CT review questions

Question 1

which is not a synonym for preliminary or localizer image taken at the Strat of a CT exam?

a.topogram
b.scout
c.scanogram
d.spiral

Answer 1

d. spiral
spiral scan is used to describe the method of scanning
other names include: tomogram, scout, pilot, CR image

Question 2

the ability of a system to differentiate, on the image, objects with similar densities is known as

a.high contrast resolution
b.low contrast resolution
c.spatial resolution
d.temporal resolution

Answer 2

b.low contrast resolution
low contrast resolution is the ability of the system to display small density differences

temporal resolution refers to acquisition speed

Question 3

each two dimensional square of data that make up the CT image is called a:
a.pixel
b.voxel
c.matrix
d.fragment

Answer 3

a.pixel

Question 4

how many pixels are contained in a 1,024 matrix image
a.1,024
b.2,048
c.262,144
d.1,048,576

Answer 4

d.1.048,576
a 1024 matrix contains 1024 rows of pixels down and 1024 columns of pixels across therefore 1-24x1024=1,048,576

Question 5

beam attenuation can be defined as
a.the phenomenon by which artifacts result when lower energy photons are preferentially absorbed, leaving only higher intensity photons to strike the detector array
b.xray energy that is produced from bombarding a substance with fast moving electrons
c.the ability of the detector ro capture transmitted photons and change them to electronic signal
d.the phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter

Answer 5

d.the phenomenon by which an xray beam passing through a structure is decreased in intensity or amount because of absorption and interaction with matter

beam attenuation is a basic radiation principle in which higher density objects absorb more of the xray beam and fewer photons reach the detector

Question 6

which of the following is a low attenuation structure
a.iodine filled aorta
b.rib
c.trachea
d.calcfied arteries

Answer 6

c.trachea
a low attenuating object is one that allows xrays to pass through relatively unimpeded
low attenuated objects show up as black therefore b/c the trachea is an air filled object it will show up as black

Question 7

an object is slightly less dense than water. what is the expected Hounsfield measurement
a.-940
b.-10
c.50
d.850

Answer 7

b.-10
the Hounsfiald unit assigned to water is 0. objects with an attenuation less than water are assigned a negative number

Question 8

why does the administration of iodinated contrast media result in an enhanced image
a.iodinated contrast material increases the ability of the enhanced structure to attenuate the x-ray beam
b.iodinated contrast material decreases the average photon energy of the xray beam, therefore more photons are absorbed by the patient
c.the administration of iodinated contrast material results in a smaller pixel, thereby increasing spatial resolution which results in a enhanced image
d.iodinated contrast material alters the atomic number od body tissues. in the case of blood vessels, it temporarily changes their colour from red to blue, hence the name xray dye

Answer 8

a.iodinated contrast material increases the ability of the enhanced structure to attenuate the x-ray beam

the contrast material doe snot change the body tissues only resides in them

Question 9

the xray beam sources for CT produce xray energy that is polychromatic this means
a.when viewed by the naked eye the beam exhibits many different colours
b.it produces as a byproduct a substance known as polychlorinated biphenyl
c.photons contained in the beam are all of the same wavelength
d.the beam comprises photons with varying energies

Answer 9

d.the beam comprises photons with varying energies

Question 10

an object that appears on the image but is not present in the object scanned is called
a.artifact
b.anomaly
c.shadow
d.ghost

Answer 10

artifact

Question 11

which is an advantage of filtering the xray beam
a.filtering reduces the anode heat load
b.a filtered beam produces images with substantially less quantum mottle
c.filtering the beam prevents energy from being converted to heat, therefore 100% of the energy is converted to xrays
d.filtering reduces the radiation dose to the patient

Answer 11

d.filtering reduces the radiation dose to the patient
filtering removes the long wavelength or short xrays that do not contribute to the CT image but contribute to the dose

Question 12

scan thickness primarily important for the part it plays in
a.noise reduction
b.the contrast scale
c.detector aperture opening
d.volume averaging

Answer 12

d.volume averaging

Question 13

you are working with the radiologists to establish examination protocols for your department.which of the following is a logical consideration when determining an appropriate slice thickness for studies of the internal auditory canal

a.because the auditor ossicles are quite small, thin slice will be necessary to reduce the chance that volume averaging will obscure their appearance on the image
b.the appropriate slice thickness will vary considerably from patient to patient. therefore each technologist should be free to adjust the slice thickness as he or she seems necessary for the particular patient
c.a slice thickness of 5-7mm is adequate because the structures of interest are not particularly small, and the examination is most often ordered as a screening study for asymptomatic patients
d.the thickest slice available should be used to reduce the radiation dose to the corneas

Answer 13

a.because the auditor ossicles are quite small, thin slice will be necessary to reduce the chance that volume averaging will obscure their appearance on the image

Question 14

how many CT numbers are assigned to each pixel in the image matrix
a.one half the number of all values recorded form the detector array
b.one
c.the number of HU per pixel is one-tenth the display field of view
d.two values of 256 matrix;4 values for 512 matrix

Answer 14

b.one
the CT number is an average of all measurements for that pixel

Question 15

which is another name for raw data
a.image data
b.scan data
c.reconstructed data
d.displayed data

Answer 15

b.scan data

Question 16

when in the anatomic position the arms are
a.raised above the head.palms facing backwards
b.crossed over the chest, palms on opposite shoulders
c.down by the sides, palms facing forward
d.by the sides, with elbows bent, palms facing backward and resting on hips

Answer 16

c.down by the sides, palms facing forward

Question 17

the arrow depicts a
a.coronal plane
b.transverse plane
c.sagittal plane
d.axial plane

Answer 17

a.coronal

Question 18

which of the following components is not housed within the gantry
a.three phase generator
b.high frequency generator
c.slip rings
d.xenon gas detectors

Answer 18

a.three hase generator
they are stand alone units located near the gantry and require cable s

Question 19

the power capacity of the generator is listed in
a.milliamperes(mA)
b.thousand heart units(KHU)
c.million heat units(MHU)
d.kilowatts(kW)

Answer 19

d.kilowatts

Question 20

which of the following describes a slip ring device
a.a recoiling system cable used to rotate the gantry frame
b.a brushlike apparatus that provides continuous electrical power and electronic communication across a rotating surface
c.a device used to shape the x-ray beam, thereby reducing the radiation dose to the patient and reducing image artifact
d.a device that restricts the xray beam emerging from the gantry to thin ribbons

Answer 20

b. brushlike apparatus that provides continuous electrical power and electronic communication across a rotating surface

slip rings permit the gantry frame to rotate continuously making helical scan modes possible
a.describes the older system of cables
c.describes filtration
d.describes collimation

Question 21

which is a disadvantage of a small focal spot size
a.reduced spatial resolution
b.reduced detector efficiency
c.increased penumbra
d.reduced heat capacity

Answer 21

d.reduced heat capacity

Question 22

the ability of the tube to withstand by-product heat is called
a.heat capacity
b.heat dissipation
c.thermal potential
d.thermal transference

Answer 22

a.heat capacity
measured in millions heat units(MHU)

Question 23

in the image what is the objected marked by an X
a.collimator
b.bowtie filter
c.focal spot
d.detector

Answer 23

b.bowtie filter

Question 24

regarding the detectors in the CT system, geometric efficiency is controlled primarily by
a.detector material(solid state crystals or xenon gas chambers)
b.type of photodiode used
c.filtration
d.detector spacing and aperture

Answer 24

d.detector spacing and aperture
the space occupied by the detector plates relative to the surface area of the detector is an aspect of the geometric efficiency of an detector system

Question 25

which of the following is a characteristic of xenon gas detectors
a.low efficiency
b.sensitive to temperature and moisture
c.may exhibit afterglow
d.also called scintillators

Answer 25

a.low efficiency
xenon gas must be kept under pressure in a casing. the casing filters the xray beam to certain extent. loss of xray photons in the casing window and space taken up by the plates are major factors in detector efficiency

Question 26

the image illustrates a scanner with a
a.second generation design
b.thrid generation design
c.fourth generation design
d.fifth generation design

Answer 26

b.thrid generation

fourth generation uses detectors fixed in a 360 circle within the gantry
fifth generation uses a xray gun as its xray source

Question 27

which component of the CT system converts the electric signal supplied by the detectors into a digital format
a.photodiode
b.array processor
c.display processor
d.analog-to-digital converter

Answer 27

d.analog to digital converter

Question 28

a precise set of steps to be performed in a specific order to solve a problem describes
a.an algorithm
b.beam attenuation
c.the mean of a random variable
d.the binomial probability formula

Answer 28

a.an algorithm

Question 29

what is interpolation
a.a technique for expressing waveform as a weighted sum of sines and cosines
b.an efficient algorithm used to compute DFT and its inverse
c.the difference between the first quartile and the third quartile.this is one way to describe the spread of a set of data
d.a mathematical method of estimating an unknown value using the known values on either side of the unknown

Answer 29

d.a mathematical method of estimating an unknown value using the known values on either side of the unknown

Question 30

which is an example of a computer input device
a.microprocessor
b.primary memory
c.CT detector mechanisms
d.laser camera

Answer 30

c. CT detector mechanisms
input devices feed data into the computer: keyboard, mouse, touch sensitive screen, CT detector mechanisms
output devices accept processed data from the computer: monitor, laser camera, printer, servers, optical disks, magnetic tape, archiving equipment

Question 31

the central processing unit(CPU) performs what function
a.dissipates excessive heat that builds up on the target material
b.interprets computer program instructions and sequences tasks
c.samples the detectors
d.restricts the xray beam to thin ribbons

Answer 31

b. interprets computer program instructions and sequences tasks
CPU is like the brain of the Ct system

Question 32

all the thousands of bits of data acquired by the CT system with each scan are called
a.image data
b.calibration vectors
c.raw data
d.ray sums

Answer 32

c. raw data
raw data includes all the measurements obtained from the detector array

image data: once the data is averaged so that each pixel has one associated number an image can be formed, this data is called image data

Question 33

the DAS reads each arriving ray and measures how much of the beam has been attenuated this is
a.ray sum
b.a view
c.back projection
d.a sample

Answer 33

a.ray sum
the path that the x ray beam takes from the tube tot he detector is referred to as a ray. The DAS reads each arriving ray and measures how much of the beam is attenuated. The measurement is called a ray sum

Question 34

in CT image creation using a third-generation designs complete set of ray sum is know as a
a.convolution equation
b.algorithm
c.spatial frequency
d.view

Answer 34

d.a view
a complete set of ray sums is known as a view
copare to observing an object from a single angle, it take many views to understand the true shape of the object

Question 35

the process of converting the data from the attenuation profile to matrix is known as
a.reformation
b.archiving
c.back projection
d.referencing

Answer 35

c. back projection
archiving is saving studies on auxiliary devices for the purpose of future viewing

Question 36

the process of applying a filter function to an attenuation profile is known as
a.data processing
b.convolution
c.archiving
d.reformation

Answer 36

d.reformation
different mathematical functions can be used to enhance or suppress parts of the data. depending on the manufacturer the filter function may be called algorithm, convolution filter, or kernel

Question 37

increasing the scan field of view
a.increases the number of detector cells collecting data
b.increases the range of HU displayed on the image
c.decreases pixel size
d.decreases the display field of view

Answer 37

a.increases the number of detector cells collecting data
the SFOV determines the size of the fan beam which the determines the number of detector cells that collect data

Question 38

the image was taken of the abdomen using a 25cm display field of view. what is necessary to reconstruct the image
a.the scanner must have an image magnification function
b.the scan field must be larger than 25 cm and raw data must be available
c.image data must be available and the scanner must have reformation software
d.scan data must be acquired in a spiral mode

Answer 38

b.the scan field must be larger than 25 cm and raw data must be available
changing the DFOV reconstructs the original data differently, therefore the raw data must be available. the data selected by the DFOV is a subset of SFOV so the DFOV can be equal or smaller than the SFOV

Question 39

what is the function of the digital-to-analog converter
a.converts data into shades of gray to be displayed
b.converts the digital signal from the computer into an analog signal for the display monitor
c.converts the light emitted from crystal detectors into an electric current
d.converts the analog signal from the detectors to a digital signal for the computers

Answer 39

b.converts the digital signal from the computer into an analog signal for the display monitor

Question 40

the window setting for the following image are intended for evaluating
a.bone
b.mediastinum
c.lung
the contrast enhanced heart

Answer 40

c.lung

Question 41

why is it necessary to convert the digitized data from reconstruction processor to shades of gray
a.to allow an HU to be assigned to each structure
b.to remove streak artifacts from the final image
c.to enhance the desirable aspects of the image and suppress the undesirable aspects
d.so that an image can be displayed on the monitor

Answer 41

d.so that an image can be displayed on the monitor

there are over 2000 HU but monitors are unable to display all 2000 and the human eye can only differentiate a fraction of that

Question 42

what housfield values are in the naturally occurring range
a.-1000 to 1000
b.-600 to 0
c.0 to 1200
d.-2000 to 4000

Answer 42

a.-1000 to 1000
-1000 air and 1000 dense bone are natural.
there are housfield units that exist outside that range but are manmade like dental fillings

Question 43

decreasing the window width in a CT image decreases
a.slice thickness
b.mAs
c.the appearance of quantum mottle(image noise)
d.the anatomic diversity displayed

Answer 43

d.the anatomic diversity displayed

the window setting is a display function that is set after the image has been acquired it is impossible for it to affect any scanning parameters like slice thickness and mAs. the appearance of quantum mottle can be decreased by widening the window width

Question 44

the window width of a specific CT image is set at 300, and the level is set at 100. How is a structure with a measurement of 280 HU displayed
a.it is white
b.it is light shade of gray
c.it is a dark shade of gray
d.it is black

Answer 44

a.it is white

the total HU to represented is 300. b/c the center is set at 100, the HU depicted are -50 to 250. since the structure is measured as 280 it is above the limit it will appear as white

calculated by dividing 300 in half then subtracting the quotient from the center(100) to find the upper limit.
everything that. falls below these numbers appears as black, everything above appears as white

300/2=150
150-100=50=lower limit
150+100=250=upper limit

Question 45

if the main tissue of interest is liver, which of the following is the best approximate window level setting
a.-600
b.0
c.50
d.600

Answer 45

c.50
the window level should be set at a point that is roughly the same value as the average attenuation number of the tissue in interest

liver window width 150 liver window level is 30

Question 46

on a CT image an ROI is placed within a structure and measured, its deviation is 0, what can be determined about this structure

a.it is composed of water or something with the same density of water
b.it is composed of fat
c.it is very homogeneous
d.it is very heterogeneous

Answer 46

c.it is very homogeneous
the standard deviation indicates the ranges of HU for the pixels within the ROI. since the standard deviation was 0 it indicates that every pixel within the ROI has the same Hounsfield value

homogeneous-of the same kind
heterogeneous-diverse in content

Question 47

for which application are the raw data necessary
a.to magnify the image
b.to decrease the display field size
c.to create a histogram
d.to obtain a hounsfield measurement of a specific structure

Answer 47

b.to decrease the display field size changing the display field size requires raw

Question 48

a magnification factor of 1.5 is used to enlarge the image data, resulting in
a.a decrease in the pixel size
b.an increase in pixel size
c.an inaccuracy in any subsequent distance measurements
d.an image that is larger and may allow a more accurate cursor placement for measurements

Answer 48

d.an image that is larger and may allow a more accurate cursor placement for measurements

image magnification only uses image data and NOT raw data pixel size is not affected. a magnified image retains accuracy in all image measurements. Image magnification simply only makes the image larger

Question 49

compared with conventional radiographic images, CT localizer images
a.do not superimpose anatomic structures
b.are of slightly poorer image quality
c.result in much higher radiation dose to the patient
d.result in much lower radiation dose to the patient

Answer 49

b. are of slightly poorer image quality

radiation dose is typically equivalent
anatomic structures are superimposed

Question 50

referring to the image what view will result when a localizer image is taken with the xray tube in this position
a.Ap view
b.PA view
c.lateral view
d.decubitus view

Answer 50

a.Ap view
in a localizer image the xray tube remains stationary, in this image the xray tube is above the patient so the beam will pass anterior to posterior

Question 51

looking at the image what is the likely outcome; should the technologist proceed with the examination

a.the images will be noisy, from too law mA setting
b.the images will contain streaks, from metallic objects in the scannable range
c.the images will be mislabeled, with the right side labeled as left and anterior will be labeled posterior
d.the image swill contain ring artifacts, from misaligned detector element

Answer 51

c.the images will be mislabeled, with the right side labeled as left and anterior will be labeled posterior

the operator incorrectly inputted directional directions

Question 52

which are key aspects of the axial method of data acquisition

a.the table remains stationary while the xray tube rotates within the gantry, collecting data
b.multiple parallel rows of detectors are needed
c.the table moves continuously throughout the data acquisition
d.each slice is created from data acquired during a 180 degree rotation of the xray tube

Answer 52

a.the table remains stationary while the xray tube rotates within the gantry, collecting data

in axial sequence, th stable moves to the correct position and then stops while the gantry rotates, each slice is created from data in a 360degree rotation

Question 53

the interscan delay inherent in an axial scan method is caused by which factor
a.tube cooling
b.detector realignment
c.table movement between data acquisitions
d.serial image reconstruction algorithms that must reconstruct data from each slice before data for the next slice can be acquired

Answer 53

c.table movement between data acquisitions

since the table remains stationary during data acquisition there must be a slight pause between acquisition while the table moves to the next location

Question 54

the practice go grouping more than one axial scan in a single breath hold is often referred to as
a.reformatting
b.clustering
c.dynamic scanning
d.volumetric scanning

Answer 54

b.clustering

Question 55

compare with helical scanning what are the primary disadvantages to the axial method of scanning
a.low contrast resolution is inferior
b.spatial resolution is inferior
c.radiation dose is much higher, noise is more pronounced
d.total examination time is longer, data reconstruction is more limited

Answer 55

d.total examination time is longer, data reconstruction is more limited

the cumulative effect of the pauses between each data acquisition adds to the total scan time
axial data does not offer as many options for reconstruction
radiation dose is the same if not less than that of helical

Question 56

what is it called when a patient breaths differently with each data acquisition and areas of the anatomy seem to be misplaced in the z axis
a.misregistration
b.retrospective reconstruction
c.slice thickness blooming
d.slice sensitivity profile degradation

Answer 56

a.misregistration

Question 57

basic ingredients defining a helical scan include all of the following EXCEPT
a.a continually rotating xray tube
b.multiple parallel rows of detectors
c.constant xray output
d.uninterrupted table movement

Answer 57

b.multiple parallel rows of detectors
helical scans can include single row of detectors or multiple parallel rows of detectors

Question 58

all of the following are synonyms for helical scanning EXCEPT
a.volumetric scanning
b.spiral scanning
c.continous acquistinon scanning
d.dynamic scanning

Answer 58

d.dynamic scanning
dynamic scanning refers to repeating data acquisition in th esame location

Question 59

all of the following were improvements necessary to make helical scanning possible EXCEPT

a.fourth generation scanner design
b.gantries with slip ring designs
c.software that adjusts for table motion
d.improved raw data management

Answer 59

a.fourth generation scanner design

helical scanners can be made of either the third or fourth generation design. however due to the the fourth generation containing so many detectors it was not easily adapted

Question 60

the goal of helical interpolation methods is to
a.calculate the appropriate mAs for a given patient size
b.take the slant and the blur out of the helical images so that they closely resemble. image taken form axial methods
c.automaticallyassign the optimal window width and level to each reconstructed image
d.eliminate artifacts from voluntary and involuntary patient motion

Answer 60

b.take the slant and the blur out of the helical images so that they closely resemble. image taken form axial methods

helical CT methods create slices that are at a slight tilt
helical interpolation methods are designed to adjust too the tilt and produce images that resemble if they were taken from axial

Question 61

what is the pitch in the following scenario: 16 slice scanner, 0.5mm slice thickness, table movement of 12mm per rotation
a.1
b.1.25
c.1.5
d.2

Answer 61

c.1.5
12/(16x0.5)=12/8=1.5

Question 62

how much anatomy(lengthwise) will be covered in helical scan when following parameters are selected: 15 seconds total acquisition time, 0.5 seconds gantry rotation time, 2 mm slice thickness, 4 slices per rotation, pitch of 1.5
a.40mm
b.90mm
c.160mm
d.360mm

Answer 62

d.360
pitch x total acquisition time x1/rotation time x(slice thickness x slices per rotation)

if you type it all into the calculator at once without following BEDMAS you get the correct answer

Question 63

which of the following is NOT a reconstruction possibility when a MDCT system produces four 1mm slices with each gantry rotation
a.slices can be combined to create 2 mm slices
b.slices can be combined to create on 4mm slice
c.slices can be divided to produce 16 0.35mm slices
d.slices can be reconstructed to create images that overlap by 0.5mm

Answer 63

c.slices can be divided to produce 16 0.35mm slices
the thinnest images that can be reconstructed for a data set are predetermined b the slice thickness used. images can be added together to create thicker slices
it is not possible to create an image that is thinner than the size of the individual detector cell

Question 64

all of the following are scan parameters EXCEPT
a.mAS
b.slice thickness
c.matrix
d.pitch

Answer 64

c.matrix
scan parameters are those that can be adjusted by the operator
other scan parameters include:DFOV,reconstruction algorithms,kVp

Question 65

which of the following combinations of mA and scan time will result in 350 mAs and be the best choice for cardiac scan
a.mA=300, scan time=0.50 seconds
b.mA=200, scan time=2 seconds
c.mA=350, scan time=1 second
d.mA=700, scan time=0.5 seconds

Answer 65

d.mA=700, scan time=0.5 seconds
a=150mAs. b=400mAs, c and d are equal at 350 mAs
however with cardiac scanning you want a short scan time to reduce the effect of cardiac motion therefore d is more preferable

Question 66

which can be attributed to uncoupling effect
a.even when mAs or kVp settings are either too high or too low, a good image results
b.when mAS or kVp settings are either too high or too low quantum mottle results
c.mA and scan time have no relationship to the quantity of xray produced
d.normal xray physics are reversed;mAs controls the quality of the xray beam and kVp controls the quantity of the xray beam

Answer 66

a.even when mAs or kVp settings are either too high or too low, a good image results

with digital technology the image quality is largely uncoupled from the dose, therefore when mAs or kVp setting used was too high a good image still results. which can make it difficult to identify when a dose too high was used

Question 67

what is a disadvantage of bone algorithm
a.it reduces spatial resolution
b.it smooths data, reducing the difference between adjacent pixels
c.it accentuates the difference between neighbouring pixels
d.it reduces the visibility soft tissue structures

Answer 67

d.it reduces the visibility of soft tissue structures

bone filters accentuate the difference between neighbouring pixels to optimize spatial resolution.
this filter is best when the interest is fine bone detail, the trade off is reduced visibility of the soft tissue structures

Question 68

what is a partial scan
a.a scan that collects two matching samples taken at 180 degrees apart
b.a scan that collects data from 360 degree tube arc
c.a scan that collects data from 360 degree tube arc plus the width of the field of view
d.a scan that collects data from 180 degree tube arc plus the degree of arc of the fan angle

Answer 68

d.a scan that collects data from 180 degree tube arc plus the degree of arc of the fan angle

Question 69

what is the true test of the quality of a specific image
a.whether it serves the purpose for which it was acquired
b.whether it has a limiting resolution 7 ip/mm or greater
c.whether it has a MTF of greater than 1
d.whether pixel size is 0.5mm or smaller

Answer 69

a.whether it serves the purpose for which it was acquired

the true test of an image is whether it is useful in providing an accurate diagnosis

Question 70

what two main features are assessed to measure image quality
a.mAs and kVp
b.spatial resolution and contrast resolution
c.temporal resolution and the degree of motion artifact
d.Focal spot size and DFOV

Answer 70

b. spatial resolution and contrast resolution

Question 71

which of the following is an imaging challenge that depends on contrast resolution
a.a calcified nodule in the lung
b.tiny, contrast filled arteries that are just 1mm apart
c.bony erosion in the ossicles of the internal auditory canal
d.distinguishing between the white matter and gray matter of the brain

Answer 71

d.distinguishing between the white matter and gray matter of the brain

contrast resolution is the ability to differentiate structures that vary only slightly in density from its surroundings

Question 72

what is spatial frequency
a.the number of line pairs visible per unit length
b.the ratio of the accuracy of the image compared with the actual object scanned
c.the ratio of pixel size to slice thickness
d.the number of xray photons detected per pixel 66yy

Answer 72

a. the number of line pairs visible per unit length

how frequently an object will fit into a given space. therefore large objects have low spatial frequency and small objects will have high spatial frequency

Question 73

a graphical representation of the CT systems capability of passing information through it to the observer is called
a.interpolation
b.modulation transfer function
c.receiver operator characteristics
d.contrast detail response

Answer 73

b.modulation function transfer
MTF is a measure of the capabilitynof the scanner to produce an image that accurately reflects the object scanned

Question 74

using standard 512 matrix for all studies which contains the smallest pixels
a.a scan of the internal auditory canals, in which DFOV is 16 cm
b.a scan of the brain in which DFOV is 25cm
c.a scan of the chest in which DFOV is 35
d.a scan of the abdomen in which DFOV is 42

Answer 74

a.a scan of the internal auditory canals in which the DFOV is 16cm
pixel size can be calculated by dividing the DFOV by matrix size therefore
a=0.31mm
b=0.49mm
c.0.68mm
d.=0.82mm

Question 75

which term describes an isotropic voxel
a. a rectangular solid
b.a square
c.a cube
d.a slab

Answer 75

c. a cube
an isotropic voxel is a cube, measuring the same x,y and z direction

Question 76

the ability to differentiate a structure that varies only slightly in density from its surroundings is referred to as
a.spatial resolution
b.high contrast resolution
c.detail resolution
d.low contrast resolution

Answer 76

d.low contrast resolution
a.b and c refer to the level of detail that is visible on the image

Question 77

an image of a water phantom displays a range of pixel values. what can be said about this image
a.it was reconstructed with a “soft” algorithm
b.it is ‘noisy”
c.the mAs setting used to produce the image was too high
d.a thick slice was used

Answer 77

b.it is “noisy”
image noise is the undesirable fluctuation of pixel values in a na image of a homogeneous material. noise is often caused by a mAs setting that is too low. using a wider slice thickness can help reduce image noise

Question 78

when discussing the quality of a CT image, what is meant by temporal resolution
a. the internal auditory canal is often used to evaluate a systems overall quality. because the internal ausitory canals are located in the temporal bone, this is called temporal resolution
b.the ability of a system to display an object that’s a density that is very similar to its background
c.how rapidly data are acquired; it is controlled by. gantry rotation speed,the number of detector channels in the system, and the speed with which the system can record changing signals
d.the ability to resolve, as separate objects small, high contrast objects

Answer 78

c.how rapidly data are acquired; it is controlled by. gantry rotation speed,the number of detector channels in the system, and the speed with which the system can record changing signals

in discussion of image quality temporal means limited by time. therefore temporal resolution refers to the speed that a scanner acquired data

Question 79

all of the following are key aspects of a quality assurance program EXCEPT
a.the test that make up the program must be performed on a regular basis
b.all tests must be completed by medical physicist
c.the results from all tests must be recorded using consistent format
d.documentation should indicate whether the tested parameter is within specified guidelines

Answer 79

b. all tests must be completed by a medical physicist
the only one done by a medical physicist is dose measurements the rest are shared responsibility among the technologist

Question 80

what does the image represent
a.line pair phantom
b.phantom used to assess slice thickness
c.water phantom
d.phantom used to assess the accuracy of the laser light

Answer 80

a. line pair phantom
used to measure spatial resolution

Question 81

how often is the accuracy of a scanner slice thickness tested
a.daily
b.weekly
c.monthly
d.semiannually

Answer 81

d.semiannually

Question 82

a water phantom is scanned and several ROIs are placed in the resulting image.The ROIs placed at the premier of the image measure differently from the ROIs near the center. this indicates a problem with
a.lineraity
b.cross field uniformity
c.noise
d.low contrast resolution

Answer 82

b.cross field uniformity

Question 83

a water phantom is scanned and ROIs are placed in the resulting image. the standard deviation measurements from the resulting ROIS range from 15 to 25. what can be said about the image?
a.it is noisy
b.the spatial resolution is 15 to 25 lp/cm
c.the low contrast resolution is within normal limits
d.the radiation dose is unnecessarily high

Answer 83

a. it is noisy
a water phantom is expected to be uniform in density
standard deviation measurements indicate fluctuation in the individual pixel measurement within the ROI
an image is noisy if the standard deviation exceeds 10

Question 84

what can be done to improve the linearity of a CT system
a.daily calibrations
b.increasing mAs
c.decreasing kVp
d.widening the window width when viewing the images

Answer 84

a.daily calibrations
with time a systems linearity can be degraded by small changes in detector channel variation and responses. daily calibration helps to avoid fluctuations in linearity

Question 85

what quality control test must be performed by a medical physicist
a.cross field uniformity
b.spatial resolution
c.radiation dose measurements
d.laser light accuracy

Answer 85

c.radiation dose measurements

Question 86

which is true statement regarding beam hardening
a.the beam is hardened more by bone and less by fat
b.the beam is hardened more by air and less by bone
c.nothing can be done to minimize beam hardening artifacts
d.lowering the kVp is the best method of reducing beam hardening artifacts

Answer 86

a.the beam is hardened more by bone and les by fat
increasing kVp will help reduce beam hardening to some extent
the best strategy to reduce beam hardening is to select the appropriate SFOV

Question 87

artifacts that result from under sampling are called
a.out of field artifacts
b.metallic artifacts
c.cone beam artifacts
d.aliasing artifacts

Answer 87

d.aliasing artifacts

Question 88

identify the type of artifact indicated by the arrows in the image
a.aliasing
b.edge gradient
c.motion
d.tube arc

Answer 88

b.edge gradient
streaks or shading arise form objects that have a pronounced difference in density from surrounding structures

Question 89

raw data that result from an MDCT scan acquisition are used so that the 1mm slices are combined to produce thicker slices for viewing. this is called
a.3d reformation
b.image reconstruction
c.segmentation
d.multiplanar reformation

Answer 89

b.image reformation
any process that reuses the raw data is called reconstruction. reformation whether its mutiplanar or 3d only uses image data

Question 90

in what situation would overlapping reconstructions for subsequent image rendering not be indicated
a.slice thickness=0.5mm, DFOV=25
b.slice thickness=2mm, DFOV=35
c.slice thickness=5mm, DFOV=42
d.slice thickness=7mm, DFOV=45

Answer 90

a.slice thickness=0.5mm, DFOV=25
when the voxels from the source data are isotropic or near isotropic overlapping reconstruction provides little benefit
to determine if a voxel is isotropic calculate the pixel size (DFOV in mm/512)
first DFOVx10 to get DFOV in mm
a.250/512=0.48
b.350/512=0.68
c.420/512=0.82
d.450/512=0.87
therefore a is closest to a voxel shape(cube)

Question 91

assume the raw data are still available. in what scenario would it be impossible to create an MPR
a.source images vary in slice thickness
b.source images vary in gantry tilt
c.source images vary in mage center
d.source images vary in DFOV

Answer 91

b.source images vary in gantry tilt
to create a reformation, source images must possess the same DFOV, image center and gantry tilt and they must be contagious. if th e raw data are available, new source images can be created that possess the same center and DFOV. Reformations can be made from images with variable slice thicknesses, however nothing can be done that will change the gantry tilt

Question 92

what plane is the MPR depicted in
a.sagittal
b.coronal
c.oblique
d.curved

Answer 92

b.coronal

Question 93

which of the following is a true statement regarding MPR
a.they are created from raw data
b.they are 3D in nature
c.all MPR images have the same image quality as the source image
d.they can be created either at the operators console or at a separate workstation

Answer 93

d.they can be created either at the operators console or at a separate workstation
all MPRs only use image data and is 2D in nature . the image quality of the MPR matches that of the source image only when source data contains isotropic voxels

Question 94

a limitation of scanner created MPRs is that
a.only one examination protocol per scanner can be programmed to automatically create MPRs
b.they take more time to create than manually produced MPRs
c.in most cases, only straight and coronal planes can be automatically generated
d.they are not consistently produced so technologist must remember to check to see whether they were created

Answer 94

c.in most cases only straight and coronal planes can be automatically generated
on most scanners if oblique or curved reformations are needed the technologist will have to manually create them

Question 95

another name for surface rendering is
a.volume rendering
b.segmentation
c.projection display
d.shaded surface display

Answer 95

d.shaded surface display

Question 96

which is a disadvantage to workstation created MPRs
a.they require that the raw data be sent to the workstation
b.to produce the highest quality MPRs the thinnest slices must be sent to the workstation. this amount of data can slow down the PACS
c.most radiologists have not been trained to create MPRs
d.workstations are only able toe create MPRs in a sagittal and coronal planes

Answer 96

b.to produce the highest quality MPRs the thinnest slices must be sent to the workstation. this amount of data can slow down the PACS

Question 97

in creating a surface rendered image, what can happen if the threshold set is too narrow
a.actual protruding structures can be imperceptible
b.nontissue materials such as fluid can be displayed as if they were tissue and can obscure protruding structures
c.too much data are included so that less powerful computers may not be able to generate a display
d.the SR image generated cannot be rotated

Answer 97

a.actual protruding structures can be imperceptible
setting the threshold,d too high will include unwanted structures that may obscure the are of interest. setting the threshold too low may cause important structures to be omitted

Question 98

an MIP is a good method to display all of the following EXCEPT
a.pulmonary nodules
b.fracture extent
c.contrast filled coronary arteries
d.bronchial tree

Answer 98

d.bronchial tree
MIPs are best used for higher attenuation structures like bone,calcifications and contrast filled structures

Question 99

what type of 3D display is depicted in the image
a.volume rendering
b.surface rendering
c.MIP
d.MinIP

Answer 99

d.MinIP
selects vowels with the minimum values for display. These are useful for displaying low attenuation structures such as bronchial tree

Question 100

in which has become the favoured 3D imaging technique in CT
a.volume rendering
b.surface rendering
c.MIP
d.MinIP

Answer 100

a.volume rendering
an advantage of volume rendering is that all voxels contribute to the image. this allows VR images to display multiple tissues and show their relationship to one another

Question 101

VR techniques assign each voxel an opacity value based on its___. this value determines the degree the voxel will contribute to the final image
a.location
b.Hounsfield unit
c.depth
d.width

Answer 101

b.Hounsfield units

Question 102

the process of selectively removing or isolating information from the 3D set is referred to as
a.clipping
b.cutting
c.segmentation
d.dissociation

Answer 102

c.segmentation
segmentation is done to remove obscuring structures from the 3D image

Question 103

in the image what is the most likely cause of the artifact indicated by the arrows on this reformatted image
a.motion
b.noise
c.metalic object
d.windmill artifacts

Answer 103

c.metallic object
dental fillings

Question 104

which electronic system allows clinicians to input an electronic order for. CT examination and transmits that order to the CT department
a.RIS
b.PACS
c.HIS
d.CPOE

Answer 104

d.CPOE
computerized physician order entry

Question 105

what two electronic elements form the radiology information infrastructure
a.RIS and PACS
b.HIS and CIS
c.CPOE and EMR
d.LAN and SSL

Answer 105

a.RIS and PACS
RIS is typically used for scheduling patients, storing reports, patient tracking, protocoling examinations and billing. PACS manages the storage, retrieval, distribution and display of images

HIS Hospital Information System focuses on administrative issues, like financial data, patient location within the hospital
CIS clinical information system-keeps track of data
CPOE-electronically transmit orders to radiology and other departments
LAN-local area network

Question 106

which of the following is NOT a true statement regarding PACS
a.vast amounts of data pass through any PACS
b.PACS technology has a huge impact on the workflow of radiologists and technologist
c.to be included in a PACS system, images must be in a digital form
d.once the hardware for the PACS is installed, the system runs virtually maintenance free

Answer 106

d.once the hardware for the PACS is installed, the system runs virtually maintenance free

Question 107

computers that act from other networked computers rather than from a person inputting directly into it are called
a.LANS
b.star topologies
c.servers
d.P2P

Answer 107

c.servers
a server is a computer that facilitates communication between, and delivers information to other computers

Question 108

the computers the are integral to the functioning of the PACS are referred to as
a.archival devices
b.core servers
c.routers
d.bridges

Answer 108

b.core servers

Question 109

the amount of data that can be transmitted between tow points in the network in a set period of time is known as
a.bandwidth
b.pixel volume
c.memory capacity
d.frequency

Answer 109

a.bandwidth
represents the capacity of the network connection

Question 110

a scheme that compresses an image without any loss of information when the image is decompressed is called
a.lossy
b.fractional coding
c.scalar and vector quantization
d.lossless

Answer 110

d.lossless
lossy compression methods( such as fractional coding and scalar and vector quantization) are known to introduce some level of artifacts

Question 111

DICOM refers to a
a.specific geometric arrangement of computers in a network
b.universally adopted standard for medical image interchange
c.type of magnetic tape use to store data
d.peer to peer computer network such as Usenet news server

Answer 111

b.universally adopted standard for medical image interchange
DICOM has standard made it possible to send images over a network form one electronic system to another

Question 112

which is NOT true of LCD monitor
a.the purchase price of an LCD is approximately half that of a CRT monitor
b.LCD monitors have a longer life span compared with CRT monitors
c.assuring the continued quality of the LCD is much simpler than that of the CRT monitor
d.LCD monitors maintain their luminosity better than do CRT monitors

Answer 112

a.the purchase price of an LCD is approximately half that of a CRT monitor
the price of a LCD monitor can be 2-3 times higher than a CRT monitor

Question 113

a device that us used to automatically load and unload optimal discs is called
a.ethernet
b.tape drive
c.media vending machine
d.optical jukebox

Answer 113

d.optical jukebox
also called optical disc libraries, robotic drives or auto changers

Question 114

MR jones is scheduled for a CT of the chest. as you review his history, he confines that he is extremely concerned that the study will find cancer, particularly as he has smoked cigarettes for more than 20 years. your response is which of the following
a.’don’t worry, everything will be fine; this test is just a precaution”
b.’I understand your concern. the U.S Surgeon General says that cigarette smoking is the major single cause of cancer mortality in the US”
c.i understand your concer, and know that waiting to get an answer can be excruciating. we will ge the results to your physician just as soon as we can”
d.you may be able to sue the cigarette companies if you do have cancer. you should probably contact a lawyer”

Answer 114

c.i understand your concer, and know that waiting to get an answer can be excruciating. we will ge the results to your physician just as soon as we can”
it is unwise to offer falsehood or to advise the patient on legal matters

Question 115

you are taking a patients medical history. you are unsure what he means when he says “oh yeah, I’ve had lots of times when my kidneys just shut down and they had to give them a kick start” using reflective speech you
a.record on the history sheet exactly what the patient said
b.say “so you’ve experienced kidney failure in the past that required dialysis”
c.ask him to repeat what he just said so that a coworker can listen also
d.say “oh, that happens to me sometimes, to. have you tried drinking a lot of water?”

Answer 115

b.say “so you’ve experienced kidney failure in the past that required dialysis”

reflective speech is a technique that can help clarify a patients message

Question 116

regarding an order for a CT examination, all of the following statements are true EXCEPT:
a.CT examinations can only be ordered by a physician
b.before beginning any examination, the technologist must verify that the correct examination is planned by checking the clinicians order
c.in many facilities clinician orders for CT examinations are transcribed by clerks; this process introduces the potential for transcription errors
d.ideally, some patient screening should occur at the time the examination is scheduled

Answer 116

a.CT examinations can only be ordered by a physician

nurse practitioners(NP), physician assistants can also order CT

Question 117

which of the following is NOT an acceptable method of verifying a patients identity
a.call the patient by their full name and then ask the patient to recite his or her birth date and year, so that it can be checked against the CT order
b.use the patients armband to check the patients name and medical record number
c.ask family members who accompany the patient to verify the patients name and address and check that against the CT order
d.use the sign on the door of the patients room or ask the patient what hospital room they are assigned to

Answer 117

d.use the sign on the door of the patients room or ask the patient what hospital room they are assigned to

at least two methods of verifying a patients identity is necessary.a sign on the door is not a reliable source

Question 118

why is a patient questioned regarding whether he or she has a history of an overactive thyroid
a.to select the correct protocol
b.to determine whether an iodinated contrast agent can be administered intravenously
c.to help the radiologist diagnose goiter
d.to determine whether a female patient could be unknowingly pregnant

Answer 118

b.to determine whether an iodinated contrast agent can be administered intravenously

patient with a history of hyperthyroidism iodinated contrast media administered intravenously can intensify thyroid toxicosis

Question 119

blood urea nitrogen(BUN),s serum creatinine, and eGFR provide information about a patients
a.thryoid function
b.kidney function
c.risk of allergy to iodinated contrast media
d.cardiac function

Answer 119

b.kidney function

Question 120

for which of the following examinations is it common to check laboratory results for prothrombin time(PT), partial thromboplastin time(PTT) and platelet count
a.coronary CT angiography
b.postmyelography CT studies
c.CT guided biopsies
d.CT abdomen and pelvis

Answer 120

c. CT-guided biopsy

procedures like biopsies carry the risk of excessive bleeding. PT, PTT, platelet count are tests that can indicate problems with blood ability clot

Question 121

which of the following is a TRUE statement regarding signed consent forms
a.in most states, a signed consent form is required before any CT examination
b.once thet patient signs the consent form he or she can no longer file a malpractice claim
c.if written consent is required, it must be signed by the patient before the administration of any medication for pain relief or sedation
d.a signed consent form is not necessary for any CT examination

Answer 121

c.if written consent is required, it must be signed by the patient before the administration of any medication for pain relief or sedation

a signed consent is not necessary for routine CT exams
the patient must sign the consent form before nay medication that can alter their metal status is given

Question 122

all the following are true statements regarding patient restraints EXCEPT
a.the immobilizer must be easy to remove quickly if necessary
b.patients are restrained primarily as a convenience for the technologist
c.if leg immobilizers are necessary, wrist immobilizers must be applied also
d.a doctors order is necessary when a patient is to be restrained against his or her will

Answer 122

b.patients are restrained primarily as a convenience for the technologist

restraints are used to protect a patient from falling or to immobilize a part to improve image quality. when possible the patient should give consent to use the restraints

Question 123

why is it important for the technologist to note the patients breathing, skin coloration, and overall health before the exam begins
a. the technologist can accurately chart each of these factors on the patients chart
b.it will help determine whether the patient is healthy enough to proceed with the study
c.if a patient has even a small problem in any of these areas he or she will not be given IV contrast material
d.it will help the technologist notice signs should adverse effects occur during the scan process

Answer 123

d.it will help the technologist notice signs should adverse effects occur during the scan process

Question 124

which of the following is nOT considered on of the vital signs
a.weight
b.pulse
c.respirations
d.blood pressure

Answer 124

a.weight

vital signs are temperature, pulse, respirations, blood pressure

Question 125

where is a pedal pulse felt
a.behind knee
b.along dorsal aspect of the great toe or arch of the foot
c.anterior ankle
d.posterior ankle or top of the foot

Answer 125

d.posterior ankle or top of the foot

Question 126

what is the normal range for the respiratory rate of an adult
a.14-20
b.21-36
c.26-30
d.30-34

Answer 126

a.14-20

Question 127

the normal range of blood pressure in children is
a.lower than in adults
b.about the same as that in adults
c.about the same as that in the elderly
d.is twice that of either adults of the elderly

Answer 127

a.lower than in adults

Question 128

to distinguish adjacent tissues on a CT, the tissues must
a.have different densities
b.have different functions
c.have sharply defined edges
d.be abnormal

Answer 128

a. have different densities

Question 129

a contrast material that is of substantially higher density than that of the surrounding structures can be referred to as a ____ agent
allow attenuation
b.positive
c.negative
d.gastrointestinal

Answer 129

b.positive

all contrast agents that contain iodine and most agents that contain barium are considered positive agents this is because their density is higher than the structure that it fills

Question 130

the structural property of a contrast agent regarding the number of particles in a solution compared with blood is known as
a.ionicity
b.osmolality
c.valence
d.viscosity

Answer 130

b.osmolality

Question 131

the intravenous infusion of HOCM may result in
a.a sharp drop in blood sugar
b.severe fetal abnormalities if given to pregnant women
c.dehydration
d.a sensitivity to seafood

Answer 131

c. dehydration

due to the significant difference in osmolality between the agent and body fluids causes a shift of fluids from the cellular spaces into the plasma

Question 132

which factors affect the viscosity of an intravenous iodinated contrast agent
1.iodine concentration
2.lipid solubility
3.total volume delivered
4.temperature of the agent
a.1 and 2
b.2 and 3
c.1 and 4
d.1,3 and 4

Answer 132

c.1 and 4
viscosity can be described as the thickness or friction of the fluid as it flows
a higher concentration of iodine results in a more viscous solution
heating the agent from room temp to body temp decreases the viscosity

molecular structure also affects viscosity so different brands will vary in viscosity

Question 133

an imaging centers protocol for routine body CT on an adult patient calls for administration of 100mL of a low osmolality contrast medium with concentration of 320mgI/mL. a particular patient has very poor veins, necessitating venipuncture with a smaller than recommended caliber indwelling catheter. concerns about the precarious venous access have resulted in the decision to use lower concentration contrast agent. what volume of a low-osmolality contrast medium with a concentration of 240mgI/mL will deliver an equivalent amount of iodine to that of the dose called for in the protocol
a.84mL
b.100mL
c.125mL
d.153mL

Answer 133

d.153mL
to compare dose of iodine from different concentrations of contrast media it is useful to calculate the total grams of iodine delivered.

multiply dose times concentration
the protocol calls for 32g of iodine(10mLx320mgI/mL =32g)
a.85mlx240mgI/mL=20g
b.100mlx240mgI/mL=24g
c.125mlx240mgI/mL=30g
d.133mlx240mgI/mL=32g

Question 134

why is there such wide variation in the literature among quoted incidences of adverse reactions to contrast media
a.there is no standard definition of adverse reactions or standard system to classify their sensitivity
b.adverse reactions are not reported of fears about possible litigation
c.adverse reactions are so rare that statistics are difficult to collect
d.the pharmaceutical companies that produce contrast agents do not allow statistics regarding the incidence of adverse reactions to be published

Answer 134

a.there is no standard definition of adverse reactions or standard system to classify their sensitivity

Question 135

which is an example of a chemo toxic reaction to intravascular contrast media
a.hives
b.contrast induced nephropathy
c.coughing
d.nasal stuffiness

Answer 135

b.contrast induced nephropathy

allergic like reactions like hives and nasal stuffiness are idiosyncratic
hemodynamic disturbances and injuries to organs like the kidneys or vessels perfused by the contrast medium are considered chemo toxic reactions

Question 136

contrast reactions that are accompanied by a temporary drop pin blood pressure, bronchospasm, facial edema,urticaria, laryngeal edema are generally classified as.
a.side effects
b.minor reactions.
c.moderate reactions
d.severe reactions

Answer 136

c.moderate reactions
moderate reactions are not immediately life threatening

Question 137

comparing the reported rate of adverse reaction
a.LOCM are somewhat lower than HOCM, by a factor of approximately 2 times
b.LOCM are much lower than HOCM, by a factor of approximately 4 to 5 times
c.LOCM and HOCM have similar reaction rates but LOCM reactions are less severe
d.some data suggest a lower mortality rate with HOCM

Answer 137

b.LOCM are much lower than HOCM, by a factor of approximately 4 to 5 times

Question 138

when a patient who previously reacted to HOCM is given LOCM for a subsequent study, risk of a repeat reaction is approximately
a.5%
b.40%
c.80%
d.95%

Answer 138

a.5%

16%-35% when HOCM is given but only 5% when LOCM is given

Question 139

what is the single best method of reducing the risk of iodsyncretic contrast medium reaction
a.premedicate the patient with steroids
b.use LOCM
c.reduce the dose
d.perform test injections

Answer 139

b.use LOCM
idiosyncratic reactions are not dose dependent
reactions have resulted from very small volumes of iodinated contrast media therefore test injections are of no predictive value
premedicating high risk patients is believed to reduce the rate of reaction however the degree at which the reaction is reduced is unknown

Question 140

the basic functioning h unit of the kidney is the
a.cortex
b.nephron
c.medulla
d.collecting tubule

Answer 140

b.nephron
the nephron produces urine by filtering out from the blood seal molecules and Ions

Question 141

which statement is true concerning the use of serum creatinine(SeCr) to assess renal function
a.SeCr is a highly accurate measure of renal function
b.SeCr uniformly overestimates the glomerular filtration rate; therefore the values can be easily adjusted for an accurate measure of renal function
c.measuring SeCr is fast an inexpensive way to estimate renal function
d.SeCr values are not affected by patient demographics

Answer 141

c.measuring SeCr is fast an inexpensive way to estimate renal function

Question 142

which id true statement regarding the risks posed by intravascular contrast media in combination with drug metformin
a.iodinated contrast media can cause lactic acidosis, which is only dangerous if the patient is also taking metformin
b.metformin causes renal impairment, exacerbating the risk of CIN
c.iodinated contrast media in combination with metformin will result in acute and in some instances chronic renal failure requiring dialysis
d.when renal dysfunction occurs in patients taking metformin, the drug can accumulate and result in lactic acidosis

Answer 142

d.when renal dysfunction occurs in patients taking metformin, the drug can accumulate and result in lactic acidosis

metformin associated lactic acidosis is rare but when it does occur it is fatal in 50% of patients. it can occur after CIN because the reduced renal function can allow for metformin to accumulate in the body

Question 143

which of the following are considered at high risk for developing CIN
a.patients older than 65 years of age
b.male patients with a history of atherosclerotic disease
c.patients with diabetes mellitus and preexisting renal insufficiency
d.patients with a history of renal calculi

Answer 143

c.patients with diabetes mellitus and preexisting renal insufficiency

Question 144

after injection of an iodinated contrast medium, patients with brain metastasis have an increased risk of
a.seizures
b.dehydration
c.anaphylactoid reaction
d.renal failure

Answer 144

a.seizures
patients that have conditions that disrupt the blood brain barrier are at increased risk of seizures after contrast medium injection

Question 145

what’s the most common type of delayed reaction to intravascular contrast medium
a.fever
b.headache
c.skin reactions
d.salivary gland swelling

Answer 145

c. skin reactions
late reactions can include headaches, skin rash, itching,nausea,dizziness,urticaria, fever, arm pain, gastrointestinal disturbances

with skin rash being the most common

Question 146

barium leaking into the peritoneal cavity is referred to as
a.barium peritonitis
b.barium impaction
c.aspiration pneumonitis
d.barium obstruction

Answer 146

a.barium peritonitis
when perforation is suspected a water soluble iodinated oral contrast should be given

Question 147

given orally compare LOCM with HOCM
a,LOCM offer no advantage and are much more expensive
b.LOCM offer a clear advantage in al patients
c.LOCM have not been approved for oral administration
d.in some instances, particularly with infants, LOCM may provide significant advantages over the HOCM

Answer 147

d.in some instances, particularly with infants, LOCM may provide significant advantages over the HOCM

LOCM are indicated when the possibility of entry of contrast agent into the lung exist or possibility of leakage from gastrointestinal tract exists

Question 148

which is nor a true statement regarding the placement of a peripheral IV line for the administration of an iodinated contrast agent for a scan of the abdomen
a.standard precautions must be adhered to
b.sterile technique must be adhered to
c.an indwelling catheter, Butterly infusion set, or straight needle can be used, depending on the preference of the technologist
d.basic consent must be obtained form the patient

Answer 148

c.an indwelling catheter, Butterly infusion set, or straight needle can be used, depending on the preference of the technologist

because of the increased risk of extravasation the use of metal needles should be avoided, particularly when mechanical injector will be used

Question 149

what type of catheter do most manufactured recommend by flushed with heparinzed saline solution after their use
a.open ended CVAD catheters
b.closed ended CVAD
c.standar peripheral indwelling catheters
d.PICCS that contain Luer activated device

Answer 149

a.open ended CVAD catheters

open ended catheters must be clamped when not in use. most manufactures recommend that between uses they be flushed with heparinized saline to maintain the catheters patency

Question 150

which is a true statement regarding implantable ports
a.implanted ports are typically used for short term injections that require high flow rates, such as blood transfusions or contrast media administration
b.among CVADs ports have the lowest incidence of infection because they are completely buried under the skin and there is no site for microorganisms to enter
c.the port can be easily accessed using standard straight needles; no special training required
d.the port is placed so that only the face of the device shows through an opening in the skin

Answer 150

b.among CVADs ports have the lowest incidence of infection because they are completely buried under the skin and there is no site for microorganisms to enter

implanted ports are typically used for long term intermittent access such as that required for chemotherapy. the port is accessed by a special needle called a huber needle which requires special training

Question 151

the difference between the bolus phase and the non equilibrium phase and the equilibrium phase of contrast enhancement is primarily determined by
a.brand of iodinated contrast agent used
b.injection rate and scan delay
c.type of pathology present
d.film processing time

Answer 151

b.injection rate and scan delay

the difference between the phases is determined by the rate at which the contrast is delivered and the time elapsed form the start of the injection and when the scan was initiated

Question 152

the arteriovenous iodine difference is calculated by
a.taking an HU measurement of the liver before and after the contrast injection
b.comparing an HU measurement of the pancreas to that of the liver
c.comparing HU measurement of the aorta to that of the inferior vena cava
d.dividing the concentration of iodine by the volume used

Answer 152

c.comparing HU measurement of the aorta to that of the inferior vena cava

the AVID indicates the point in the circulatory process the injected contrast media is at a given time. this is done by comparing the degree of contrast enhancement in the arteries specifically aorta to that contained in the venous structures specifically IVF

Question 153

another name for the bolus phase of contrast enhancement is the
a.arterial phase
b.venous phase
c.portal venous phase
d.delayed phase

Answer 153

a.arterial phase
immediately follows the injection. arterial structures are filled with contrast
contrast has not yet reached the venous structures

Question 154

iodinated contrast is administered at a rate of 3 mL/s for a routine abdominal scan in which the protocol calls for a delay of 60 seconds between the start of the injection and the start of scanning. soon after the start of the contrast injection the patient begins to experience intense warm feeling and being surprised by this calls for the technologist. how long beyond 60 seconds can the technologist delay the scan acquisition without risk of degrading the diagnostic utility of the study
a.5 to 10 seconds
b.30 to 40 seconds
c.5 to 8 minutes
d.12 to 15 minutes

Answer 154

b.30 to 40 seconds
scanning the liver must take place before equilibrium phase which can begin 2 minutes after the contrast bolus
since there is a delay of 60 seconds the scan can be delayed 40 seconds and still acquire al of the scans before 2 minutes

Question 155

the general rules of contrast media injection regarding injection rate and scan delay do not apply to
a.routine brain scanning
b.coronary angiography
c.routine abdominal scanning
d.thoracic scanning

Answer 155

a.routine brain scanning
te scan delay has to be long enough to allow contrast to leak across a disrupted blood brain barrier which is usually minutes instead of seconds

Question 156

when Can drip infusion technique for contrast media administration be used
a.for a study of the chest when clinical indication is suspicion of pulmonary emboli
b.for an angiographic study of the brain performed to demonstrate a suspected middle cerebral artery occlusion
c.for a study of the brain when clinical indication is a suspicion of tumour
d.a drip infusion technique can never be used for contrast enhanced Ct studies

Answer 156

c. for a study of the brain when clinical indication is suspicion of tumour

the drip infusion method doe snot allow scans of the body to be acquired before equilibrium. it cannot produce peak enhancement of sufficient magnitude for CT angiography
since routine brain studies flow rates and scan delays are not critical it can be used

Question 157

all of the following are disadvantages of the hand bolus technique of contrast administration EXEPCT
a.flow rate is variable
b.scan delay cannot be precisely controlled
c.it requires two operators
d.it cannot be used for injecting into standard PICC lines

Answer 157

d.it cannot be used for injecting into standard PICC lines
if a standard PICC line is the only option available for contrast injection, most manufactures recommend contrast be administered using hand bolus technique

Question 158

the volume of contrast administered is increased from 100ml to 150ml the flow rate is. unchanged at 3ml/s. what can be expected
a.the time to reach peace aortic enhancement is decreased
b.the magnitude of the peace enhancement is decreased
c.the duration of the contrast injection is increased
d.the duration of the scan acquisition is increased

Answer 158

c.c.the duration of the contrast injection is increased
if the flow rate remains the same it will take longer to inject a higher volume of contrast material.if the same flow rate is used the contrast will reach a specific enhancement point at the same time regardless of the total volume. however increasing the total volume means the magnitude of the enhancement will continue to climb

Question 159

because of the patients IV access the flow rate of a contrast injection is reduced from the protocol of 4 to 2mL/s. what other adjustment is likely made
a.the scan delay is increased
b.the scan delay is decreased
c.the volume of contrast is decreased
d.the volume of contrast is increased

Answer 159

a.the scan delay is increased

when the flow rate is reduced it takes longer for contrast to reach peak enhancement so the scan delay must be increased. in most case the total volume if contracts remains the same

Question 160

what injection technique is used for most clinical applications
a.a drip infusion technique
b.a uniphasic injection with constant flow rate
c.a biphasic injection in which the initial 50Ml bolus is delivered at a higher flow rate
d.a multiphase injection with two or more contrast flow rates, followed by a saline flush

Answer 160

b.a uniphasic injection with constant flow rate
for most clinical application, a single injection rate and a set scan delay can be used. CT angiography and other specialized studies often use more complex injection techniques

Question 161

what effects does a patients cardiac output status have on contrast enhancement
a.as cardiac output is reduced, the magnitude of the peak aortic enhancement is diminished
b.as cardiac output is reduced, the magnitude of the peak aortic enhancement is increased
c.as cardiac output is reduced, there is progressively longer delay in the time required for the contrast bolus to reach peak aortic enhancement
d.as cardiac output is reduced there is progressively shorter delay in the time required for contrast bolus to reach peak aortic enhancement

Answer 161

c.as cardiac output is reduced, there is progressively longer delay in the time required for the contrast bolus to reach peak aortic enhancement

a reduction in a patient cardiac output will not reduce the magnitude of the peak enhancement, only the time it takes to achieve it. when the patients heart pumps less efficiently the contrast will take longer to reach vessels and organs. this require the scan delay to be extended in proportion to the degree of cardiac impairment

Question 162

the test bolus method is used to determine the scan delay for a CT angiography study. Ten trial images are taken at 2 second intervals beginning 12 seconds after the start of the test injection. maximum enhancement is the selected ROI is seen on the fourth image. what scan delay range is optimal
a.5 to 8 seconds
b.20 to 23 seconds
c.32 to 35 seconds
d.100 to 120 seconds

Answer 162

b.20 to 23 seconds
the optimal scan delay time is equal to the time that elapsed from the start of the test injection to that of the imaging showing maximum enhancement. therefore 12 +2 x 4= 20
trial scan delay + interval between trail scans x image showing maximum enhancement

Question 163

the rational use of CT involves which two key components
a.halving the mAs and doubling the kVp
b.eliminating most paediatric examinations and requiring a second physicians opinion to order adult examinations
c.reducing the use of helical scanning and increasing the frequency of visits by physicists to assess radiation dose delivered
d.appropriate selection of patents and the minimization of the radiation dose without compromising diagnostic quality

Answer 163

d.appropriate selection of patents and the minimization of the radiation dose without compromising diagnostic quality
it is up to the technologist to ensure that adequate image quality is achieved with the lowest possible dose

Question 164

which unit universally expresses dose
a.effective dose
b.organ dose
c.absorbed dose
d.there is no consensus regarding an expression of dose, and many units have been used

Answer 164

d.there is no consensus regarding an expression of dose, and many units have been used
comparisons of reported dose can be difficult as it is reported in various units

Question 165

the unit of ionizing radiation exposure in air is the
a.roentgen(R)
b.radiation absorbed dose (rad)
c.gray(Gy)
d.sievert(Sv)

Answer 165

a.rotentgen (R)

Question 166

the unit of absorbed dose is the
a.roentgen(R)
b.radiation absorbed dose(rad) or gray(Gy)
c.computed tomography dose index(CTDI)
d.multiscan average dose(MSAD)

Answer 166

b.radiation absorbed dose(rad) or gray(Gy)
gray is the unit for absorbed dose, rad was the older unit that is now obsolete

Question 167

the system International d’Unites(SI) for ionizing radiation
1.is used internationally
2.replaces the unit known as rad
3.replaces the unit know as rem

a.1 only
b.1 and 2
c.1 and 3
d.1,2 and 3

Answer 167

d.1,2 and 3

Question 168

the quality factor (Q) is used to
a.account for the different health effects produced from different types of ionizing radiation
b.account foe the pitch in helical CT
c.describe exposure from scatter radiation
d.convert older units to SI

Answer 168

a.account for the different health effects produced from different types of ionizing radiation
the quality factor or the radiation weighting factor must be applied to the absorbed dose to account for the different degree of biological damage caused by different types of radiation

Question 169

which of the following statements is true concerning the measurement referred to as effective dose
a.it is measured in rad or Gy
b.it is a weighted average of organ doses
c.there is no agreement on the weighting factors to be applied to each radiosensitive organ
d.it is relatively easy to calculate accurately and is therefore used universally

Answer 169

b.it is a weighted average of organ doses

effective dos wis difficult to calculate because it depends on an accurate estimate of the dose to radiosensitive organs from CT procedure

Question 170

the areas of scatter radiation into adjacent tissue are sometimes called
a.tails
b.overflow
c.excess
d.collimation

Answer 170

a.tails

Question 171

the dose to the central slice plus the dose from the scatter into nearby slices equals the
a.MSAD
b.Sv
c.mAs setting
d.R

Answer 171

a.MSAD
multiscan average dose
MSAD and CTDI calculate the dose for multiple scans

Question 172

which is now the preferred expression of radiation dose in CT dosimetry
a.R
b.CTDI vol
c.DLP
d.MSAD

Answer 172

b.CTDI vol

Question 173

the relationship between mAs and dose is
a.inversely proportional; the higher the mAs, the lower the dose
b.linear;the higher the mAs the higher the dose
c.represented by the equation: dose=1/ square root(mAs)
d.highly variable and impossible to quantify

Answer 173

b.linear;the higher the mAs the higher the dose

if the mAs is doubled the dos wis doubled
if the mAs is haled the dose is halved

Question 174

when looking at the overall radiation dose from radiology sources Ct contributes
a.a very low percentage of the total
b.a proportional amount-that is CT examines repsenet approximately 11% of all diagnostic procedures and account for approximately 11% of the total dose
c.a disproportionately high percentage of the total
d.nearly 90% of the total

Answer 174

c.a disproportionately high percentage of the total

CT exams carry a higher radiation dose than do most radiographic procedures

Question 175

keeping in mind how a parent will perceive risk to hi or her child, guideline have been outlined for CT examinations of paediatric patients. which of the following is NOT one of the recommendations
a.the parent should be told that CT exam of a child is associated with a small risk
b.the parent should sign a consent form acknowledging that out of every 100 children who undergo CT examination 1 will develop a fatal cancer in life
c.the examination should be restricted to cases in which it is specifically indicated and cannot reasonably be substituted for with a diagnostic examination that does not use ionizing radiation
d.scan parameters must be customized according to the size of the child

Answer 175

b.the parent should sign a consent form acknowledging that out of every 100 children who undergo CT examination 1 will develop a fatal cancer in life

parents should be assured that there is a small risk everthig possible is going to be done to minimize that risk, and also that the CT is the appropriate choice to answer the diagnostic question posed

Question 176

the latency time for cancer induction is the dose ranges used in CT is estimated to be between
a.10 to 30 days
b.1 to 5 years
c.10 to 30 years
d.40 to 60 years

Answer 176

c.10 to 30 years

Question 177

children are more sensitive to radiation than are adults for all the following except
a.children have more time to express a cancer than do adults
c.radiation exposure is cumulative and children may undergo more than one CT examination in their lifetime
d.children have more dividing cells, land adverse effects of radiation act on dividing cells

Answer 177

b.in children the latency time for cancer induction is only a few months

Question 178

which of the following are strategies that may reduce the radiation dose to the patient
1.adjusting mAs to suit individual patient size
2.avoid increasing kVp beyond 120
3.increasing pitch
4.performing multiphase studies only when clinical indications exist

a.1 and 2
b.1 and 3
c.2 and 4
d1,2.3 and 4

Answer 178

d.1,2.3 and 4

Question 179

a patient is being positioned for a routine scan of the brain why is he asked to tuck his chin down toward his chest
a.so that the scan time can be reduced
b.to allow immobilization sponges to be used
c.to reduce the radiation exposure to the lens of the eye
d.to eliminate the need to tilt the gantry so that the axial scan mode can be used

Answer 179

c.to reduce the radiation exposure to the lens of the eye

Question 180

what is the expected HU value of a measurement taken in a lateral ventricle
a.-70 to -60
b.4 to 8
c.20 to 30
d.40 to 50

Answer 180

b.4 to 8
the ventricles of the brain are filled with cerebrospinal fluid that typically measures from 4 to 8 HU

Question 181

which is a typical injection protocol for a routine examination of the brain
a.100mL delivered at 1mL/s, scan delay of 5 minutes
b.150 mL delivered at 2 mL/s, scans begin when injection is complete
c.split bolus:50 mLdelivered at 1.5mL/s, wait 2 minutes 50 mL delivered at 1.5mL/s, scan begin when second injection is complete
d.60 mL(concentration 370) delivered at 4 mL/s, scan delay from timing bolus using carotid artery as the reference vessel

Answer 181

a.100mL delivered at 1mL/s, scan delay of 5 minutes

the protocol for routine brain scan must allow time for contrast to leak across a disrupted bloodbrian barrier

b. does not have long enough scan delay
c.is a protocol typically for necks

Question 182

compared with a cerebral CTA, what parameter must be changed for a cerebral CTV
a.slice thickness is reduced
b.delay from the start of injection to start of scanning is increased
c.scan are performed in the axial mode, rather than the helical mode
d.kVp is increased

Answer 182

b.delay from the start of injection to start of scanning is increased

CTV is used for the depiction of venous anatomy. scan parameters are quite similar to CTA except images are acquired while contrast is in the venous enhancement phase

Question 183

which is true statement regarding an emergency department patient who is suspected of suffering from acute stroke
a.a CT scan of the behalf is only done if the patient has a previous history of stroke
b.an MRI of the head is the first choice of imaging procedures a CT of the head is only done if MRI cannot be done within 24 hours
c.a CT scan of the head must be done as soon as possible because it is necessary examination in determining whether a patient can receive t-PA treatment
d.an unenhanced CT scan will provide no useful information in the diagnosis and treatment of acute stroke. only CTA and CT perfusion studies are indicated

Answer 183

c.a CT scan of the head must be done as soon as possible because it is necessary examination in determining whether a patient can receive t-PA treatment

Question 184

what is the goal in performing perfusion studies for patients with acute stroke
a.to determine whether the stroke is hemorrhagic or ischemic
b.to determine the onset time of the stroke
c.to depict the spatial relationship of complex vascular lesions to the surrounding structures
d.to distinguish infarcted tissue from the penumbra

Answer 184

d.to distinguish infarcted tissue from the penumbra

CT perfusion techniques measure cerebral blood flow which can be used to distinguish infarcted tissue from penumbra
a CT unenhanced head is done to rule out intracranial bleeding

Question 185

for what study might data be acquired when the patient is lying prone
a.routine chest
b.CT angiography for suspected pulmonary embolism
c.cardiac scoring
d.High resolution Chest

Answer 185

d.High resolution chest

prone images can help differentiate disease from the effects of gravity that can mimic disease

Question 186

a volumetric HRCT study refers to a protocol that includes which o the following
a.thin sections taken at interval of 20 mm or more between slices, during inspiration with the paint in a supine position
b,a smapling technique that is intended to provide representative areas of the lung
c.thin sections in a helical mode taken contiguously so as to cover the entire lung during inspiration with the patient in supine position
d.three series of thin sections, in a helical mode taken contiguously so as to cover the entire lung; series on his supine inspiratory, series two is supine expiratory series three is prone inspiratory

Answer 186

c.thin sections in a helical mode taken contiguously so as to cover the entire lung during inspiration with the patient in supine position

supine expiratory and prone inspiratory are done in repsentativie slices as to limit the radiation exposure to patient

Question 187

why do many protocols for the evaluation of PE scan in the caudal to cranial direction
a.to chase the contrast bolus through pulmonary circulation
b.to reduce radiation exposure
c.to reduce artifacts attributable to patient motion
d.to eliminate the need for the patient yo hold their breath

Answer 187

c.to reduce artifacts attributable to patient motion
respiratory motion is greatest at lung bases. scanning caudal to cranial minimizes there artifact as scan through the lung bases are done when patient is more likely able to hold their breath( at the beginning of breath h old not end)

Question 188

what must happen to a thrombus for it to be referred to as a embolus
a.it must detach from its original site
b.it must be formed in the right side of the heart
c.it must be formed from clotted blood
d.it must lodge in a pulmonary vessel

Answer 188

a.it must detach form its original site
an embolus can be formed from a number of different materials and can originate in many different sites in the body

Question 189

at a particular institution the PE protocol includes a second scan series performed 180 seconds after the IV contrast injection that extends from the iliac crest to the knees. what I sth purpose of this second series
a.to check ureteral obstruction
b.to check that the pelvis and lower extremities for deep vein thrombosis
c.to check that the patient is excreting the iodinated contrast
d.to assess the patients cardiac output

Answer 189

b.to check that the pelvis and lower extremities for deep vein thrombosis many pulmonary embolus are caused from thrombi originating in the lower extremities. a delayed scan sometime called CT venography can help identify these clots

Question 190

what heart valve is located between the right atrium and the right ventricle
a.mitral
b.pulmonary
c.aortic
d.tricuspid

Answer 190

d.tricuspid

the pulmonary valve is on the right side of the heart between the high ventricle and the entrance of the pulmonary artery.
the aortic valve is in the left side of the heart between the left ventricle and the entrance of the aorta

Question 191

b-blockers are likely to be used as a part of a cardiac CT protocol when
a.patient has history of iodine allergy
b.patient has asthma and is being treated with an albuterol inhaler
c.patient heart rate is higher than 65bpm
d.patient heart rate is less than 60bpm

Answer 191

c.patient heart rate is higher than 65bpm

a rapid heart rate increase sth chance that motion artifact will degrade cardiac CT images. b-blockers are used to lower the heart. rate to less than 65bpm and make rhythm more regular

Question 192

an imaging technique that attempts to acquire data only during cardiac segments with lowest cardiac motion is called
a.a slit bolus
b.prospective ECG triggering
c.retrospective ECG gating
d.electron beam CT

Answer 192

b.prospective ECG triggering

Question 193

a patient who is scheduled for a CT study has an irregular heartbeat with a rate of approximately 85 bpm for which clinical indications is this the most problematic
a.coronary artery disease
b.assessment of ventricular function
c.possible thoracic aortic dissection
d.evaluation of congenital aortic arch anomaly

Answer 193

a.coronary artery disease
because the coronary arteries are relatively small caliber and are often tortuous in shape is more sensitive to cardiac motion artifacts and image missregistration

Question 194

why is it recommended that cardiac CT calcium scoring be restricted to paints with risk factors for coronary artery disease, rather than using it as a screening tool for all patients
a.it has not proven to be an accurat measure of coronary artery calcification
b.a correlation has not been proven between a positive calcium score and a future risk of developing heart disease
c.the examination us uncomfortable for the patient
d.risks related to the radiation dose are a concern; for asymptomatic patients with no cardiac risk factors, it is not certain that he benefit of the examination outweighs the risk from the radiation exposure

Answer 194

d.risks related to the radiation dose are a concern; for asymptomatic patients with no cardiac risk factors, it is not certain that he benefit of the examination outweighs the risk from the radiation exposure

Question 195

although patient compliance can sometimes be a factor what volume of oral contrast is typically considered the minimum amount needed for a routine CT study of the abdomen and pelvis
a.100mL
b.400mL
c.600mL
d.1500mL

Answer 195

c.600mL

Question 196

which is the window setting used to visualize subtle liver lesions
a.150ww;70wl
b.350ww;50wl
c.1500ww;-600wl
d.2000ww;600wl

Answer 196

a.150ww;70wl
when narrow window widths are used t number of HU values distributed over a set number of shades of gray is reduced. therefore making subtle density differences more noticeable

Question 197

a non contrast CT of the abdomen is ordered on Mr smith the primary indication is a 15 year history of alcoholism what can the technologist do to help the radiologist determine whether the patient has a fatty liver
a.administer contrast and repeat the series
b.administer additional oral contrast and repeat the series
c.contiue scanning through the pelvis even though a pelvis examination was not ordered
d.place a region of interest HU measurement within the liver and spleen

Answer 197

d.place a region of interest HU measurement within the liver and spleen
fatty infiltration reduces the CT attenuation of the involved liver. this can be confirmed by including HU measurement of the liver and spleen
A spleen measurement that I store than 10 HU higher than that of the liver indicates fatty infiltrate of the liver

Question 198

the phase of liver enhancement that occurs 60-70 seconds after IV bolus contrast injection is called the
a.early arterial phase
b.late arterial phase
c.portal venous phase
d.equilibrium phase

Answer 198

c.portal venous phase
the portal venous phase occurs between 60-70 seconds after IV injection
early arterial phase occurs within 20 seconds of IV injection
later arterial phase occurs between 30-35 second after Iv injection
equilibrium or delayed phase occurs minutes after. injection

Question 199

for what clinical indication might dual phase(late arterial and portal venous) CT of the abdomen be requested
a.to assess possible liver metastasis from primary thyroid tumour
b.detection of suspected liver abscess
c.characterization of fatty infiltration of the liver
d.acute cholecystitis

Answer 199

a.assess possible liver metastasis from primary thyroid tumour
some tumours are supplied by an abnormal number of blood vessels. because of this increased blood supply; these tumours will display more intense enhancement after an IV contrast injection

Question 200

the nephrogram phase is seen approximately _____ after IV injection
a.30 seconds
b.70 seconds
c.110 seconds
d.5 minutes

Answer 200

c.110 seconds

Question 201

an adrenal mass that measures less than or equal to 10 HU on unenhanced CT
a. is an adenoma
b.is most likely malignant
c.can be either an adenoma or a malignant mass
d.is lipid poor

Answer 201

a, is an adenoma
a adrenal mass that measures less than 10 Hu is high in fat. malignant adrenal masses contain very little fat. therefore a mass that measures than 10HU on a non contrast CT is benign

Question 202

what explains the diversity in clinical presentation of acute appendicitis
a.the variable position of the appendix
b.the skill of the examiner
c.the varying ability of patients to accurately describe their symptoms
d.the underlying cause of the obstruction

Answer 202

a.the variable position of the appendix

Question 203

a focused appendices CT refers to a scan protocol that
a. limits the scan area to the lower abdomen and upper pelvis
b.uses rectal contrast agent
c.does not include any type of contrast media
d.scans the entire abdomen and pelvis with IV and oral contrast material

Answer 203

a. limits the scan area to the lower abdomen and upper pelvis

Question 204

select the arrow that points to the appendix
a.1
b.2
c.3
d.4

Answer 204

a.1

Question 205

what percentage of urinary tract calculi will be seen on non contrast helical CT
a.40%
b.60%
c.85%
d.99%

Answer 205

d.99%

Question 206

why are isotropic voxels particularly important in image of the musculoskeletal system
a.isotropic voxels will allow good reformations, even if there is motion artifact on the source image s
b.isotropic voxels enable MPR images to be created in any plane with the same spatial resolution as the original sections
c.becasue voxels are isotropic a wis Elsie thickness can be used, thereby reducing the data acquisition time
d.isotropic voxels eliminate streak artifacts form prosthetic devices and metallic objects

Answer 206

b.isotropic voxels enable MPR images to be created in any plane with the same spatial resolution as the original sections
a thin slice is necessary to produce isotropic voxels

Question 207

which of the following clinical indications may result in a musculoskeletal examination being performed with IV contrast enhancement
a.trauma
b.detection of suspected loose bodies within a joint
c.suspected tibial plateau fracture
d.suspected infection

Answer 207

d.suspected infection
IV contrast is often used for tumour, infection or abscess
intra-articular contrast adminstration may improve the detection of loose Rosie within a joint

Question 208

why is it recommended to position the patient for a shoulder CT so that the unaffected arm is extended over the patients head
a.to reduce streak artifact
b.so the IV injection site can be more easily monitored
c.to make the patient more comfortable
d.so as no not to confuse the unaffected shoulder with that of the symptomatic one

Answer 208

a.to reduce streak artifact
the dense bone of the shoulder often absorbs a high percentage of the xray beam, resulting in streak artifact

Question 209

all of the following are methods to reduce radiation dose to the patient and staff from CTF EXCEPT
a.using intermittent fluoroscopy whenever possible
b.using a stand off needle holder to avoid exposure to the hands
c.keeping the tube current as low as possible
d.changing matrix size to 1024

Answer 209

d.changing matrix size to 1024
can also drop non biopsied areas with lead to reduce scatter and therefore reduce dose

Question 210

which of the following is a contraindication to Ct-guided biopsy
a.infection
b.contrast media allergy
c.bleeding disorder that does not respond to treatment
d.congestive heart failure

Answer 210

c.bleeding disorder that does not respond to treatment