CT midterm
True or False? A number of independent studies have established a link between effective communication and a reduction in malpractice claims.
True
True or False? An undesired surge of electrical current within the x-ray tube causes tube arcing.
True
True or False? Axial slices lie parallel to one another.
True
True or False? Children interact at a close distance, whereas adults interact at a farther distance.
True
True or False? End-users interact directly with client computers to send data requests to one or more connected servers.
True
True or False? Higher mA settings allow shorter scan times to be used.
True
True or False? Lossy compression methods introduce compression artifacts because not all data are restored.
True
True or False? MDCT designs were responsible for the demise of fourth-generation scanning systems.
True
True or False? Reconstructing raw data to create new images can only be done from the operator's console.
True
True or False? Surface rendering is useful for examining tubular structures.
True
True or False? The American College of Radiology CT accreditation phantom is a solid phantom that contains four modules, and is constructed primarily from a water-equivalent material.
True
True or False? When voxels are isotropic, any oblique plane can be created with virtually no loss of image quality.
True
True or false. Using a narrow screen width when displaying the brain makes it possible to differentiate between white matter and gray matter.
True
True or False? There is always the same specific pattern in the appearance of tube arc artifacts.
False
True or False? Tube arcing is patient-induced artifact.
False
True or False? WANs typically use Ethernet connections to attach computers to the network.
False
True or False? When storing large amounts of data, tape can be substantially more expensive than other data storage options
False
True or false. The scan field of view (SFOV) is also called zoom or target.
False
True or false. The window level should be set at a point that greater than the average attenuation number of the tissue of interest.
False
True or false. Wider window width settings increase image contrast.
False
True or False? The terms scout, surview, topogram, scanogram, preview, and pilot are alternative names for step-and-shoot scans.
False
True or False. Detectors restrict the x-ray beam to a specific area, reducing scatter radiation.
False
True or False. If the patient's weight exceeds the specified limits, scanning is not possible.
False
True or False. RAM is imprinted at the factory and is used to store frequently used instructions such as those required for starting the system.
False
True or False. Selecting too large a DFOV makes the image appear unnecessarily large.
False
True or False. The larger the object being scanned, the thinner the CT slice required.
False
True or False. To differentiate adjacent objects on a CT image, there cannot be a density difference between the two objects.
False
True or False? A voxel is isotropic when the z direction is equal to the slice thickness.
False
True or False? Axial scans are typically used in protocols in which the acquisition speed is a major concern and optimal resolution is not required.
False
True or False? Communication is the transmission of meaning.
False
True or False? In communication, you should assume that a nonresponsive patient cannot hear you.
False
True or False? Localizer images are cross-sectional in nature.
False
True or False? Milliampere level and scan time together define the quality of the beam.
False
True or False? Multiplanar reformations (MPRs) are 3D image displays.
False
True or False? Networks that use radio waves to transmit data between computers are referred to as "wired."
False
True or False? On CT images, objects with a 5% contrast variation can be distinguished.
False
True or False? Optimal images can be achieved with standardized window widths.
False
True or False? Raw data storage requires less computer storage space than that of image data.
False
True or False? Research has found that African-Americans stand closest to one another.
False
True or False? Ring artifacts appear only on MDCT helical systems.
False
True or False? Slice thickness has a no impact on image quality.
False
True or False? The selection of 160 mA and a 2-second scan time provides a greater quantity of x-ray energy than 640 mA and a 0.5-second scan.
False
True or False. The sagittal plane divides the body into right and left sections.
True
True or False. A microphone is a component of the gantry.
True
True or False. Artifacts always degrade the quality of an image.
True
True or False. Collimators control the slice thickness by narrowing or widening the x-ray beam.
True
True or False. High-frequency generators are currently used in CT.
True
True or False. In CT systems, software instructs the computer to automatically save reconstructed images to a permanent storage device.
True
True or False. On the Hounsfield, scale values higher than 2,000 HU represent very dense materials.
True
True or False. The degree to which an x-ray beam is reduced by an object is known as attenuation.
True
If the window width is 500 and the range of Hounsfield numbers to be included in the gray scale is -250 to 250, what is the window level? a. 0 b. 50 c. 300 d. 400
a. 0
What is the typical range of values for scan time for a full rotation? a. 0.5 second to 2 seconds b. 1 second to 2 seconds c. 0.1 second to 3 seconds d. 1 second to 5 seconds
a. 0.5 second to 2 seconds
What percent of the data available does surface rendering typically use? a. 10% b. 25% c. 50% d. 100%
a. 10%
The General Electric Lightspeed QX/I scanner system uses 16 detector rows, each 1.25 mm wide, arranged side-by-side along the z axis. If three detector rows are combined, how thick will the resultant slices be? a. 3.75 mm b. 1.25 mm c. 2.5 mm d. 5 mm
a. 3.75 mm
Which of the following statements is true? a. A small object will have a low spatial frequency, and a large object will have a high spatial frequency. b. A large object will have no spatial frequency, and a small objects will have a high spatial frequency. c. A large object will have a high spatial frequency, and small objects will have no spatial frequency. d. A large object will have a low spatial frequency, and small objects will have a high spatial frequency.
a. A small object will have a low spatial frequency, and a large object will have a high spatial frequency.
What is an overscan? a. A tube arc greater than 360°. b. A thin x-ray beam passed linearly over the patient. c. The occurrence of ring artifacts. d. Streaking on the CT image.
a. A tube arc greater than 360°.
What is ghosting? a. A type of image artifact where objects appear to have a shadow b. A type of filter used to eliminate beam hardening c. Another name for the edge gradient effect d. Another name for tube arcing
a. A type of image artifact where objects appear to have a shadow
How are metals represented on a CT image? a. As white areas b. As black areas c. As grey areas
a. As white areas
Which of the following does not have to be identical to reformat a CT study? a. Beam pitch b. Image center c. Gantry tilt d. DFOV
a. Beam pitch
Why doesn't the uncoupling effect play a role when the mA or kVp setting is too low? a. Because quantum noise will result and provide evidence of the inadequate exposure settings. b. Because when the settings are too low, the radiation dose cannot be at a dangerous level. c. Because there is no relationship between dose and image quality when the mA or kVp setting is too low
a. Because quantum noise will result and provide evidence of the inadequate exposure settings.
In what units is bandwidth commonly expressed? a. Bits per second b. Bytes per second c. Kilobytes per second d. Megabytes per second
a. Bits per second
Which has the greatest storage capacity? a. Blu-ray disk b. DVD c. CD
a. Blu-ray disk
How is noise is measured? a. By finding the standard deviation of the CT numbers within the region of interest b. By finding the mean of the CT numbers within the region of interest c. By finding the standard median of the CT numbers within the region of interest d. By finding the variance of the CT numbers within the region of interest
a. By finding the standard deviation of the CT numbers within the region of interest
Which part of a computer interprets program instructions? a. CPU b. Hard disk c. Output devices d. ROM
a. CPU
Which is the first step in many image display and measurement functions? a. Defining a region of interest b. Performing distance measurements c. Calculating the standard deviation for an area of interest d. Calculating the Hounsfield for an area of interest
a. Defining a region of interest
Which generation of scanners used a thin x-ray beam passed linearly over the patient with a single detector following on the opposite side of the patient? a. First-generation b. Second-generation c. Third-generation d. Fourth-generation
a. First-generation
What do filtered back-projection algorithms use to reduce statistical noise? a. Fourier theory b. Linear interpolation c. Array processors d. Convolution
a. Fourier theory
What barrier to communication is a result of messages being unreliable or inconsistent? a. Fuzzy transmission b. Receiver distortion c. Power struggles d. Language
a. Fuzzy transmission
Why did array processors become obsolete? a. Increases in performance and processor design eliminated the need for them. b. They became too expensive to use. c. They were no longer compatible with all computer types.
a. Increases in performance and processor design eliminated the need for them.
Which directional term refers to movement towards the feet? a. Inferior b. Anterior c. Posterior d. Superior
a. Inferior
What is the name for the slight pause in scanning between data acquisitions? a. Interscan delay b. Interpolation c. Back projection d. Convolution
a. Interscan delay
What causes the edge gradient effect? a. Irregularly shaped objects that have a pronounced difference in density from surrounding structures b. More than one type of tissue is contained within a voxel. c. Patient motion d. Anatomy that extends out-side of the selected SFOV
a. Irregularly shaped objects that have a pronounced difference in density from surrounding structures
Which is a drawback of manual segmentation? a. It can be very hard to separate the object from the image background. b. Low contrast between structures can cause otherwise robust automatic algorithms to fail. c. Image complexity and the variety of image types and clinical indications make it impractical.
a. It can be very hard to separate the object from the image background
Why does using a small pixel size reduce the likelihood of volume averaging? a. It limits the amount of data to be volume averaged. b. It decreases the thickness of the plane. c. It changes the temporal resolution. d. It increase beam attenuation.
a. It limits the amount of data to be volume averaged.
What does the source collimator do? a. It limits the amount of x-ray emerging to thin ribbons. b. It cools the imaging components. c. It captures transmitted photons and changes them to electronic signals. d. It ionizes Xenon gas.
a. It limits the amount of x-ray emerging to thin ribbons.
Which is a drawback of back projecting data onto a matrix? a. It produces streak artifacts. b. Data manipulation becomes limited. c. Important parts of anatomy are cut from the image. d. Raw data for the image is lost.
a. It produces streak artifacts.
Which of the following interactions is the closest? a. Male-female b. Male-male c. Female-female
a. Male-female
In which 3D technique does the image appear flat? a. Maximum-intensity projections b. Surface rendering c. Volume rendering d. Shaded-surface display
a. Maximum-intensity projections
Which is true about meanings with respect to communication? a. Meanings are not entirely contained in the message. They are interpreted by the message receivers. b. Meanings are not entirely contained in the message. They are interpreted by the message senders. c. Meanings are entirely contained in the message. d. Meanings never contained in the message.
a. Meanings are not entirely contained in the message. They are interpreted by the message receivers.
Which American College of Radiology (ACR) CT accreditation phantom module is used to asses positioning and alignment? a. Module 1 b. Module 2 c. Module 3 d. Module 4
a. Module 1
What device is used to display CT images? a. Monitor b. Converter c. Filter d. Scanner
a. Monitor
What does it mean for an axial scan to be clustered? a. More than one scan can be taken during a single breath-hold b. Scanners can repeat scans at the same slice location c. The pauses between each data acquisition will be less than 30 seconds
a. More than one scan can be taken during a single breath-hold
Which is an input device for a computer? a. Mouse b. Printer c. Monitor d. Laser camera
a. Mouse
Which is not true about image reformation? a. Raw data are used b. It may be either 2D or 3D c. It is used to better display relationships d. It generates images in a different plane or orientation
a. Raw data are used
What is the next step a computer takes after it is turned on? a. The computer loads data from ROM and performs test to make certain all major components are functioning properly. b. The computer loads the operating system into RAM. c. The computer copies the operating system from the hard drive to RAM. d. The computer loads the operating system into SAM.
a. The computer loads data from ROM and performs test to make certain all major components are functioning properly.
What plays the biggest role in body language? a. The face b. Posture c. Gestures
a. The face
Which statement is true about overlapping reconstructions? a. The more the slice thickness exceeds pixel size, the greater the benefit of overlapping reconstructions for source data in multiplanar reformation (MPR) and 3D reformation. b. The more the slice thickness exceeds pixel size, the less the benefit of overlapping reconstructions for source data in multiplanar reformation (MPR) and 3D reformation. c. The more the pixel size exceeds slice thickness, the greater the benefit of overlapping reconstructions for source data in multiplanar reformation (MPR) and 3D reformation. d. The more the pixel size exceeds slice thickness, the less the benefit of overlapping reconstructions for source data in multiplanar reformation (MPR) and 3D reformation.
a. The more the slice thickness exceeds pixel size, the greater the benefit of overlapping reconstructions for source data in multiplanar reformation (MPR) and 3D reformation.
Which is a drawback of using thicker CT slices when imaging? a. They increase the likelihood of missing very small objects. b. They increase radiation dosage. c. They increase the number of slices that are produced. d. They decrease the pixel size.
a. They increase the likelihood of missing very small objects.
What is the goal of data compression? a. To minimize the size (in bytes) of an image file without degrading the quality of the image to an unacceptable level b. To increase the bandwidth of a WAN c. To route data from one computer to another
a. To minimize the size (in bytes) of an image file without degrading the quality of the image to an unacceptable level
Why is multiple image display often used? a. To provide multiple copies of the image b. To allow two individuals to view the image simultaneously c. To view and print the image simultaneously d. To save film
a. To provide multiple copies of the image
Which nonverbal communication category includes facial expression and posture? a. Visual b. Tactile c. Vocal d. Distance
a. Visual
What is the name of the process in CT by which different attenuation values are averaged to produce one less accurate pixel reading? a. Volume averaging b. Pixel averaging c. Z axis averaging d. Image averaging
a. Volume averaging
What is slice thinkness blooming? a. When interpolation methods result in a scan that is wider than that selected by the operator b. A parameter that is commonly used to describe the CT table movement. c. Grouping more than one scan in a single breath-hold. d. The delay in axial scanning sequences
a. When interpolation methods result in a scan that is wider than that selected by the operator
If the range of Hounsfield numbers on the image is 0 to 200, a value of 250 will display as what color? a. White b. Black c. Gray
a. White
What determines the center pixel value in gray scale? a. Window level b. Window width c. Window height d. Window contrast
a. Window level
What determines which Hounsfield values are displayed as shades of gray? a. Window level b. Window width c. Window height d. Window contrast
a. Window level
What is another name for incrementation? a. feed b. repositioning c. detection d. overscan
a. feed
What is the unit of measure for the power capacity of the generator? a. kW b. HU c. MHU d. KHU
a. kW
What is the unit of measurement for current of electrons that flow from the filament to the anode? a. mA b. kVp c. HU d. kW
a. mA
What is the name for each two-dimensional square in a CT slice? a. pixel b. matrix c. cross-section d. cube
a. pixel
Which equation correctly describes the relationship between pixel size, matrix size, and DFOV? a. pixel size = DFOV/matrix size b. pixel size = matrix size/DFOV c. pixel size = DFOV × matrix size d. pixel size = (DFOV/matrix size) + 1
a. pixel size = DFOV/matrix size
How often should noise and uniformity testing be done? a. weekly b. monthly c. semiannually d. annually
a. weekly
What is the maximum variation from the intended slice thickness for a slice thickness of 5 mm or less? a. ±0.5 mm b. ±1 mm c. ±0.5 cm d. ±1 cm
a. ±0.5 mm
The DFOV used for a study is 30 cm and a 512 matrix is used. What is the approximate pixel size in mm? a. 0.06 mm b. 0.59 mm c. 1.71 mm d. 17.07 mm
b. 0.59 mm
What is the most common range for pitch values in both SDCT and MDCT systems? a. 0-1 b. 1-1.5 c. 1-2 d. 1.5-2
b. 1-1.5
What is considered personal distance for North Americans? a. 18 inches or less b. 1.5 to 4 feet c. 3-6 feet d. 6-10 feet
b. 1.5 to 4 feet
As a general rule, the human eye cannot appreciate contrast differences of less than about what percent? a. 5% b. 10% c. 20% d. 50%
b. 10%
What is the kVp range for routine body CT for adult patients? a. 80 kvP to 100 kVp b. 120 kVP to 140 kVp c. 80 kVp to 140 kVp d. 100 kVp to 160kVp
b. 120 kVP to 140 kVp
What percent reduction in radiation dose do automatic tube current modulations provide without degrading image quality? a. 10% to 25% b. 15% to 40% c. 5% to 50% d. 15% to 60%
b. 15% to 40%
Open ended questions invite a narrative response from a patient. How long is an uninterrupted narrative response on average? a. 15 -30 seconds b. 30 seconds to 1 minute c. 1 minute to 2 minutes d. 3 minutes to 5 minutes
b. 30 seconds to 1 minute
What window width should be used for tissue types with similar densities? a. 0-50 HU b. 50-500 HU c. 500-2,000 HU d. 2,000-2,500 HU
b. 50-500 HU
What is the range of aperture size for a gantry? a. 60 cm - 70 cm b. 70 cm - 90 cm c. 70 cm - 80 cm d. 90 cm - 100 cm
b. 70 cm - 90 cm
What is a computer network? a. Multiple input devices used on a single computer b. A group of two or more computers linked together c. Multiple output devices used on a single computer d. A group of two or more processors on a workstation
b. A group of two or more computers linked together
Which is not part of the structure of a solid-state detector array? a. Circuit board b. Amplifier c. Photodiode d. Scintillator crystal
b. Amplifier
Where does a localizer image for a CT of the chest usually begin? a. At the top of the head b. At the lower neck c. At mid-abdomen d. At the base of the spine
b. At the lower neck
If the range of Hounsfield numbers on the image is -100 to 300, a value of -150 will display as what color? a. White b. Black c. Gray
b. Black
Who often share the responsibility for performing and documenting quality control tests? a. CT technologists and physicians b. CT technologists and medical physicists c. Physicians and medical physicists d. Medical physicists and scanner manufacturers
b. CT technologists and medical physicists
Which is not a component of a CT scanner? a. Operator's console b. Camera c. Computer system d. Scanning gantry
b. Camera
What is the process of applying a filter function to an attenuation profile called? a. Interpolation b. Convolution c. Back projection d. Progressive reconstruction
b. Convolution
What is the name of the universally adopted standard for medical image interchange? a. ACR b. DICOM c. NEMA d. HL7
b. DICOM
Which is not task of the radiology information system (RIS)? a. Scheduling patients b. Image archiving c. Protocoling examinations d. Patient tracking
b. Image archiving
Among healthcare workers, what has been cited as the primary reason for not talking more with patients? a. Poor patient communication skills b. Lack of time c. Poor worker communication skills d. Language barriers
b. Lack of time
Which is not a desired characteristic of a detector? a. Low afterglow b. Low scatter suppression c. High stability d. High efficiency
b. Low scatter suppression
What barrier to communication has likely occurred when nonverbal messages are ignored? a. Fuzzy transmission b. Misreading of body language, tone, and other non-verbal forms of communication c. Power struggles d. Language
b. Misreading of body language, tone, and other non-verbal forms of communication
What happens when hard disk capacity is reached? a. The computer shuts down. b. New data cannot be saved until some or all of the existing data is deleted or archived c. Memory will be used to permanently store data. d. The input and output devices stop working.
b. New data cannot be saved until some or all of the existing data is deleted or archived
What are image artifacts? a. Substances used to create a temporary artificial density between objects b. Objects seen on a CT image that are not present in the object scanned c. The data that form the CT slice d. The photons in an x-ray beam
b. Objects seen on a CT image that are not present in the object scanned
Which is not a scanning parameter? a. Slice thickness b. Patient size c. Field of view d. Reconstruction algorithm
b. Patient size
Which is not an optical storage device? a. Blu-ray disk b. RAID c. CD d. DVD
b. RAID
What is the name for the path the x-ray beam takes from the tube to the detector? a. Ray sum b. Ray c. Angle d. View
b. Ray
What is interactive reformation? a. Another name for three-dimensional reformation b. Reformation that allows the operator to use a mouse or other device to manually change the image plane while the software continually updates the image. c. Reformation that is specifically designed to look inside the lumen of a structure
b. Reformation that allows the operator to use a mouse or other device to manually change the image plane while the software continually updates the image.
What is another name for surface rendering? a. Projection display b. Shaded-surface display c. Volume rendering d. Endoluminal imaging
b. Shaded-surface display
Which is another name for helical scanning? a.Step-and-shoot scanning b. Spiral scanning c. Axial scanning d. Localizer scanning
b. Spiral scanning
Which type of artifacts can occur when voxels are not isotropic? a. Motion b. Stair-step c. Streak d. Ring
b. Stair-step
Which nonverbal communication category involves the use of touch to impart meaning? a. Visual b. Tactile c. Vocal d. Distance
b. Tactile
What is low-contrast resolution? a. The ability of the system to differentiate between objects of similar sizes. b. The ability of the system to differentiate between objects with similar densities. c. The system's ability to resolve, as separate forms, small objects that are very close together. d. The level of detail that is visible on the image.
b. The ability of the system to differentiate between objects with similar densities.
Which is bandwidth? a. The width of the Ethernet cable connecting computers in a network b. The amount of data that can be transmitted between two points in the network in a set period of time c. A strategy for routing data between computers in a network d. A network topology
b. The amount of data that can be transmitted between two points in the network in a set period of time
What measures the number of photons that strikes the detector, converts the information to a digital signal, and sends the signal to the computer? a. A solid-state detector array b. The data-acquisition system c. An Xenon gas detector array d. High-frequency generators
b. The data-acquisition system
Which is not an advantage of CT over conventional radiography? a. The elimination of superimposed structures b. The depiction of a three-dimensional object as a two-dimensional image c. The superior quality of the images d. The ability to differentiate small differences in density of anatomic structures and abnormalities
b. The depiction of a three-dimensional object as a two-dimensional image
What determines the shades of gray on a CT image? a. Air-filled structures b. The quantity of x-ray photons c. The thickness of the CT slice d. The scanning protocol
b. The quantity of x-ray photons
Which generation of CT systems typically used a 360° rotation for each acquisition? a. Fourth generation b. Third generation c. Second generation d. First generation
b. Third generation
Which is not another name for the filter function? a. Algorithm b. View c. Convolution filter d. Kernel
b. View
What is frame grabbing? a. When an image on the monitor is converted to analog format b. When an image on the monitor is converted to digital format c. When an image on the monitor is compressed d. When an image on the monitor is transmitted
b. When an image on the monitor is converted to digital format
Which is not a type of segmentation? a. Manual b. Workstation-created c. Semiautomatic d. Fully automated
b. Workstation-created
What is the name for the radiation emitted from the collimated x-ray source in multidetector row systems? a. adaptive array b. cone beam c. misregistration d. pitch
b. cone beam
What is the name for the area of the anode where the electrons strike and the x-ray beam is produced? a. gantry b. focal spot c. space cloud d. reconstruction processor
b. focal spot
What is the pitch for a 64-slice MDCT with 0.5-mm slice thickness and a table-feed of 48 mm per rotation? a. 0.6 b. 0.75 c. 1.5 d. 1.75
c. 1.5
What is the maximum variation from the intended slice thickness for a slice thickness of 5 mm or greater? a. ±0.5 mm b. ±1 mm c. ±0.5 cm d. ±1 cm
b. ±1 mm
If an image reproduced the object exactly, what is the MTF of the system? a. 0 b. 0.5 c. 1 d. 1.5
c. 1
The DFOV used for an abdominal study is 42 cm and a 256 matrix is used. What is the approximate pixel size in mm? a. 0.164 mm b. 0.61 mm c. 1.64 mm d. 6.10 mm
c. 1.64 mm
If the window level is 200 and the window width is also 200, what is the range of Hounsfield numbers to be included in the gray scale? a. -200 to 200 b. -100 to 300 c. 100 to 300 d. 50 to 150
c. 100 to 300
What is considered intimate distance for North Americans? a. 12 inches or less b. 15 inches or less c. 18 inches or less d. 25 inches or less
c. 18 inches or less
How many shades of gray can the monitor display? a. 64 b. 128 c. 256 d. 512
c. 256
If 30 lines can be seen in a 1-cm section in an image of a line pairs phantom, what is the spatial resolution? a. 1 lp/cm b. 15 lp/cm c. 30 lp/cm d. 60 lp/cm
c. 30 lp/cm
An examination protocol calls for contiguous, 5-mm slices to be taken and 70 slices are planned. How much of the patient anatomy in the z direction will be covered with cross-sectional slices? a. 75 mm b. 159 mm c. 350 mm d. 700 mm
c. 350mm
What is the most common matrix size in CT? a. 128 b. 256 c. 512 d. 1024
c. 512
How many bits are in a byte of storage? a. 1 b. 2 c. 8 d. 128
c. 8
Proper street behavior among Americans permits passersby to look at each other until they are approximately how many feet apart? a. 2 feet b. 6 feet c. 8 feet d. 10 feet
c. 8 feet
Studies have shown that what percent of the meaning we derive from communication comes from the nonverbal cues that the other person gives? a. 50% b. 75% c. 90% d. 100%
c. 90%
Which statement about interpolation is true? a. As the angle of the slice becomes less steep, the interpolation required to adjust the data increases. b. As the angle of the slice becomes less steep, the interpolation required to adjust the data decreases. c. As the angle of the slice becomes steeper, the interpolation required to adjust the data increases. d. As the angle of the slice becomes steeper, the interpolation required to adjust the data decreases.
c. As the angle of the slice becomes steeper, the interpolation required to adjust the data increases.
Which is another name for step-and-shoot scanning? a. Helical scanning b. Spiral scanning c. Axial scanning d. Localizer scanning
c. Axial scanning
What is the name for the process of converting the data from the attenuation profile to a matrix? a. Attenuation b. Interpolation c. Back projection d. Fourier transform
c. Back projection
Where are laser lights located? a. Inside the gantry b. Outside the gantry c. Both inside and outside the gantry
c. Both inside and outside the gantry
What device changes the image on the monitor to film? a. Analog-to-digital converter b. Digital-to-analog converter c. Camera d. Scanner
c. Camera
What can be used to create a temporary artificial density difference between two objects on a CT image? a. Low-energy x-ray photons b. High-energy x-ray photons c. Contrast agents d. Artifacts
c. Contrast agents
What are the computers that are integral to the functioning of the PACS called? a. Client servers b. Nodes c. Core servers
c. Core servers
Which is a major drawback of workstation-created MPRs? a. If oblique or curved images are needed, the technologist must create them manually b. Operators cannot use trial and error to obtain the ideal image plane c. Data contain hundreds of images potentially slowing down the PACS network d. There is significant loss of image quality
c. Data contain hundreds of images potentially slowing down the PACS network
Which is not a segment of the CT process? a. Image reconstruction b. Data acquisition c. Data dispersal d. Image display
c. Data dispersal
Which type of imaging visualizes a structure as if it were hollow and the viewer were inside of it. a. Surface rendering b. Projection displays c. Endoluminal imaging d. Volume rendering
c. Endoluminal imaging
Which classification of image artifacts causes ring artifacts? a. Physics-based b. Patient-based c. Equipment-based
c. Equipment-based
If the range of Hounsfield numbers on the image is -50 to 50, a value of 0 will display as what color? a. White b. Black c. Gray
c. Gray
What is the term for the ability of an x-ray tube to withstand resultant heat? a. Kinetic energy b. Heat dissipation c. Heat capacity d. Thermal energy
c. Heat capacity
Which is not a characteristic of a pressurized Xenon gas detector? a. High stability b. No afterglow c. High photon absorption d. Low-density material
c. High photon absorption
In which part of the CT process are the data converted into shades of gray for viewing? a. Data acquisition b. Image reconstruction c. Image display
c. Image display
Which describe the software part of a computer? a. The part of the computer that can be physically touched b. The devices which allow information to be output. c. Instructions that tell a computer what to do d. The memory that is volatile
c. Instructions that tell a computer what to do
Which is a benefit of filtering the x-ray beam? a. It increases the intensity of the beam. b. It reduces scatter radiation. c. It reduces overscan. d. It decreases the time of CT imaging.
c. It reduces overscan.
Which is not a network routing mechanism? a. Bridging b. Switching c. LANs d. Hubs
c. LANs
Which is not a factor that produces a high standard deviation? a. Mixed attenuation tissue within the region of interest b. A region of interest that includes a streak artifact c. No variation within the region of interest d. A region of interest that is not inside the margins of the object being measured
c. No variation within the region of interest
Which is an advantage of step-and-shoot scanning? a. The cumulative effect of the pauses between each data acquisition adds to the total examination time b. Misregistration often occurs during scanning c. On phantoms, they result in the highest quality image d. Data acquired are more limited in how they can be reconstructed
c. On phantoms, they result in the highest quality image
What barrier to communication is likely to occur when either the sender or receiver is insecure or suffer from low self-esteem? a. Fuzzy transmission b. Receiver distortion c. Power struggles d. Language
c. Power struggles
What barrier to communication is likely to occur when the receiver doesn't like portions of the sender's message? a. Fuzzy transmission b. Language c. Receiver distortion d. Assumptions
c. Receiver distortion
Which is not a type of device used to display CT images? a. CRT monitor b. Camera c. Scanner d. LCD monitor
c. Scanner
What is another name for solid-state detectors? a. Apertures b. Detector array c. Scintillation detectors d. Detector bank
c. Scintillation detectors
What do current systems use to rotate the gantry frame? a. Recoiling system cables b. Collimators c. Slip rings d. Detectors
c. Slip rings
Which is not a feature CT systems use to minimize beam hardening? a. Filtration b. Calibration correction c. Slowing gantry rotation speed d. Beam-hardening correction software
c. Slowing gantry rotation speed
Why is it important to correctly input the patient's position before the localizer image is obtained? a. The optimal display field of view will be distorted b. Data acquired during axial scanning will not be contiguous. c. Subsequent images will be incorrectly annotated which can result in misdiagnosis and serious medical errors
c. Subsequent images will be incorrectly annotated which can result in misdiagnosis and serious medical errors
What is the primary reason for changing the image plane from axial to coronal? a. To eliminate volume averaging b. To attenuate the x-ray beam c. The anatomy of interest lies vertically rather than horizontally d. To reduce artifacts created by surrounding structures
c. The anatomy of interest lies vertically rather than horizontally
Which statement is not true about a LAN? a. It can be a combination of network topologies. b. It typically uses Ethernet cables to connect computers. c. The computers in a LAN are geographically distant. d. A LAN can be a wired network.
c. The computers in a LAN are geographically distant.
What is density? a. The number of photons that pass through a structure b. The degree to which an x-ray beam is reduced by an object c. The degree to which matter is concentrated d. The amount of x-ray beam that is absorbed per unit of thickness
c. The degree to which matter is concentrated
Which statement is true? a. The higher the mAs setting, the shorter the time between scans. b. The lower the mAs setting, the longer the time between scans. c. The higher the mAs setting, the longer the time between scans.
c. The higher the mAs setting, the longer the time between scans.
What is tube current? a. The loss of resolution caused by a larger filament b. The time the x-ray beam is on for the collection of data for each slice c. The product of milliampere setting and scan time
c. The product of milliampere setting and scan time
Which is a not a benefit of localizer images? a. They allow the technologist to prescribe the location of cross-sectional slices. b. They help the technologist select the optimal display field of view. c. They speed up the examination process. d. They help the technologist select the correct image center.
c. They speed up the examination process.
What is the goal of using a thin slice for scanning and reconstruction and thicker slices for viewing and storing? a. To generate scans that are generated with isotropic, or near isotropic voxels b. To create reformatted images that better display anatomic relationship c. To maintain the advantage of high-resolution imaging but also create image files that are manageable and more easily reviewed by radiologists
c. To maintain the advantage of high-resolution imaging but also create image files that are manageable and more easily reviewed by radiologists
What is the purpose of filtering? a. To increase computer processing speed b. To reduce image noise c. To reduce the radiation dose to the patient d. To minimize streak artifacts
c. To reduce the radiation dose to the patient
Which is a communication habit to avoid? a. Nodding or head-shaking b. Acknowledging the many possibilities for misunderstanding c. Using false reassurance d. Asking questions of a listener to see whether he or she understands
c. Using false reassurance
Which nonverbal communication category refers to the intonation of a person's voice. a. Visual b. Tactile c. Vocal d. Distance
c. Vocal
Which describes a cupping artifact? a. When the object appears in only a small number of views collected from the tube's 360° path b. When there is an appearance of dark bands or streaks between dense objects in the image c. When the periphery of the image is lighter d. When fine stripes appear to be radiating from a dense structure
c. When the periphery of the image is lighter
Which is a disadvantage of using Xenon gas detectors? a. They are highly unstable. b. They are the most expensive type of detector to produce. c. Xenon gas must be kept under pressure in an aluminum casing. d. They are more difficult to calibrate than the solid state variety.
c. Xenon gas must be kept under pressure in an aluminum casing.
What is the thickness of a cross-sectional CT slice called? a. X axis b. Y axis c. Z axis d. Q axis
c. Z axis
How often is direct spatial resolution testing using a line pairs phantom performed in most quality assurance programs? a. daily b. weekly c. monthly d. annually
c. monthly
Which is not a typical classification for the causes of artifacts? a. Physics-based b. Equipment-induced c. Patient-based d. Technologist-based
d. Technologist-based
How often is slice thickness accuracy testing performed in most quality assurance programs? a. weekly b. monthly c. semiannually d. annually
c. semiannually
Which is not another name for reconstruction algorithm? a. convolution filter b. FC filter c. spatial frequency algorithm d. algorithm
c. spatial frequency algorithm
Which is not a usual degree of tilt for a CT gantry? a. +15° b. -25° c. -5° d. +35°
d. +35°
A scanner allows mA choices in 20-mA increments from 20 to 700, and offers a choice of scan times from 0.4, 0.6, 0.8, 1.0, and 2.0 seconds. Which combination of mA and scan time will produce an mAs of 336? a. 0.6 second and 500 mA b. 1.0 second and 320 mAs c. 0.4 second and 680 mAs d. 0.8 second and 420 mA
d. 0.8 second and 420 mA
What is considered public distance for North Americans? a. 4 feet or more b. 6 feet or more c. 8 feet or more d. 12 feet or more
d. 12 feet or more
What is considered social distance for North Americans? a. 18 inches or less b. 12 feet or more c. 1.5 to 4 feet d. 4-12 feet
d. 4-12 feet
What do social psychologists estimate as the percent in loss of meaning in the transmission of messages from sender to receiver? a. 0% to 10% b. 10% to 25% c. 30% to 50% d. 40% to 60%
d. 40% to 60%
If the window level is 50 and the range of Hounsfield numbers to be included in the gray scale is -150 to 250, what is the window width? a. 0 b. 50 c. 300 d. 400
d. 400
What is the tube rotation of an overscan? a. 180° b. 360° c. 380° d. 400°
d. 400°
According to the ACR reference CTDI what is the recommended radiation dose for an adult head? a. 20 mGy b. 25 mGy c. 50 mGy d. 75 mGy
d. 75 mGy
What is interpolation? a. Software instructions that tell the computer what to do and when to do it b. A technique for expressing a waveform as a weighted sum of sines and cosines c. A set of steps used to solve a problem d. A mathematical method of creating missing data
d. A mathematical method of creating missing data
Which is/are not a principal physical component of a computer? a. The CPU b. Memory c. Input and output devices d. Algorithms.
d. Algorithms.
What is another name for step-and-shoot scan mode? a. Spiral b. Volumetric c. Helical d. Axial
d. Axial
In which type of scans doe the CT table move to the desired location and remain stationary while the x-ray tube rotates. a. Helical scans b. Spiral scans c. Localizer scans d. Step-and-shoot scans
d. Step-and-shoot scans
Which is not a factor that affects contrast resolution? a. Slice thickness b. Patient size c. Reconstruction algorithm d. CTDI phantoms
d. CTDI phantoms
Which is typically not displayed in color on the display monitor? a. Text fields b. Patient information c. Scan parameters d. Cross-sectional images
d. Cross-sectional images
Which is not a basic attribute of a helical scan process? a. A continually rotating x-ray tube b. Uninterrupted table movement c. Constant x-ray output d. Each slice of the image is parallel to every other slice
d. Each slice of the image is parallel to every other slice
Which is a generic term for a digital patient record? a. Patient health record b. Digital health record c. Computerized health record d. Electronic health record
d. Electronic health record
Which generation of scanners uses a detector array that is fixed in a 360° circle within the gantry? a. First-generation b. Second-generation c. Third-generation d. Fourth-generation
d. Fourth-generation
What are used to quantify the degree that a structure attenuates an x-ray beam? a. Attenuation coefficients b. Pixels c. Contrasting agents d. Hounsfield units
d. Hounsfield units
What does the selected display field of view (DFOV) determine? a. The area, within the gantry, from which the raw data are acquired b. The number of detector cells collecting data c. Whether half-field or full-field is used d. How much of the collected raw data is used to create an image
d. How much of the collected raw data is used to create an image
Which is another name for image reformation? a. Projection display b. Segmentation c. Surface rendering d. Image rendering
d. Image rendering
What is the absolute center of the gantry called? a. Median b. Epicenter c. Image center d. Isocenter
d. Isocenter
Which directional term refers to movement towards the head? a. Inferior b. Anterior c. Posterior d. Superior
d. Superior
Which is not true about the effect of mAs and kVp setting on the radiation dose? a. Excessively lowering the kVp may result in a dramatic increase in the amount of x-ray attenuated by patient tissue. b. Reducing the kVp while holding the mAs constant reduces the radiation dose to the patient. c. Reducing the mAs while holding the kVp constant reduces the radiation dose to the patient. d. It is a more common to manipulate the kVp, rather than the mAs.
d. It is a more common to manipulate the kVp, rather than the mAs.
Which is a reason why a technologist should take one cross-sectional slice to check the accuracy of a localizer image? a. The patient is placed head first in the gantry. b. The intravenous contrast material is critical. c. The localizer image will be an anterior-posterior projection. d. It is impossible to use readily identifiable landmarks.
d. It is impossible to use readily identifiable landmarks.
Which type of scans are digital image acquisitions that are created while the tube is stationary and the table moves through the scan field? a. Helical scans b. Spiral scans c. Axial scans d. Localizer scans
d. Localizer scans
What is the best way to reduce metallic artifact? a. Select a SFOV that is larger than the patient. b. Recalibrate the scanner c. Give the patient clear breathing instructions d. Minimize the metal present in the SFOV
d. Minimize the metal present in the SFOV
Which type of computer storage is volatile? a. ROM b. Hard disk c. WORM d. RAM
d. RAM
What is dual window setting? a. Recording two different window settings to display two images b. Displaying two windows simultaneously c. Using a dual processor to create an image d. Recording two different window settings, superimposed on one another in a single image
d. Recording two different window settings, superimposed on one another in a single image
What is another name for region-of-interest editing? a. Surface rendering b. Overlapping reconstruction c. Minimum-intensity projection d. Segmentation
d. Segmentation
What determines the number of detector elements? a. The cooling system b. The slip rings c. The gantry d. The fan beam
d. The fan beam
What is region-of-interest editing? a. A form of volume rendering that is designed to look inside the lumen of a structure b. Creating images by comparing the intensity of each voxel in the data set to some predetermined threshold c. The process of selectively removing or isolating information from the data set d. The method of examining each voxel along a line from the viewer's eye through the data set and selecting only the voxel with the highest value for inclusion in the displayed image.
d. The method of examining each voxel along a line from the viewer's eye through the data set and selecting only the voxel with the highest value for inclusion in the displayed image.
What causes spiral interpolation artifacts? a. Too few samples b. Images are created from views not in the same plane c. Patient motion d. The x-ray beams are composed of different energies
d. The x-ray beams are composed of different energies
What is the name for a complete set of ray sums? a. Attenuation profile b. Collimators c. Image data d. View
d. View
What determines the number of Hounsfield units assigned to each level of gray in a gray-scale image? a. The CPU b. The display processor c. Window level d. Window width
d. Window width
Which is not a manifestation of patient motion? a. streaking b. blurring c. ghosting d. concentric rings
d. concentric rings