# CT Physics 2 Hhh

51 Questions  Settings  Ct resistry review physichs

Related Topics
• 1.
Filment sizes for modern CT x-ray tubes range between
• A.

0.5 and 1.2 mm

• B.

2.0 and 3.0 mm

• C.

5.5 and 7.8 mm

• D.

25.0 and31.5 mm

• 2.
The mathematical process that allows MDCT images to be reconstructed at any point along the acquired volume is commonly referred to ass
• A.

Iteration

• B.

Filtered back-projection

• C.

Fourier reconstruction

• D.

Z-filtering

• 3.
During ct x-ray exposure, the product of the seleted mA setting and the scan time is called
• A.

Effective mAs

• B.

Peak mAs

• C.

Absorbed mAs

• D.

Constant mAs

• 4.
The matematical manipulations required during the reconstruction of a ct image are accomplished using a (n)
• A.

Algorithm

• B.

Kerenel

• C.

Mathematical filter function

• D.

1 and 2

• E.

1,2 and 3

• 5.
The electronic combination of signals from adjacent detectors to form a CT image is called
• A.

Binning

• B.

Interpolaation

• C.

Z-filtering

• D.

Partial volume averaging

• 6.
The streaking artifact that occurs in the area of the posterior fossa during a CT examination of the brain may be referred to as
• A.

Cupping

• B.

Boiled egg

• C.

Stairstep

• D.

The Hounsfield bar

• 7.
Which of the following 3D imaging techniques is utilized to provide "fly-through" images during CT colonography
• A.

Orthographic volume rendering

• B.

• C.

Perspective volume rendering

• D.

Minimum intensity projection (min-IP)

• 8.
An MDCT image is reconstructed using a 512 matrix and aDFOV of 38 cm. if the detector collimation is set to a section width of 1.25 mm, what is the volume of each voxel?
• A.

0.69mm

• B.

0.93mm

• C.

1.26 mm

• D.

1.68mm

• 9.
Which of the following sttements about collimation of the CT x-ray beam is false?
• A.

Collimation of the x-ray beam occurs both before and after the patients

• B.

Collimation of the beam occurs in the z-axis, thus affecting slice thickness

• C.

Increases in collimation increase the intensity of the primary beam

• D.

Collimation of the ct x-ray beam is used to limit the detection of scatter radiation

• 10.
The major disadvantage of the back-projection method of image reconstruction is the appearance of the
• A.

Partial volume effect

• B.

Ring artifact

• C.

Gibb phenomenon

• D.

Star artifact

• 11.
• A.

Euler constant

• B.

Incident intensity

• C.

Absorber thickness

• D.

Transmitted intensity

• 12.
A high-resolution comb is utilized by an MSCT detector array in an effort to reduce:
• A.

• B.

• C.

Low spatial frequency signal

• D.

High spatial frequency signal

• 13.
When choosing a scan field of view, the CT technologist is controlling the
• A.

Diameter of data acquistion

• B.

Number activated detectors within the array

• C.

Correction factors for the specific area of anatomic interest

• D.

1and 2

• E.

1,2,3

• 14.
The geometric efficiency of a CT detector is influenced primarily by the
• A.

Atomic number of the detector material

• B.

Size of the detector element

• C.

Size of the tube filament

• D.

Amount of interspace material between detectors

• 15.
Which of the following factors may affect the attenuation of an object during CT data acquisition?
• A.

Beam pitch

• B.

MA

• C.

KVp

• D.

Algorithm

• 16.
An image that is reconstructed a second time with some change in technical factor is said to be
• A.

Reiterated

• B.

Post-processed

• C.

Retrospective

• D.

Reformatted

• 17.
The FDK algorithm may be applied to MSCT acquisition data to overcome image artifacts from
• A.

Patient motion

• B.

Beam hardening

• C.

Paartial volume averaging

• D.

Beam divergence

• 18.
The polyenergetic x-ray beam emitted from a cT x-ray tube is susceptible to artifacts due to the phenomenon known as
• A.

Beam hardening

• B.

Density bloom

• C.

Kerma

• D.

Partial volume

• 19.
Daily air or water calibration performed to evaluate which of the following components of image quality
• A.

Contrast resolution

• B.

Temporal resolution

• C.

Uniformity

• D.

Linearity

• 20.
The limiting resolution is determined (MTF) at a pint where the signal frequency corresponding to a particular object has reached
• A.

10%

• B.

20%

• C.

50%

• D.

100%

• 21.
Which of the following is not a part of the ct tube?
• A.

Tungsten target

• B.

Collimator

• C.

Rotating anode

• D.

Filiament

• 22.
X-rays are produced whenever fas-moving electrons collide with any form of matter because
• A.

The electron splits into two-x-ray photons of equal enery up in impact with the matter

• B.

The electron loses kinetic enery which is converted into the emission of an x-ray photon

• C.

The electron converts the electron it collides with in to an xprayphoton

• D.

1 and 2

• E.

2 only

• 23.
Which of th following is FALSE regarding CT systmes
• A.

They are limited to non-oblique transverse scanning

• B.

They cannot generate a straight coronal or sagittal image

• C.

They have no moving parts

• D.

1 and3

• E.

1 2 3

• 24.
Which of the following statements is FALSE regarding 3D SSD
• A.

Helical image data is well suited for 3d ssd because there is minimal misregistration or gaps

• B.

The volume data, from which the 3d ssd is generated, is created by combining transverse, sagittal, and coronal reconstructions

• C.

The tissue surface may be selected by using a threshold value equal to the tissue's ct number

• D.

Patient motion during the scan is detrimental to the quality of th 3d images

• 25.
In which technique are tissues other than the surface of a structure excluded by setting a treshold value and eliminating pixels above or below that threshold
• A.

Volume rendering

• B.

Multi-planar reconstruction

• C.

Maximum intensity projection

• D.

• 26.
Which of the following is TRUE regading the slice thickness of an image reconstructed from a helical scan
• A.

On a multi-row detector scanner, the thickness is equal to the beam collimation

• B.

On a single -row detector scanner, the thickness is equal to the beam collimation

• C.

On a single-row detector scanner, the thickness can be varied retrospectively

• 27.
An increase in ---------does NOT occure in the resulting images when applying a sharp,or high-pass reconstruction filter during the image reconstruction of CT raw data
• A.

Contrast resolution

• B.

Edge enhancement

• C.

The appearance of noise

• 28.
The------determines the intensity of the laser beam in a laser camera
• A.

Intensifying grid

• B.

Pixel values in the image data

• C.

Magnifying power of the lens

• D.

1 and 3

• E.

2 only

• 29.
MDCT scanners capable of collecting 64 slices in a single rotation do NOT
• A.

Perform converntional CT scans

• B.

Perform helical CT scans

• C.

Use filtered back projection as their method of image reconstruction

• D.

Perform localizer scan

• 30.
MIP images
• A.

Are most frequently used for visualizing air-filed spaces

• B.

Can NOT be run in a cine loop

• C.

Are most accurate when a large volume of interest is selected

• D.

Do not demonstrate detail beneath the brightes pixel

• 31.
Which of the following does Not occur when reconstruction FOV is decreased
• A.

Spatial resolution is increased

• B.

Pixel size is increased

• C.

Noise in the image increased

• D.

1 and 2

• E.

2 only

• 32.
A set of images is reconstructed with a 150 mm DFO. Second with a 300 mm DFOV.
• A.

The resolution of the second set of images is better than the firs set

• B.

The apparent noise in the second set more pronounced than the first set

• C.

The patient dose of the first set of images is higher than the second set

• D.

1 and 3

• E.

1 2 3

• 33.
For a given distance of coverage, which of the following is TRUE
• A.

As reconstruction FOV increases, pt dose increases

• B.

As pitch increases, pt dose decreases

• C.

As slice thickness increases, pt dose decreases

• D.

1 and 2

• E.

2 and 3

• 34.
Which of the following intravenous contrast agent administration methods provides the greatest over all plasma iodine concentration
• A.

Drip infusion

• B.

Bolus technique

• C.

Biphasic technique

• D.

CT portography

• 35.
Advantages of a saline flush immediately following the IV administration of iodinated contrast material include
• A.

Reduction in required contrast agent dose

• B.

Reduction in the incidence of contrast-induced nephrotoxicity (CIN)

• C.

Reduction of streaking artifact from dense contrast agent in a vasculature

• D.

3 and 2

• E.

1,2, and 3

• 36.
Radiation exposure and its potentially harmful effects have a relationship that is termed -----in nature
• A.

Stochastic

• B.

Nonstochastic

• C.

Negligible

• D.

Somatic

• 37.
Which of the following types of isolation techniques protects against infection transmitted through fecal material
• A.

Acid-fast bacillus isolation

• B.

Contact isolation

• C.

Enteric precautions

• D.

Drainage-secretion precautions

• 38.
The radiation dose index calculation that takes into account the variations in absorption across the field of view due to beam hardening is termed
• A.

CTDI w

• B.

CTDI100

• C.

CTDI vol

• D.

• 39.
Direct contraindications to the administration of iodinated contrast material include:
• A.

Prior life-threatening reaction to iodinated contrast material

• B.

Multiple myeloma

• C.

Diabetes

• D.

1 only

• E.

1 2 and 3

• 40.
Which of the following units is used to express the total patient dose from helically acquired CT examination
• A.

Roentgens (R)

• B.

Curies

• C.

R-cm

• D.

MGy-cm (milligrays per centimeter)

• 41.
Which of the following technical changes would serve to decrease patient radiation dose during a CT examination?
• A.

Increase in matrix size

• B.

Change from soft tissue to bone algorithm

• C.

Decrease of tube from 360 to 180 degress rotation

• D.

Decrease in DFOV

• 42.
Risk factors for contrast-induced nephrotoxicity (CIN) include:
• A.

Pheochromocytoma

• B.

Allergy to shellfish

• C.

Dehydration

• D.

1 and 2

• E.

3 only

• 43.
The International Normalized Ration (INR) is calculated to standardize which of the following laboratory values?
• A.

PT

• B.

Partial thromboplastin time (PTT)

• C.

Blood urea nitrogen (BUN)

• D.

GFR

• 44.
An intathecal injection prior to a CT examination of the lumber spine places iodinated contrast material directly into the:
• A.

Subarachnoid space

• B.

Dura mater

• C.

Vertebral foramen

• D.

Subdural space

• 45.
The range of serum iodine concentration for adequate tissue opacification during contrast-enhanced CT examinations is
• A.

2-8mg/ml

• B.

12-20 mg/ml

• C.

30-42 mg/ml

• D.

75-105 mg/ml

• 46.
A(n)----------contrast material may be described as one that does not dissociate into charged paticles in solution
• A.

Neutral

• B.

Non-ionic

• C.

Osmolar

• D.

Ionic

• 47.
Effective dose is  a relative radiation dose measurement term that accounts for the
• A.

Beam pitch

• B.

• C.

Detector pitch

• D.

Collimation

• 48.
Urticaria is which of the following
• A.

Severe nausea with associated vomiting

• B.

Urinary tract infection

• C.

Hives

• D.

Bronchospasm

• 49.
Which of the following angiocatheter sizes may be safely used for the automated power injection of iodinated contrast agents at flow rates higher than 3mL/sec
• A.

18-gauge

• B.

20-gauge

• C.

22-gauge

• D.

1 and3

• E.

1 and 2

• 50.
Used in determining the biologic effect of iodinated contrast media, the term________refers to the number of ions formed when a substance dissociated in solution
• A.

Solublility

• B.

Osmolality

• C.

Concentration

• D.

Iodination

• 51.
Compared with single -slice ct patient radiation dose during a multidetector CT study may be higher becasue of
• A.

Use of a cone beam of radiation

• B.

Acquisitions at thinner section witdths

• C.

Higher-powered x-ray tubes

• D.

2 and 3

• E.

1 and 2