the tube exit b. at the detector entrance c. twice d. all of the above

mA

The CT radiographer usually varies the ____ to control the primary beam. Select one: a. mA b. time c. kVp d. detail

all of the above

The CT table is Select one: a. made of carbon graphite b. rated for maximum weight c. motor-driven d. all of the above

Images large objects better than small objects.

The MTF characteristics of system A suggest that it: Select one: a. Can image down to approximately 0.8 mm. b. Can image down to approximately 6 cm. c. Images large objects better than small objects. d. Images small objects better than large objects. e. Is a better system than B.

System B has better spatial resolution than system A.

The MTF curves describe two imaging systems. Which of the following statements is true? Select one: a. System A detects smaller objects than system B. b. System A has better spatial resolution than system B. c. System A has more image noise than system B. d. System B has better contrast for coarse details than system A. e. System B has better spatial resolution than system A.

conversion efficiency

The ____ is determined by how well the detector converts the absorbed photon information to a digital signal for the computer. Select one: a. capture efficiency b. absorption efficiency c. conversion efficiency d. response time

absoprtion efficiency

The ____ is how well the detectors convert incoming photons. Select one: a. capture efficiency b. absoprtion efficiency c. conversion efficiency d. response time

ring

The _____ artifact is caused by detector error when performing CT. Select one: a. beam-hardening b. ring c. star d. streak

True

The amount of noise controls the low-contrast resolving ability of the CT unit. Select one: True False

Head only

The first commercial CT scanner could image the ________ . Select one: a. Abdomen only b. Head only c. Head and abdomen d. Total body

x-ray tube

The gantry of the CT unit contains the: Select one: a. film b. menu c. x-ray tube d. all of the above

A cross section

The image produced by CT scanning is which of the following? Select one: a. An anteroposterior view b. Dynamic (moving) c. A cross section d. All of the above

One of the greatest milestones in medical imaging.

The invention of computed tomography is heralded as ________ . Select one: a. The advanced use of three-dimensional computation in medical imaging. b. One of the greatest milestones in medical imaging. c. The stepping stone for the development of MRI. d. The first modality to use PACS.

Thousands

The largest number of individual detectors in a multislice CT imager is approximately: Select one: a. Two b. Four c. Ten d. Hundreds e. Thousands

scanogram

The locilization image produced by the CT scanner is called: Select one: a. fluoroscopy b. scout film c. scanogram d. all of the above

Dose-length product (DLP)

The most common reporting method of dose reporting on the present CT scanners is: Select one: a. Multiple Scan Average Dose (MSAD) b. Computed Tomography Dose Index (CTDI) c. Dose-length product (DLP) d. Computed Tomography Dose Index Volume (CTDIvol)

helical

The most recent generation CT scanners use a ____ motion. Select one: a. spiral b. helical c. linear d. elliptical

1, 2, and 3 are correct

The operating console of a CT imager will normally have controls for which of the following? 1. kVp 2. Exposure time 3. Slice thickness 4. SID indicator Select one: a. 1, 2, and 3 are correct b. 1 and 3 are correct c. 2 and 4 are correct d. Only 4 is correct e. All of the above are correct

The x-ray attenuation coefficient

The precise pixel value in HU depends on which of the following? Select one: a. 32 shades of gray. b. Light field, x-ray beam coincidnce. c. Pixel size. d. The x-ray attenuation coefficient. e. X-ray beam size.

Fourier

The primary mathematical method used in the creation of computerize medical images is the ______ transformation. Select one: a. Pythagorean b. Bohr c. Einstein d. Fourier

convolution

The process of modifying pixel values by a mathematical formula is called: Select one: a. convolution b. deconvolution c. calculus d. all of the above

all of the above

The resolution of the CT image depends on the: Select one: a. pixel b. voxel c. matrix d. all of the above

Maximum-intensity projection

The simplest form of three-dimensional imaging is: Select one: a. Isometric b. Maximum-intensity projection c. Shaded surface display d. Shaded volume display e. Slip-ring technology

Imaging of a large volume of anatomy in one breath-hold.

The single most important advantage of spiral CT is which of the following? Select one: a. Imaging of a large volume of anatomy at low patient dose. b. Imaging of a large volume of anatomy in one breath-hold. c. Improved contrast resolution. d. Improved spatial resolution.I e. Improved z-axis resolution.

Predetector collimation

The thickness of section in CT depends primarily on: Select one: a. kVp b. mAs c. Matrix size d. Predetector collimation e. Prepatient collimation

Describes both first- and second-generation CT imaging systems.

The translate-rotate mode: Select one: a. Collects data only during the rotate portion. b. Describes both first- and second-generation CT imaging systems. c. Requires higher heat capacity x-ray tubes. d. Requires only solid-state detectors. e. Results in imaging times as short as 1 second.

Rotate-rotate geometry

Third-generation CT imaging systems have which of the following? Select one: a. Multiple-detector, area-beam geometry b. Rotate-rotate geometry c. Rotate-translate geometry d. Single-detector, fan-beam geometry e. Translate-translate geometry

30 s

Thirty centimeters of tissue along the z-axis is to be imaged with a 5 mm slice thickness at a pitch of 2.0. What imaging time is required? Select one: a. 20 s b. 25 s c. 30 s d. 35 s e. 40 s

reconfiguration software is implemented

To achieve coronal or sagittal sections with computed tomography: Select one: a. the gantry is repositioned b. the patient is repositioned c. reconfiguration software is implemented d. none of the above

A little harder than what you are used to. Each step has 15 numbers. We are looking for bones. The 8th step has values of 67.5 to 82.5, that puts 75 right in the middle. Now 75 is a lower number than 300, so automatically, you know the bones will look lighter than step 8 (harder to penetrate). So working down on the scale. Step 7 is 82.5 to 97.5, Step 6 is 97.5 to 112.5, Step 5 is 112.5 to 127.5, Step 4 is 127.5 to 142.5, Step 3 is 142.5 to 157.5, Step 2 is 157.5 to 172.5, and Step 1 is anything higher than 172.5. That makes the answer Step 1. The correct answer is: 1

Using the attached image, calculate the appropriate step that would represent the bone of the pelvis when using a +75 window level and a 225 window width. (The bone of the pelvis have been assigned a value of +300) For ease in calculation, the first and last number of each shade will overlap. As they did in class. Select one: a. 1 b. 8 c. 9 d. 15

The width is 750 so each step has 50 numbers in it. The level is +100. Now the bones of the pelvis have been given the number +300 which means they would be harder to penetrate than any thing in step 8, so we are looking down the scale at the lighter colors. Step 8 has +100 in the middle of the scale and a total of 50 numbers, so this step goes from +75 to +125, Step 7 goes from +125 to +175, Step 6 goes from +175 to +225, Step 5 goes from +225 to +275, and Step 4 goes from +275 to +325. Here they are. The correct answer is: 4

Using the attached image, calculate the appropriate step that would represent the bones of the pelvis when using a +100 window level and a 750 window width. The bones of the pelvis have been assigned a value of +300. For ease in calculation, the first and last number of each step will overlap as they did in class. Select one: a. 1 b. 4 c. 9 d. 14 e. 15

1

Using the attached image, calculate the appropriate step that would represent the bones of the pelvis when using a +50 window level and a 150 window width. (The bones of the pelvis have been assigned a value of +300) For ease in calculation, the first and last number of each shade will overlap. As they did in class.

5

Using the attached image, calculate the appropriate step that would represent the bones of the pelvis when using a -400 window level and a 3000 window width. The bones of the pelvis have been assigned a value of +300. For ease in calculation, the first and last number of each step will overlap as they did in class.

11

Using the attached image, calculate the appropriate step that would represent the tissue of the liver when using a +75 window level and a 225 window width. (The tissue of the liver have been assigned a value of +35) For ease in calculation, the first and last number of each shade will overlap. As they did in class.

6

Using the attached image, calculate the appropriate step that would represent the tissue of the liver when using a -400 window level and a 3000 window width. The tissue of the liver have been assigned a value of +35. For ease in calculation, the first and last number of each step will overlap as they did in class.

9

Using the attached image, calculate the appropriate step that would represent the tissues of the liver when using a +100 window level and a 1500 window width. The tissue of the liver have been assigned a value of +35. For ease in calculation, the first and last number of each step will overlap as they did in class.

9

Using the attached image, calculate the appropriate step that would represent the tissues of the liver when using a +100 window level and a 750 window width. The tissue of the liver have been assigned a value of +35. For ease in calculation, the first and last number of each step will overlap as they did in class. (no pic attached)

9

Using the attached image, calculate the appropriate step that would represent the tissues of the liver when using a +50 window level and a 150 window width. (The liver has been assigned the value of +35) For ease in calculation, the first and last number of each step will overlap.

11

Using the attached image, calculate the appropriate step that would represent the tissues of the lung when using a +100 window level and a 1500 window width. The tissue of the lung have been assigned a value of -200. For ease in calculation, the first and last number of each step will overlap as they did in class.

14

Using the attached image, calculate the appropriate step that would represent the tissues of the lung when using a +100 window level and a 750 window width. The tissue of the lung have been assigned a value of -200. For ease in calculation, the first and last number of each step will overlap as they did in class.

15

Using the attached image, calculate the appropriate step that would represent the tissues of the lung when using a +50 window level and a 150 window width. (The lung tissue has been assigned a value of -200) For ease in calculation, the first and last number in each step will overlap. As they did in class.

10

Using the attached image, calculate the appropriate step that would represent the tissues of the lung when using a -155 window level and a 300 window width. (The lung tissue has been assigned a value of -200) For ease in calculation, the first and last number in each step will overlap. As they did in class.

7

Using the attached image, calculate the appropriate step that would represent the tissues of the lung when using a -350 window level and a 3000 window width. The tissue of the lung have been assigned a value of -200. For ease in calculation, the first and last number of each step will overlap as they did in class.

0.75 mm

What is the pixel size of an image reconstructed from a 24 cm diameter region of interest (ROI) in a 320 x 320 matrix? Select one: a. 0.25 mm b. 0.5 mm c. 0.75 mm d. 1.3 mm e. 1.5 mm

Is limited by the noise of the system.

When a CT image is described, contrast resolution: Select one: a. Is limited by the MTF of the system. b. Is limited by the noise of the system. c. Is not as good as in conventional radiography. d. Is the same as spatial resolution. e. Means that contrast material was injected.

Surface-rendered

When a shaded surface display reformation is implemented, the image will appear: Select one: a. As CT angiography b. As z-axis reformation c. Isometric d. Surface-rendered e. Volume-rendered

SSD

Which advanced function allows the user to remove all tissue above and below a certain threshold and to show the object in three-dimensions for better visualization? Select one: a. MPR b. MIP c. MinIP d. SSD

MIP

Which advanced function is used most often in CT to visualize contrast medium-filled vessels separate from the surrounding tissue? Select one: a. MPR b. MIP c. MinIP d. SSD

VRT

Which advanced function uses a histogram-type graph to differentiate various structures using different colors that represent each of the intensities in the image? Select one: a. MPR b. MIP c. VRT d. SSD

20 HU

Which of the following Hounsfield unit (HU) values most closely represents the value for blood? Select one: a. -80 HU b. -40 HU c. -2 HU d. 20 HU e. 100 HU

High anode heat capacity

Which of the following characteristics is specific to a spiral CT x-ray tube? Select one: a. High anode heat capacity b. High rotation speed c. Large effective focal spots d. Large target angle e. Small effective focal spots

Bismuth germanate

Which of the following has been used as a detector in a CT imaging system? Select one: a. Bismuth germanate b. CaWO4 c. High-pressure air d. Selenium e. Silver halide

1, 2, and 3 are correct

Which of the following is a constituent of a CT imager? 1. A computer 2. A television monitor 3. An algorithm 4. An image intensifier Select one: a. 1, 2, and 3 are correct b. 1 and 3 are correct c. 2 and 4 are correct d. Only 4 is correct e. All of the above are correct

Reduced scanning time.

Which of the following is an advantage of spiral CT over conventional CT? Select one: a. Better patient dose utilization. b. Improved contrast resolution. c. Improved spatial resolution. d. Large matrix reconstruction. e. Reduced scanning time.

Section sensitivity profile

Which of the following is another term for slice thickness? Select one: a. Dose profile b. Interpolation profile c. Reconstruction index d. Section sensitivity profile e. Z-axis profile

Better contrast resolution is obtained.

Which of the following is characteristic of a CT image but not of a conventional radiograph? Select one: a. Anatomic structures are superimposed. b. Better contrast resolution is obtained. c. Better spatial resolution is obtained. d. More scatter radiation reaches the image receptor. e. Overlying and underlying tissues are blurred.

A pencil x-ray beam

Which of the following is characteristic of first-generation CT imaging systems? Select one: a. A pencil x-ray beam b. A selenium or film image receptor c. Multiple sources and multiple detectors d. Rotate-only geometry e. Slip rings

Lack of motion artifact

Which of the following is one advantage of spiral CT over conventional CT? Select one: a. Better patient dose utilization b. Improved contrast resolution c. Improved spatial resolution d. Lack of motion artifact e. Large matrix reconstruction

Continuous x-ray tube rotation in one direction

Which of the following is specifically characteristic of spiral CT? Select one: a. Continuous bidirectional rotation of the x-ray tube. b. Continuous x-ray tube rotation in one direction. c. Rotating detector array. d. Stationary patient couch. e. Step-like motion of the patient couch.

180-degree interpolation

Which of the following reconstruction techniques exhibits the most image noise? Select one: a. 180-degree interpolation b. 360-degree interpolation c. Back-projected conventional CT d. Filtered back projection conventional CT e. High-dose CT

The detector array

Which of the following subsystems would normally be associated with the CT gantry assembly? Select one: a. Image postprocessing b. The detector array c. The algorithm d. The physicians viewing console

The detector array.

Which of the following subsystems would normally be associated with the gantry assembly? Select one: a. Image postprocessing. b. The algorithms. c. The detector array. d. The physician's viewing console. e. The software.

Slip rings

Which of the following technique developments made spiral CT possible? Select one: a. Dose-efficiency detectors b. High-frequency generators c. Interpolation algorithms d. Slip rings e. Volume imaging

Helical

Which of the following terms is equivalent to spiral? Select one: a. Elliptical b. Helical c. Interpolation d. Paraboloid e. Trispiral

Godfrey Hounsfield

Who was the first to incorporate digital imaging with the CT scanner? Select one: a. Paul Lauterbor b. Godfrey Hounsfield c. Sol Nudleman d. M. Paul Capp

Poor z-axis resolution

Why is it recommended that beam pitch should not exceed 2.0? Select one: a. Increased noise b. Poor contrast resolution c. Poor patient dose utilization d. Poor spatial resolution e. Poor z-axis resolution

The section sensitivity profile increases.

With increasing slice pitch: Select one: a. Image noise is reduced. b. Patient dose is increased. c. Sagittal/coronal reconstruction is improved. d. The section sensitivity profile decreases. e. The section sensitivity profile increases.