Computed Tomography Questions and Correct Answers/ Latest Update / Already Graded

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Computed Tomography Questions and
Correct Answers/ Latest Update /
Already Graded
CT vs X-Ray


Ans: •For both: Radiodensities of body tissues are represented as shades

of gray


•The main difference CT images based on cross-sectional slices.


•Different setup as well




Helical Pattern of Image Acquisition


Ans: •Helical x-ray beam around the patient in tube-> radiation strikes

either stationary or moving detectors -> computer creates a 2 (or 3)-

dimensional image -> post-production enhancement (image can be

recreated in any plane and enhanced contrast of mid grays)




Houndsfield Units

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Ans: Rate density of a substance; A continuum of tissue density expressed

in HU looks similar to an x-ray scale (Air is lowest and Metal is highest).




Gantry


Ans: -contains the x-ray tube, collimator assembly, detectors and data

acquisition system




Collimators


Ans: -apertures through which the x-rays pass (control scatter,

narrow/focus beam of x-rays to determine field of view and determine

slice thickness)




Detectors


Ans: -collect remnant photons not attenuated by body tissues. There can

be up to 1000 detectors surrounding the patient




Data acquisition system