CT Physics 2 Hhh

51 Questions

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Computed Tomography Quizzes & Trivia

Ct resistry review physichs


Questions and Answers
  • 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. 

      Shaded surface display

    • 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. 

      Scatter radiation

    • B. 

      Patient radiation dose

    • 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. 

      3d shaded surface display

  • 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. 

      MSAD

  • 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. 

      Tissue radiosensitivity

    • 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