Computed Tomography 2 Flashcards

CT scanner equipment

1
Q

What does a CT scanner consist of

A

Gantry = houses the x-ray tube, detectors and generator

X-ray tube which rotates 360 degrees in the axial plane around the patient’s body

Filter = which improve the efficiency of the x-ray beam

Collimators = reduce patient dose and improve image quality

Detectors = arranged in rows rotating in a continuous arch directly opposite the x-ray tube

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2
Q

What features do CT x-ray tubes have to help them dissipate heat quickly?

A
  • High-speed rotors which provide good heat dissipation
  • Direct oil cooling of the anode
  • Scanners are designed to use focal spot cooling algorithms
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3
Q

Where are the collimators in a CT scanner located?

A

Ct scanners have collimators in two positions.
There are pre patient collimators that collimate the x-ray beam at the x-ray tube

There are pre detectors that collimate the x-ray beam after it passes through the patient.

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4
Q

What is the purpose of collimators in CT

A
  • Collimators reduce the radiation dose by limiting the volume of tissue irradiates.
  • They also improve the image contrast by limiting scatter and reducing noise
  • The pre detector collimators provide a contrast beam width on the detectors.
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5
Q

What is the purpose of detectors in CT ?

A

Detectors convert x-ray photons into electrical signals called analog data which is then converted to digital information for computer reconstruction.

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6
Q

What are the ideal properties of a CT detector?

A
  • They should have a high dynamic range to allow the detector to respond to a wide range of X-ray intensities.
  • The detector should be highly efficient so it can capture, absorb and convert x-ray photons to electrical signals
  • The detector should be robust, stable, and have a fast response.
  • The detector should produce little after glow to maintain image quality
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