CT Physics 2 Hhh
Ct resistry review physichs
- 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
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