CT Physics 2 Hhh

51 Questions | By Hiw8 | Updated: Mar 21, 2022 | Attempts: 1120

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Ct resistry review physichs

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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.

In the formula used to calculate the linear attenuation coefficient, I=Ioe-ux, the symbol Io identifies:
- 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