CT Physics 2 Hhh

51 Questions | Total Attempts: 415

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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