CT HOMEWORK QUESTIONS

With regard to human development, the embryonic stage lasts approximately _____ week(s). 1 2 4 6

6

As postpatient collimation decreases, slice thickness: decreases. increases. remains the same.

decreases

The palatine processes are part of which bone? vomer palatine maxilla sphenoid

maxilla

The _____ controls balance and equilibrium. vestibule and semicircular canals cochlea tympanic membrane ossicles

vestibule and semicircular canals

In sixth generation CT scanners, which of the following elements rotate around the patient? the x-ray tube detectors x-ray tube and detectors No choices are correct.

x-ray tube and detectors

Which of the following includes a sampler, quantizer and a coder? DAC ADC DAS detector array

ADC

Second generation scanning employed: a pencil beam/a single detector. a fan beam/multidetectors. more indexing (compared with first generation scanners) B and C are correct.

a fan beam/multidetectors.

Compared with traditional single-slice axial scanners, helical/spiral scanners acquire images at _____ rate. a faster a slower the same

a faster

Human chorionic gonadotropin (HCG) is secreted by the: blastocyst zygote ovum. sperm.

blastocyte

Which of the following structures produces cerebrospinal fluid as the result of filtration and secretion? choroid plexus lateral ventricles fourth ventricle pineal gland

choroid plexus

When manipulating an image using the zoom tool, the resolution: increases decreases. stays the same.

decreases

To view a CT image on a LCD monitor, data must undergo: digital-to-analog conversion. analog-to-digital conversion. digitization. quantization.

digital-to-analog conversion.

Which of the following terms refers to the posterior surface of the body? caudal ventral dorsal prone

dorsal

The window width (WW) determines the: image density. image contrast. voxel depth. voxel width.

image contrast.

Compared with volume acquisition, axial acquisition results in: increased noise. lower partial volume averaging. better high-contrast resolution. thinner slices

lower partial volume averaging.

Scintillation detectors are associated with _____ patient dose and _____ image noise. lower; reduced higher; reduced lower; increased higher; increased

lower; reduced

Ghosting refers to _____ artifacts. motion cupping ring static

motion

All power to the gantry of a spiral-helical CT scanner is conveyed via: high-tension cables. rotating wire brushes. photon flux. slip rings.

slip rings

Edge gradient artifacts appear as a: streak ring. band of noise across the image. white circles.

streak

In multislice CT scanners, detector systems with equal-size detector elements are called _____ arrays. linear curved adaptive symmetric

symmetric

The half-scan algorithm technique is used to improve: temporal resolution uniformity. linearity. spatial resolution.

temporal resolution

With respect to detectors, the term "dynamic range" refers to: detector consistency. detectors gather the photons coming from the patient. the accuracy of response to both low- and high-energy radiation. No choice is correct.

the accuracy of response to both low- and high-energy radiation.

Which of the following results in better resolution? thick collimation thin collimation Collimation does not affect resolution.

thin collimation

Partial volume averaging can be improved by using: smaller pixel sizes. a smaller SFOV. thinner slice thicknesses. a larger DFO

thinner slice thicknesses.

Which generation of CT scanners was the first to use a curved array of rotating detectors? second third fourth fifth

third

Ring artifacts usually only appear in _____ scanners. first generation second generation third generation multislice

third generation

Nutating refers to the process of: tilting the detector ring. tilting the x-ray tube. tilting the gantry. translation.

tilting the detector ring.

CT scanner x-ray tubes incorporate rotating anodes composed of: tungsten, copper and molybdenum. molybdenum, tungsten and rhodium tungsten, molybdenum and rhenium rhenium, tungsten and rhodium.

tungsten, molybdenum and rhenium

Which of the following CT numbers represents water? 0 +1000 -1000 +3000

0

Modern CT scanners are able to differentiate tissue with density differences of less than _____ %. 1.0 0.5 0.1 0.15

0.5

Spatial resolution can be improved by using: 1. thin slice thicknesses. 2. a matrix with large pixel sizes. 3. small detector sizes. 1 and 2 1 and 3 2 and 3 1, 2 and 3

1 and 3

Which of the following are functions of the patient table? 1. contributes to patient safety 2. enhances subject contrast 3. transports the patient through the gantry 1 and 2 1 and 3 2 and 3 1, 2 and 3

1 and 3

Window level (WL) refers to: 1. the midpoint in a range of CT numbers. 2. image contrast. 3. image brightness. 1 and 2 1 and 3 2 and 3 1, 2 and 3

1 and 3

Spatial resolution can be increased by using: 1. larger-size detectors. 2. a smaller pixel size. 3. thinner slice thicknesses. 1 and 2 1 and 3 2 and 3 1, 2 and 3

2 and 3

The ability of the CT scanner to calculate image data from multiple, overlapping acquisition data sets is called _____ sampling. 1. interpretive 2. interleaved 3. interlaced 1 and 2 1 and 3 2 and 3 1, 2 and 3

2 and 3

Which of the following workstation applications would most likely be used by cardiologists? 1. ejection fraction 2. calcium scoring 3. stereotaxis 1 and 2 1 and 3 2 and 3 1, 2 and 3

3. stereotaxis 1 and 2

The frontal sinuses are evident radiographically by age: 1 3 5 7

7

CT scanner x-ray tube voltages range from ______ to _____ kilovolts (kV). 60; 100 80; 120 80; 140 100; 160

80; 140

The term "translation" is associated with _____ generation scanners. first second third A and B are correct.

A and B are correct.

Beam-shaping filters are generally composed of: aluminum. copper. teflon. A and C are correct.

A and C are correct.

Which of the following terms is associated with seventh generation spiral-helical technology? multisection scanner multidetector scanner multiple detector array scanner All choices are correct.

All choices are correct.

Spiral-helical CT scanning is based on: sequential data acquisition. slip-ring technology. volume data acquisition. B and C are correct.

B and C are correct.

Sampling occurs at the: CT detectors. prepatient collimators. analog-to-digital converter (ADC). digital-to-analog converter (DAC).

CT detectors

Which of the following tests determines the uniformity of CT numbers throughout the image? high-contrast resolution low-contrast resolution standard deviation of CT numbers in water CT number flatness

CT number flatness

The scan field of view (SFOV) is determined by the: pitch. prepatient collimators. postpatient collimators. CT technologist before the scan begins.

CT technologist before the scan begins.

One advantage of reformatting is that image detail is increased. T/F

False

Virtual reality (VR) and volume rendering imaging techniques are identical. T/F

False

A log amplifier calculates the amount of attenuation that occurs during data acquisition. T/F

True

Absorption efficiency refers to how efficiently x-ray photons are captured by the detectors. T/F

True

Which of the following would most likely be associated with a CT scan of the lung? WW 80; WL 40 WW 1600; WL 300 WW 80; WL -400 WW 1500; WL - 400

WW 1500; WL - 400

Which of the following sources of radiation were used in Hounsfield's first primitive CT scanner? x-ray americium radium radon

americium

Filtered backprojection is most closely associated with: ring artifacts. aliasing artifacts artifact-free images. misregistration.

artifact-free images.

What is the linearity phantom used to test? spatial resolution assignment of CT numbers to known linear attenuation coefficients contrast resolution temporal resolution

assignment of CT numbers to known linear attenuation coefficients

What does the Fourier transform calculate? attenuation-to-detector time patient dose convolution projection data

attenuation-to-detector

The z-axis refers to the ______ plane. coronal axial sagittal

axial

Tube arcing appears as a: ring artifact. streak artifact band of increased noise across the image. cone-beam artifact.

band of increased noise across the image.

The pons is a division of the: midbrain. brainstem. pituitary gland. thalamus.

brainstem

A CT gantry includes all of the following components except: collimators. detectors. central processing unit. bow tie filters.

central processing unit.

Beam-shaping filters are designed to: remove higher-energy photons from the beam. change the spatial distribution of the beam. decrease subject contrast. restrict the path of photons coming from the x-ray tube.

change the spatial distribution of the beam.

Which of the following structures contains the pineal gland? chiasmatic cistern cisterna ambiens interpeduncular cistern pontine cistern

cisterna ambiens

The process related to the first computed tomography scanner was called: computer-assisted tomography. reconstructive tomography. Hounsfield tomography. computerized transverse axial scanning.

computerized transverse axial scanning.

Which of the following types of beam geometry results in increased scatter? pencil beam cone beam fan beam parallel beam

cone beam

Which of the following x-ray beam geometries is used by modern, multidetector CT scanners? pencil beam cone beam fan beam pinpoint beam

cone beam

Cupping artifacts are most closely related to which image quality? linearity contrast resolution uniformity temporal resolution

contrast resolution

Which of the following is a filtering technique in which the reformatted raw data are copied to create what looks like the original raw data set? convolution kernel mulitplanar reconstruction sectional reformatting

convolution

Which of the following structures connects the left and right hemispheres of the cerebrum? choroid plexus corpus callosum longitudinal fissure central sulcus

corpus callosum

Fourth generation scanners employed detectors that were: curved/nonrotating. linear/rotating curved/rotating. linear/nonrotating.

curved/nonrotating.

What is the effect of increased image noise? increased contrast resolution decreased contrast resolution improved image quality A and C are correct.

decreased contrast resolution

Which of the following arteries supply blood to the face and scalp? internal carotids external carotids vertebrals cerebrals

external carotids

Which of the following structures is located between the cerebral hemispheres? falx cerebelli diaphragma sellae tentorium cerebelli falx cerebri

falx cerebri

Compared with conventional (axial) CT scanning, spiral-helical CT has: longer interscan delays. faster imaging times. increased misregistration artifacts. B and C are correct.

faster imaging times.

Which generation of CT scanners is associated with the term "EBCT" and the use of an electron beam gun? seventh sixth fifth fourth

fifth

Which of the following terms is most closely associated with image reconstruction immediately following a scan? filtered backprojection interleaved sampling longitudinal interpolation multiplanar postprocessing

filtered backprojection

Which of the following terms refers to the automatic removal of artifacts that occur in anatomy of various densities?backprojection filtered backprojection z-axis filtering interleaved sampling

filtered backprojection

Which of the following types of scanners used water bags? first generation only first and second generation first, second and third generation Water bags have never been used with CT scanning.

first generation only

First generation scanners were only capable of imaging the: head/brain. extremities. chest, abdomen and pelvis. A and B are correct.

head/brain.

In a _____ CT scanner, the x-ray tube rotates continuously around the patient as the patient travels through the gantry. high-speed axial helical/spiral second-generation

helical/spiral

Generators are often times located within the gantry. These types of generators are typically: full wave/three-phase. medium frequency. high frequency. multiwave/two-phase.

high frequency.

Spiral-helical scanners incorporate _____ slip rings. high-voltage low-voltage high- and low-voltage No choice is correct.

high- and low-voltage

The Lambert-Beer Law is most closely associated with a _____ beam. polychromatic fanned homogeneous heterogeneous

homogeneous

The term "misregistration" refers to: backprojection reconstruction noise incorrect image reconstruction. convolution.

incorrect image reconstruction.

Increased pitch results in: increased spatial resolution. increased partial volume averaging increased image contrast. ring artifacts.

increased partial volume averaging

Images acquired in ciné mode require overlapping thin data sets. This results in _____ spatial resolution and _____ patient dose. increased; increased increased; decreased decreased; increased decreased; decreased

increased; increased

Which of the following is not considered part of the ethmoid bone? superior nasal conchae middle nasal conchae inferior nasal conchae perpendicular plate

inferior nasal conchae

Which of the following is not an example of a kernel? edge enhancement filter smoothing filter standard convolution algorithm interative algorithm

interative algorithm

What does longitudinal interpolation with z-axis filtering calculate? interslice distance ring artifacts filtered backprojection scan time

interslice distance

Which of the following terms is also referred to as a convolution algorithm? kernel interpolation ring artifact iterative algorithm

kernel

Which of the following is not formed by the mesoderm? cardiac muscle kidneys dermis of the skin liver

liver

Which of the following is not a postprocessing technique? image smoothing maximum intensity projection (MIP) volume rendering longitudinal interpolation

longitudinal interpolation

A smoothing filter is applied to scans that display very: high contrast. high brightness. low brightness. low contrast.

low contrast.

The typical modern CT scanner generator converts: low-voltage AC to high-voltage DC. low-voltage DC to high-voltage DC. high-voltage DC to low-voltage DC. high-voltage AC.

low-voltage AC to high-voltage DC.

Which type of post processing technique would most likely be used for CT virtual colonography exams? MIP minIP volume rendering shaded surface rendering

minIP

Modern CT scanners rely on _____ to rapidly process the collected scan data. supercomputers mainframe computers minicomputers microcomputers

minicomputers

Cone-beam artifacts only appear in _____ scanners. first generation second generation third generation multislice

multislice

Which lobe(s) of the cerebrum is(are) responsible for vision? occipital temporal frontal parietal

occipital

First generation CT scanners used _____ beam scanning. cone pencil fan pinpoint

pencil

Large array parallel processors are responsible for: executing several tasks sequentially performing numerous tasks simultaneously assessing faulty detector arrays. hardening the x-ray beam.

performing numerous tasks simultaneously

When image data is acquired by a CT scanner, it goes through a process known as: convolution. photon flux digitization. quantization.

quantization.

Which of the following techniques would be used for a patient who has trouble holding his or her breath or has an irregular heart beat? half-scan algorithm prospective gating smoothing retrospective gating

retrospective gating

The cranial end of the neural tube separates into three primary vesicles. Which of these primary vesicles corresponds to the hindbrain? prosencephalon rhombencephalon mesencephalon vesencephalon

rhombencephalon

Which of the following artifacts is a result of faulty detector elements? partial volume averaging ring artifacts aliasing artifacts streaking

ring artifacts

How can partial volume averaging be reduced? scanning with thicker slices scanning with thinner slices using a half-scan algorithm B and C are correct.

scanning with thinner slices

Which of the following techniques reduces edge gradient artifacts? scanning with thinner slices decreasing data sampling rates scanning with thicker slices using detectors with large apertures

scanning with thinner slices

Which of the following detector types produces higher quality images? gas scintillation linear

scintillation

Which of the following is the most effective type of CT detector? scintillation xenon gas linear array photodiode

scintillation

Partial volume averaging occurs when: similar tissue types share the same voxel cardiac studies are performed metal objects are present within the patient or the patient's clothing. detector elements fail.

similar tissue types share the same voxel

Modern CT scanners have x-ray tubes designed to withstand large amounts of heat. The anode on these tubes includes a target made of: molybdenum. copper. rhodium. tungsten.

tungsten.

Which of the following post processing techniques is sometimes referred to as 4-D reconstruction? volume rendering shaded surface rendering curved multiplanar reconstruction edge enhancement

volume rendering